Consolidated Statements of Stockholders’ Equity (Deficit) - USD ($) shares in Thousands, $ in Thousands	Total		Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit	Restricted Stock Common Stock	Unvested restricted stock units Common Stock
Beginning balance (in shares) at Jan. 31, 2016			190,509
Beginning balance at Jan. 31, 2016	$ 563,354		$ 19	$ 1,118,670	$ 0	$ (555,335)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect adjustment from adoption of ASC 606 | Accounting Standards Update 2016-09	0			2,079		(2,079)
Cumulative effect adjustment from adoption of ASC 606 | Accounting Standards Update 2014-09	35,237			0		35,237
Issuance of common stock upon exercise of stock options, net of repurchases (in shares)			10,180
Issuance of common stock upon exercise of stock options	15,031		$ 1	15,030
Stock-based compensation expense	116,668			116,668
Vesting of early exercised stock options	3,399			3,399
Vesting of restricted stock units ( in shares)								1,238
Vesting of restricted stock units	0		$ 0	0
Common stock issued under employee stock purchase plan (in shares)			2,437
Common stock issued under employee stock purchase plan	25,606			25,606
Other comprehensive loss	(562)				(562)
Net loss	(221,532)	[1],[2],[3]				(221,532)
Ending balance (in shares) at Jan. 31, 2017			204,364
Ending 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 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 loss	(1,355)				(1,355)
Net loss	(159,878)	[1],[2],[3]				(159,878)
Ending balance (in shares) at Jan. 31, 2018			220,979
Ending balance at Jan. 31, 2018	574,401	[4]	$ 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 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 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)

[1] * As adjusted to reflect the impact of ASU 2016-18 and the full retrospective adoption of

[2] * As adjusted to reflect the impact of the full retrospective adoption of ASC 606 - see Note 2.

[3] *As adjusted to reflect the impact of the full retrospective adoption of ASC 606 - see Note 2.

[4] * As adjusted to reflect the impact of the full retrospective adoption of ASC 606