Schedule of Weighted Average Option Fair Values and Assumptions (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Weighted average fair value of grants	$ 12.97	$ 11.40	$ 12.30
Dividend yield	1.57%	1.59%	1.46%
Volatility	30.92%	32.00%	32.72%
Risk-free interest rate, minimum	0.17%	0.17%	0.28%
Risk-free interest rate, maximum	4.12%	3.96%	5.61%
Expected life (in years)	5 years 10 months 10 days	5 years 11 months 23 days	6 years 1 month 21 days