Pension and Other Postretirement Benefit Plans - Assumptions Used to Determine Benefit Obligation and Net Periodic Benefit Costs (Details)		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Minimum [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate		4.39%	3.81%	4.53%
Maximum [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate		4.53%	3.96%	4.57%
Pension [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Costs, Future Period		6.75%
Assumptions Used to Determine Net Periodic Benefit Costs [Abstract]
Expected Long-Term Return on Plan Assets	[1]	7.25%	7.50%	7.50%
Pension [Member] | Minimum [Member]
Assumptions Used to Determine Benefit Obligation [Abstract]
Discount Rate		3.34%	4.39%
Rate of Compensation Increase		3.70%	3.70%
Assumptions Used to Determine Net Periodic Benefit Costs [Abstract]
Rate of Compensation Increase		3.70%	3.70%	3.70%
Pension [Member] | Maximum [Member]
Assumptions Used to Determine Benefit Obligation [Abstract]
Discount Rate		3.47%	4.53%
Rate of Compensation Increase		4.10%	4.10%
Assumptions Used to Determine Net Periodic Benefit Costs [Abstract]
Rate of Compensation Increase		4.10%	4.10%	4.30%
Postretirement Health and Life [Member]
Assumptions Used to Determine Benefit Obligation [Abstract]
Discount Rate		3.45%	4.47%
Health Care Trend Rates [Abstract]
Ultimate Trend Rate		4.50%	4.50%
Year Ultimate Trend Rate Effective		2038	2038
Postretirement Health and Life [Member] | Minimum [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Costs, Future Period		5.40%
Health Care Trend Rates [Abstract]
Trend Rate		5.00%	5.00%
Assumptions Used to Determine Net Periodic Benefit Costs [Abstract]
Expected Long-Term Return on Plan Assets	[1]	5.80%	6.00%	6.00%
Postretirement Health and Life [Member] | Maximum [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Costs, Future Period		6.75%
Health Care Trend Rates [Abstract]
Trend Rate		6.20%	6.46%
Assumptions Used to Determine Net Periodic Benefit Costs [Abstract]
Expected Long-Term Return on Plan Assets	[1]	7.25%	7.50%	7.50%

[1] The expected long-term rates of return used to determine net periodic benefit expense for 2020 have been reduced to 6.75 percent for pension expense and 5.40 percent to 6.75 percent for postretirement health and life expense.