Regulatory Matters - Public Utilities General Disclosures (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Revenue accounts:
Beginning Balance	$ 18,451	$ 10,043
Regulatory Asset Increase (Decrease)	2,404	1,601
Refunds (Collections) Adjustments	(6,493)	1
Ending Balance	14,362	11,645
Cost-recovery accounts:
Beginning Balance	19,883	15,420
Regulatory Asset Increase (Decrease)	(369)	1,153
Refunds (Collections) Adjustments	(76)	(81)
Ending Balance	19,438	16,492
Total
Beginning Balance	38,334	25,463
Regulatory Asset Increase (Decrease)	2,035	2,754
Refunds (Collections) Adjustments	(6,569)	(80)
Ending Balance	33,800	28,137
MWRAM
Revenue accounts:
Beginning Balance	16,866	12,077
Regulatory Asset Increase (Decrease)	2,193	1,776
Refunds (Collections) Adjustments	1	0
Ending Balance	19,060	13,853
WCMA
Revenue accounts:
Beginning Balance	3,534	666
Regulatory Asset Increase (Decrease)	(100)	0
Refunds (Collections) Adjustments	(6,495)	0
Ending Balance	(3,061)	666
Cost of capital memorandum account
Revenue accounts:
Beginning Balance	(1,563)	(1,561)
Regulatory Asset Increase (Decrease)	(1)	0
Refunds (Collections) Adjustments	0	0
Ending Balance	(1,564)	(1,561)
All others
Revenue accounts:
Beginning Balance	(386)	(1,139)
Regulatory Asset Increase (Decrease)	312	(175)
Refunds (Collections) Adjustments	1	1
Ending Balance	(73)	(1,313)
Cost-recovery accounts:
Beginning Balance	445	445
Regulatory Asset Increase (Decrease)	128	0
Refunds (Collections) Adjustments	0	0
Ending Balance	573	445
Water supply costs
Cost-recovery accounts:
Beginning Balance	10,545	8,123
Regulatory Asset Increase (Decrease)	244	787
Refunds (Collections) Adjustments	0	0
Ending Balance	10,789	8,910
Pension
Cost-recovery accounts:
Beginning Balance	4,941	3,478
Regulatory Asset Increase (Decrease)	65	366
Refunds (Collections) Adjustments	0	0
Ending Balance	5,006	3,844
PRVMA
Cost-recovery accounts:
Beginning Balance	707	1,108
Regulatory Asset Increase (Decrease)	1	0
Refunds (Collections) Adjustments	(76)	(81)
Ending Balance	632	1,027
CEMA
Cost-recovery accounts:
Beginning Balance	3,245	2,266
Regulatory Asset Increase (Decrease)	(807)	0
Refunds (Collections) Adjustments	0	0
Ending Balance	$ 2,438	$ 2,266