Employee and Retiree Benefit Plans - Amounts Included in Accumulated Other Comprehensive Income Expected to be Amortized into Net Periodic Benefit Expense (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	$ (17,096)
Prior service cost	(734)
Amounts included in accumulated other comprehensive loss expected to be amortized into net periodic benefit expense	(17,830)
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	0
Prior service cost	0
Amounts included in accumulated other comprehensive loss expected to be amortized into net periodic benefit expense	$ 0