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, 2020	$ 682,604	$ 106,289	$ 576,419	$ (104)
Balance, Shares at Dec. 31, 2020		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 $0.455, $0.455, $0.455, $0.435, $0.435 and $0.435 per share for three months ended March 31, 2022, June 30,2022, September 30, 2022 and three months ended March 31, 2021, June 30, 2021, September 30, 2021	(10,650)		(10,650)
Other comprehensive income (loss)	38			38
Balance at Mar. 31, 2021	687,685	$ 104,584	583,167	(66)
Balance, Shares at Mar. 31, 2021		24,206,000
Balance at Dec. 31, 2020	682,604	$ 106,289	576,419	(104)
Balance, Shares at Dec. 31, 2020		24,128,000
Net income	61,258
Balance at Sep. 30, 2021	712,456	$ 106,744	605,754	(42)
Balance, Shares at Sep. 30, 2021		24,247,000
Balance at Mar. 31, 2021	687,685	$ 104,584	583,167	(66)
Balance, Shares at Mar. 31, 2021		24,206,000
Net income	20,608		20,608
Share-based compensation	1,820	$ 1,820
Common stock issued under stock Plans, net of shares withheld for employee taxes, Shares		39,000
Taxes paid related to net share settlement of stock awards	(1,346)	$ (1,346)
Dividends accrued of $0.455, $0.455, $0.455, $0.435, $0.435 and $0.435 per share for three months ended March 31, 2022, June 30,2022, September 30, 2022 and three months ended March 31, 2021, June 30, 2021, September 30, 2021	(10,643)		(10,643)
Other comprehensive income (loss)	(3)			(3)
Balance at Jun. 30, 2021	698,121	$ 105,058	593,132	(69)
Balance, Shares at Jun. 30, 2021		24,245,000
Net income	23,252		23,252
Share-based compensation	1,705	$ 1,705
Common stock issued under stock Plans, net of shares withheld for employee taxes, Shares		2,000
Taxes paid related to net share settlement of stock awards	(19)	$ 19
Dividends accrued of $0.455, $0.455, $0.455, $0.435, $0.435 and $0.435 per share for three months ended March 31, 2022, June 30,2022, September 30, 2022 and three months ended March 31, 2021, June 30, 2021, September 30, 2021	(10,630)		10,630
Other comprehensive income (loss)	27			27
Balance at Sep. 30, 2021	712,456	$ 106,744	605,754	(42)
Balance, Shares at Sep. 30, 2021		24,247,000
Balance at Dec. 31, 2021	$ 732,021	$ 108,610	623,465	(54)
Balance, Shares at Dec. 31, 2021	24,260,000	24,260,000
Net income	$ 18,793		18,793
Share-based compensation	1,760	$ 1,760
Common stock issued under stock Plans, net of shares withheld for employee taxes, Shares		75,000
Taxes paid related to net share settlement of stock awards	(3,605)	$ (3,605)
Dividends accrued of $0.455, $0.455, $0.455, $0.435, $0.435 and $0.435 per share for three months ended March 31, 2022, June 30,2022, September 30, 2022 and three months ended March 31, 2021, June 30, 2021, September 30, 2021	(11,084)		(11,084)
Other comprehensive income (loss)	3			3
Balance at Mar. 31, 2022	737,888	$ 106,765	631,174	(51)
Balance, Shares at Mar. 31, 2022		24,335,000
Balance at Dec. 31, 2021	$ 732,021	$ 108,610	623,465	(54)
Balance, Shares at Dec. 31, 2021	24,260,000	24,260,000
Net income	$ 75,497
Balance at Sep. 30, 2022	$ 773,068	$ 107,463	665,530	75
Balance, Shares at Sep. 30, 2022	24,382,000	24,382,000
Balance at Mar. 31, 2022	$ 737,888	$ 106,765	631,174	(51)
Balance, Shares at Mar. 31, 2022		24,335,000
Net income	26,137		26,137
Share-based compensation	1,652	$ 1,652
Common stock issued under stock Plans, net of shares withheld for employee taxes, Shares		43,000
Taxes paid related to net share settlement of stock awards	(2,523)	$ (2,523)
Dividends accrued of $0.455, $0.455, $0.455, $0.435, $0.435 and $0.435 per share for three months ended March 31, 2022, June 30,2022, September 30, 2022 and three months ended March 31, 2021, June 30, 2021, September 30, 2021	(11,181)		(11,181)
Other comprehensive income (loss)	61			61
Balance at Jun. 30, 2022	752,034	$ 105,894	646,130	10
Balance, Shares at Jun. 30, 2022		24,378,000
Net income	30,567		30,567
Share-based compensation	1,694	$ 1,694
Common stock issued under stock Plans, net of shares withheld for employee taxes, Shares		4,000
Taxes paid related to net share settlement of stock awards	(125)	$ (125)
Dividends accrued of $0.455, $0.455, $0.455, $0.435, $0.435 and $0.435 per share for three months ended March 31, 2022, June 30,2022, September 30, 2022 and three months ended March 31, 2021, June 30, 2021, September 30, 2021	(11,167)		11,167
Other comprehensive income (loss)	65			65
Balance at Sep. 30, 2022	$ 773,068	$ 107,463	$ 665,530	$ 75
Balance, Shares at Sep. 30, 2022	24,382,000	24,382,000