Fair Value Measurements (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
7.75% Senior Notes due 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Amount	$ 475,000	$ 475,000
Fair Value	$ 237,500	372,875
Interest rate	7.75%
7.75% Senior Notes due 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Amount	$ 300,000	300,000
Fair Value	$ 146,250	$ 225,000
Interest rate	7.75%