Income Taxes - Reconciliation of the Federal Statutory Rate (Detail)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Income tax provision at federal statutory rate	35.00%	35.00%	35.00%
Increase (decrease) in tax resulting from:
State tax provision, net of federal benefit	4.00%	4.20%	3.40%
Foreign tax rate differential	(2.70%)	(3.20%)	(4.90%)
Stock option compensation deduction	2.50%	2.60%	2.00%
Non-deductible expenses	1.70%	1.10%	2.40%
Change in valuation allowance	(0.70%)	(1.00%)	0.50%
Change in tax legislation	(3.10%)
Foreign tax credits			(3.70%)
Out-of-period adjustment		2.50%
Other, net	1.20%	(0.30%)	0.20%
Effective tax rate	37.90%	40.90%	34.90%