Postretirement Benefit Plans - Net Periodic Benefit Costs (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 36	$ 42
Interest cost	142	46
Expected return on plan assets	(149)	(59)
Accretion of prior service cost	0	0
Amortization of net (gain) loss	(5)	(2)
Net periodic benefit expense	24	27
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	4
Interest cost	3	17
Expected return on plan assets	0	0
Accretion of prior service cost	(2)	(5)
Amortization of net (gain) loss	0	4
Net periodic benefit expense	$ 2	$ 20