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Document and Entity Information Document - shares	6 Months Ended
Document and Entity Information Document - shares	Jan. 31, 2018	Feb. 15, 2018
Document Information [Abstract]
Entity Registrant Name	Palo Alto Networks Inc
Entity Central Index Key	0001327567
Document Type	10-Q
Document Period End Date	Jan. 31, 2018
Amendment Flag	false
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q2
Document Fiscal Year End Date	--07-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		91,848,283

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Jan. 31, 2018	Jul. 31, 2017
Current assets:
Cash and cash equivalents	$ 915.0	$ 744.3
Short-term investments	720.7	630.7
Accounts receivable, net of allowance for doubtful accounts of $1.0 and $0.7 at January 31, 2018 and July 31, 2017, respectively	365.1	432.1
Prepaid expenses and other current assets	209.4	169.2
Total current assets	2,210.2	1,976.3
Property and equipment, net	264.7	211.1
Long-term investments	722.3	789.3
Goodwill	238.8	238.8
Intangible assets, net	48.3	53.7
Other assets	143.2	169.1
Total assets	3,627.5	3,438.3
Current liabilities:
Accounts payable	33.4	35.5
Accrued compensation	113.2	117.5
Accrued and other liabilities	83.6	79.9
Deferred revenue	1,088.8	968.4
Convertible senior notes, net	537.4	0.0
Total current liabilities	1,856.4	1,201.3
Convertible senior notes, net	0.0	524.7
Long-term deferred revenue	907.9	805.1
Other long-term liabilities	196.6	147.6
Commitments and contingencies (Note 6)
Temporary equity	33.5	0.0
Stockholders' equity:
Preferred stock; $0.0001 par value; 100.0 shares authorized; none issued and outstanding at January 31, 2018 and July 31, 2017	0.0	0.0
Common stock and additional paid-in capital; $0.0001 par value; 1,000.0 shares authorized; 91.8 and 91.5 shares issued and outstanding at January 31, 2018 and July 31, 2017, respectively	1,575.9	1,599.7
Accumulated other comprehensive loss	(7.2)	(3.4)
Accumulated deficit	(935.6)	(836.7)
Total stockholders’ equity	633.1	759.6
Total liabilities, temporary equity, and stockholders’ equity	$ 3,627.5	$ 3,438.3

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) shares in Millions, $ in Millions	Jan. 31, 2018	Jul. 31, 2017
Current assets:
Allowance for doubtful accounts (in usd)	$ 1.0	$ 0.7
Stockholders' equity:
Preferred stock, par value (in usd per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)	100.0	100.0
Preferred stock, shares issued (in shares)	0.0	0.0
Preferred stock, shares outstanding (in shares)	0.0	0.0
Common stock, par value (in usd per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	1,000.0	1,000.0
Common stock, shares issued (in shares)	91.8	91.5
Common stock, shares outstanding (in shares)	91.8	91.5

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2018	Jan. 31, 2017
Revenue:
Product	$ 202.2	$ 168.8	$ 388.7	$ 332.6
Subscription and support	340.2	253.8	659.2	488.1
Total revenue	542.4	422.6	1,047.9	820.7
Cost of revenue:
Product	63.9	45.8	121.5	88.0
Subscription and support	95.4	67.4	179.2	126.4
Total cost of revenue	159.3	113.2	300.7	214.4
Total gross profit	383.1	309.4	747.2	606.3
Operating expenses:
Research and development	96.6	89.9	190.8	174.1
Sales and marketing	265.0	226.7	523.5	446.8
General and administrative	53.3	47.2	119.0	88.8
Total operating expenses	414.9	363.8	833.3	709.7
Operating loss	(31.8)	(54.4)	(86.1)	(103.4)
Interest expense	(6.4)	(6.1)	(12.7)	(12.1)
Other income, net	4.9	2.7	9.7	5.2
Loss before income taxes	(33.3)	(57.8)	(89.1)	(110.3)
Provision for income taxes	1.6	2.8	9.8	7.2
Net loss	$ (34.9)	$ (60.6)	$ (98.9)	$ (117.5)
Net loss per share, basic and diluted	$ (0.38)	$ (0.67)	$ (1.09)	$ (1.30)
Weighted-average shares used to compute net loss per share, basic and diluted	91.1	90.7	91.0	90.2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2018	Jan. 31, 2017
Net loss	$ (34.9)	$ (60.6)	$ (98.9)	$ (117.5)
Other comprehensive loss, net of tax:
Change in unrealized gains (losses) on investments	(5.3)	(2.9)	(7.2)	(4.7)
Change in unrealized gains (losses) on cash flow hedges	5.1	(0.3)	3.4	(1.4)
Other comprehensive loss	(0.2)	(3.2)	(3.8)	(6.1)
Comprehensive loss	$ (35.1)	$ (63.8)	$ (102.7)	$ (123.6)

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	6 Months Ended
	Jan. 31, 2018	Jan. 31, 2017
Cash flows from operating activities
Net loss	$ (98.9)	$ (117.5)
Adjustments to reconcile net loss to net cash provided by operating activities:
Share-based compensation for equity based awards	256.5	240.6
Depreciation and amortization	43.4	28.0
Cease-use loss related to facility exit	16.7	0.0
Amortization of debt discount and debt issuance costs	12.7	12.1
Amortization of investment premiums, net of accretion of purchase discounts	0.6	1.4
Changes in operating assets and liabilities:
Accounts receivable, net	67.0	(37.3)
Prepaid expenses and other assets	(39.0)	(3.8)
Accounts payable	(6.4)	0.2
Accrued compensation	(4.3)	5.3
Accrued and other liabilities	46.3	31.0
Deferred revenue	223.2	257.8
Net cash provided by operating activities	517.8	417.8
Cash flows from investing activities
Purchases of investments	(372.5)	(562.7)
Proceeds from maturities of investments	341.8	384.0
Purchases of property, equipment, and other assets	(57.8)	(65.6)
Net cash used in investing activities	(88.5)	(244.3)
Cash flows from financing activities
Repurchases of common stock	(259.1)	(170.1)
Proceeds from sales of shares through employee equity incentive plans	23.4	23.6
Payments for taxes related to net share settlement of equity awards	(22.9)	0.0
Net cash used in financing activities	(258.6)	(146.5)
Net increase in cash and cash equivalents	170.7	27.0
Cash and cash equivalents—beginning of period	744.3	734.4
Cash and cash equivalents—end of period	915.0	761.4
Non-cash investing and financing activities
Property and equipment acquired through lease incentives	$ 37.8	$ 0.0

Description of Business, Basis of Presentation, Principles of Consolidation, and Summary of Significant Accounting Policies (Notes)

6 Months Ended

Jan. 31, 2018

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Description of business, basis of presentation, principles of consolidation, and summary of significant accounting policies

Description of Business and Summary of Significant Accounting Policies

Description of Business

Palo Alto Networks, Inc. (the “Company,” “we,” “us,” or “our”), located in Santa Clara, California, was incorporated in March 2005 under the laws of the State of Delaware and commenced operations in April 2005. We offer a next-generation security platform that empowers enterprises, service providers, and government entities to secure their organizations by safely enabling applications running on their networks and by preventing breaches that stem from targeted cyberattacks.

Basis of Presentation and Principles of Consolidation

The accompanying condensed consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (“GAAP”), consistent in all material respects with those applied in our Annual Report on Form 10-K for the fiscal year ended July 31, 2017, filed with the Securities and Exchange Commission (“SEC”) on September 7, 2017. Our condensed consolidated financial statements include our accounts and our wholly owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation.

Our condensed consolidated financial statements are unaudited, but include all adjustments of a normal recurring nature necessary for a fair presentation of our quarterly results. We have made estimates and judgments affecting the amounts reported in our condensed consolidated financial statements and the accompanying notes. The actual results that we experience may differ materially from our estimates. Certain prior-period amounts have been reclassified to conform to current-period presentation.

Our condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and related notes in our Annual Report on Form 10-K for the fiscal year ended July 31, 2017.

Summary of Significant Accounting Policies

There have been no material changes to our significant accounting policies as of and for the six months ended January 31, 2018, as compared to the significant accounting policies described in our Annual Report on Form 10-K for the fiscal year ended July 31, 2017.

Recently Adopted Accounting Pronouncements

Derivatives and Hedging

In August 2017, the Financial Accounting Standards Board (“FASB”) issued new authoritative guidance on derivatives and hedging to better align an entity’s risk management activities and financial reporting for hedging relationships through changes to both the designation and measurement guidance for qualifying hedging relationships, and the presentation of hedge results. We early adopted the standard in our second quarter of fiscal 2018 on a modified retrospective basis. The adoption of this standard did not have a material impact on our condensed consolidated financial statements.

Recently Issued Accounting Pronouncements

Business Combinations - Definition of a Business

In January 2017, the FASB issued authoritative guidance clarifying the definition of a business to assist companies with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The standard is effective for us in our first quarter of fiscal 2019 and will be applied on a prospective basis. Early adoption is permitted. We do not expect the adoption of the standard will have a material impact on our condensed consolidated financial statements.

