Debt - Summary of Carrying Amounts and Estimated Fair Values of Long-Term Debt (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Senior Secured Credit Facilities [Member]
Debt Instrument [Line Items]
Carrying value	$ 575,339	$ 575,339
Estimated fair value	577,658	571,024
Senior Secured Notes, Due 2018 [Member]
Debt Instrument [Line Items]
Carrying value	625,425	625,489
Estimated fair value	652,006	637,217
Junior Lien Secured Notes, Due 2018 [Member]
Debt Instrument [Line Items]
Carrying value	531,581	500,265
Estimated fair value	549,522	463,370
Senior Notes, Due 2018 [Member]
Debt Instrument [Line Items]
Carrying value	371,028	370,139
Estimated fair value	$ 356,762	$ 322,569