Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings
Beginning balance (in shares) at Dec. 31, 2019		15,178
Beginning balance at Dec. 31, 2019	$ 296,733	$ 152	$ 190,620	$ 105,961
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee benefit plans (in shares)		258
Issuance of common stock under employee benefit plans	0	$ 2	(2)
Deemed repurchased shares of common and restricted stock for tax withholding (in shares)		(79)
Deemed repurchased shares of common and restricted stock for tax withholding	(2,097)	$ (1)	(2,096)
Stock-based compensation	5,265		5,265
Repurchased and retired shares of common stock (in shares)		(548)
Repurchased and retired shares of common stock	(13,608)	$ (5)		(13,603)
Net income	11,751			11,751
Ending balance (in shares) at Sep. 30, 2020		14,809
Ending balance at Sep. 30, 2020	298,044	$ 148	193,787	104,109
Beginning balance (in shares) at Dec. 31, 2020		14,809
Beginning balance at Dec. 31, 2020	306,925	$ 148	195,597	111,180
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock in public offering (in shares)		3,680
Issuance of common stock in public offering	86,205	$ 37	86,168
Issuance of common stock under employee benefit plans (in shares)		319
Issuance of common stock under employee benefit plans	0	$ 3	(3)
Deemed repurchased shares of common and restricted stock for tax withholding (in shares)		(99)
Deemed repurchased shares of common and restricted stock for tax withholding	(3,032)	$ (1)	(3,031)
Stock-based compensation	5,969		5,969
Net income	8,371			8,371
Ending balance (in shares) at Sep. 30, 2021		18,709
Ending balance at Sep. 30, 2021	$ 404,438	$ 187	$ 284,700	$ 119,551