Statement of Cash Flows - Restricted Cash

In November 2016, the FASB issued authoritative guidance on the presentation of restricted cash or restricted cash equivalents in the statement of cash flows. Under the new standard, restricted cash or restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. The standard is effective for us in our first quarter of fiscal 2019 and will be applied on a retrospective basis. Early adoption is permitted. We do not expect the adoption of the standard will have a material impact on our condensed consolidated financial statements because our restricted cash balance has not been material.

Income Taxes - Intra-Entity Asset Transfers

In October 2016, the FASB issued authoritative guidance requiring the recognition of income tax consequences of an intra-entity transfer of an asset, other than inventory, when the transfer occurs. The standard is effective for us in our first quarter of fiscal 2019 and will be applied on a modified retrospective basis. Early adoption is permitted. We plan to adopt the standard in our first quarter of fiscal 2019. The adoption of this standard may have a material impact on our condensed consolidated financial statements, subject to any potential intra-entity transfers of assets (excluding inventory) and additional guidance and interpretations issued by U.S. regulatory and standard-setting bodies related to the Tax Cuts and Jobs Act (“TCJA”) enacted into law on December 22, 2017. Refer to Note 9. Income Taxes for more information on the TCJA.

Statement of Cash Flows - Classification of Certain Cash Receipts and Cash Payments

In August 2016, the FASB issued new authoritative guidance addressing eight specific cash flow issues with the objective of reducing the existing diversity in practice in how certain transactions are presented and classified in the statement of cash flows. The standard is effective for us in our first quarter of fiscal 2019 and will be applied on a retrospective basis. Early adoption is permitted. We do not expect the adoption of the standard will have a material impact on our condensed consolidated financial statements.

Financial Instruments - Credit Losses

In June 2016, the FASB issued new authoritative guidance on the accounting for credit losses on most financial assets and certain financial instruments. The standard replaces the existing incurred loss model with an expected credit loss model for financial assets measured at amortized cost, including trade receivables, and requires that credit losses on available-for-sale debt securities be presented as an allowance rather than as a write-down. The standard is effective for us in our first quarter of fiscal 2021 and will be applied on a modified retrospective basis. Early adoption is permitted beginning our first quarter of fiscal 2020. We are currently evaluating whether this standard will have a material impact on our condensed consolidated financial statements.

Leases

In February 2016, the FASB issued new authoritative guidance on lease accounting. Among its provisions, the standard requires lessees to recognize right-of-use assets and lease liabilities on the balance sheet for operating leases and also requires additional qualitative and quantitative disclosures about lease arrangements. The standard is effective for us in our first quarter of fiscal 2020 and will be applied on a modified retrospective basis, with the option to elect certain practical expedients. Early adoption is permitted. We are currently evaluating whether this standard will have a material impact on our condensed consolidated financial statements.

Revenue Recognition

In May 2014, the FASB issued new authoritative guidance on revenue from contracts with customers. The new standard provides principles for recognizing revenue for the transfer of promised goods or services to customers with the consideration to which the entity expects to be entitled in exchange for those goods or services, as well as guidance on the recognition of costs related to obtaining and fulfilling customer contracts. The standard also requires expanded disclosures about the nature, amount, timing, and uncertainty of revenues and cash flows arising from customer contracts, including significant judgments and changes in judgments, and assets recognized from costs incurred to obtain or fulfill a contract. The standard is effective for us in our first quarter of fiscal 2019 using either of two methods: (i) retrospective to each prior reporting period presented with the option to elect certain practical expedients as defined within the guidance (“full retrospective method”); or (ii) retrospective with the cumulative effect of initially applying the guidance recognized at the date of initial application and providing certain additional disclosures as defined per the guidance (“modified retrospective method”).

We will adopt the standard in our first quarter of fiscal 2019 using the full retrospective method. However, our ability to apply the full retrospective method is dependent on system readiness and the completion of our analysis of information necessary to restate prior-period financial statements.

We are continuing to evaluate the impact of the new standard on our accounting policies, processes, internal controls over financial reporting, and system requirements, and have assigned cross-functional internal resources and engaged third-party service providers to assist in our evaluation and system implementation. Furthermore, we have made and will continue to make investments in systems to enable timely and accurate reporting under the new standard.

We are also continuing to evaluate the impact the standard will have on our condensed consolidated financial statements, including reviewing the provisions of our customer contracts and identifying performance obligations under the requirements of the new standard, and comparing to our current accounting policies and practices. Although we have not yet determined whether the effect will be material, we believe the new standard will impact our accounting for revenue arrangements in the following areas:


•	removal of the current limitation on contingent revenue may result in revenue being recognized earlier for certain contracts;


•	term license revenue associated with our virtual firewalls will be recognized upfront;


•	allocation of revenue related to software due to the removal of the residual method of revenue recognition; and


•	amortization period for deferred commissions.

We will continue to assess the new standard along with industry trends and additional interpretive guidance, and may adjust our implementation plan accordingly.

Fair Value Measurements (Notes)

6 Months Ended

Jan. 31, 2018

Fair Value Disclosures [Abstract]

Fair value measurements

Fair Value Measurements

We categorize assets and liabilities recorded or disclosed at fair value on our condensed consolidated balance sheets based upon the level of judgment associated with inputs used to measure their fair value. The categories are as follows:


•	Level 1—Inputs are unadjusted quoted prices in active markets for identical assets or liabilities.


•	Level 2—Inputs are quoted prices for similar assets and liabilities in active markets or inputs that are observable for the assets or liabilities, either directly or indirectly through market corroboration, for substantially the full term of the financial instruments.


•	Level 3—Inputs are unobservable inputs based on our own assumptions used to measure assets and liabilities at fair value. The inputs require significant management judgment or estimation.

The following table presents the fair value of our financial assets and liabilities measured at fair value on a recurring basis using the above input categories as of January 31, 2018 and July 31, 2017 (in millions):



	January 31, 2018								July 31, 2017
	Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	325.7	$	—	$	—	$	325.7	$	—	$	—	$	—	$	—
U.S. government and agency securities	—		3.5		—		3.5		—		—		—		—
Total cash equivalents	325.7		3.5		—		329.2		—		—		—		—
Short-term investments:
Certificates of deposit	—		5.4		—		5.4		—		—		—		—
Corporate debt securities	—		183.3		—		183.3		—		159.4		—		159.4
U.S. government and agency securities	—		532.0		—		532.0		—		471.3		—		471.3
Total short-term investments	—		720.7		—		720.7		—		630.7		—		630.7
Prepaid expenses and other current assets:
Foreign currency forward contracts	—		4.7		—		4.7		—		—		—		—
Total prepaid expenses and other current assets	—		4.7		—		4.7		—		—		—		—
Long-term investments:
Certificates of deposit	—		—		—		—		—		5.4		—		5.4
Corporate debt securities	—		166.8		—		166.8		—		186.5		—		186.5
U.S. government and agency securities	—		555.5		—		555.5		—		597.4		—		597.4
Total long-term investments	—		722.3		—		722.3		—		789.3		—		789.3
Total assets measured at fair value	$	325.7	$	1,451.2	$	—	$	1,776.9	$	—	$	1,420.0	$	—	$	1,420.0

Accrued and other liabilities:
Foreign currency forward contracts	$	—	$	0.1	$	—	$	0.1	$	—	$	—	$	—	$	—
Total accrued and other liabilities	—		0.1		—		0.1		—		—		—		—
Total liabilities measured at fair value	$	—	$	0.1	$	—	$	0.1	$	—	$	—	$	—	$	—

As of January 31, 2018, we did not have any assets required to be measured at fair value on a nonrecurring basis. As of July 31, 2017, we determined that certain property and equipment related to our prior corporate headquarters were impaired. In connection with our planned relocation to our new corporate headquarters, we assessed the recoverability of certain leasehold improvements and other long-lived assets associated with our previous headquarter facilities and determined that the carrying amount of these assets exceeded their fair value of $4.2 million. The resulting impairment loss of $20.9 million was recorded as general and administrative expense in our consolidated statements of operations during the fiscal year ended July 31, 2017. We calculated the fair value of the leasehold improvements and other long-lived assets based on estimated future discounted cash flows and classified the fair value as a Level 3 measurement due to the significance of unobservable inputs, which included the amount and timing of estimated sublease rental receipts that we could reasonably obtain over the remaining lease term and the discount rate. We did not have any liabilities required to be measured at fair value on a nonrecurring basis as of January 31, 2018 and July 31, 2017.

