Accumulated Other Comprehensive Income (Loss) - Amounts Reclassified to Net Income from Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Pre-tax amount	$ 89,983	$ 77,159	$ 51,325
Tax (provision) benefit	21,386	19,368	14,065
Reclassification of gain (loss) to net income	68,597	57,791	37,260
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification of gain (loss) to net income	1,664	(5,153)	(226)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Foreign Currency Translation Gain (Loss) [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification of gain (loss) to net income	(647)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Actuarial Gain (Loss) Related to Pension Liability [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Tax (provision) benefit	12	(15)	(19)
Reclassification of gain (loss) to net income	53	35	41
Reclassification out of Accumulated Other Comprehensive Income [Member] | Gain (Loss) on Cash Flow Hedging Instruments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Tax (provision) benefit	45	105	226
Reclassification of gain (loss) to net income	2,195	(5,237)	(321)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Gain (Loss) on Post Retirement Obligation [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification of gain (loss) to net income	63	49	54
Reclassification out of Accumulated Other Comprehensive Income [Member] | Other Income (Expense) [Member] | Foreign Currency Translation Gain (Loss) [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Pre-tax amount	(647)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Direct Salaries and Related Costs [Member] | Actuarial Gain (Loss) Related to Pension Liability [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Pre-tax amount	41	50	60
Reclassification out of Accumulated Other Comprehensive Income [Member] | Revenues [Member] | Gain (Loss) on Cash Flow Hedging Instruments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Pre-tax amount	2,150	(5,342)	(547)
Reclassification out of Accumulated Other Comprehensive Income [Member] | General and Administrative [Member] | Gain (Loss) on Post Retirement Obligation [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Pre-tax amount	$ 63	$ 49	$ 54