Condensed Consolidated Statement of Stockholders' Equity (Unaudited) - 6 months ended Jun. 30, 2017 - USD ($) $ in Thousands	2007 Incentive Plan [Member] Common Stock [Member] Common Class A [Member]	2007 Incentive Plan [Member] Common Stock [Member]	2007 Incentive Plan [Member] Treasury Stock [Member] Common Class A [Member]	2007 Incentive Plan [Member] Treasury Stock [Member]	2007 Incentive Plan [Member]	2017 Equity and Incentive Compensation Plan [Member] Common Stock [Member] Common Class A [Member]	2017 Equity and Incentive Compensation Plan [Member]	Common Stock [Member] Common Class A [Member]	Common Stock [Member]	Retained Earnings [Member]	Treasury Stock [Member] Common Class A [Member]	Treasury Stock [Member]	AOCI Attributable to Parent [Member]	Common Class A [Member]	Total
Balance (in shares) at Dec. 31, 2016								8,073,993	71,229,497		(1,669,131)	(5,135,406)
Balance at Dec. 31, 2016								$ 21,764	$ 658,135	$ (101,365)	$ (23,340)	$ (44,688)	$ (17,645)	$ 492,861	$ 492,861
Adoption of ASU 2016-09 excess tax benefit for stock-based compensation at Dec. 31, 2016										1,107					1,107
Balance at Jun. 30, 2017								23,039	$ 659,647	(19,192)	$ (24,232)	$ (49,562)	$ (17,645)	$ 572,055	572,055
Net income										$ 81,066					81,066
401(k) plan (in shares)									1,135
401(k) plan									$ 15						15
Issuance of restricted stock			$ (892)	$ (874)	$ (1,766)
Issuance of restricted stock (in shares)	198,220	307,943	(81,561)	(77,632)		76,856
Repurchase of common stock (in shares)												(322,038)
Repurchase of common stock												$ (4,000)			(4,000)
Share-based compensation								$ 1,275	$ 1,497						$ 2,772
Balance (in shares) at Jun. 30, 2017								8,349,069	71,538,575		(1,750,692)	(5,535,076)