Supplemental Condensed Consolidated Financial Information (Condensed Consolidated Balance Sheet Additional Information) (Detail) - USD ($) $ / shares in Units, $ in Thousands	Sep. 30, 2016	Dec. 31, 2015	May 13, 2011
Condensed Balance Sheet Statements, Captions [Line Items]
Allowance for doubtful accounts	$ 5,207	$ 4,923
Interest rate	7.75%	7.75%
Treasury stock, shares	2,806,187	2,805,743
Class A common stock
Condensed Balance Sheet Statements, Captions [Line Items]
Common stock, par value	$ 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	29,224,867	29,182,118
Class C common stock
Condensed Balance Sheet Statements, Captions [Line Items]
Common stock, par value	$ 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:
Condensed Balance Sheet Statements, Captions [Line Items]
Interest rate	7.75%	7.75%	7.75%