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Pensions (Details) - Pension Plans [Member] - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2022
Mar. 31, 2021
Dec. 31, 2021
Components of Net Periodic Pension Cost [Abstract]      
Service cost $ 256 $ 271  
Interest cost 334 302  
Expected return on plan assets (1,055) (913)  
Amortization of actuarial loss 0 121  
Amortization of prior service cost (3) (3)  
Rate-regulated adjustment 1,043 797  
Net periodic pension expense 575 $ 575  
Employer Contributions [Abstract]      
Estimated employer contributions in 2022     $ 2,300
Contributions made by employer 575    
Estimated future contributions in 2022 $ 1,725