Condensed Consolidated Statements of Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Balance at Dec. 31, 2019	$ 634,036	$ 106,360	$ 527,746	$ (70)
Balance, Shares at Dec. 31, 2019		24,296,000
Net income	20,159		20,159
Share-based compensation	1,723	$ 1,723
Common stock issued under stock Plans, net of shares withheld for employee taxes, Shares		50,000
Repurchased common stock	(7,852)	$ (725)	(7,127)
Repurchased common stock, Shares		(164,000)
Taxes paid related to net share settlement of stock awards	(401)	$ (401)
Dividends accrued of $0.435 and $0.42 per share for three months ended March 31, 2021 and March 31,2020	(10,219)		(10,219)
Other comprehensive income	158			158
Balance at Mar. 31, 2020	637,604	$ 106,957	530,559	88
Balance, Shares at Mar. 31, 2020		24,182,000
Balance at Dec. 31, 2020	$ 682,604	$ 106,289	576,419	(104)
Balance, Shares at Dec. 31, 2020	24,128,000	24,128,000
Net income	$ 17,398		17,398
Share-based compensation	1,777	$ 1,777
Common stock issued under stock Plans, net of shares withheld for employee taxes, Shares		78,000
Taxes paid related to net share settlement of stock awards	(3,482)	$ (3,482)
Dividends accrued of $0.435 and $0.42 per share for three months ended March 31, 2021 and March 31,2020	(10,650)		(10,650)
Other comprehensive income	38			38
Balance at Mar. 31, 2021	$ 687,685	$ 104,584	$ 583,167	$ (66)
Balance, Shares at Mar. 31, 2021	24,206,000	24,206,000