Supplemental Condensed Consolidating Financial Information Condensed Consolidating Balance Sheet (Additional Information) (Details) - USD ($) $ / shares in Units, $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	May. 13, 2011
Condensed Balance Sheet Statements, Captions [Line Items]
Allowance for doubtful accounts	$ 5,677	$ 6,004
Treasury stock, shares	22,395,642	22,619,554
Class A common stock
Condensed Balance Sheet Statements, Captions [Line Items]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	750,000,000	750,000,000
Common stock, shares issued	255,443,945	254,997,925
Common stock, shares outstanding	233,048,303	232,378,371
Class C common stock
Condensed Balance Sheet Statements, Captions [Line Items]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	644,871	644,871
Common stock, shares issued	644,871	644,871
Common stock, shares outstanding	644,871	644,871
7.75% senior notes
Condensed Balance Sheet Statements, Captions [Line Items]
Interest on borrowings, per annum	7.75%	7.75%	7.75%