Share-based Compensation Plans - Assumptions (Details) - Stock options - $ / shares	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Assumptions used in the calculation of the weighted average fair value of options granted
Expected volatility (as a percent)	31.85%	38.04%
Expected term	5 years	5 years
Dividend yield (as a percent)	3.30%	2.58%
Risk free rate (as a percent)	1.31%	1.57%
Weighted-average grant date fair value (in dollars per share)	$ 1.50	$ 2.15