Common Stock - Schedule of Assumptions Used to Determine Fair Value (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Risk-free interest rate	0.41%	0.38%	0.96%
Expected lives (in years)	3 years	3 years	3 years
Expected stock volatility	19.04%	20.99%	34.61%
Dividend yield	4.83%	4.78%	4.48%