Refer to Note 5. Convertible Senior Notes for the carrying amount and estimated fair value of our convertible senior notes as of January 31, 2018 and July 31, 2017.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Cash Equivalents and Investments (Notes)

6 Months Ended

Jan. 31, 2018

Investments, Debt and Equity Securities [Abstract]

Cash equivalents and investments

Cash Equivalents and Investments

The following tables summarize the amortized cost, unrealized gains and losses, and fair value of our available-for-sale securities as of January 31, 2018 and July 31, 2017 (in millions):



	January 31, 2018
	Amortized Cost		Unrealized Gains		Unrealized Losses			Estimated Fair Value
Cash equivalents:
Money market funds	$	325.7	$	—	$	—		$	325.7
U.S. government and agency securities	3.5		—		—			3.5
Total cash equivalents	$	329.2	$	—	$	—		$	329.2

Investments:
Certificates of deposit	$	5.4	$	—	$	—		$	5.4
Corporate debt securities	352.1		0.1		(2.1		)	350.1
U.S. government and agency securities	1,095.4		—		(7.9		)	1,087.5
Total investments	$	1,452.9	$	0.1	$	(10.0	)	$	1,443.0



	July 31, 2017
	Amortized Cost		Unrealized Gains		Unrealized Losses			Estimated Fair Value
Investments:
Certificates of deposit	$	5.4	$	—	$	—		$	5.4
Corporate debt securities	346.1		0.3		(0.5		)	345.9
U.S. government and agency securities	1,071.2		0.1		(2.6		)	1,068.7
Total investments	$	1,422.7	$	0.4	$	(3.1	)	$	1,420.0

Unrealized losses related to these securities are due to interest rate fluctuations as opposed to credit quality. In addition, we do not intend to sell and it is not likely that we would be required to sell these securities before recovery of their amortized cost basis, which may be at maturity. As a result, there were no other-than-temporary impairments for these securities at January 31, 2018 and July 31, 2017.

The following table summarizes the amortized cost and fair value of our available-for-sale securities as of January 31, 2018, by contractual years-to-maturity (in millions):



	Amortized Cost		Fair Value
Due within one year	$	1,052.1	$	1,049.9
Due between one and three years	730.0		722.3
Total	$	1,782.1	$	1,772.2

- Definition

The entire disclosure for investments in certain debt and equity securities.

+ References + Details

Derivative Instruments (Notes)	6 Months Ended
Derivative Instruments (Notes)	Jan. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative instruments	Derivative Instruments As a global business, we are exposed to currency exchange rate risk. Substantially all of our revenue is transacted in U.S. dollars, however, a portion of our operating expenditures are incurred outside of the United States and are denominated in foreign currencies, making them subject to fluctuations in foreign currency exchange rates. We enter into foreign currency derivative contracts with maturities of 13 months or less which we designate as cash flow hedges to manage the foreign currency exchange rate risk associated with these expenditures. These derivative contracts expose us to credit risk to the extent that the counterparties may be unable to meet the terms of the arrangement. We mitigate this credit risk by transacting with major financial institutions with high credit ratings and also enter into master netting arrangements, which permit net settlement of transactions with the same counterparty. We are not required to pledge, and are not entitled to receive, cash collateral related to these derivative instruments. We do not enter into derivative contracts for trading or speculative purposes. Our derivative financial instruments are recorded at fair value, on a gross basis, as either assets or liabilities in our condensed consolidated balance sheets. Gains or losses related to our cash flow hedges are recorded as a component of accumulated other comprehensive income (loss) (“AOCI”) in our condensed consolidated balance sheets and are reclassified into the financial statement line item associated with the underlying hedged transaction in our condensed consolidated statements of operations when the underlying hedged transaction is recognized in earnings. If it becomes probable that the hedged transaction will not occur, the cumulative unrealized gain or loss is reclassified immediately from AOCI into the financial statement line item associated with the underlying hedged transaction in our condensed consolidated statements of operations. Gains or losses related to non-designated derivative instruments are recognized in other income (expense), net in our condensed consolidated statements of operations for each period until the instrument matures, is terminated, is re-designated as a qualified cash flow hedge, or is sold. Derivatives designated as cash flow hedges are classified in our condensed consolidated statements of cash flows in the same manner as the underlying hedged transaction, primarily within cash flows from operating activities. As of January 31, 2018, the total notional amount of our outstanding foreign currency forward contracts was $149.4 million. We did not have any forward contracts outstanding as of July 31, 2017. Refer to Note 2. Fair Value Measurements for the fair value of our derivative instruments as reported in our condensed consolidated balance sheets as of January 31, 2018. During the three and six months ended January 31, 2018 and 2017, both unrealized gains (losses) recognized in AOCI related to our cash flow hedges and amounts reclassified into earnings were not material. Total unrealized gains (losses) in AOCI related to our cash flow hedges as of January 31, 2018 and 2017 were not material.

- Definition

The entire disclosure for derivative instruments and hedging activities including, but not limited to, risk management strategies, non-hedging derivative instruments, assets, liabilities, revenue and expenses, and methodologies and assumptions used in determining the amounts.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6441202&loc=d3e80720-113993

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5624171-113959

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=64837297&loc=d3e41620-113959

Reference 4: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5624163-113959

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5579240-113959

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
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-Section 50
-Paragraph 4D
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5624177-113959

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 30
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=35736893&loc=d3e80784-113994

Reference 8: http://www.xbrl.org/2003/role/presentationRef
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+ Details

Convertible Senior Notes (Notes)

6 Months Ended

Jan. 31, 2018

Debt Disclosure [Abstract]

Convertible senior notes

Convertible Senior Notes

On June 30, 2014, we issued $575.0 million aggregate principal amount of 0.0% Convertible Senior Notes due 2019 (the “Notes”). The Notes mature on July 1, 2019 unless converted or repurchased in accordance with their terms prior to such date. The Notes do not contain any financial covenants and we cannot redeem the Notes prior to maturity.

The Notes are convertible for up to 5.2 million shares of our common stock at an initial conversion price of approximately $110.28 per share of common stock, subject to adjustment. Holders of the Notes may surrender their Notes for conversion at their option at any time prior to the close of business on the business day immediately preceding January 1, 2019, only under the following circumstances:

•

during any fiscal quarter commencing after the fiscal quarter ending on October 31, 2014 (and only during such fiscal quarter), if the last reported sale price of our common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on the last trading day of the immediately preceding fiscal quarter is greater than or equal to 130% of the conversion price for the Notes on each applicable trading day (the “sale price condition”);


•	during the five business day period after any five consecutive trading day period, in which the trading price per $1,000 principal amount of Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of our common stock and the conversion rate for the Notes on each such trading day; or


•	upon the occurrence of specified corporate events.

On or after January 1, 2019, holders may convert all or any portion of their Notes at any time prior to the close of business on the second scheduled trading day immediately preceding the maturity date regardless of the foregoing conditions. Upon conversion, holders will receive cash equal to the aggregate principal amount of the Notes to be converted, and, at our election, cash and/or shares of our common stock for any amounts in excess of the aggregate principal amount of the Notes being converted. As of January 31, 2018, all of the Notes remained outstanding.

The sale price condition was met during the fiscal quarter ended January 31, 2018, and as a result, holders may convert their Notes at any time during the fiscal quarter ending April 30, 2018. Accordingly, the net carrying amount of the Notes was reclassified into current liabilities and the portion of the equity component representing the conversion option was reclassified into temporary equity in our condensed consolidated balance sheets as of January 31, 2018. The portion of the equity component classified as temporary equity is measured as the difference between the principal and net carrying amount of the Notes, excluding debt issuance costs. The sale price condition was not met during the fiscal quarter ended July 31, 2017. Since the Notes were not convertible, the net carrying amount of the Notes was classified as a long-term liability and the equity component was included in additional paid-in capital in our condensed consolidated balance sheets as of July 31, 2017.

The following table sets forth the components of the Notes as of January 31, 2018 and July 31, 2017 (in millions):



	January 31, 2018		July 31, 2017
Liability:
Principal	$	575.0	$	575.0
Less: debt discount and debt issuance costs, net of amortization	37.6		50.3
Net carrying amount	$	537.4	$	524.7

Equity (including temporary equity)	$	109.8	$	109.8

The total estimated fair value of the Notes was $839.6 million and $747.5 million at January 31, 2018 and July 31, 2017, respectively. The fair value was determined based on the closing trading price per $100 of the Notes as of the last day of trading for the period. We consider the fair value of the Notes at January 31, 2018 and July 31, 2017 to be a Level 2 measurement. The fair value of the Notes is primarily affected by the trading price of our common stock and market interest rates. As of January 31, 2018, the if-converted value of the Notes exceeded its principal amount by $218.2 million.

The following table sets forth interest expense recognized related to the Notes (dollars in millions):



	Three Months Ended						Six Months Ended
	January 31,						January 31,
	2018			2017			2018			2017
Amortization of debt discount	$	5.8		$	5.5		$	11.4		$	10.9
Amortization of debt issuance costs	0.6			0.6			1.3			1.2
Total interest expense recognized	$	6.4		$	6.1		$	12.7		$	12.1

Effective interest rate of the liability component	4.8		%	4.8		%	4.8		%	4.8		%

Note Hedges

To minimize the impact of potential economic dilution upon conversion of the Notes, we entered into convertible note hedge transactions (the “Note Hedges”) with respect to our common stock concurrent with the issuance of the Notes. The Note Hedges cover up to 5.2 million shares of our common stock at a strike price per share that corresponds to the initial conversion price of the Notes, which are also subject to adjustment, and are exercisable upon conversion of the Notes. The Note Hedges will expire upon maturity of the Notes. The Note Hedges are separate transactions and are not part of the terms of the Notes. Holders of the Notes will not have any rights with respect to the Note Hedges. The shares receivable related to the Note Hedges are excluded from the calculation of diluted earnings per share as they are antidilutive.

