CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Oct. 31, 2017	Oct. 31, 2016
Cash flows from operating activities
Net loss	$ (69,985)	$ (64,861)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	2,789	2,781
Stock-based compensation	15,066	16,517
Deferred income taxes	163	37
Change in fair value of warrant liability	(101)	(144)
Change in operating assets and liabilities:
Accounts receivable	(4,653)	4,600
Prepaid expenses and other current assets	(2,120)	(1,435)
Deferred commissions	(2,217)	(2,344)
Other long-term assets	(670)	(203)
Accounts payable	687	(272)
Deferred rent	(85)	(493)
Accrued liabilities	2,163	2,057
Deferred revenue	21,794	15,768
Net cash used in operating activities	(37,169)	(27,992)
Cash flows from investing activities
Purchases of property and equipment	(1,714)	(1,422)
Proceeds from maturities of marketable securities	74,230	114,792
Purchases of marketable securities	(72,879)	(82,036)
Net cash (used in) provided by investing activities	(363)	31,334
Cash flows from financing activities
Proceeds from exercise of stock options, including early exercised stock options	8,201	7,187
Repurchase of early exercised stock options	(149)	(22)
Proceeds from the initial public offering, net of underwriting discounts and commissions	205,494	0
Proceeds from exercise of redeemable convertible preferred stock warrants	1	0
Payment of initial public offering costs	(2,344)	0
Net cash provided by financing activities	211,203	7,165
Effect of exchange rate changes on cash, cash equivalents, and restricted cash	182	42
Net increase in cash, cash equivalents, and restricted cash	173,853	10,549
Cash, cash equivalents, and restricted cash, beginning of period	69,412	33,313
Cash, cash equivalents, and restricted cash, end of period	243,265	43,862
Supplemental Disclosure of Noncash Investing and Financing Activities
Vesting of early exercised stock options	950	707
Costs related to initial public offering included in accounts payable and accrued liabilities	1,529	0
Conversion of redeemable convertible preferred stock warrant liability to redeemable convertible preferred stock as a result of warrant exercise	$ 1,171	$ 0