Fair Value Measurements - Schedule of Assets and Liabilities Measured at Fair Value (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Liabilities:
Derivative financial instruments	$ 8,384	$ 628
Long-term obligations	1,624,713	1,615,635
Significant Other Observable Inputs (Level 2) [Member]
Liabilities:
Derivative financial instruments	8,384	628
Long-term obligations	$ 1,624,713	1,352,438
Significant Unobservable Inputs (Level 3) [Member]
Liabilities:
Long-term obligations		$ 263,197