Employee Benefit Plans - Schedule of Net Periodic Costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Components of Net Periodic Benefits Cost:
Regulatory adjustments - deferred			$ (3,001)	$ (70,875)
Pension Benefits
Components of Net Periodic Benefits Cost:
Service cost	$ 850	$ 846	1,700	1,692
Interest cost	2,550	2,513	5,100	5,026
Expected return on plan assets	(3,009)	(2,623)	(6,018)	(5,246)
Amortization of prior service cost	109	108	217	216
Amortization of actuarial (gain) loss	0	0	0	0
Net periodic benefits costs under accounting standards	500	844	999	1,688
Regulatory adjustments - deferred	0	(92)	0	(184)
Total expense (benefit) recognized, before surcharges and allocation to overhead pool	500	752	999	1,504
Other Postretirement Benefits
Components of Net Periodic Benefits Cost:
Service cost	32	33	64	66
Interest cost	26	26	49	51
Expected return on plan assets	(142)	(119)	(284)	(239)
Amortization of prior service cost	0	0	0	0
Amortization of actuarial (gain) loss	(293)	(242)	(556)	(482)
Net periodic benefits costs under accounting standards	(377)	(302)	(727)	(604)
Regulatory adjustments - deferred	0	0	0	0
Total expense (benefit) recognized, before surcharges and allocation to overhead pool	(377)	(302)	(727)	(604)
SERP
Components of Net Periodic Benefits Cost:
Service cost	358	312	716	624
Interest cost	426	411	852	822
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	0	0	0	0
Amortization of actuarial (gain) loss	(3)	(8)	(7)	(16)
Net periodic benefits costs under accounting standards	781	715	1,561	1,430
Regulatory adjustments - deferred	0	0	0	0
Total expense (benefit) recognized, before surcharges and allocation to overhead pool	$ 781	$ 715	$ 1,561	$ 1,430