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Stock-Based Compensation Plans Stock-Based Compensation Plans (Details 3) - Performance Shares
3 Months Ended
Mar. 31, 2019
$ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Dividend yield 3.10%
Estimated volatility, Minimum (as a percent) 13.90%
Estimated volatility, Maximum (as a percent) 18.80%
Risk-free interest rate, minimum (as a percent) 2.46%
Risk-free interest rate, maximum (as a percent) 2.57%
Average estimated fair value (in dollars per share) $ 204.15
Historical volatility (as a percent) 50.00%
Implied volatility (as a percent) 50.00%