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Share-Based Compensation Plans - Estimated Fair Value of Share Awards (Details) - Stock option
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Average risk-free interest rate (as a percent) 1.60% 1.80% 1.10%
Expected dividend yield (as a percent) 1.50% 1.20% 1.70%
Expected volatility (as a percent) 32.00% 37.00% 42.00%
Expected term (years) 6 years 5 years 10 months 24 days 5 years 10 months 24 days