Warrants

Separately, but concurrently with our issuance of the Notes, we entered into transactions whereby we sold warrants (the “Warrants”) to acquire up to 5.2 million shares of our common stock at a strike price of approximately $137.85 per share, subject to adjustments. The shares issuable under the Warrants will be included in the calculation of diluted earnings per share when the average market value per share of our common stock for the reporting period exceeds the strike price of the Warrants. The Warrants are separate transactions and are not part of the Notes or Note Hedges, and are not remeasured through earnings each reporting period. Holders of the Notes and Note Hedges will not have any rights with respect to the Warrants.

For more information on the Notes, the Note Hedges, and the Warrants, refer to Note 8. Convertible Senior Notes included in Part II, Item 8 of our Annual Report on Form 10-K for the fiscal year ended July 31, 2017.

Commitments and Contingencies (Notes)

6 Months Ended

Jan. 31, 2018

Commitments and Contingencies Disclosure [Abstract]

Commitments and contingencies

Commitments and Contingencies

Leases

We lease our facilities under various non-cancelable operating leases, which expire through the year ending July 31, 2028.

In May 2015 and October 2015, we entered into a total of three lease agreements for approximately 941,000 square feet of corporate office space in Santa Clara, California, which serves as our new corporate headquarters. The leases contain rent holiday periods, scheduled rent increases, lease incentives, and renewal options which allow the lease terms to be extended beyond their expiration dates of July 2028 through July 2046. In September 2017, per the terms of the lease agreements, the landlords exercised their option to amend our lease payment schedules and eliminate our rent holiday periods, which increased our rental payments by $24.4 million, $11.8 million, and $2.0 million for fiscal 2018, 2019, and 2020, respectively. In exchange, we received an upfront cash reimbursement of $38.2 million during the three months ended October 31, 2017, which we will apply against the future additional rental payments when due. As amended, rental payments under the three lease agreements are approximately $412.0 million over the lease terms.

In May 2015, we also entered into a lease agreement for approximately 122,000 square feet of space in Santa Clara, California, to serve as an extension of our previous corporate headquarters. The lease contains scheduled rent increases, lease incentives, and renewal options which allow the lease term to be extended beyond the expiration date of April 2021 through July 2046. Rental payments under the lease agreement are approximately $23.1 million over the lease term. In December 2017, we entered into an agreement to sublease this office space for the remaining lease term. Proceeds from this sublease will be approximately $16.3 million over the sublease term.

In September 2012, we entered into two lease agreements for a total of approximately 300,000 square feet of space in Santa Clara, California, which served as our previous corporate headquarters through August 2017, when we relocated to our new corporate campus. The leases contain rent holiday periods and two separate five-year options to extend the lease terms beyond their expiration dates of July 2023. Rental payments under these lease agreements are approximately $94.3 million over the lease term. In August 2017, we exited our previous headquarter facilities and relocated to our new corporate campus, which resulted in the recognition of a cease-use loss of $15.4 million as general administrative expense in our condensed consolidated statements of operations during the three months ended October 31, 2017, and a corresponding liability in our condensed consolidated balance sheets. The cease-use loss of $15.4 million was calculated as the present value of the excess of the remaining lease obligation for the vacated facilities, adjusted for the effects of any deferred items recognized under the leases and related costs, over the estimated sublease rentals that could be reasonably obtained. The amount of the cease-use loss may vary if the timing or amount of estimated cash flows change. During the three and six months ended January 31, 2018, we released $2.7 million and $4.6 million, respectively, of the cease-use liability through rental payments. As of January 31, 2018, the remaining balance of the cease-use liability was $10.8 million, which is expected to be paid through the end of the lease term in July 2023.

The following table presents details of the aggregate future non-cancelable minimum rental payments under our operating leases as of January 31, 2018 (in millions):



	Amount
Fiscal years ending July 31:
Remaining 2018	$	32.1
2019	65.8
2020	66.1
2021	60.2
2022	56.8
2023 and thereafter	267.9
Committed gross lease payments	548.9
Less: proceeds from sublease rentals	15.4
Net operating lease obligation	$	533.5

Manufacturing Purchase Commitments

Our electronics manufacturing service provider (“EMS provider”) procures components and assembles our products based on our forecasts. These forecasts are based on estimates of demand for our products primarily for the next 12 months, which are in turn based on historical trends and an analysis from our sales and product management organizations, adjusted for overall market conditions. In order to reduce manufacturing lead times and plan for adequate supply, we may issue non-cancelable orders for products and components to our manufacturing partners or component suppliers. As of January 31, 2018, our purchase commitments under such orders were $121.5 million, excluding obligations under contracts that we can cancel without a significant penalty.

Litigation

We are subject to legal proceedings, claims, and litigation arising in the ordinary course of business, including intellectual property litigation. Such matters are subject to many uncertainties and outcomes are not predictable with assurance. We accrue for contingencies when we believe that a loss is probable and that we can reasonably estimate the amount of any such loss.

To the extent there is a reasonable possibility that a loss exceeding amounts already recognized may be incurred and the amount of such additional loss would be material, we will either disclose the estimated additional loss or state that such an estimate cannot be made. As of January 31, 2018, we have not recorded any significant accruals for loss contingencies associated with such legal proceedings, determined that an unfavorable outcome is probable or reasonably possible, or determined that the amount or range of any possible loss is reasonably estimable.

Stockholders' Equity (Notes)	6 Months Ended
Stockholders' Equity (Notes)	Jan. 31, 2018
Equity [Abstract]
Stockholders’ equity	Stockholders’ Equity Share Repurchase In August 2016, our board of directors authorized a $500.0 million share repurchase that is funded from available working capital. In February 2017, our board of directors authorized a $500.0 million increase to our repurchase program, bringing the total authorization to $1.0 billion. Repurchases may be made at management’s discretion from time to time on the open market, through privately negotiated transactions, transactions structured through investment banking institutions, block purchase techniques, 10b5-1 trading plans, or a combination of the foregoing. The repurchase authorization will expire on December 31, 2018, and may be suspended or discontinued at any time. During the three and six months ended January 31, 2018, we repurchased and retired 0.9 million and 1.7 million shares, respectively, of our common stock under the authorization for an aggregate purchase price of $125.0 million and $250.0 million, respectively, including transaction costs. The total price of the shares repurchased and related transaction costs are reflected as a reduction to common stock and additional paid-in capital on our condensed consolidated balance sheets. As of January 31, 2018, $330.0 million remained available for future share repurchases under the repurchase authorization.

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

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+ Details

Equity Award Plans (Notes)

6 Months Ended

Jan. 31, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Equity award plans

Equity Award Plans

2012 Employee Stock Purchase Plan

Our 2012 Employee Stock Purchase Plan was adopted by our board of directors and approved by the stockholders on June 5, 2012, and was effective upon completion of our initial public offering (“IPO”). On August 29, 2017, we amended and restated our 2012 Employee Stock Purchase Plan (our “2012 ESPP”) to extend the length of our offering periods from six to 24 months. Under our 2012 ESPP, each 24-month offering period consists of four consecutive six-month purchase periods, with purchase dates on the first trading day on or after February 28 and August 31 of each year. Our 2012 ESPP permits eligible employees to acquire shares of our common stock at 85% of the lower of the fair market value of our common stock on the first trading day of each offering period or on the purchase date. If the fair market value of our common stock on the purchase date is lower than the first trading day of the offering period, the current offering period will be cancelled after purchase and a new 24-month offering period will begin. Participants may purchase shares of common stock through payroll deductions of up to 15% of their eligible compensation, subject to purchase limits of 625 shares per six-month purchase period and $25,000 worth of stock for each calendar year.

Stock Option Activities

The following table summarizes the stock option activity under our stock plans during the reporting period (in millions, except per share amounts):



	Options Outstanding
	Number of Shares		Weighted-Average Exercise Price Per Share		Weighted-Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value
Balance—July 31, 2017	1.6		$	13.11	4.2	$	190.6
Options granted	—		$	—
Options forfeited	—		$	—
Options exercised	(0.2	)	$	11.11
Balance—January 31, 2018	1.4		$	13.41	3.8	$	201.5
Options exercisable—January 31, 2018	1.4		$	13.41	3.8	$	201.5

Restricted Stock Award (“RSA”), Performance-Based Stock Award (“PSA”), Restricted Stock Unit (“RSU”), and Performance-Based Stock Unit (“PSU”) Activities

Our PSAs and PSUs vest over a period of four years from the date of grant. The actual number of PSAs and PSUs earned and eligible to vest are determined based on level of achievement against a pre-established billings target for the fiscal year in which the awards are granted. We recognize share-based compensation expense for our PSAs and PSUs on a straight-line basis over the requisite service period for each separately vesting portion of the award when it is probable that the performance condition will be achieved.

