Retirement Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Jan. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Weighted-average expected long-term rate of return	5.50%
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0	$ 0
Interest cost on benefit obligations	1,377	1,166
Expected return on plan assets	(3,669)	(3,595)
Recognized net loss (gain)	422	1,019
Net periodic benefit (income) cost	(1,870)	(1,410)
Pension Plan | Sterling
Defined Benefit Plan Disclosure [Line Items]
Benefit obligations assumed			$ 30,500
SERP
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0
Interest cost on benefit obligations	15	7
Expected return on plan assets	0	0
Recognized net loss (gain)	7	8
Net periodic benefit (income) cost	22	15
OPEB
Defined Benefit Plan Disclosure [Line Items]
Service cost	6	0
Interest cost on benefit obligations	144	4
Expected return on plan assets	0	0
Recognized net loss (gain)	(18)	(20)
Net periodic benefit (income) cost	$ 132	$ (16)