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Stock-Based Incentive Compensation Plans (Option price assumptions used for stock appreciation rights plan) (Details) - Non-employee Stock Appreciation Rights [Member] - $ / shares
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Assumptions used for stock-based incentive compensation plans [Abstract]      
Weighted-average fair value per option granted (in dollars per share) $ 19.09 $ 20.06 $ 10.25
Dividend yield 1.60% 1.50% 2.90%
Expected volatility 27.00% 34.40% 35.80%
Risk-free interest rate 2.80% 2.20% 1.40%
Expected life (in years) 5 years 5 years 5 years