Investment Assets (Excluding Equity and Cost Method Investments) and Derivatives Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Derivative Financial Instruments, Liabilities | Interest rate derivatives
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Fair value of liabilities, recurring basis	$ (4,024)	$ (9,006)
Derivative Financial Instruments, Liabilities | Foreign currency contracts
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Fair value of liabilities, recurring basis	(8,802)	(3,671)
Derivative Financial Instruments, Assets | Interest rate derivatives
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Fair value of assets, recurring basis	10,156	7,860
Derivative Financial Instruments, Assets | Foreign currency contracts
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Fair value of assets, recurring basis	405	7,369
Certificates of deposit (non-U.S.)
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Fair value of assets, recurring basis	12,809	87,372
Corporate bonds
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Fair value of assets, recurring basis	11,065	34,133
Short-term bond fund
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Fair value of assets, recurring basis		5,046
Corporate obligations
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Fair value of assets, recurring basis	13	3
Money markets
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Fair value of assets, recurring basis	38	54
Mutual funds
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Fair value of assets, recurring basis	79	101
Other Investments
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Fair value of assets, recurring basis	5,588	4,235
Level 1 | Short-term bond fund
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Fair value of assets, recurring basis		5,046
Level 1 | Money markets
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Fair value of assets, recurring basis	38	54
Level 1 | Mutual funds
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Fair value of assets, recurring basis	79	101
Level 2 | Derivative Financial Instruments, Liabilities | Interest rate derivatives
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Fair value of liabilities, recurring basis	(4,024)	(9,006)
Level 2 | Derivative Financial Instruments, Liabilities | Foreign currency contracts
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Fair value of liabilities, recurring basis	(8,802)	(3,671)
Level 2 | Derivative Financial Instruments, Assets | Interest rate derivatives
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Fair value of assets, recurring basis	10,156	7,860
Level 2 | Derivative Financial Instruments, Assets | Foreign currency contracts
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Fair value of assets, recurring basis	405	7,369
Level 2 | Certificates of deposit (non-U.S.)
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Fair value of assets, recurring basis	12,809	87,372
Level 2 | Corporate bonds
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Fair value of assets, recurring basis	11,065	34,133
Level 2 | Corporate obligations
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Fair value of assets, recurring basis	13	3
Level 2 | Other Investments
Fair Value Assets Liabilities Measured On Recurring Basis [Line Items]
Fair value of assets, recurring basis	$ 5,588	$ 4,235