Retirement Benefit Plans (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 Disclosure [Line Items]
Weighted-average expected long-term rate of return	5.50%		5.50%
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0	$ 0	$ 0	$ 0
Interest cost	2,211	1,380	4,422	2,757
Expected return on plan assets	(2,699)	(3,668)	(5,398)	(7,337)
Amortization of actuarial loss (gain)	1,216	423	2,432	845
Net periodic benefit cost (income)	728	(1,865)	1,456	(3,735)
SERP
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	0	0
Interest cost	47	17	114	32
Expected return on plan assets	0	0	0	0
Amortization of actuarial loss (gain)	2	6	3	13
Net periodic benefit cost (income)	49	23	117	45
OPEB
Defined Benefit Plan Disclosure [Line Items]
Service cost	7	9	14	15
Interest cost	263	213	643	357
Expected return on plan assets	0	0	0	0
Amortization of actuarial loss (gain)	(677)	(19)	(1,352)	(37)
Net periodic benefit cost (income)	$ (407)	$ 203	$ (695)	$ 335