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Employee Benefit Plans - Schedule of Assumed Health Care Cost and Trend Rates for Medical Plans (Details) - Other Postretirement Benefit Plan
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]    
Medical cost trend rate (as a percent) 6.75% 7.00%
Ultimate medical cost trend rate (as a percent) 4.50% 4.50%
Year ultimate medical cost trend rate will be reached 2030 2027