Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Apr. 30, 2016	Apr. 30, 2015
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss	$ (63,459)	$ (49,120)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	10,432	6,479
Stock-based compensation expense	22,134	8,859
Other	484	0
Changes in operating assets and liabilities:
Accounts receivable, net	28,593	4,070
Inventory	(2,623)	(1,470)
Deferred commissions	4,141	1,763
Prepaid expenses and other assets	(2,744)	(2,985)
Accounts payable	166	(285)
Accrued compensation and other liabilities	(11,017)	(3,626)
Deferred revenue	20,653	22,198
Net cash provided by (used in) operating activities	6,760	(14,117)
CASH FLOWS FROM INVESTING ACTIVITIES
Purchases of property and equipment	(24,376)	(6,742)
Purchases of marketable securities	(343,466)	0
Sales of marketable securities	23,327	0
Change in restricted cash	706	0
Net cash used in investing activities	(343,809)	(6,742)
CASH FLOWS FROM FINANCING ACTIVITIES
Net proceeds from exercise of stock options	3,324	1,691
Proceeds from issuance of common stock under employee stock purchase plan	15,079	0
Payments of deferred offering costs	0	(313)
Net cash provided by financing activities	18,403	1,378
Net decrease in cash and cash equivalents	(318,646)	(19,481)
Cash and cash equivalents, beginning of period	604,742	192,707
Cash and cash equivalents, end of period	286,096	173,226
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Cash paid for income taxes	1,323	274
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING INFORMATION
Property and equipment purchased but not yet paid	9,448	4,580
Vesting of early exercised stock options	176	430
Unpaid deferred offering costs	$ 0	$ 679