Subsequent Event - Additional Information (Details) $ / shares in Units, $ in Thousands						12 Months Ended
	Jan. 30, 2020 USD ($) $ / shares shares	Jan. 30, 2020 USD ($) $ / shares shares	Jan. 21, 2020 USD ($) $ / shares shares	Oct. 16, 2018 mi² service_connection	Jul. 20, 2018 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) mi² $ / shares	Dec. 31, 2018 USD ($) $ / shares	Dec. 31, 2017 $ / shares
Subsequent Event [Line Items]
Sale of Stock, Number of Shares Issued in Transaction | shares					1,720,000
Sale of Stock, Price Per Share | $ / shares					$ 9.25
Option Indexed to Issuer's Equity, Indexed Shares | shares					220,000
Sale of Stock, Consideration Received on Transaction					$ 14,600
Area Of Certificated Service Areas | mi²						354
Dividends declared per common share | $ / shares						$ 0.29	$ 0.28	$ 0.26
Payments of Stock Issuance Costs						$ 0	$ 1,274
Subsequent Event
Subsequent Event [Line Items]
Sale of Stock, Number of Shares Issued in Transaction | shares			870,000
Sale of Stock, Price Per Share | $ / shares	$ 12.50	$ 12.50	$ 12.50
Option Indexed to Issuer's Equity, Indexed Shares | shares	130,000	130,000
Sale of Stock, Consideration Received on Transaction	$ 1,600	$ 11,600	$ 10,900
Payments of Stock Issuance Costs		900
Sale of Stock, Consideration Received Per Transaction		$ 12,500
Red Rock Utilities [Member]
Subsequent Event [Line Items]
Active water connections | service_connection				1,650
Area Of Certificated Service Areas | mi²				9