Pensions and Other Post-retirement Benefits - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 3,099	$ 3,242	$ 6,198	$ 6,484
Interest cost	3,613	2,817	7,226	5,634
Expected return on plan assets	(12,418)	(9,147)	(24,836)	(18,294)
Amortization of prior service cost (credit)	36	66	72	132
Recognized net actuarial losses	3,018	4,421	6,036	8,842
Settlements			0	(1,879)
Net periodic benefit (income) cost	(2,652)	1,399	(5,304)	919
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	82	99	164	198
Interest cost	148	116	296	232
Expected return on plan assets	0	0	0	0
Amortization of prior service cost (credit)	(84)	(90)	(168)	(180)
Recognized net actuarial losses	310	399	620	798
Settlements			0	0
Net periodic benefit (income) cost	$ 456	$ 524	$ 912	$ 1,048