Employee Retirement Plans and Postretirement Benefits Target And Actual Allocations (Details)	Dec. 31, 2019
Equity funds
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Target allocations (as a percent)	9.70%
Actual allocations (as a percent)	7.20%
Fixed Income Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Target allocations (as a percent)	64.60%
Actual allocations (as a percent)	70.10%
Real estate funds
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Target allocations (as a percent)	6.30%
Actual allocations (as a percent)	5.50%
Annuities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Target allocations (as a percent)	15.00%
Actual allocations (as a percent)	15.10%
Other assets
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Target allocations (as a percent)	4.40%
Actual allocations (as a percent)	2.10%