Fair Value Measurements - Schedule of Assets and Liabilities Measured at Fair Value (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Assets:
Derivative financial instruments	$ 0	$ 71,000
Liabilities:
Derivative financial instruments	628,000
Long-term obligations	1,615,635,000	1,662,756,000
Significant Other Observable Inputs (Level 2) [Member]
Assets:
Derivative financial instruments		71,000
Liabilities:
Derivative financial instruments	628,000
Long-term obligations	1,352,438,000	1,397,975,000
Significant Unobservable Inputs (Level 3) [Member]
Liabilities:
Long-term obligations	$ 263,197,000	$ 264,781,000