Share-Based Compensation - Fair Value of Options Granted (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions And Methodology [Abstract]
Dividend yields	1.98%	2.56%	2.77%
Volatility factors of expected market price of common stock	29.75%	29.47%	29.89%
Risk-free interest rates	2.16%	1.84%	1.91%
Expected life of options	8 years	8 years	8 years