Pensions (Details) - Pension Plans [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Components of Net Periodic Pension Cost [Abstract]
Service cost	$ 150	$ 256	$ 299	$ 512
Interest cost	469	334	938	668
Expected return on plan assets	(903)	(1,054)	(1,806)	(2,109)
Amortization of prior service cost	(3)	(3)	(6)	(6)
Rate-regulated adjustment	676	1,042	1,477	2,085
Net periodic pension expense	389	$ 575	902	$ 1,150
Employer Contributions [Abstract]
Estimated employer contributions in 2023					$ 1,680
Employer contributions made in 2023			902
Estimated remaining employer contributions in 2023	$ 778		$ 778