Employee Benefit Plans - Components of Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Net periodic benefit cost	$ 4,032	$ 3,209	$ 8,327	$ 6,999
Defined benefit plans
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Interest cost	5,935	4,333	11,870	8,666
Expected return on plan assets, net of expenses	(6,307)	(6,224)	(12,613)	(12,448)
Amortization of actuarial loss and prior service cost	4	1,015	9	2,029
Total for defined benefit pension plan	(368)	(876)	(734)	(1,753)
SERPs
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Net periodic benefit cost	234	214	466	428
Defined contribution plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Net periodic benefit cost	$ 4,166	$ 3,871	$ 8,595	$ 8,324