Postretirement Benefits - Other Comprehensive Income (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($) participant	Dec. 31, 2020 USD ($)
Amounts recognized in other comprehensive income for pension plans:
Net actuarial gain arising during the year	$ (75,091)	$ (11,832)
Amortization of net actuarial loss	(16,106)	(12,125)
Amortization of prior service cost	(1,428)	(1,343)
Amendments	4,059	0
Total recognized in other comprehensive income	$ (88,566)	$ (25,300)
Supplemental employee retirement plan (SERP) | Nonqualified Plan | Unfunded plan
Amounts recognized in other comprehensive income for pension plans:
Number of new plan participants resulting in charges recognized as amendments | participant	4