Stock-Based Compensation - Assumptions Used in Options Pricing Model (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Summary of assumptions used in option models
Risk-free interest rate, minimum	0.56%	0.23%	0.16%
Risk-free interest rate, maximum	1.86%	2.25%	2.83%
Weighted-average volatility	24.00%	23.00%	22.90%
Dividend yield	2.12%	2.11%	2.46%
Minimum
Summary of assumptions used in option models
Expected years until exercise	6 years 10 months 25 days	6 years 10 months 25 days	6 years 8 months 12 days
Maximum
Summary of assumptions used in option models
Expected years until exercise	7 years 8 months 12 days	8 years	7 years 10 months 24 days