The following table summarizes the RSA, PSA, RSU, and PSU activity under our stock plans during the reporting period (in millions, except per share amounts):



	RSAs and PSAs Outstanding				RSUs and PSUs Outstanding
	Number of Shares		Weighted-Average Grant-Date Fair Value Per Share		Number of Shares		Weighted-Average Grant-Date Fair Value Per Share		Weighted-Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value
Balance—July 31, 2017	1.0		$	163.55	6.5		$	141.16	1.3	$	854.1
Granted⁽¹⁾	—		$	—	2.4		$	146.94
Vested	(0.2	)	$	167.69	(1.9	)	$	136.33
Forfeited	(0.2	)	$	156.56	(0.4	)	$	142.34
Balance—January 31, 2018	0.6		$	164.01	6.6		$	144.59	1.5	$	1,040.7

______________


(1)	For PSAs and PSUs, shares granted represents the aggregate maximum number of shares that may be earned and issued with respect to these awards over their full terms.

Share-Based Compensation

The following table summarizes share-based compensation included in costs and expenses (in millions):



	Three Months Ended				Six Months Ended
	January 31,				January 31,
	2018		2017		2018		2017
Cost of product revenue	$	1.9	$	2.0	$	3.8	$	3.7
Cost of subscription and support revenue	19.9		15.0		35.8		27.3
Research and development	35.5		41.3		73.0		79.3
Sales and marketing	53.3		49.7		104.5		93.5
General and administrative	20.2		19.3		39.4		36.8
Total share-based compensation	$	130.8	$	127.3	$	256.5	$	240.6

As of January 31, 2018, total compensation cost related to unvested share-based awards not yet recognized was $976.2 million. This cost is expected to be amortized on a straight-line basis over a weighted-average period of approximately 2.7 years.

- Definition

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.

+ References + Details

Income Taxes (Notes)	6 Months Ended
Income Taxes (Notes)	Jan. 31, 2018
Income Tax Disclosure [Abstract]
Income taxes	Income Taxes Our provision for income taxes for the three and six months ended January 31, 2018 reflects an effective tax rate of (4.8)% and (11.0)%, respectively. Our effective tax rates for these periods were negative as we recorded a provision for income taxes on year to date losses. The key components of our income tax provision primarily consist of foreign income taxes, withholding taxes, amortization of our deferred tax charges, and a one-time tax benefit during the three months ended January 31, 2018, resulting from new tax legislation enacted during the period. Our effective tax rate differs from the U.S. statutory tax rate primarily due to changes in non-deductible share-based compensation, foreign income at other than U.S. tax rates, and changes in our valuation allowance. Our provision for income taxes for the three and six months ended January 31, 2017 reflects an effective tax rate of (4.8)% and (6.5)%, respectively. Our effective tax rates for these periods were negative as we recorded a provision for income taxes on year to date losses. The key components of our income tax provision primarily consisted of foreign income taxes, withholding taxes, and amortization of our deferred tax charges. On December 22, 2017, the TCJA was enacted into law. The TCJA provides for significant tax law changes and modifications including, but not limited to, the reduction of the U.S. federal corporate statutory tax rate from 35% to 21% as of January 1, 2018, the requirement for companies to pay a one-time transition tax on earnings of certain foreign subsidiaries that were previously tax deferred, and the creation of new taxes on certain foreign-sourced earnings. As a fiscal year-end taxpayer, certain provisions of the TCJA began to impact us during the three months ended January 31, 2018, while other provisions will impact us beginning in our fiscal year ending July 31, 2019. As a result of the TCJA, we recorded a one-time provisional benefit of $6.2 million for the three months ended January 31, 2018, relating to alternative minimum tax credits that will be refundable if not utilized. We expect adjustments to our deferred tax assets resulting from the TCJA to be offset by a corresponding adjustment to our valuation allowance. We have not recorded any amounts relating to the transition tax because we had no unremitted earnings as of the measurement date, based on our current estimate. Accounting standards require companies to recognize the effect of tax law changes in the period of enactment. However, the SEC staff issued guidance which will allow companies to record provisional amounts during a measurement period not to extend beyond one year from the enactment date. In accordance with the guidance, we have determined the amounts recorded and positions taken, as discussed, are provisional as of January 31, 2018. The final impact of the TCJA recorded by us may differ from the provisional amounts due to a number of uncertainties and factors, including information not available until the close of our fiscal year ending July 31, 2018, the need for further guidance and clarification of the new law by U.S. federal and state tax authorities, and the need for further guidance on the related income tax accounting. In addition to the previously discussed impacts on our fiscal year ending January 31, 2018, the TCJA also establishes new tax laws that will be effective beginning with our fiscal year ending July 31, 2019, including a provision for low-taxed income of foreign subsidiaries. Due to its complexity, we are continuing to evaluate this provision of the TCJA. Based on recent FASB deliberations, we will be allowed to make an accounting policy election to either (i) treat taxes due on future U.S. inclusions in taxable income as a current-period expense when incurred or (ii) factor such amounts into our measurement of deferred taxes. Our selection of accounting policy will depend, in part, on analyzing our facts and circumstances to determine the expected impact under each method.

Net Loss Per Share (Notes)

6 Months Ended

Jan. 31, 2018

Earnings Per Share [Abstract]

Net loss per share

Net Loss Per Share

Basic net loss per share is computed by dividing net loss by basic weighted-average shares outstanding during the period. Diluted net loss per share is computed by dividing net loss by diluted weighted-average shares outstanding, including potentially dilutive securities.

The following table presents the computation of basic and diluted net loss per share of common stock (in millions, except per share data):



	Three Months Ended						Six Months Ended
	January 31,						January 31,
	2018			2017			2018			2017
Net loss	$	(34.9	)	$	(60.6	)	$	(98.9	)	$	(117.5	)
Weighted-average shares used to compute net loss per share, basic and diluted	91.1			90.7			91.0			90.2
Net loss per share, basic and diluted	$	(0.38	)	$	(0.67	)	$	(1.09	)	$	(1.30	)

The following securities were excluded from the computation of diluted net loss per share of common stock for the periods presented as their effect would have been antidilutive (in millions):



	Three and Six Months Ended
	January 31,
	2018	2017
RSUs and PSUs	6.6	6.7
Convertible senior notes	5.2	5.2
Warrants related to the issuance of convertible senior notes	5.2	5.2
Options to purchase common stock	1.4	1.7
RSAs and PSAs	0.6	1.2
ESPP shares	0.2	0.1
Total	19.2	20.1

Description of Business, Basis of Presentation, Principles of Consolidation, and Summary of Significant Accounting Policies (Policies)

6 Months Ended

Jan. 31, 2018

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Description of business, basis of presentation, principles of consolidation, and summary of significant accounting policies

Description of Business

Basis of Presentation and Principles of Consolidation

Summary of Significant Accounting Policies

Recent accounting pronouncements

Recently Adopted Accounting Pronouncements

Derivatives and Hedging

Recently Issued Accounting Pronouncements

Business Combinations - Definition of a Business

Statement of Cash Flows - Restricted Cash

Income Taxes - Intra-Entity Asset Transfers

Statement of Cash Flows - Classification of Certain Cash Receipts and Cash Payments

Financial Instruments - Credit Losses

Leases

Revenue Recognition


•	removal of the current limitation on contingent revenue may result in revenue being recognized earlier for certain contracts;


•	term license revenue associated with our virtual firewalls will be recognized upfront;


•	allocation of revenue related to software due to the removal of the residual method of revenue recognition; and


•	amortization period for deferred commissions.

We will continue to assess the new standard along with industry trends and additional interpretive guidance, and may adjust our implementation plan accordingly.

Fair value measurements

Fair Value Measurements


•	Level 1—Inputs are unadjusted quoted prices in active markets for identical assets or liabilities.


•	Level 2—Inputs are quoted prices for similar assets and liabilities in active markets or inputs that are observable for the assets or liabilities, either directly or indirectly through market corroboration, for substantially the full term of the financial instruments.


•	Level 3—Inputs are unobservable inputs based on our own assumptions used to measure assets and liabilities at fair value. The inputs require significant management judgment or estimation.

Derivative instruments

Our derivative financial instruments are recorded at fair value, on a gross basis, as either assets or liabilities in our condensed consolidated balance sheets. Gains or losses related to our cash flow hedges are recorded as a component of accumulated other comprehensive income (loss) (“AOCI”) in our condensed consolidated balance sheets and are reclassified into the financial statement line item associated with the underlying hedged transaction in our condensed consolidated statements of operations when the underlying hedged transaction is recognized in earnings. If it becomes probable that the hedged transaction will not occur, the cumulative unrealized gain or loss is reclassified immediately from AOCI into the financial statement line item associated with the underlying hedged transaction in our condensed consolidated statements of operations. Gains or losses related to non-designated derivative instruments are recognized in other income (expense), net in our condensed consolidated statements of operations for each period until the instrument matures, is terminated, is re-designated as a qualified cash flow hedge, or is sold. Derivatives designated as cash flow hedges are classified in our condensed consolidated statements of cash flows in the same manner as the underlying hedged transaction, primarily within cash flows from operating activities.

