Share-Based Compensation (Black-Scholes Pricing Model Assumptions) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Assumptions of Black-Scholes option pricing model
Expected dividend yield	3.30%	3.50%	3.00%
Risk-free interest rate	1.39%	1.78%	2.16%
Expected stock price volatility	27.90%	39.10%	42.20%
Expected life of options — in years	6 years 6 months	7 years	7 years
Weighted average fair value of options granted (USD per share)	$ 6.15	$ 8.40	$ 9.64