CONSOLIDATED STATEMENTS STOCKHOLDERS EQUITY - USD ($) $ in Thousands	Total	Class A and B Common Stock [Member]	Additional Paid-in Capital [Member]	Purchase Price in Excess Of Predecessor Basis, Net Of Tax [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income [Member]	Treasury Stock [Member]
Beginning Balance at Dec. 31, 2019	$ 1,075,279	$ 419	$ 179,637	$ (15,458)	$ 1,179,601	$ (186)	$ (268,734)
Beginning Balance (in shares) at Dec. 31, 2019		41,887,088					7,870,888
Stock withheld for payments of withholding taxes	(3,944)						$ (3,944)
Stock withheld for payments of withholding taxes (in shares)							(75,595)
Issuance of restricted stock awards, net of forfeitures			(8,932)				$ 8,932
Issuance of restricted stock awards, net of forfeitures (in shares)							239,845
Share-based compensation expense	8,209		8,209
Net income	26,390				26,390
Foreign currency translation adjustment	(97)					(97)
Ending Balance at Jun. 30, 2020	1,105,837	$ 419	178,914	(15,458)	1,205,991	(283)	$ (263,746)
Ending Balance (in shares) at Jun. 30, 2020		41,887,088					7,706,638
Beginning Balance at Mar. 31, 2020	1,088,709	$ 419	175,370	(15,458)	1,192,837	(320)	$ (264,139)
Beginning Balance (in shares) at Mar. 31, 2020		41,887,088					7,680,505
Stock withheld for payments of withholding taxes	(175)						$ (175)
Stock withheld for payments of withholding taxes (in shares)							(3,878)
Issuance of restricted stock awards, net of forfeitures			(568)				$ 568
Issuance of restricted stock awards, net of forfeitures (in shares)							(22,255)
Share-based compensation expense	4,112		4,112
Net income	13,154				13,154
Foreign currency translation adjustment	37					37
Ending Balance at Jun. 30, 2020	1,105,837	$ 419	178,914	(15,458)	1,205,991	(283)	$ (263,746)
Ending Balance (in shares) at Jun. 30, 2020		41,887,088					7,706,638
Beginning Balance at Dec. 31, 2020	1,157,923	$ 419	186,058	(15,458)	1,253,160	(191)	$ (266,065)
Beginning Balance (in shares) at Dec. 31, 2020		41,887,088					7,675,084
Stock withheld for payments of withholding taxes	(3,973)						$ (3,973)
Stock withheld for payments of withholding taxes (in shares)							(69,208)
Issuance of restricted stock awards, net of forfeitures			(9,137)				$ 9,137
Issuance of restricted stock awards, net of forfeitures (in shares)							224,551
Share-based compensation expense	9,289		9,289
Net income	43,822				43,822
Foreign currency translation adjustment	15					15
Ending Balance at Jun. 30, 2021	1,207,076	$ 419	186,210	(15,458)	1,296,982	(176)	$ (260,901)
Ending Balance (in shares) at Jun. 30, 2021		41,887,088					7,519,741
Beginning Balance at Mar. 31, 2021	1,176,501	$ 419	182,005	(15,458)	1,270,390	(201)	$ (260,654)
Beginning Balance (in shares) at Mar. 31, 2021		41,887,088					7,469,756
Stock withheld for payments of withholding taxes	(214)						$ (214)
Stock withheld for payments of withholding taxes (in shares)							(3,229)
Issuance of restricted stock awards, net of forfeitures			33				$ (33)
Issuance of restricted stock awards, net of forfeitures (in shares)							(46,756)
Share-based compensation expense	4,172		4,172
Net income	26,592				26,592
Foreign currency translation adjustment	25					25
Ending Balance at Jun. 30, 2021	$ 1,207,076	$ 419	$ 186,210	$ (15,458)	$ 1,296,982	$ (176)	$ (260,901)
Ending Balance (in shares) at Jun. 30, 2021		41,887,088					7,519,741