Condensed Consolidated Statements of Cash Flows $ in Thousands	3 Months Ended
	Apr. 30, 2018 USD ($)	Apr. 30, 2017 USD ($)	[1]
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss	$ (64,304)	$ (57,159)	[2],[3]
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	16,417	14,825
Amortization of debt discount and debt issuance costs	1,455	0
Stock-based compensation expense	43,955	32,219
Other	152	451
Changes in operating assets and liabilities:
Accounts receivable, net	47,143	36,571
Inventory	(4,429)	(16,105)
Deferred commissions	1,269	(1,367)
Prepaid expenses and other current assets	11,111	(3,944)
Accounts payable	(18,802)	(3,982)
Accrued compensation and other liabilities	(29,881)	(24,194)
Deferred revenue	14,510	8,384
Net cash provided by (used in) operating activities	18,596	(14,301)
CASH FLOWS FROM INVESTING ACTIVITIES
Purchases of property and equipment	(22,296)	(12,769)
Purchases of marketable securities	(81,702)	(55,976)
Sales of marketable securities	10,454	5,384
Maturities of marketable securities	61,023	46,321
Net cash used in investing activities	(32,521)	(17,040)
CASH FLOWS FROM FINANCING ACTIVITIES
Net proceeds from exercise of stock options	9,614	2,257
Proceeds from issuance of common stock under employee stock purchase plan	19,698	14,166
Proceeds from issuance of convertible senior notes, net of issuance costs	562,062	0
Payment for purchase of capped calls	(64,630)	0
Repurchase of common stock	(20,000)	0
Net cash provided by financing activities	506,744	16,423
Net increase (decrease) in cash, cash equivalents and restricted cash	492,819	(14,918)
Cash, cash equivalents and restricted cash, beginning of period	258,820	196,409
Cash, cash equivalents and restricted cash, end of period	751,639	181,491
CASH, CASH EQUIVALENTS AND RESTRICTED CASH AT END OF PERIOD:
Cash and cash equivalents	735,140	168,757
Restricted cash	16,499	12,734
Cash, cash equivalents and restricted cash, end of period	751,639	181,491
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Cash paid for income taxes	1,839	790
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING INFORMATION
Property and equipment purchased but not yet paid	8,316	9,685
Vesting of early exercised stock options	$ 320	$ 298

[1] * Prior period information has been adjusted to reflect the adoption impact of ASC 606 and ASU 2016-18, which we adopted on February 1, 2018

[2] * Prior period information has been adjusted to reflect the adoption impact of ASC 606, which we adopted on February 1, 2018.

[3] * Prior period information has been adjusted to reflect the adoption impact of ASC 606, which we adopted on February 1, 2018.