Consolidated Statements of Stockholders’ Equity - USD ($) shares in Thousands, $ in Thousands	Total		Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Restricted Stock Common Stock	Restricted Stock Units Common Stock	Restricted Stock Units Additional Paid-In Capital
Beginning balance (in shares) at Jan. 31, 2017			204,364
Beginning balance at Jan. 31, 2017	$ 537,201		$ 20	$ 1,281,452	$ (562)	$ (743,709)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options, net of repurchases (in shares)			8,814
Issuance of common stock upon exercise of stock options	24,581		$ 1	24,580
Stock-based compensation expense	150,673			150,673
Vesting of early exercised stock options	1,042			1,042
Vesting and net issuance of restricted stock units ( in shares)								5,278
Vesting of restricted stock units	0		$ 1	(1)
Common stock issued under employee stock purchase plan (in shares)			2,523
Common stock issued under employee stock purchase plan	22,137			22,137
Other comprehensive income (loss)	(1,355)				(1,355)
Net loss	(159,878)	[1]				(159,878)
Ending balance (in shares) at Jan. 31, 2018			220,979
Ending balance at Jan. 31, 2018	574,401		$ 22	1,479,883	(1,917)	(903,587)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options, net of repurchases (in shares)			9,397
Issuance of common stock upon exercise of stock options	47,750		$ 1	47,749
Stock-based compensation expense	210,645			210,645
Vesting of early exercised stock options	320			320
Vesting and net issuance of restricted stock units ( in shares)							2,398	8,378
Vesting of restricted stock units	0							$ 1	$ (1)
Tax withholding on vesting of restricted stock	(632)			(632)
Common stock issued under employee stock purchase plan (in shares)			3,381
Common stock issued under employee stock purchase plan	33,444			33,444
Repurchase of Common Stock (in shares)			(1,009)
Repurchase of common stock	(20,000)			(20,000)
Purchase of capped calls	(64,630)			(64,630)
Equity component of convertible senior notes, net	133,265			133,265
Other comprehensive income (loss)	1,579				1,579
Net loss	(178,362)					(178,362)
Ending balance (in shares) at Jan. 31, 2019			243,524
Ending balance at Jan. 31, 2019	737,780		$ 24	1,820,043	(338)	(1,081,949)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options, net of repurchases (in shares)			7,770
Issuance of common stock upon exercise of stock options	42,931		$ 1	42,930
Stock-based compensation expense	226,705			226,705
Vesting and net issuance of restricted stock units ( in shares)							624	9,215
Vesting of restricted stock units								$ 1	$ (1)
Tax withholding on vesting of restricted stock	(10,379)			(10,379)
Common stock issued under employee stock purchase plan (in shares)			3,743
Common stock issued under employee stock purchase plan	43,298			43,298
Repurchase of Common Stock (in shares)			(868)
Repurchase of common stock	(15,017)			(15,017)
Other comprehensive income (loss)	5,787				5,787
Net loss	(200,987)					(200,987)
Ending balance (in shares) at Feb. 02, 2020			264,008
Ending balance at Feb. 02, 2020	$ 830,118		$ 26	$ 2,107,579	$ 5,449	$ (1,282,936)

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