Financial Assets and Liabilities Measured at Fair Value on Nonrecurring Basis (Detail) - Fair Value, Measurements, Nonrecurring - USD ($)		Dec. 31, 2017		Dec. 31, 2016
Derivatives Designated as Hedging Instruments
Derivatives Fair Value [Line Items]
Nominal volume	[1]	$ 66,600,000		$ 84,800,000
Derivative asset	[1]	400,000		7,600,000
Derivative liability	[1]	1,300,000		500,000
Not Designated as Hedging Instrument
Derivatives Fair Value [Line Items]
Nominal volume		468,200,000		251,800,000
Derivative asset		2,400,000		1,100,000
Derivative liability		300,000		100,000
Less Than One Year | Derivatives Designated as Hedging Instruments | Foreign Exchange Forward | Cash Flow Hedging
Derivatives Fair Value [Line Items]
Nominal volume	[1]	66,600,000		74,000,000
Derivative asset	[1]	400,000		7,600,000
Derivative liability	[1]	1,300,000		300,000
Less Than Two Years | Derivatives Designated as Hedging Instruments | Foreign Exchange Forward | Cash Flow Hedging
Derivatives Fair Value [Line Items]
Nominal volume	[1]			10,800,000
Derivative asset	[1]			0
Derivative liability	[1]			200,000
Less Than Six Months | Not Designated as Hedging Instrument | Foreign Exchange Swaps
Derivatives Fair Value [Line Items]
Nominal volume		468,200,000	[2]	251,800,000	[3]
Derivative asset		2,400,000	[4]	1,100,000	[5]
Derivative liability		$ 300,000	[6]	$ 100,000	[7]

[1] There is no netting since there are no offsetting contracts.

[2] Net nominal amount after deducting for offsetting swaps under ISDA agreements is $468.2 million.

[3] Net nominal amount after deducting for offsetting swaps under ISDA agreements is $226.5 million.

[4] Net amount after deducting for offsetting swaps under ISDA agreements is $2.4 million.

[5] Net amount after deducting for offsetting swaps under ISDA agreements is $1.1 million.

[6] Net amount after deducting for offsetting swaps under ISDA agreements is $0.3 million.

[7] Net amount after deducting for offsetting swaps under ISDA agreements is $0.0 million.