Share-Based Compensation - Weighted Average Fair Value for Stock Options Granted (Detail) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Dividend yield	0.80%	0.90%	1.10%
Volatility	22.20%	25.20%	24.50%
Risk-free interest rate	1.70%	1.80%	1.10%
Expected life (years)	5 years 3 months 18 days	5 years 6 months	6 years 1 month 6 days
Weighted average fair value of options granted	$ 22.30	$ 22.59	$ 16.33
Intrinsic value of options exercised (in millions)	$ 49.4	$ 99.6	$ 97.9