Consolidated Statements of Stockholders' Equity (Deficit) (USD $) In Thousands, except Share data	Total USD ($)	Treasury Stock	Additional Paid-in Capital USD ($)	Accumulated Deficit USD ($)	Accumulated Other Comprehensive Income (Loss) USD ($)	Class A common stock USD ($)	Class B common stock USD ($)	Class U common stock USD ($)
Balance, Beginning at Dec. 31, 2011	$ (561)		$ 938,453	$ (939,022)		$ 5	$ 2	$ 1
Balance, Beginning, Shares at Dec. 31, 2011						53,514,769	22,188,161	9,352,729
Issuance of common stock upon exercise of stock options or awards of restricted stock units	23		23
Issuance of common stock upon exercise of stock options or awards of restricted stock units, Shares	50,000					889,457
Stock-based compensation expense	2,651		2,651
Dividends paid	(10,313)		(10,313)
Change in fair value of interest rate swap agreements	0
Net income (loss)	13,601			13,601
Balance, Ending at Dec. 31, 2012	5,401		930,814	(925,421)		5	2	1
Balance, Ending, Shares at Dec. 31, 2012						54,404,226	22,188,161	9,352,729
Issuance of common stock upon exercise of stock options or awards of restricted stock units	2,807		2,806			1
Issuance of common stock upon exercise of stock options or awards of restricted stock units, Shares	1,683,000					2,170,438
Stock-based compensation expense	4,771		4,771
Class B common stock exchanged for Class A common stock						3,218,939	(3,218,939)
Dividends paid	(11,014)		(11,014)
Change in fair value of interest rate swap agreements	234				234
Net income (loss)	133,825			133,825
Balance, Ending at Dec. 31, 2013	136,024		927,377	(791,596)	234	6	2	1
Balance, Ending, Shares at Dec. 31, 2013						59,793,603	18,969,222	9,352,729
Issuance of common stock upon exercise of stock options or awards of restricted stock units	1,841		1,841
Issuance of common stock upon exercise of stock options or awards of restricted stock units, Shares	1,042,000					1,531,100
Stock-based compensation expense	4,351		4,351
Class B common stock exchanged for Class A common stock						39,187	(39,187)
Repurchase of Class A common stock	(12,543)		(12,543)			(12,500)
Repurchase of Class A common stock, Shares		(2,469,920)				2,500,000
Retirement of treasury stock, Shares		2,469,920				(2,469,920)
Dividends paid	(8,865)		(8,865)
Change in fair value of interest rate swap agreements	(2,372)				(2,372)
Net income (loss)	27,122			27,122
Balance, Ending at Dec. 31, 2014	$ 145,558		$ 912,161	$ (764,474)	$ (2,138)	$ 6	$ 2	$ 1
Balance, Ending, Shares at Dec. 31, 2014						58,893,970	18,930,035	9,352,729