Postretirement Benefits - Pension Liability (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
PBO	$ 778,934	$ 763,313
ABO	689,562	683,579
Defined Benefit Plan, Pension Plan with Project Benefit Obligation in Excess of Plan Assets [Abstract]
Funded benefit pension plans PBO	686,917	667,753
Funded benefit pension plans fair value of plan assets	597,547	529,532
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets [Abstract]
Funded benefit pension plans ABO	601,647	594,510
Funded benefit pension plans fair value of plan assets	597,547	529,532
Pension plans
Defined Benefit Plan Disclosure [Line Items]
PBO	778,934	763,313	$ 665,207
Qualified Plan | Pension plans | Funded defined benefit pension
Defined Benefit Plan Disclosure [Line Items]
PBO	686,917	667,753
ABO	601,647	594,510
Nonqualified Plan | SERP
Defined Benefit Plan Disclosure [Line Items]
PBO	92,017	95,560
ABO	$ 87,915	$ 89,069