Fair Value Measurements (Tables)

6 Months Ended

Jan. 31, 2018

Fair Value Disclosures [Abstract]

Schedule of fair value of financial assets and liabilities measured on a recurring basis



	January 31, 2018								July 31, 2017
	Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	325.7	$	—	$	—	$	325.7	$	—	$	—	$	—	$	—
U.S. government and agency securities	—		3.5		—		3.5		—		—		—		—
Total cash equivalents	325.7		3.5		—		329.2		—		—		—		—
Short-term investments:
Certificates of deposit	—		5.4		—		5.4		—		—		—		—
Corporate debt securities	—		183.3		—		183.3		—		159.4		—		159.4
U.S. government and agency securities	—		532.0		—		532.0		—		471.3		—		471.3
Total short-term investments	—		720.7		—		720.7		—		630.7		—		630.7
Prepaid expenses and other current assets:
Foreign currency forward contracts	—		4.7		—		4.7		—		—		—		—
Total prepaid expenses and other current assets	—		4.7		—		4.7		—		—		—		—
Long-term investments:
Certificates of deposit	—		—		—		—		—		5.4		—		5.4
Corporate debt securities	—		166.8		—		166.8		—		186.5		—		186.5
U.S. government and agency securities	—		555.5		—		555.5		—		597.4		—		597.4
Total long-term investments	—		722.3		—		722.3		—		789.3		—		789.3
Total assets measured at fair value	$	325.7	$	1,451.2	$	—	$	1,776.9	$	—	$	1,420.0	$	—	$	1,420.0

Accrued and other liabilities:
Foreign currency forward contracts	$	—	$	0.1	$	—	$	0.1	$	—	$	—	$	—	$	—
Total accrued and other liabilities	—		0.1		—		0.1		—		—		—		—
Total liabilities measured at fair value	$	—	$	0.1	$	—	$	0.1	$	—	$	—	$	—	$	—

Cash Equivalents and Investments (Tables)

6 Months Ended

Jan. 31, 2018

Investments, Debt and Equity Securities [Abstract]

Schedule of available-for-sale securities

The following tables summarize the amortized cost, unrealized gains and losses, and fair value of our available-for-sale securities as of January 31, 2018 and July 31, 2017 (in millions):



	January 31, 2018
	Amortized Cost		Unrealized Gains		Unrealized Losses			Estimated Fair Value
Cash equivalents:
Money market funds	$	325.7	$	—	$	—		$	325.7
U.S. government and agency securities	3.5		—		—			3.5
Total cash equivalents	$	329.2	$	—	$	—		$	329.2

Investments:
Certificates of deposit	$	5.4	$	—	$	—		$	5.4
Corporate debt securities	352.1		0.1		(2.1		)	350.1
U.S. government and agency securities	1,095.4		—		(7.9		)	1,087.5
Total investments	$	1,452.9	$	0.1	$	(10.0	)	$	1,443.0



	July 31, 2017
	Amortized Cost		Unrealized Gains		Unrealized Losses			Estimated Fair Value
Investments:
Certificates of deposit	$	5.4	$	—	$	—		$	5.4
Corporate debt securities	346.1		0.3		(0.5		)	345.9
U.S. government and agency securities	1,071.2		0.1		(2.6		)	1,068.7
Total investments	$	1,422.7	$	0.4	$	(3.1	)	$	1,420.0

Schedule of contractual maturities of available-for-sale securities

The following table summarizes the amortized cost and fair value of our available-for-sale securities as of January 31, 2018, by contractual years-to-maturity (in millions):



	Amortized Cost		Fair Value
Due within one year	$	1,052.1	$	1,049.9
Due between one and three years	730.0		722.3
Total	$	1,782.1	$	1,772.2

- Definition

Tabular disclosure of available-for-sale securities which includes, but is not limited to, changes in the cost basis and fair value, fair value and gross unrealized gain (loss), fair values by type of security, contractual maturity and classification, amortized cost basis, contracts to acquire securities to be accounted for as available-for-sale, debt maturities, transfers to trading, change in net unrealized holding gain (loss) net of tax, continuous unrealized loss position fair value, aggregate losses qualitative disclosures, other than temporary impairment (OTTI) losses or other disclosures related to available for sale securities.

+ References + Details

Convertible Senior Notes (Tables)

6 Months Ended

Jan. 31, 2018

Debt Disclosure [Abstract]

Components of convertible senior notes

The following table sets forth the components of the Notes as of January 31, 2018 and July 31, 2017 (in millions):



	January 31, 2018		July 31, 2017
Liability:
Principal	$	575.0	$	575.0
Less: debt discount and debt issuance costs, net of amortization	37.6		50.3
Net carrying amount	$	537.4	$	524.7

Equity (including temporary equity)	$	109.8	$	109.8

Interest expense recognized related to the convertible senior notes

The following table sets forth interest expense recognized related to the Notes (dollars in millions):



	Three Months Ended						Six Months Ended
	January 31,						January 31,
	2018			2017			2018			2017
Amortization of debt discount	$	5.8		$	5.5		$	11.4		$	10.9
Amortization of debt issuance costs	0.6			0.6			1.3			1.2
Total interest expense recognized	$	6.4		$	6.1		$	12.7		$	12.1

Effective interest rate of the liability component	4.8		%	4.8		%	4.8		%	4.8		%

Commitments and Contingencies (Tables)

6 Months Ended

Jan. 31, 2018

Commitments and Contingencies Disclosure [Abstract]

Schedule of future non-cancelable minimum rental payments for operating leases

The following table presents details of the aggregate future non-cancelable minimum rental payments under our operating leases as of January 31, 2018 (in millions):



	Amount
Fiscal years ending July 31:
Remaining 2018	$	32.1
2019	65.8
2020	66.1
2021	60.2
2022	56.8
2023 and thereafter	267.9
Committed gross lease payments	548.9
Less: proceeds from sublease rentals	15.4
Net operating lease obligation	$	533.5

Equity Award Plans (Tables)

6 Months Ended

Jan. 31, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of stock option activity

The following table summarizes the stock option activity under our stock plans during the reporting period (in millions, except per share amounts):



	Options Outstanding
	Number of Shares		Weighted-Average Exercise Price Per Share		Weighted-Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value
Balance—July 31, 2017	1.6		$	13.11	4.2	$	190.6
Options granted	—		$	—
Options forfeited	—		$	—
Options exercised	(0.2	)	$	11.11
Balance—January 31, 2018	1.4		$	13.41	3.8	$	201.5
Options exercisable—January 31, 2018	1.4		$	13.41	3.8	$	201.5

Schedule of restricted stock award (“RSA”), performance-based stock award (“PSA”), restricted stock unit (“RSU”), and performance-based stock unit (“PSU”) activities

The following table summarizes the RSA, PSA, RSU, and PSU activity under our stock plans during the reporting period (in millions, except per share amounts):



	RSAs and PSAs Outstanding				RSUs and PSUs Outstanding
	Number of Shares		Weighted-Average Grant-Date Fair Value Per Share		Number of Shares		Weighted-Average Grant-Date Fair Value Per Share		Weighted-Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value
Balance—July 31, 2017	1.0		$	163.55	6.5		$	141.16	1.3	$	854.1
Granted⁽¹⁾	—		$	—	2.4		$	146.94
Vested	(0.2	)	$	167.69	(1.9	)	$	136.33
Forfeited	(0.2	)	$	156.56	(0.4	)	$	142.34
Balance—January 31, 2018	0.6		$	164.01	6.6		$	144.59	1.5	$	1,040.7

______________


(1)	For PSAs and PSUs, shares granted represents the aggregate maximum number of shares that may be earned and issued with respect to these awards over their full terms.

Schedule of allocation of share-based compensation expense

The following table summarizes share-based compensation included in costs and expenses (in millions):



	Three Months Ended				Six Months Ended
	January 31,				January 31,
	2018		2017		2018		2017
Cost of product revenue	$	1.9	$	2.0	$	3.8	$	3.7
Cost of subscription and support revenue	19.9		15.0		35.8		27.3
Research and development	35.5		41.3		73.0		79.3
Sales and marketing	53.3		49.7		104.5		93.5
General and administrative	20.2		19.3		39.4		36.8
Total share-based compensation	$	130.8	$	127.3	$	256.5	$	240.6

Net Loss Per Share (Tables)

6 Months Ended

Jan. 31, 2018

Earnings Per Share [Abstract]

Computation of basic and diluted net loss per share of common stock

The following table presents the computation of basic and diluted net loss per share of common stock (in millions, except per share data):



	Three Months Ended						Six Months Ended
	January 31,						January 31,
	2018			2017			2018			2017
Net loss	$	(34.9	)	$	(60.6	)	$	(98.9	)	$	(117.5	)
Weighted-average shares used to compute net loss per share, basic and diluted	91.1			90.7			91.0			90.2
Net loss per share, basic and diluted	$	(0.38	)	$	(0.67	)	$	(1.09	)	$	(1.30	)

Schedule of antidilutive securities excluded from the computation of net loss per share

The following securities were excluded from the computation of diluted net loss per share of common stock for the periods presented as their effect would have been antidilutive (in millions):



	Three and Six Months Ended
	January 31,
	2018	2017
RSUs and PSUs	6.6	6.7
Convertible senior notes	5.2	5.2
Warrants related to the issuance of convertible senior notes	5.2	5.2
Options to purchase common stock	1.4	1.7
RSAs and PSAs	0.6	1.2
ESPP shares	0.2	0.1
Total	19.2	20.1

