CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Common Stock	Retained Earnings Reclassify upon adoption of ASU	Retained Earnings	Accumulated Other Comprehensive Income (Loss) Reclassify upon adoption of ASU	Accumulated Other Comprehensive Income (Loss)	Reclassify upon adoption of ASU	Total
Beginning balance at Dec. 31, 2017	$ 353,392		$ 321,408		$ 1,534		$ 676,334
Beginning balance (in shares) at Dec. 31, 2017	50,248
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)			42,017				42,017
Other comprehensive income (loss)					(3,567)		(3,567)
Stock-based compensation expense	$ 6,117						6,117
Options exercised	$ 10,634						10,634
Options exercised (in shares)	690
Issuance of common stock under Employee Stock Purchase Plan	$ 1,087						1,087
Issuance of common stock under Employee Stock Purchase Plans (in shares)	22
Issuance of common stock, net of offering costs	$ 205,030						205,030
Issuance of common stock, net of offering costs (in shares)	4,025
Shares surrendered in exchange for payment of payroll tax liabilities	$ (2,616)						(2,616)
Shares surrendered in exchange for payment of payroll tax liabilities (in shares)	(49)
Shares surrendered in exchange for exercise of stock options	$ (2,261)						$ (2,261)
Shares surrendered in exchange for exercise of stock options (in shares)	(43)						(43)
Ending balance (ASU 2016-02) at Dec. 31, 2018		$ 93				$ 93
Ending balance (ASU 2018-02) at Dec. 31, 2018		(748)		$ 748
Ending balance at Dec. 31, 2018	$ 571,383		363,425		(2,033)		$ 932,775
Ending balance (in shares) at Dec. 31, 2018	54,893
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)			5,451				5,451
Other comprehensive income (loss)					(4,009)		(4,009)
Stock-based compensation expense	$ 9,382						9,382
Options exercised	$ 4,930						4,930
Options exercised (in shares)	288
Issuance of common stock under Employee Stock Purchase Plan	$ 1,415						1,415
Issuance of common stock under Employee Stock Purchase Plans (in shares)	35
Shares surrendered in exchange for exercise of stock options	$ (93)						$ (93)
Shares surrendered in exchange for exercise of stock options (in shares)	(3)						(3)
Ending balance (ASU 2016-13) at Dec. 31, 2019		$ (575)				$ (575)
Ending balance at Dec. 31, 2019	$ 587,017		368,221		(5,294)		$ 949,944
Ending balance (in shares) at Dec. 31, 2019	55,213						55,213
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)			(9,843)				$ (9,843)
Other comprehensive income (loss)					(158)		(158)
Stock-based compensation expense	$ 13,433						13,433
Options exercised	$ 6,948						$ 6,948
Options exercised (in shares)	442						442
Issuance of common stock under Employee Stock Purchase Plan	$ 1,159						$ 1,159
Issuance of common stock under Employee Stock Purchase Plans (in shares)	30
Shares surrendered in exchange for payment of payroll tax liabilities	$ (866)						(866)
Shares surrendered in exchange for payment of payroll tax liabilities (in shares)	(23)
Shares surrendered in exchange for exercise of stock options	$ (1,467)						$ (1,467)
Shares surrendered in exchange for exercise of stock options (in shares)	(39)						(39)
Ending balance at Dec. 31, 2020	$ 606,224		$ 357,803		$ (5,452)		$ 958,575
Ending balance (in shares) at Dec. 31, 2020	55,623						55,623