Condensed Consolidated Statements of Changes In Stockholders' Equity - USD ($) $ in Thousands	Total	Adjustment related to Accounting Standards Update 2018-02 adoption	Capital Stock Preferred	Issued Common	Additional Paid-In Capital	Retained Earnings	Retained Earnings Adjustment related to Accounting Standards Update 2018-02 adoption	Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss Adjustment related to Accounting Standards Update 2018-02 adoption	Treasury Stock
Beginning Balance at Dec. 31, 2018	$ 201,441	$ 0	$ 4	$ 6,715	$ 15,375	$ 198,914	$ (69)	$ (164)	$ 69	$ (19,403)
Comprehensive income:
Net income	9,720					9,720
Other comprehensive income	14							14
Dividends and dividend equivalents of $0.12 per common share and per restricted stock unit, net of estimated forfeitures	(1,714)					(1,714)
Share-based compensation	1,031				1,031
Stock shares awarded, forfeited or vested	94				(3,770)					3,864
Stock shares repurchased	(5,467)									(5,467)
Ending Balance at Mar. 31, 2019	$ 205,119		4	6,715	12,636	206,851		(81)		(21,006)
Comprehensive income:
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201802Member
Beginning Balance at Dec. 31, 2018	$ 201,441	$ 0	4	6,715	15,375	198,914	$ (69)	(164)	$ 69	(19,403)
Comprehensive income:
Net income	25,846
Ending Balance at Sep. 30, 2019	219,420		4	6,715	13,601	219,551		(104)		(20,347)
Beginning Balance at Mar. 31, 2019	205,119		4	6,715	12,636	206,851		(81)		(21,006)
Comprehensive income:
Net income	7,911					7,911
Other comprehensive income	(16)							(16)
Dividends and dividend equivalents of $0.12 per common share and per restricted stock unit, net of estimated forfeitures	(1,713)					(1,713)
Share-based compensation	481				481
Stock shares awarded, forfeited or vested	660									660
Ending Balance at Jun. 30, 2019	212,442		4	6,715	13,117	213,049		(97)		(20,346)
Comprehensive income:
Net income	8,215					8,215
Other comprehensive income	(7)							(7)
Dividends and dividend equivalents of $0.12 per common share and per restricted stock unit, net of estimated forfeitures	(1,713)					(1,713)
Share-based compensation	484				484
Stock shares repurchased	(1)									(1)
Ending Balance at Sep. 30, 2019	219,420		4	6,715	13,601	219,551		(104)		(20,347)
Beginning Balance at Dec. 31, 2019	231,044		4	6,715	14,029	230,784		(246)		(20,242)
Comprehensive income:
Net income	9,842					9,842
Other comprehensive income	(6)							(6)
Dividends and dividend equivalents of $0.12 per common share and per restricted stock unit, net of estimated forfeitures	(2,059)					(2,059)
Share-based compensation	902				902
Stock shares awarded, forfeited or vested	237				(567)					804
Stock shares repurchased	(4,395)									(4,395)
Ending Balance at Mar. 31, 2020	235,565		4	6,715	14,364	238,567		(252)		(23,833)
Beginning Balance at Dec. 31, 2019	231,044		4	6,715	14,029	230,784		(246)		(20,242)
Comprehensive income:
Net income	28,713
Ending Balance at Sep. 30, 2020	252,001		4	6,715	15,284	253,354		(157)		(23,199)
Beginning Balance at Mar. 31, 2020	235,565		4	6,715	14,364	238,567		(252)		(23,833)
Comprehensive income:
Net income	8,490					8,490
Other comprehensive income	21							21
Dividends and dividend equivalents of $0.12 per common share and per restricted stock unit, net of estimated forfeitures	(2,041)					(2,041)
Share-based compensation	662				662
Ending Balance at Jun. 30, 2020	242,697		4	6,715	15,026	245,016		(231)		(23,833)
Comprehensive income:
Net income	10,381					10,381
Other comprehensive income	74							74
Dividends and dividend equivalents of $0.12 per common share and per restricted stock unit, net of estimated forfeitures	(2,043)					(2,043)
Share-based compensation	258				258
Stock shares awarded, forfeited or vested	634									634
Ending Balance at Sep. 30, 2020	$ 252,001		$ 4	$ 6,715	$ 15,284	$ 253,354		$ (157)		$ (23,199)