Acquisitions (Details) $ in Thousands		1 Months Ended						3 Months Ended		12 Months Ended
	Aug. 06, 2021 USD ($) customer	Mar. 31, 2022 USD ($) 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 ($) item customer	Mar. 31, 2022 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2021 USD ($) customer
Business Acquisition [Line Items]
Goodwill		$ 2,340,815						$ 2,340,815		$ 2,340,815
Operating revenues								699,275	$ 583,565
Net income								$ 199,376	$ 183,689
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