Pension and Other Postretirement Benefits - Amounts Recognized in Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Amounts recognized in the balance sheets:
Accrued benefit liability, noncurrent	$ (120,997)	$ (160,400)
Pension Benefits
Pension And Other Employee Benefit Plans [Line Items]
Funded status, end of year	(77,808)	(131,123)
Amounts recognized in the balance sheets:
Prepaid benefit cost	20,177	4,780
Accrued benefit liability, current	(3,173)	(3,558)
Accrued benefit liability, noncurrent	(94,812)	(132,345)
Net funded status	(77,808)	(131,123)
Other Benefits
Pension And Other Employee Benefit Plans [Line Items]
Funded status, end of year	(27,625)	(29,498)
Amounts recognized in the balance sheets:
Prepaid benefit cost	0	0
Accrued benefit liability, current	(1,440)	(1,443)
Accrued benefit liability, noncurrent	(26,185)	(28,055)
Net funded status	$ (27,625)	$ (29,498)