Postretirement Benefits - Analysis of Impact on Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan, Impact on Other Comprehensive Income
Balance at January 1	$ (131,239)	$ (208,770)	$ (182,233)
Prior service cost (credit)	1,077	631	632
Net actuarial (gain) loss	12,677	20,166	16,000
Total amortization	13,754	20,797	16,632
Plan amendments	0	(4,565)	0
Experience gain (loss)	119,055	61,299	(43,169)
Balance at December 31	1,570	(131,239)	(208,770)
Other Benefits
Defined Benefit Plan, Impact on Other Comprehensive Income
Total amortization	$ 289	$ 228	$ 302