Acquisitions (Details) $ in Thousands		1 Months Ended							3 Months Ended				6 Months Ended		12 Months Ended
	Aug. 06, 2021 USD ($) customer	Jul. 31, 2022 USD ($)	Mar. 31, 2022 USD ($) customer	Oct. 31, 2021 USD ($) customer	Jul. 31, 2021 USD ($) customer	Apr. 30, 2021 USD ($) customer	Jan. 31, 2021 USD ($) customer	Sep. 30, 2019 USD ($) customer item	Jun. 30, 2022 USD ($)	Mar. 31, 2022 USD ($)	Jun. 30, 2021 USD ($)	Mar. 31, 2021 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)	Dec. 31, 2021 USD ($) customer
Business Acquisition [Line Items]
Goodwill									$ 2,340,792				$ 2,340,792		$ 2,340,815
Operating revenues									448,756		$ 397,032		1,148,031	$ 980,597
Net income									$ 82,291	$ 199,376	$ 80,914	$ 183,689	$ 281,667	$ 264,603
Illinois [Member] | Water Utility System [Member]
Business Acquisition [Line Items]
Number of customers | customer	6,500
Total purchase price	$ 32,100
Illinois [Member] | Water And Wastewater Utility Systems [Member]
Business Acquisition [Line Items]
Number of customers | customer						4,000
Total purchase price						$ 12,500
Illinois [Member] | Wastewater Utility System [Member]
Business Acquisition [Line Items]
Number of customers | customer				7,600
Total purchase price				$ 41,250
Pennsylvania [Member] | Water Utility System [Member]
Business Acquisition [Line Items]
Number of customers | customer					2,930
Total purchase price					$ 12,000
Pennsylvania [Member] | Wastewater Utility System [Member]
Business Acquisition [Line Items]
Number of customers | customer							10,500
Total purchase price							$ 72,400
Delaware [Member] | Wastewater Utility System [Member]
Business Acquisition [Line Items]
Number of customers | customer								16,000
Retail customers | customer								198,000
Municipalities | item								42
Total purchase price								$ 276,500
Texas [Member] | Water Utility System [Member]
Business Acquisition [Line Items]
Number of customers | customer	992
Total purchase price	$ 4,000
Lower Makefield Township [Member] | Wastewater Utility System [Member]
Business Acquisition [Line Items]
Number of customers | customer			11,000
Total purchase price			$ 53,000
Southern Oaks [Member] | Water Utility System [Member]
Business Acquisition [Line Items]
Number of customers | customer															740
Total purchase price															$ 3,300
Subsequent Event [Member] | Wastewater Utility System [Member]
Business Acquisition [Line Items]
Total purchase price		$ 885,000