Share-based Compensation Plans - Schedule of Share-based Payment Award, Valuation Assumptions (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions And Methodology [Abstract]
Expected term	4 years 6 months	5 years	5 years
Expected volatility	31.10%	31.70%	32.10%
Expected volatility	31.60%	34.50%	50.80%
Risk free interest rate, minimum	1.37%	1.52%	0.58%
Risk free interest rate, maximum	1.54%	1.70%	1.52%
Weighted average fair value of options granted during the year	$ 9.49	$ 10.45	$ 10.83