Income Taxes Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Income Taxes [Line Items]
Income Tax Expense (Benefit)	$ 61,556		$ 55,586
Effective Income Tax Rate Reconciliation, Percent	31.10%		37.30%
Tax Cuts and Jobs Act - Provisional
Income Taxes [Line Items]
Income Tax Expense (Benefit)		$ (39,000)
Transition Tax For Accumulated Foreign Earnings
Income Taxes [Line Items]
Income Tax Expense (Benefit)	$ 1,800
UNITED STATES
Income Taxes [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%		35.00%