Share-Based Compensation - Stock Options Assumptions Table (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Weighted-average grant-date fair value	$ 18.18	$ 23.55	$ 26.27
Assumptions
Expected option life—years	4 years 10 months 24 days	4 years 10 months 24 days	4 years 9 months 18 days
Volatility	32.40%	29.90%	33.90%
Risk-free interest rate	1.40%	1.60%	1.30%
Dividend yield	1.40%	1.10%	0.80%