Accumulated Other Comprehensive Loss - Reclassification out of Accumulated Other Comprehensive Loss (Details) - Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] - Reclassification out of Accumulated Other Comprehensive Income [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Amortization of net prior service cost	$ (140)	$ (200)
Amortization of net loss	1,372	2,038
Adjustment due to effects of regulation	(1,255)	(1,489)
Other comprehensive (income) loss, defined benefit plan, reclassification adjustment from AOCI, before tax	(23)	349
Other comprehensive (income) loss, defined benefit plan, reclassification adjustment from AOCI, tax	5	(73)
Other comprehensive (income) loss, defined benefit plan, reclassification adjustment from AOCI, after tax	$ (18)	$ 276