Fair Values of Derivative Designated as Hedging Instruments Recorded in Consolidated Balance Sheet (Detail) - Interest rate derivatives - Derivatives Designated as Hedging Instruments - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Other current assets
Derivatives, Fair Value [Line Items]
Derivative Assets, Fair Value	$ 3,590	$ 222
Other assets
Derivatives, Fair Value [Line Items]
Derivative Assets, Fair Value	6,566	8,043
Other accrued liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities, Fair Value	(3,053)	(2,989)
Other long-term liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities, Fair Value	$ (971)	$ (6,421)