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Shareholders' Equity (Assumptions Used In The Weighted Average Fair Value Of Stock Options Granted) (Details)
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]      
Expected term 6 years 6 years 5 years 6 months 29 days
Expected volatility 22.58% 25.44% 23.86%
Expected dividend yield 0.82% 1.10% 1.00%
Risk-free interest rate 2.29% 2.18% 1.90%