Share Based Compensation (Fair Values of all Options Granted Estimated Using Binomial Option-Pricing Model with Weighted-average Assumptions) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Disclosure Fair Values Of All Options Granted Estimated Using Binomial Option Pricing Model With Weightedaverage Assumptions [Abstract]
Dividend yield	3.04%	2.80%	2.17%
Weighted average expected volatility	46.78%	53.87%	50.90%
Weighted average risk-free interest rate	1.56%	0.83%	1.14%
Weighted average expected lives (in years)	5 years 0 months 28 days	5 years 4 months 2 days	5 years 4 months 6 days
Weighted average grant-date fair value	$ 8.05	$ 7.99	$ 7.85