Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	May 13, 2011
Allowance for doubtful accounts	$ 4,691	$ 4,923
Debt issuance cost (premium)	$ 29,909	$ 37,524
Treasury stock, shares	2,806,187	2,805,743
Class A Common Stock
Common stock, par value (USD per share)	$ 0.01	$ 0.01
Common stock, shares authorized	93,750,000	93,750,000
Common stock, shares issued	32,031,054	31,987,862
Common stock, shares outstanding	29,225,765	29,182,118
Class C Common Stock
Common stock, par value (USD per share)	$ 0.01	$ 0.01
Common stock, shares authorized	80,609	80,609
Common stock, shares issued	80,609	80,609
Common stock, shares outstanding	80,609	80,609
7.75% Senior Notes
Interest rate	7.75%	7.75%	7.75%
Debt issuance costs	$ 6,200	$ 8,515