Description of Business, Basis of Presentation, Corporate Transactions, Significant Accounting Policies, and Recent Accounting Pronouncements - Corporate Transactions (Details)							1 Months Ended	12 Months Ended		64 Months Ended
	Dec. 31, 2034	Oct. 16, 2018 USD ($) mi² active_water_connection	Jul. 20, 2018 USD ($) $ / shares shares	May 30, 2018 USD ($)	Jun. 02, 2016 USD ($)	Jul. 14, 2015 USD ($)	Sep. 30, 2013 USD ($)	Dec. 31, 2019 USD ($) mi²	Dec. 31, 2018 USD ($) shares	Dec. 31, 2018 USD ($)	Dec. 31, 2021 USD ($)
Property, Plant and Equipment [Line Items]
Gross amount to be received from transfer of project agreement							$ 4,100,000
Other income (expense)								$ 1,309,000	$ 592,000
Deferred tax liabilities, gross								$ 13,754,000	14,041,000	$ 14,041,000
Area of certificated service areas | mi²								354
Sale of Stock, Number of Shares Issued in Transaction | shares			1,720,000
Sale of Stock, Price Per Share | $ / shares			$ 9.25
Proceeds from sale of stock								$ 0	15,910,000
Option Indexed to Issuer's Equity, Indexed Shares | shares			220,000
Sale of Stock, Consideration Received on Transaction			$ 14,600,000
Regulatory Assets, Noncurrent								$ 1,715,000	1,793,000	1,793,000
carrying cost on reg liabilities and assets								4.25%
Cash received from the sale of Loop 303 contracts								$ 1,000,000	$ 0	3,100,000
Valencia Water Company
Property, Plant and Equipment [Line Items]
Proceeds from the condemnation of Valencia						$ 55,000,000.0
Proceeds From Additional Working Capital Adjustments						$ 100,000
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 Expiration Date	Dec. 31, 2034
Maximum Payout Of Growth Premium Receivable								45,000,000.0
Deferred tax liabilities, gross								100,000
Common Stock
Property, Plant and Equipment [Line Items]
Sale of Stock, Number of Shares Issued in Transaction | shares									1,720,000
Proceeds from sale of stock			$ 15,900,000
General Partners' Offering Costs								1,300,000
Private Letter Ruling
Property, Plant and Equipment [Line Items]
Gain on condemnation of Valencia					$ 19,400,000
Tax Cuts and Jobs Act
Property, Plant and Equipment [Line Items]
Regulatory assets									$ 1,900,000	1,900,000
Tax Cuts and Jobs Act
Property, Plant and Equipment [Line Items]
Regulatory liabilities									$ 600,000	$ 600,000
Turner Ranches Water and Sanitation Company [Member]
Property, Plant and Equipment [Line Items]
Payments to Acquire Businesses, Gross				$ 2,800,000
Red Rock Utilities [Member]
Property, Plant and Equipment [Line Items]
Active water connections | active_water_connection		1,650
Square miles of approved service area | mi²		9
Payments to Acquire Businesses, Gross		$ 5,900,000
santa cruz [Member] | Tax Cuts and Jobs Act
Property, Plant and Equipment [Line Items]
Tax Reform Revenue Reduction								346,000			$ 415,000
Palo Verde [Member] | Tax Cuts and Jobs Act
Property, Plant and Equipment [Line Items]
Tax Reform Revenue Reduction								523,000			669,000
Tonopah [Member] | Tax Cuts and Jobs Act
Property, Plant and Equipment [Line Items]
Tax Reform Revenue Reduction								16,000			16,000
Northern Scottsdale [Member] | Tax Cuts and Jobs Act
Property, Plant and Equipment [Line Items]
Tax Reform Revenue Reduction								$ 5,000			$ 5,000