Share-Based Compensation Plans - Weighted Average Assumptions, Options Granted (Details) - Equity Options - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Weighted-average assumptions used for options granted
Expected dividends	2.80%	2.30%	3.00%
Expected volatility	29.40%	28.50%	35.20%
Risk-free rate	2.70%	1.90%	1.10%
Expected term in years	4 years 4 months 10 days	4 years 4 months 10 days	4 years 3 months 18 days
Grant-date fair value (in dollars per share)	$ 15.89	$ 15.71	$ 12.53