Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Oct. 31, 2016	Oct. 31, 2015
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss	$ (202,151)	$ (169,458)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	35,978	23,118
Stock-based compensation expense	79,129	36,198
Contribution of common stock to Pure Good Foundation	0	11,900
Other	1,051	0
Changes in operating assets and liabilities:
Accounts receivable, net	(38,186)	(53,094)
Inventory	(189)	(3,420)
Deferred commissions	1,844	(8,472)
Prepaid expenses and other assets	39	(2,065)
Accounts payable	3,639	10,224
Accrued compensation and other liabilities	6,786	17,216
Deferred revenue	60,180	87,987
Net cash used in operating activities	(51,880)	(49,866)
CASH FLOWS FROM INVESTING ACTIVITIES
Purchases of property and equipment	(64,602)	(29,495)
Purchase of intangible assets	(1,000)	0
Purchases of marketable securities	(483,558)	0
Sales of marketable securities	79,815	0
Maturities of marketable securities	38,213	0
Net increase in restricted cash	(5,600)	(2,484)
Net cash used in investing activities	(436,732)	(31,979)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from initial public offering, net	0	459,425
Net proceeds from exercise of stock options	10,725	4,710
Proceeds from issuance of common stock under employee stock purchase plan	25,606	0
Payments of deferred offering costs	0	(1,690)
Net cash provided by financing activities	36,331	462,445
Net increase (decrease) in cash and cash equivalents	(452,281)	380,600
Cash and cash equivalents, beginning of period	604,742	192,707
Cash and cash equivalents, end of period	152,461	573,307
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Cash paid for income taxes	2,510	820
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING INFORMATION
Conversion of convertible preferred stock to common stock upon initial public offering	0	543,940
Property and equipment purchased but not yet paid	5,956	1,750
Vesting of early exercised stock options	794	1,543
Unpaid deferred offering costs	$ 0	$ 2,748