CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Treasury Stock	Accumulated Deficit	Total
BALANCE at Dec. 31, 2018	$ 11	$ 462,004	$ (3,831)	$ (404,067)	$ 54,117
BALANCE (in shares) at Dec. 31, 2018	106,206,545
BALANCE at Mar. 31, 2019	$ 11	477,389	(7,432)	(421,167)	48,801
BALANCE (in shares) at Mar. 31, 2019	108,670,420
BALANCE at Dec. 31, 2018	$ 11	462,004	(3,831)	(404,067)	54,117
BALANCE (in shares) at Dec. 31, 2018	106,206,545
Issuance of common stock for stock option exercises		1,720			1,720
Issuance of common stock for stock option exercises (in shares)	557,404
Issuance of common stock pursuant to the Employee Stock Purchase Plan		2,047			2,047
Issuance of common stock pursuant to the Employee Stock Purchase Plan (in shares)	518,112
Issuance of common stock pursuant to the Employee Stock-Settled Bonus Plans		10,485			10,485
Issuance of common stock pursuant to the Employee Stock-Settled Bonus Plans (in shares)	2,170,855
Shares withheld for net settlement of equity awards		(4,784)			(4,784)
Shares withheld for net settlement of equity awards (in shares)	(962,042)
Repurchase of common stock			(6,591)		(6,591)
Repurchase of common stock (in shares)	(1,281,186)
Vesting of restricted stock units (in shares)	2,560,333
Stock-based compensation		13,121			13,121
Net loss				(32,689)	(32,689)
BALANCE at Jun. 30, 2019	$ 11	484,593	(10,422)	(436,756)	37,426
BALANCE (in shares) at Jun. 30, 2019	109,770,021
BALANCE at Mar. 31, 2019	$ 11	477,389	(7,432)	(421,167)	48,801
BALANCE (in shares) at Mar. 31, 2019	108,670,420
Issuance of common stock for stock option exercises		921			921
Issuance of common stock for stock option exercises (in shares)	306,936
Shares withheld for net settlement of equity awards		(375)			(375)
Shares withheld for net settlement of equity awards (in shares)	(67,848)
Repurchase of common stock			(2,990)		(2,990)
Repurchase of common stock (in shares)	(542,220)
Vesting of restricted stock units (in shares)	1,402,733
Stock-based compensation		6,658			6,658
Net loss				(15,589)	(15,589)
BALANCE at Jun. 30, 2019	$ 11	484,593	(10,422)	(436,756)	37,426
BALANCE (in shares) at Jun. 30, 2019	109,770,021
BALANCE at Dec. 31, 2019	$ 11	504,041	(15,141)	(452,913)	35,998
BALANCE (in shares) at Dec. 31, 2019	112,725,391
BALANCE at Mar. 31, 2020	$ 12	517,575	(15,825)	(465,574)	36,188
BALANCE (in shares) at Mar. 31, 2020	115,369,759
BALANCE at Dec. 31, 2019	$ 11	504,041	(15,141)	(452,913)	35,998
BALANCE (in shares) at Dec. 31, 2019	112,725,391
Issuance of common stock for stock option exercises		499			$ 499
Issuance of common stock for stock option exercises (in shares)	142,300				142,300
Issuance of common stock pursuant to the Employee Stock Purchase Plan		2,151			$ 2,151
Issuance of common stock pursuant to the Employee Stock Purchase Plan (in shares)	562,233
Issuance of common stock pursuant to the Employee Stock-Settled Bonus Plans	$ 1	7,633			7,634
Issuance of common stock pursuant to the Employee Stock-Settled Bonus Plans (in shares)	1,730,682
Shares withheld for net settlement of equity awards		(3,542)			$ (3,542)
Shares withheld for net settlement of equity awards (in shares)	(815,527)				(815,527)
Repurchase of common stock			(684)		$ (684)
Repurchase of common stock (in shares)	(210,618)				(210,618)
Vesting of restricted stock units (in shares)	2,709,043
Stock-based compensation		14,601			$ 14,601
Net loss				(21,169)	(21,169)
BALANCE at Jun. 30, 2020	$ 12	525,383	(15,825)	(474,082)	35,488
BALANCE (in shares) at Jun. 30, 2020	116,843,504
BALANCE at Mar. 31, 2020	$ 12	517,575	(15,825)	(465,574)	36,188
BALANCE (in shares) at Mar. 31, 2020	115,369,759
Issuance of common stock for stock option exercises		382			382
Issuance of common stock for stock option exercises (in shares)	112,503
Shares withheld for net settlement of equity awards		(360)			(360)
Shares withheld for net settlement of equity awards (in shares)	(77,294)
Vesting of restricted stock units (in shares)	1,438,536
Stock-based compensation		7,786			7,786
Net loss				(8,508)	(8,508)
BALANCE at Jun. 30, 2020	$ 12	$ 525,383	$ (15,825)	$ (474,082)	$ 35,488
BALANCE (in shares) at Jun. 30, 2020	116,843,504