Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss	$ (336,582)	$ (192,649)	$ (369,672)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Depreciation and amortization	92,156	17,428	12,102
Non-cash lease expense	45,640	0	0
Stock-based compensation expense	220,354	117,365	290,006
Accretion and amortization of marketable securities	(2,294)	(1,406)	512
Amortization of deferred costs	47,552	30,634	23,284
Loss (gain) on disposal of fixed assets	414	(25)	(111)
Release of deferred tax valuation allowance	0	0	(806)
Changes in assets and liabilities:
Accounts receivable	(8,956)	54,231	(28,780)
Contract assets	176	(1,891)	(285)
Prepaid expenses and other assets	(8,456)	16,497	(16,194)
Deferred costs	(68,575)	(39,665)	(34,557)
Accounts payable	(4,089)	3,795	(667)
Accrued compensation	5,570	(17,962)	5,179
Accrued expenses and other liabilities	109	5,413	7,664
Operating lease liabilities	(51,059)	0	0
Net cash (used in) provided by operating activities	(36,826)	34,273	(42,268)
CASH FLOWS FROM INVESTING ACTIVITIES
Purchases of marketable securities and other investments	(494,252)	(462,737)	(620,329)
Proceeds from sale of marketable securities and other investments	86,739	56,702	79,069
Maturities of marketable securities and other investments	413,557	435,478	321,552
Cash used in business combinations, net of cash acquired	(4,500)		(1,937)
Cash acquired in business combination		42,557
Capital expenditures	(7,203)	(10,086)	(12,954)
Proceeds from sale of equipment	0	45	145
Net cash (used in) provided by investing activities	(5,659)	61,959	(234,454)
CASH FLOWS FROM FINANCING ACTIVITIES
Net proceeds from issuance of common stock in initial public offering	0	0	237,422
Net proceeds from issuance of common stock in follow-on offering	0	0	46,008
Taxes paid related to net share settlement of restricted stock units	(32,621)	(16,218)	(59,781)
Proceeds from employee stock plans	25,664	21,844	23,673
Net cash (used in) provided by financing activities	(6,957)	5,626	247,322
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(1,607)	(1,118)	1,067
Net (decrease) increase in cash, cash equivalents and restricted cash	(51,049)	100,740	(28,333)
Cash, cash equivalents and restricted cash — Beginning of period	162,039	61,299	89,632
Cash, cash equivalents and restricted cash — End of period	110,990	162,039	61,299
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Cash paid for income taxes	7,760	4,775	2,694
Additional Cash Flow Elements and Supplemental Cash Flow Information [Abstract]
Purchases of property and equipment in accounts payable and other accrued liabilities	45	208	1,130
Fair value of common stock issued as consideration for business combinations	0	1,154,230	2,081
Fair value of equity awards assumed	0	48,197	0
Conversion of redeemable convertible preferred stock to common stock	0	0	657,687
Right-of-use assets obtained in exchange for new operating lease liabilities	7,392	0	0
Other
Changes in assets and liabilities:
Other contract liabilities	(5,438)	5,922	12,509
Deferred Revenue
Changes in assets and liabilities:
Other contract liabilities	$ 36,652	$ 36,586	$ 57,548