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Employee Benefit Plans (Schedule of Assumptions Used in Determining Actuarial Information) (Details)
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Pension Plan [Member]      
Discount rate used to determine net periodic pension cost 3.97% 4.17% 3.82%
Discount rate used to calculate end of year liability disclosures 3.46% 3.97% 4.17%
Expected long-term rate of return on assets 7.75% 7.75% 7.75%
Rate of compensation increase
SERP [Member]      
Discount rate used to determine net periodic pension cost 3.97% 4.17% 3.82%
Discount rate used to calculate end of year liability disclosures 3.46% 3.97% 4.17%
Expected long-term rate of return on assets
Rate of compensation increase