Consolidated Statements of Changes in Mezzanine Equity and Stockholders’ Equity - USD ($) $ in Thousands	Total	Revision of Prior Period, Accounting Standards Update, Adjustment	Series A Convertible Preferred Stock	Common Stock	Additional Paid-in Capital	Additional Paid-in Capital Revision of Prior Period, Accounting Standards Update, Adjustment	Accumulated Deficit	Accumulated Deficit Revision of Prior Period, Accounting Standards Update, Adjustment	Accumulated Other Comprehensive Income/(Loss)
Beginning balance (in shares) at Dec. 31, 2019				93,001,597
Beginning balance at Dec. 31, 2019	$ 331,446			$ 93	$ 583,097		$ (251,786)		$ 42
Increase (Decrease) in Stockholders' Equity
Common Stock Dividends, Shares				30,640
Issuance of common stock, net (in shares)				4,484,305
Issuance of common stock, net	69,701			$ 4	69,697
Issuance of common stock pursuant to employee stock purchase program (in shares)				186,925
Issuance of common stock pursuant to employee stock purchase program	3,436				3,436
Issuance of common stock pursuant to exercise of stock options (in shares)				1,825,684
Issuance of common stock pursuant to exercise of stock options	11,502			$ 2	11,500
Issuance of common stock pursuant to settlement of restricted stock units (in shares)				1,017,675
Issuance of common stock pursuant to settlement of restricted stock units	0			$ 1	(1)
Common stock surrendered for employees' tax liability upon settlement of restricted stock units (in shares)				(305,410)
Common stock surrendered for employees' tax liability upon settlement of restricted stock units	(10,987)				(10,987)
Stock-based compensation	27,477				27,477
Other comprehensive loss	266								266
Net (loss) income	(32,562)						(32,562)
Ending balance (in shares) at Sep. 30, 2020				100,241,416
Ending balance at Sep. 30, 2020	400,279			$ 100	684,219		(284,348)		308
Beginning balance (in shares) at Dec. 31, 2019			0
Beginning balance at Dec. 31, 2019			$ 0
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of convertible preferred stock, net (in shares)			40,000
Issuance of convertible preferred stock, net			$ 39,812
Ending balance (in shares) at Sep. 30, 2020			40,000
Ending balance at Sep. 30, 2020			$ 39,812
Beginning balance (in shares) at Jun. 30, 2020				99,394,432
Beginning balance at Jun. 30, 2020	355,260			$ 99	673,234		(318,514)		441
Increase (Decrease) in Stockholders' Equity
Common Stock Dividends, Shares				30,640
Issuance of common stock pursuant to exercise of stock options (in shares)				567,854
Issuance of common stock pursuant to exercise of stock options	3,998			$ 1	3,997
Issuance of common stock pursuant to settlement of restricted stock units (in shares)				353,160
Common stock surrendered for employees' tax liability upon settlement of restricted stock units (in shares)				(104,670)
Common stock surrendered for employees' tax liability upon settlement of restricted stock units	(4,922)
Stock-based compensation	11,910				11,910
Other comprehensive loss	(133)								(133)
Net (loss) income	34,166						34,166
Ending balance (in shares) at Sep. 30, 2020				100,241,416
Ending balance at Sep. 30, 2020	$ 400,279			$ 100	684,219		(284,348)		308
Beginning balance (in shares) at Jun. 30, 2020			40,000
Beginning balance at Jun. 30, 2020			$ 39,801
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of convertible preferred stock, net			$ 11
Ending balance (in shares) at Sep. 30, 2020			40,000
Ending balance at Sep. 30, 2020			$ 39,812
Beginning balance (in shares) at Dec. 31, 2020	103,000,594			103,000,594
Beginning balance at Dec. 31, 2020	$ 590,557	$ (162,478)		$ 103	860,556	$ (170,240)	(270,313)	$ 7,762	211
Increase (Decrease) in Stockholders' Equity
Common Stock Dividends, Shares				91,920
Issuance of common stock pursuant to employee stock purchase program (in shares)				135,426
Issuance of common stock pursuant to employee stock purchase program	$ 7,299				7,299
Issuance of common stock pursuant to exercise of stock options (in shares)	1,354,078			1,354,078
Issuance of common stock pursuant to exercise of stock options	$ 6,896			$ 1	6,895
Issuance of common stock pursuant to settlement of restricted stock units (in shares)				1,072,378
Issuance of common stock pursuant to settlement of restricted stock units	0			$ 1	(1)
Common stock surrendered for employees' tax liability upon settlement of restricted stock units (in shares)				(319,229)
Common stock surrendered for employees' tax liability upon settlement of restricted stock units	(21,088)				(21,088)
Purchases of capped calls related to convertible senior notes	(62,647)				(62,647)
Issuance of common stock in connection with conversion of convertible senior notes (in shares)				40,768
Issuance of common stock in connection with conversion of convertible senior notes	(63)				(63)
Stock-based compensation	42,183				42,183
Other comprehensive loss	(164)								(164)
Net (loss) income	$ (82,611)						(82,611)
Ending balance (in shares) at Sep. 30, 2021	105,375,935			105,375,935
Ending balance at Sep. 30, 2021	$ 317,884			$ 105	662,894		(345,162)		47
Beginning balance (in shares) at Dec. 31, 2020	40,000		40,000
Beginning balance at Dec. 31, 2020	$ 39,823		$ 39,823
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of convertible preferred stock, net			$ 34
Ending balance (in shares) at Sep. 30, 2021	40,000		40,000
Ending balance at Sep. 30, 2021	$ 39,857		$ 39,857
Beginning balance (in shares) at Jun. 30, 2021				104,838,095
Beginning balance at Jun. 30, 2021	325,596			$ 105	651,627		(326,213)		77
Increase (Decrease) in Stockholders' Equity
Common Stock Dividends, Shares				30,640
Issuance of common stock pursuant to exercise of stock options (in shares)				264,875
Issuance of common stock pursuant to exercise of stock options	1,696			$ 0	1,696
Issuance of common stock pursuant to settlement of restricted stock units (in shares)				334,283
Common stock surrendered for employees' tax liability upon settlement of restricted stock units (in shares)				(95,122)
Common stock surrendered for employees' tax liability upon settlement of restricted stock units	(4,558)				(4,558)
Issuance of common stock in connection with conversion of convertible senior notes (in shares)				3,164
Issuance of common stock in connection with conversion of convertible senior notes	(10)				(10)
Stock-based compensation	14,139				14,139
Other comprehensive loss	(30)								(30)
Net (loss) income	$ (18,949)						(18,949)
Ending balance (in shares) at Sep. 30, 2021	105,375,935			105,375,935
Ending balance at Sep. 30, 2021	$ 317,884			$ 105	$ 662,894		$ (345,162)		$ 47
Beginning balance (in shares) at Jun. 30, 2021			40,000
Beginning balance at Jun. 30, 2021			$ 39,846
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of convertible preferred stock, net	$ 0		$ 11
Ending balance (in shares) at Sep. 30, 2021	40,000		40,000
Ending balance at Sep. 30, 2021	$ 39,857		$ 39,857