Pension and Post-Retirement Benefits - Weighted-Average Assumptions Used (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Pension Benefits
Pension Plans, Postretirement and Other Employee Benefits
Discount rate	3.20%	4.40%
Long-term rate of return on plan assets	6.30%
Pension Benefits | Minimum
Pension Plans, Postretirement and Other Employee Benefits
Long-term rate of compensation increase	3.00%	3.00%
Long-term rate of return on plan assets		6.25%
Pension Benefits | Maximum
Pension Plans, Postretirement and Other Employee Benefits
Long-term rate of compensation increase	3.50%	3.50%
Long-term rate of return on plan assets		7.15%
Post-retirement Health Care
Pension Plans, Postretirement and Other Employee Benefits
Discount rate	3.20%	4.30%
Post-retirement Health Care | Pre-65 | Minimum
Pension Plans, Postretirement and Other Employee Benefits
Initial rate	7.00%	7.30%
Post-retirement Health Care | Pre-65 | Maximum
Pension Plans, Postretirement and Other Employee Benefits
Ultimate rate	4.50%	4.50%
Post-retirement Health Care | Post-65 | Minimum
Pension Plans, Postretirement and Other Employee Benefits
Initial rate	7.50%	8.00%
Post-retirement Health Care | Post-65 | Maximum
Pension Plans, Postretirement and Other Employee Benefits
Ultimate rate	4.50%	4.50%