Employee Benefit Plans - Assumptions Used in Calculations (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Discount rate, percent	4.11%	3.48%	4.01%
Rate of compensation, percent	0.00%	0.00%	4.16%
Assumptions used to determine net periodic benefit cost for years ended December 31:
Discount rate (post-spin off), percent	3.48%	4.01%	4.20%
Expected long-term return on plan assets, percent	7.17%	7.17%	7.70%
Rate of compensation increase, percent	0.00%	0.00%	4.16%
Postretirement
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Discount rate, percent	4.18%	3.56%	4.12%
Rate of compensation, percent	4.50%	4.50%	4.50%
Assumptions used to determine net periodic benefit cost for years ended December 31:
Discount rate (post-spin off), percent	3.56%	4.12%	4.34%
Expected long-term return on plan assets, percent	0.00%	0.00%	0.00%
Rate of compensation increase, percent	4.50%	4.50%	4.50%