Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	$ 289,412	$ 264,378	$ 252,967	$ 260,503
Net income	24,233	18,261	66,497	33,720
Class A conversion	0	0	0	0
Acquisition of treasury stock	(19,493)	(12,899)	(19,493)	(19,708)
Restricted stock issuances			(2,894)	(876)
Amortization of restricted stock	1,800	1,325	6,456	3,362
Director's compensation plan			870	557
Director's compensation plan		(5)
Other comprehensive income	50	30	148	90
Ending balance	291,541	267,377	291,541	267,377
Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared	$ (4,164)	$ (3,423)	$ (12,142)	$ (9,475)
Dividends declared (in dollars per share)	$ 0.25	$ 0.20	$ 0.72	$ 0.55
Class A Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared	$ (297)	$ (290)	$ (868)	$ (796)
Dividends declared (in dollars per share)	$ 0.23	$ 0.19	$ 0.65	$ 0.52
Common Stock [Member] | Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	$ 29,903	$ 29,538	$ 29,600	$ 29,431
Class A conversion	3	17	186	17
Restricted stock issuances			120	107
Ending balance	29,906	29,555	29,906	29,555
Common Stock [Member] | Class A Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	1,813	2,054	1,996	2,054
Class A conversion	(3)	(17)	(186)	(17)
Ending balance	1,810	2,037	1,810	2,037
Additional Paid-In Capital [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	99,016	94,581	96,850	93,208
Restricted stock issuances			(3,014)	(983)
Amortization of restricted stock	1,800	1,325	6,456	3,362
Director's compensation plan			524	314
Director's compensation plan		(5)
Ending balance	100,816	95,901	100,816	95,901
Retained Earnings [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	338,341	304,900	304,626	295,999
Net income	24,233	18,261	66,497	33,720
Ending balance	358,113	319,448	358,113	319,448
Retained Earnings [Member] | Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared	(4,164)	(3,423)	(12,142)	(9,475)
Retained Earnings [Member] | Class A Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared	(297)	(290)	(868)	(796)
Accumulated Other Comprehensive Loss [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(2,462)	(2,027)	(2,560)	(2,087)
Other comprehensive income	50	30	148	90
Ending balance	(2,412)	(1,997)	(2,412)	(1,997)
Treasury Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(177,199)	(164,668)	(177,545)	(158,102)
Acquisition of treasury stock	(19,493)	(12,899)	(19,493)	(19,708)
Director's compensation plan			346	243
Ending balance	$ (196,692)	$ (177,567)	$ (196,692)	$ (177,567)