BASIS OF PRESENTATION, CORPORATE TRANSACTIONS, SIGNIFICANT ACCOUNTING POLICIES, AND RECENT ACCOUNTING PRONOUNCEMENTS - Corporate Transactions (Details) $ / shares in Units, $ in Thousands					3 Months Ended		9 Months Ended
	Apr. 25, 2024 USD ($) waterSystem service_connection	Jun. 08, 2023 USD ($) $ / shares shares	Feb. 01, 2023 USD ($) mi² service_connection	Jul. 14, 2015 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Growth premiums received					$ 900	$ 700	$ 2,200	$ 1,600
Accumulated growth premiums received					$ 12,900		$ 12,900
Farmers Water Company
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of active water connections | service_connection			3,300
Square miles of approved service area | mi²			21.5
Maximum payout of growth premium receivable			$ 3,500
Valencia Water Company
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Growth premium receivable for each new water meter installed				$ 3,000
Period for maximum payout of growth premium receivable				20 years
Maximum payout of growth premium receivable				$ 45,000
Private Placement Offering
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of common stock to be issued and sold (in shares) | shares		230,000
Purchase price (in dollars per share) | $ / shares		$ 12.07
Gross proceeds from sale of stock		$ 2,800
Affiliates | Private Placement Offering
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of common stock issued (in shares) | shares		30,000
Affiliates | GW-Acquisition | Tucson City Council, Asset Acquisition
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of water systems acquired | waterSystem	7
Number of active water connections | service_connection	2,200
Cash transaction	$ 8,400
Estimated rate base	$ 7,800