Fair Value Measurements (Details) - USD ($) $ in Millions	12 Months Ended
Fair Value Measurements (Details) - USD ($) $ in Millions	Jul. 31, 2017	Jan. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash equivalents	$ 0.0	$ 329.2
Short-term investments	630.7	720.7
Prepaid expenses and other current assets	0.0	4.7
Long-term investments	789.3	722.3
Total assets measured at fair value	1,420.0	1,776.9
Accrued and other liabilities	0.0	0.1
Total liabilities measured at fair value	0.0	0.1
Impairment of property and equipment	20.9
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash equivalents	0.0	325.7
Short-term investments	0.0	0.0
Prepaid expenses and other current assets	0.0	0.0
Long-term investments	0.0	0.0
Total assets measured at fair value	0.0	325.7
Accrued and other liabilities	0.0	0.0
Total liabilities measured at fair value	0.0	0.0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash equivalents	0.0	3.5
Short-term investments	630.7	720.7
Prepaid expenses and other current assets	0.0	4.7
Long-term investments	789.3	722.3
Total assets measured at fair value	1,420.0	1,451.2
Accrued and other liabilities	0.0	0.1
Total liabilities measured at fair value	0.0	0.1
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash equivalents	0.0	0.0
Short-term investments	0.0	0.0
Prepaid expenses and other current assets	0.0	0.0
Long-term investments	0.0	0.0
Total assets measured at fair value	0.0	0.0
Accrued and other liabilities	0.0	0.0
Total liabilities measured at fair value	0.0	0.0
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash equivalents	0.0	325.7
Money market funds \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash equivalents	0.0	325.7
Money market funds \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash equivalents	0.0	0.0
Money market funds \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash equivalents	0.0	0.0
U.S. government and agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash equivalents	0.0	3.5
Short-term investments	471.3	532.0
Long-term investments	597.4	555.5
U.S. government and agency securities \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash equivalents	0.0	0.0
Short-term investments	0.0	0.0
Long-term investments	0.0	0.0
U.S. government and agency securities \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash equivalents	0.0	3.5
Short-term investments	471.3	532.0
Long-term investments	597.4	555.5
U.S. government and agency securities \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cash equivalents	0.0	0.0
Short-term investments	0.0	0.0
Long-term investments	0.0	0.0
Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Short-term investments	0.0	5.4
Long-term investments	5.4	0.0
Certificates of deposit \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Short-term investments	0.0	0.0
Long-term investments	0.0	0.0
Certificates of deposit \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Short-term investments	0.0	5.4
Long-term investments	5.4	0.0
Certificates of deposit \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Short-term investments	0.0	0.0
Long-term investments	0.0	0.0
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Short-term investments	159.4	183.3
Long-term investments	186.5	166.8
Corporate debt securities \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Short-term investments	0.0	0.0
Long-term investments	0.0	0.0
Corporate debt securities \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Short-term investments	159.4	183.3
Long-term investments	186.5	166.8
Corporate debt securities \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Short-term investments	0.0	0.0
Long-term investments	0.0	0.0
Foreign currency forward contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Prepaid expenses and other current assets	0.0	4.7
Accrued and other liabilities	0.0	0.1
Foreign currency forward contracts \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Prepaid expenses and other current assets	0.0	0.0
Accrued and other liabilities	0.0	0.0
Foreign currency forward contracts \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Prepaid expenses and other current assets	0.0	4.7
Accrued and other liabilities	0.0	0.1
Foreign currency forward contracts \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Prepaid expenses and other current assets	0.0	0.0
Accrued and other liabilities	0.0	$ 0.0
Fair Value, Measurements, Nonrecurring \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Leasehold improvements and other long-lived assets related to previous corporate headquarters	$ 4.2

Cash Equivalents and Investments (Available-for-Sale Securities) (Details) - USD ($) $ in Millions	Jan. 31, 2018	Jul. 31, 2017
Schedule of Available-for-sale Securities
Estimated fair value	$ 1,772.2
Cash equivalents
Schedule of Available-for-sale Securities
Amortized cost	329.2
Unrealized gains	0.0
Unrealized losses	0.0
Estimated fair value	329.2
Cash equivalents \| Money market funds
Schedule of Available-for-sale Securities
Amortized cost	325.7
Unrealized gains	0.0
Unrealized losses	0.0
Estimated fair value	325.7
Cash equivalents \| U.S. government and agency securities
Schedule of Available-for-sale Securities
Amortized cost	3.5
Unrealized gains	0.0
Unrealized losses	0.0
Estimated fair value	3.5
Investments
Schedule of Available-for-sale Securities
Amortized cost	1,452.9	$ 1,422.7
Unrealized gains	0.1	0.4
Unrealized losses	(10.0)	(3.1)
Estimated fair value	1,443.0	1,420.0
Investments \| U.S. government and agency securities
Schedule of Available-for-sale Securities
Amortized cost	1,095.4	1,071.2
Unrealized gains	0.0	0.1
Unrealized losses	(7.9)	(2.6)
Estimated fair value	1,087.5	1,068.7
Investments \| Certificates of deposit
Schedule of Available-for-sale Securities
Amortized cost	5.4	5.4
Unrealized gains	0.0	0.0
Unrealized losses	0.0	0.0
Estimated fair value	5.4	5.4
Investments \| Corporate debt securities
Schedule of Available-for-sale Securities
Amortized cost	352.1	346.1
Unrealized gains	0.1	0.3
Unrealized losses	(2.1)	(0.5)
Estimated fair value	$ 350.1	$ 345.9

Cash Equivalents and Investments (Available-for-Sale Securities, Contractual Maturities) (Details) $ in Millions	Jan. 31, 2018 USD ($)
Amortized Cost
Due within one year	$ 1,052.1
Due between one and three years	730.0
Total	1,782.1
Fair Value
Due within one year	1,049.9
Due between one and three years	722.3
Total	$ 1,772.2

Derivative Instruments (Details) - USD ($) $ in Millions	6 Months Ended
Derivative Instruments (Details) - USD ($) $ in Millions	Jan. 31, 2018	Jul. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Maximum contract term of cash flow hedge	13 months
Notional amount of derivatives	$ 149.4	$ 0.0

Convertible Senior Notes (Additional Information) (Details) $ / shares in Units, shares in Millions, $ in Millions	Jan. 31, 2018 USD ($)	Jun. 30, 2014 USD ($) shares $ / shares	Jul. 31, 2017 USD ($)
Debt Instrument
Aggregate principal amount \| $		$ 575.0
Contractual interest rate (in percentage)		0.00%
Number of common stock convertible at initial conversion rate (in shares) \| shares		5.2
Initial conversion price (in usd per share) \| $ / shares		$ 110.28
Convertible senior notes, threshold trading days (in days)		20
Convertible senior notes, threshold consecutive trading days (in days)		30 days
Convertible senior notes, threshold percentage of stock price trigger (in percentage)		130.00%
Convertible senior notes, threshold business days, per $1,000 principal (in days)		5
Convertible senior notes, threshold consecutive trading days, per $1,000 principal (in days)		5 days
Convertible senior notes, threshold percentage of Note price trigger, per $1,000 principal (in percentage)		98.00%
If-converted value in excess of principal \| $	$ 218.2
Shares of common stock covered by note hedges (in shares) \| shares		5.2
Warrants sold, shares authorized to sell to counterparties (in shares) \| shares		5.2
Strike price of warrants (in usd per share) \| $ / shares		$ 137.85
Level 2
Debt Instrument
Fair value of convertible senior notes \| $	$ 839.6		$ 747.5

Convertible Senior Notes (Components of Convertible Senior Notes) (Details) - USD ($) $ in Millions	Jan. 31, 2018	Jul. 31, 2017
Debt Disclosure [Abstract]
Principal	$ 575.0	$ 575.0
Less: debt discount and debt issuance costs, net of amortization	37.6	50.3
Net carrying amount	537.4	524.7
Equity (including temporary equity)	$ 109.8	$ 109.8

Convertible Senior Notes (Schedule of Interest Expense Recognized) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2018	Jan. 31, 2017
Debt Disclosure [Abstract]
Amortization of debt discount	$ 5.8	$ 5.5	$ 11.4	$ 10.9
Amortization of debt issuance costs	0.6	0.6	1.3	1.2
Total interest expense recognized	$ 6.4	$ 6.1	$ 12.7	$ 12.1
Effective interest rate of the liability component (in percentage)	4.80%	4.80%	4.80%	4.80%

