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Significant Accounting Policies (Schedule of Fair Value Assumptions and Methodology) (Details)
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Accounting Policies [Abstract]      
Risk-free interest rate 1.22% 2.43% 2.94%
Dividend yield 0.50% 0.50% 0.50%
Volatility factors 30.00% 31.20% 34.50%
Weighted-average expected life 8 years 8 years 8 years