Accumulated Other Comprehensive Loss - Reclassification out of Accumulated Other Comprehensive Income (Details) - Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] - Reclassification out of Accumulated Other Comprehensive Income [Member] - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Amortization of net prior service cost	$ (200)	$ (200)
Amortization of net loss	2,038	3,191
Adjustment due to effects of regulation	(1,489)	(2,592)
Other comprehensive (income) loss, defined benefit plan, reclassification adjustment from AOCI, before tax	349	399
Other comprehensive (income) loss, defined benefit plan, reclassification adjustment from AOCI, tax	(73)	(84)
Other comprehensive (income) loss, defined benefit plan, reclassification adjustment from AOCI, after tax	$ 276	$ 315