Commitments and Contingencies (Lease Arrangements) (Details) $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	Sep. 30, 2012 USD ($) ft² lease_agreement lease_renewal_option	Jan. 31, 2018 USD ($)	Oct. 31, 2017 USD ($)	Jan. 31, 2018 USD ($)	Jan. 31, 2017 USD ($)	Dec. 31, 2017 USD ($) lease_agreement	Aug. 31, 2017 USD ($)	Oct. 31, 2015 USD ($) ft² lease_agreement	May 31, 2015 USD ($) ft² lease_agreement
Operating Leased Assets
Total payments under the lease agreements		$ 548.9		$ 548.9
Proceeds from sublease		15.4		15.4
Cease-use loss related to facility exit				16.7	$ 0.0
Q415 and Q116 New lease arrangements, new corporate headquarters
Operating Leased Assets
Number of lease agreements \| lease_agreement								3
Area of office space (in square feet) \| ft²								941,000
Increase in annual rental payments for fiscal 2018			$ 24.4
Increase in annual rental payments for fiscal 2019			11.8
Increase in annual rental payments for fiscal 2020			2.0
Cash reimbursement from lessors			38.2
Total payments under the lease agreements								$ 412.0
Q415 New lease arrangements, previous corporate headquarters
Operating Leased Assets
Number of lease agreements \| lease_agreement									1
Area of office space (in square feet) \| ft²									122,000
Total payments under the lease agreements									$ 23.1
Q113 New lease arrangements, previous corporate headquarters
Operating Leased Assets
Number of lease agreements \| lease_agreement	2
Area of office space (in square feet) \| ft²	300,000
Total payments under the lease agreements	$ 94.3
Number of lease renewal options \| lease_renewal_option	2
Renewal term (in years)	5 years
Cease-use loss related to facility exit			$ 15.4
Cease-use liability		10.8		10.8			$ 15.4
Liability release through rental payments		$ (2.7)		$ (4.6)
Q218 New sublease arrangement, previous corporate headquarters
Operating Leased Assets
Number of lease agreements \| lease_agreement						1
Proceeds from sublease						$ 16.3

Commitments and Contingencies (Lease Commitment) (Details) $ in Millions	Jan. 31, 2018 USD ($)
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Remaining 2018	$ 32.1
2019	65.8
2020	66.1
2021	60.2
2022	56.8
2023 and thereafter	267.9
Committed gross lease payments	548.9
Less: proceeds from sublease rentals	15.4
Net operating lease obligation	$ 533.5

Commitments and Contingencies (Manufacturing Purchase Commitments) (Details) $ in Millions	Jan. 31, 2018 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Manufacturing purchase commitments	$ 121.5

Stockholders' Equity (Details) - USD ($) shares in Millions, $ in Millions	1 Months Ended		3 Months Ended	6 Months Ended
	Feb. 28, 2017	Aug. 31, 2016	Jan. 31, 2018	Jan. 31, 2018
Equity [Abstract]
Share repurchase, authorized amount	$ 500.0	$ 500.0
Share repurchase, total authorized amount			$ 1,000.0	$ 1,000.0
Repurchase and retirement of common stock (in shares)			0.9	1.7
Repurchase and retirement of common stock			$ 125.0	$ 250.0
Share repurchase, remaining authorized repurchase amount			$ 330.0	$ 330.0

Equity Award Plans (Share-Based Compensation Plans) (Details) - 2012 Employee stock purchase plan	6 Months Ended
	Jan. 31, 2018 USD ($) shares
Share-based Compensation Arrangement by Share-based Payment Award
Award vesting period	24 months
Purchase price of common stock in percentage of the lower of the fair market value of our common stock on the first trading day of each offering period or on the exercise date (in percentage)	85.00%
Maximum subscription rate (in percentage)	15.00%
Purchase limit per employee, number of shares, during each offering period (in shares) \| shares	625
Purchase limit per employee, total fair value of common stock, for each calendar year \| $	$ 25,000

Equity Award Plans (Stock Option Activities) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	6 Months Ended	12 Months Ended
	Jan. 31, 2018	Jul. 31, 2017
Options, Outstanding Roll Forward
Balance, beginning (in shares)	1.6
Options granted (in shares)	0.0
Options forfeited (in shares)	0.0
Options exercised (in shares)	(0.2)
Balance, ending (in shares)	1.4	1.6
Options, Outstanding, Weighted Average Exercise Price Roll Forward
Balance, beginning (in usd per share)	$ 13.11
Options granted (in usd per share)	0.00
Options forfeited (in usd per share)	0.00
Options exercised (in usd per share)	11.11
Balance, ending (in usd per share)	$ 13.41	$ 13.11
Options, Additional Disclosures
Weighted-average remaining contractual life (in years)	3 years 9 months	4 years 2 months
Aggregate intrinsic value	$ 201.5	$ 190.6
Options exercisable (in shares)	1.4
Options exercisable, weighted-average exercise price (in usd per share)	$ 13.41
Options exercisable, weighted-average remaining contractual term (in years)	3 years 9 months
Options exercisable, aggregate intrinsic value	$ 201.5

Equity Award Plans (Restricted Stock Award (RSA), Performance-Based Stock Award (PSA), Restricted Stock Unit (RSU), and Performance-Based Stock Unit (PSU) Activities) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	6 Months Ended	12 Months Ended
	Jan. 31, 2018	Jul. 31, 2017
RSAs and PSAs
RSAs, PSAs, RSUs, and PSUs, Outstanding
Balance, beginning (in shares)	1.0
Granted (in shares)	0.0
Vested (in shares)	(0.2)
Forfeited (in shares)	(0.2)
Balance, ending (in shares)	0.6	1.0
RSAs, PSAs, RSUs, and PSUs, Outstanding, Weighted Average Grant-Date Fair Value Per Share
Balance, beginning (in usd per share)	$ 163.55
Granted (in usd per share)	0.00
Vested (in usd per share)	167.69
Forfeited (in usd per share)	156.56
Balance, ending (in usd per share)	$ 164.01	$ 163.55
RSUs and PSUs
RSAs, PSAs, RSUs, and PSUs, Outstanding
Balance, beginning (in shares)	6.5
Granted (in shares)	2.4
Vested (in shares)	(1.9)
Forfeited (in shares)	(0.4)
Balance, ending (in shares)	6.6	6.5
RSAs, PSAs, RSUs, and PSUs, Outstanding, Weighted Average Grant-Date Fair Value Per Share
Balance, beginning (in usd per share)	$ 141.16
Granted (in usd per share)	146.94
Vested (in usd per share)	136.33
Forfeited (in usd per share)	142.34
Balance, ending (in usd per share)	$ 144.59	$ 141.16
RSAs, PSAs, RSUs, and PSUs, Additional Disclosures
Weighted-average remaining contractual term (in years)	1 year 6 months	1 year 3 months
Aggregate intrinsic value	$ 1,040.7	$ 854.1

Equity Award Plans (Allocation of Share-Based Compensation Expense) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2018	Jan. 31, 2017
Employee Service Share-based Compensation, Allocation of Recognized Period Costs
Share-based compensation expense	$ 130.8	$ 127.3	$ 256.5	$ 240.6
Total compensation cost not yet recognized, unvested awards	976.2		$ 976.2
Period for recognition of total compensation cost not yet recognized (in years)			2 years 8 months
Cost of product revenue
Employee Service Share-based Compensation, Allocation of Recognized Period Costs
Share-based compensation expense	1.9	2.0	$ 3.8	3.7
Cost of subscription and support revenue
Employee Service Share-based Compensation, Allocation of Recognized Period Costs
Share-based compensation expense	19.9	15.0	35.8	27.3
Research and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs
Share-based compensation expense	35.5	41.3	73.0	79.3
Sales and marketing
Employee Service Share-based Compensation, Allocation of Recognized Period Costs
Share-based compensation expense	53.3	49.7	104.5	93.5
General and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs
Share-based compensation expense	$ 20.2	$ 19.3	$ 39.4	$ 36.8

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
Income Taxes (Details) - USD ($) $ in Millions	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2018	Jan. 31, 2017
Income Tax Disclosure [Abstract]
Effective income tax rate (in percentage)	(4.80%)	(4.80%)	(11.00%)	(6.50%)
Provisional income tax expense (benefit) related to alternative minimum tax credits as a result of the Tax Cuts and Jobs Act of 2017	$ (6.2)

Net Loss Per Share (Computation of Basic and Diluted Net Loss Per Share) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2018	Jan. 31, 2017
Earnings Per Share [Abstract]
Net loss	$ (34.9)	$ (60.6)	$ (98.9)	$ (117.5)
Weighted-average shares used to compute net loss per share, basic and diluted (in shares)	91.1	90.7	91.0	90.2
Net loss per share, basic and diluted (in usd per share)	$ (0.38)	$ (0.67)	$ (1.09)	$ (1.30)

Net Loss Per Share (Schedule of Antidilutive Securities Excluded from Computation) (Details) - shares shares in Millions	3 Months Ended		6 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2018	Jan. 31, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive securities (in shares)	19.2	20.1	19.2	20.1
RSUs and PSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive securities (in shares)	6.6	6.7	6.6	6.7
Convertible senior notes
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive securities (in shares)	5.2	5.2	5.2	5.2
Warrants related to the issuance of convertible senior notes
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive securities (in shares)	5.2	5.2	5.2	5.2
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive securities (in shares)	1.4	1.7	1.4	1.7
RSAs and PSAs
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive securities (in shares)	0.6	1.2	0.6	1.2
ESPP shares
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive securities (in shares)	0.2	0.1	0.2	0.1