Employee Benefit Plans - Assumptions, Additional Information (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.30%	3.30%	3.30%
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.33%	4.35%
Expected long-term rate of return on plan assets	6.45%	6.60%	6.60%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Expected Long-Term Return On Assets Rate	6.00%
Pension Benefits | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	60.00%
Pension Benefits | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	40.00%
Other postretirement obligations
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.15%	4.23%
Expected long-term rate of return on plan assets	6.00%	6.60%	6.60%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Expected Long-Term Return On Assets Rate	5.60%
Other postretirement obligations | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	70.00%
Other postretirement obligations | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	30.00%