UNAUDITED CONDENSED CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS’ EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Treasury Stock
Shares at beginning of period (in shares) at Dec. 31, 2018			71,856					45,822
Balance at beginning of period at Dec. 31, 2018	$ 168,331		$ 719	$ 447,337	$ 1,296	$ 237,308		$ (518,329)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	26,855					26,855
Reclassification of stranded tax effects	0				168	(168)
Issuance for stock-based compensation and dividends, net of forfeitures (in shares)			4
Issuance for stock-based compensation and dividends, net of forfeitures	0			233		(233)
Stock-based compensation expense	2,620			2,620
Employee stock purchase plan (in shares)								(5)
Employee stock purchase plan	140			86				$ 54
Dividends	(4,406)					(4,406)
Change in fair value of interest rate swaps, net of tax	(280)				(280)
Repurchases of common stock (in shares)								432
Repurchases of common stock	(14,688)							$ (14,688)
Shares at end of period (in shares) at Mar. 31, 2019			71,860					46,249
Balance at end of period at Mar. 31, 2019	178,572		$ 719	450,276	1,184	259,356		$ (532,963)
Shares at beginning of period (in shares) at Dec. 31, 2018			71,856					45,822
Balance at beginning of period at Dec. 31, 2018	168,331		$ 719	447,337	1,296	237,308		$ (518,329)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	101,714
Employee stock purchase plan	283
Change in fair value of interest rate swaps, net of tax	(758)
Shares at end of period (in shares) at Jun. 30, 2019			71,865					47,293
Balance at end of period at Jun. 30, 2019	214,856		$ 719	454,071	706	329,760		$ (570,400)
Shares at beginning of period (in shares) at Mar. 31, 2019			71,860					46,249
Balance at beginning of period at Mar. 31, 2019	178,572		$ 719	450,276	1,184	259,356		$ (532,963)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	74,859					74,859
Issuance for stock-based compensation and dividends, net of forfeitures (in shares)			5
Issuance for stock-based compensation and dividends, net of forfeitures	0			177		(177)
Stock-based compensation expense	3,524			3,524
Employee stock purchase plan (in shares)								(4)
Employee stock purchase plan	143			94				$ 49
Dividends	(4,278)					(4,278)
Change in fair value of interest rate swaps, net of tax	(478)				(478)
Repurchases of common stock (in shares)								1,048
Repurchases of common stock	(37,486)							$ (37,486)
Shares at end of period (in shares) at Jun. 30, 2019			71,865					47,293
Balance at end of period at Jun. 30, 2019	214,856		$ 719	454,071	706	329,760		$ (570,400)
Shares at beginning of period (in shares) at Dec. 31, 2019			72,202					49,277
Balance at beginning of period at Dec. 31, 2019	167,263	$ (214)	$ 722	459,545	(1,526)	350,545	$ (214)	$ (642,023)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	9,106					9,106
Issuance for stock-based compensation and dividends, net of forfeitures (in shares)			4
Issuance for stock-based compensation and dividends, net of forfeitures	0			218		(218)
Stock-based compensation expense	2,896			2,896
Employee stock purchase plan (in shares)								(4)
Employee stock purchase plan	142			93				$ 49
Dividends	(4,293)					(4,293)
Change in fair value of interest rate swaps, net of tax	(1,121)				(1,121)
Repurchases of common stock (in shares)								685
Repurchases of common stock	(20,380)							$ (20,380)
Shares at end of period (in shares) at Mar. 31, 2020			72,198					49,958
Balance at end of period at Mar. 31, 2020	153,399		$ 722	462,752	(2,647)	354,926		$ (662,354)
Shares at beginning of period (in shares) at Dec. 31, 2019			72,202					49,277
Balance at beginning of period at Dec. 31, 2019	167,263	$ (214)	$ 722	459,545	(1,526)	350,545	$ (214)	$ (642,023)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	18,991
Employee stock purchase plan	276
Change in fair value of interest rate swaps, net of tax	(1,591)
Shares at end of period (in shares) at Jun. 30, 2020			72,237					50,295
Balance at end of period at Jun. 30, 2020	152,476		$ 722	465,957	(3,117)	360,409		$ (671,495)
Shares at beginning of period (in shares) at Mar. 31, 2020			72,198					49,958
Balance at beginning of period at Mar. 31, 2020	153,399		$ 722	462,752	(2,647)	354,926		$ (662,354)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	9,885					9,885
Issuance for stock-based compensation and dividends, net of forfeitures (in shares)			39
Issuance for stock-based compensation and dividends, net of forfeitures	0			240		(240)
Stock-based compensation expense	2,903			2,903
Employee stock purchase plan (in shares)								(5)
Employee stock purchase plan	134			62				$ 72
Dividends	(4,162)					(4,162)
Change in fair value of interest rate swaps, net of tax	(470)				(470)
Repurchases of common stock (in shares)								342
Repurchases of common stock	(9,213)							$ (9,213)
Shares at end of period (in shares) at Jun. 30, 2020			72,237					50,295
Balance at end of period at Jun. 30, 2020	$ 152,476		$ 722	$ 465,957	$ (3,117)	$ 360,409		$ (671,495)