Share Based Compensation (Fair Values of all Options Granted Estimated Using Binomial Option-Pricing Model with Weighted-average Assumptions) (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share Based Compensation [Abstract]
Dividend yield	3.40%	3.04%	2.80%
Weighted average expected volatility	42.98%	46.78%	53.87%
Weighted average risk-free interest rate	1.42%	1.56%	0.83%
Weighted average expected lives (in years)	5 years 5 months 1 day	5 years 29 days	5 years 4 months 2 days
Weighted average grant-date fair value	$ 7.63	$ 8.05	$ 7.99