Employee Benefit Plans - Components of Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Net periodic benefit cost	$ 3,279	$ 2,575	$ 11,606	$ 9,574
Defined benefit plans
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Interest cost	5,814	4,333	17,684	12,999
Expected return on plan assets, net of expenses	(6,302)	(6,227)	(18,915)	(18,675)
Amortization of actuarial loss and prior service cost	5	997	14	3,026
Total for defined benefit pension plan	(483)	(897)	(1,217)	(2,650)
SERPs
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Net periodic benefit cost	232	214	698	642
Defined contribution plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Net periodic benefit cost	$ 3,530	$ 3,258	$ 12,125	$ 11,582