Fair Value of Financial Instruments - Gains and Losses on Derivative Instruments in Consolidated Statement of Operations (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Derivatives Designated as Cash Flow Hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Other Comprehensive Income on Derivative (Effective Portion)	$ 9,020	$ 2,943	$ (1,770)
Amount of Gain Reclassified from Cumulative Other Comprehensive Loss into Income (Effective Portion)	3,699	1,085	5,699
Amount of Gain (Loss) Recognized in Income on Derivative (Ineffective Portion)	(188)	(122)	256
Not Designated as Hedging Instruments [Member] | Other Income (Expense) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	$ 121	$ (366)	$ 590