CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Cash flows from operating activities:
Net loss	$ (114,359)	$ (83,509)	$ (76,302)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation, amortization and accretion	7,001	4,568	2,889
Stock-based compensation	49,860	17,127	9,832
Amortization of deferred commissions	17,584	13,734	8,438
Deferred income taxes	(534)	0	0
Write-off of intangible assets	1,114	0	0
Non-cash charitable contributions	708	0	0
Other, net	719	704	934
Changes in operating assets and liabilities:
Accounts receivable	(18,321)	(11,993)	(10,668)
Deferred commissions	(21,437)	(19,391)	(15,952)
Prepaid expenses and other assets	(10,128)	(3,422)	(1,056)
Accounts payable	3,505	1,529	962
Accrued compensation	3,582	1,967	3,340
Accrued expenses and other liabilities	521	2,387	3,929
Deferred revenue	54,945	34,198	32,118
Net cash used in operating activities	(25,240)	(42,101)	(41,536)
Cash flows from investing activities:
Capitalized internal-use software costs	(5,431)	(5,489)	(2,608)
Purchases of property and equipment	(6,550)	(6,253)	(4,093)
Purchases of securities available for sale	(129,086)	0	(46,360)
Proceeds from maturities and redemption of securities available for sale	39,825	12,500	41,576
Proceeds from sales of securities available for sale	1,538	6,207	12,645
Net cash provided by (used in) investing activities	(99,704)	6,965	1,160
Cash flows from financing activities:
Proceeds from initial public offering, net of underwriters' discounts and commissions	199,948	0	0
Payments of deferred offering costs	(4,038)	(1,584)	0
Proceeds from exercise of stock options, net of repurchases and other	33,646	2,437	3,630
Proceeds from issuance of convertible redeemable preferred stock, net of issuance costs	0	0	73,424
Proceeds from shares issued in connection with employee stock purchase plan	8,369	0	0
Other	(517)	(396)	(213)
Net cash provided by financing activities	237,408	457	76,841
Effects of changes in foreign currency exchange rates on cash, cash equivalents and restricted cash	487	(120)	(42)
Net increase (decrease) in cash, cash equivalents and restricted cash	112,951	(34,799)	36,423
Cash, cash equivalents and restricted cash at beginning of year	23,282	58,081	21,658
Cash, cash equivalents and restricted cash at end of year	136,233	23,282	58,081
Cash paid during the period for:
Income taxes	747	0	0
Non-cash investing and financing activities:
Vesting of early exercised common stock options	1,335	1,297	1,014
Issuance of common stock in connection with warrant exercises	272	0	0
Common stock issued as charitable contribution	708	129	132
Assets acquired under financing arrangement	0	386	853
Deferred offering costs, accrued but not yet paid	0	2,106	368
Property and equipment acquired through tenant improvement allowances	0	1,332	0
Property and equipment and other accrued but not yet paid	111	1,367	317
Issuance of common stock in connection with business combination	2,160	0	0
Conversion of redeemable convertible preferred stock to common stock	228,362	0	0
Reconciliation of cash, cash equivalents, and restricted cash within the consolidated balance sheets to the amounts shown in the statements of cash flows above:
Total cash, cash equivalents and restricted cash	$ 23,282	$ 58,081	$ 21,658