Fair Value Measurements - Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Liabilities:
Derivative financial instruments	$ 8,455	$ 22,808
Fair Value, Measurements, Recurring
Liabilities:
Derivative financial instruments	8,455	22,808
Long-term obligations	1,560,046	1,598,001
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) [Member]
Liabilities:
Derivative financial instruments	8,455	22,808
Long-term obligations	$ 1,560,046	$ 1,598,001