CONSOLIDATED STATEMENTS OF STOCKHOLDERS EQUITY - USD ($) $ in Thousands	Total		Class A and Class B Common Stock	Class A and Class B Common Stock Non-employee	Additional Paid-in Capital	Treasury Stock	Accumulated Other Comprehensive (Loss) Income	Accumulated Deficit
Balance, Beginning at Jan. 31, 2015	$ 268,129		$ 12		$ 798,743	$ (1,177)	$ (56)	$ (529,393)
Balance, Beginning, Shares at Jan. 31, 2015			119,655,000
Issuance of common stock upon stock option exercises	7,164				7,164
Issuance of common stock upon stock option exercises (in shares)			2,197,000
Issuance of common stock in connection with acquisitions	6,108				6,108
Issuance of common stock in connection with acquisitions (in shares)			344,000
Stock-based compensation related to stock awards	59,504				59,504
Vesting of restricted stock units and restricted stock awards, net of shares withheld for employee payroll taxes			1,016,000
Employee payroll taxes withheld related to vesting of restricted stock units and restricted stock awards	(10,436)				(10,436)
Restricted stock awards granted to non-employees (in shares)			11,000
Restricted stock awards forfeited due to termination (in shares)			(13,000)
Vesting of shares subject to repurchase	126				126
Repurchase of shares			(24,000)
Common stock issued under employee stock purchase plan	10,282				10,282
Common stock issued under employee stock purchase plan (in shares)			935,000
Other comprehensive income (loss)	(28)	[1]					(28)
Net loss	(202,948)							(202,948)
Balance, Ending at Jan. 31, 2016	137,901		$ 12		871,491	(1,177)	(84)	(732,341)
Balance, Ending, Shares at Jan. 31, 2016			124,121,000
Issuance of common stock upon stock option exercises	$ 11,087		$ 1		11,086
Issuance of common stock upon stock option exercises (in shares)	2,908,077		2,908,000
Issuance of common stock in connection with acquisitions	$ 1,011				1,011
Issuance of common stock in connection with acquisitions (in shares)			71,000
Issuance of common stock in connection with prior year acquisitions (in shares)			8,000
Stock-based compensation related to stock awards	78,372				78,372
Vesting of restricted stock units and restricted stock awards, net of shares withheld for employee payroll taxes			1,987,000
Employee payroll taxes withheld related to vesting of restricted stock units and restricted stock awards	(17,552)				(17,552)
Common stock issued to non-employees for services rendered (in shares)				8,000
Vesting of shares subject to repurchase	10				10
Common stock issued under employee stock purchase plan	15,726				15,726
Common stock issued under employee stock purchase plan (in shares)			1,508,000
Other comprehensive income (loss)	(36)	[1]					(36)
Net loss	(151,787)							(151,787)
Balance, Ending at Jan. 31, 2017	74,732		$ 13		960,144	(1,177)	(120)	(884,128)
Balance, Ending, Shares at Jan. 31, 2017			130,611,000
Issuance of common stock upon stock option exercises	$ 14,558				14,558
Issuance of common stock upon stock option exercises (in shares)	2,098,726		2,099,000
Stock-based compensation related to stock awards	$ 97,485				97,485
Vesting of restricted stock units and restricted stock awards, net of shares withheld for employee payroll taxes			3,008,000
Employee payroll taxes withheld related to vesting of restricted stock units and restricted stock awards	(34,776)				(34,776)
Common stock issued under employee stock purchase plan	17,521				17,521
Common stock issued under employee stock purchase plan (in shares)			1,599,000
Other comprehensive income (loss)	408	[1]					408
Net loss	(154,960)							(154,960)
Balance, Ending at Jan. 31, 2018	$ 14,968		$ 13		$ 1,054,932	$ (1,177)	$ 288	$ (1,039,088)
Balance, Ending, Shares at Jan. 31, 2018			137,317,000

[1] Tax effect was not material