Pension and Other Post-Retirement Benefit Plans - Net Funded Status (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Pension Plans
Change in benefit obligation
Obligation, beginning balance	$ 839,267	$ 873,826
Service cost	0	0	$ 0
Interest cost	24,173	22,387	27,880
Special termination benefits	0	0
Plan amendment	0	0
Plan transfers	2,386	3,125
Return of excess premiums	0	0
Benefits paid	(37,998)	(36,109)
Settlement payments	0	0
Curtailments and settlement	0	0
Actuarial gain	(179,586)	(23,962)
Obligation, ending balance	648,242	839,267	873,826
Change in plan assets
Actual (loss) gain on plan assets	(188,855)	37,626
Employer contributions	1,304	1,658
Funded status
Funded status	13,194	30,867
Pension Plans | Fair Value, Recurring
Change in plan assets
Plan assets, beginning balance	850,195	843,895
Plan assets, ending balance	627,032	850,195	843,895
Pension Plans | Current liabilities
Funded status
Funded status	(1,343)	(1,345)
Pension Plans | Non-current liabilities
Funded status
Funded status	(33,063)	(18,594)
Post-retirement Healthcare Plans
Change in benefit obligation
Obligation, beginning balance	3,142	3,484
Service cost	76	95	139
Interest cost	59	42	91
Special termination benefits	0	0
Plan amendment	0	0
Plan transfers	0	0
Return of excess premiums	0	0
Benefits paid	(308)	(250)
Settlement payments	0	0
Curtailments and settlement	0	0
Actuarial gain	(297)	(229)
Obligation, ending balance	2,672	3,142	3,484
Change in plan assets
Actual (loss) gain on plan assets	0	0
Employer contributions	308	250
Funded status
Funded status	0	0
Post-retirement Healthcare Plans | Fair Value, Recurring
Change in plan assets
Plan assets, beginning balance	0	0
Plan assets, ending balance	0	0	$ 0
Post-retirement Healthcare Plans | Current liabilities
Funded status
Funded status	(401)	(399)
Post-retirement Healthcare Plans | Non-current liabilities
Funded status
Funded status	$ (2,271)	$ (2,743)