Capitalization (Details)						1 Months Ended	3 Months Ended		9 Months Ended
	Aug. 09, 2021 USD ($) $ / agreement shares	Apr. 19, 2021 USD ($)	Mar. 16, 2020 USD ($)	Apr. 23, 2019 USD ($) $ / shares	Mar. 29, 2019 USD ($) item $ / shares shares	Aug. 31, 2020 USD ($) shares	Sep. 30, 2021 USD ($) $ / shares shares	Mar. 31, 2020 shares	Sep. 30, 2021 USD ($) $ / shares shares	Sep. 30, 2020 USD ($)	Apr. 15, 2021 USD ($)	Dec. 31, 2020 $ / shares shares
Debt Instrument [Line Items]
Private Placement | shares					21,661,095
Proceeds from private placement			$ 749,907,000
Common stock, par value | $ / shares					$ 0.50		$ 0.50		$ 0.50			$ 0.50
Common stock, shares authorized | shares							600,000,000		600,000,000			600,000,000
Issuance expense			20,606,000
Private placement discount					4.50%
Issuance of common stock from forward equity sale agreement	$ 299,739,000						$ 4,341,000
Issuance of common stock from forward equity sale agreement , shares | shares	6,700,000						92,993
Trading days | item					20
Diligence expenses					$ 4,000,000
Stock purchase contracts early settled by holders of the contracts | shares									107,904
Shares settled | shares							7,603,234		7,603,234
Issuance of common stock from stock purchase contracts , shares | shares							6,700,000	2,335,654	127,749
Private placement price | $ / shares					$ 34.62
Repayments of long-term debt									$ 717,816,000	$ 1,647,354,000
Initial Forward Equity Sale Agreement [Member]
Debt Instrument [Line Items]
Forward price | $ / agreement	46.00
Forward Equity Sale Agreement [Member]
Debt Instrument [Line Items]
Proceeds from private placement						$ 0
Common stock, shares authorized | shares						6,700,000
Forward price | $ / agreement	44.74
Long-Term Debts [Member]
Debt Instrument [Line Items]
Face Amount		$ 400,000,000
Debt issuance expense		$ 4,010,000
Interest Rate		2.40%
Aqua Ohio, Inc [Member] | Mortgage Bonds [Member]
Debt Instrument [Line Items]
Face Amount											$ 100,000,000
Aqua Ohio, Inc [Member] | Mortgage Bonds Due 2031 [Member]
Debt Instrument [Line Items]
Face Amount											$ 50,000,000
Interest Rate											2.37%
Aqua Ohio, Inc [Member] | Mortgage Bonds Due 2051 [Member]
Debt Instrument [Line Items]
Face Amount											$ 50,000,000
Interest Rate											3.35%
Aqua Pennsylvania, Inc [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt term		5 years
Repayments of long-term debt		$ 50,000,000
LDC Funding LLC [Member]
Debt Instrument [Line Items]
Private placement, per share | $ / shares				$ 50
Proceeds from tangible equity units				$ 690,000,000
Initial principal amount				$ 119,081,000
Initial principal amount per share | $ / shares				$ 8.62909
Cash installment | $ / shares				$ 0.75000
Cash installment rate				6.00%
Debt issuance expense				$ 16,358,000
Interest Rate				3.00%
LDC Funding LLC [Member] | July 30, 2019 [Member]
Debt Instrument [Line Items]
Cash installment | $ / shares				$ 0.80833
LDC Funding LLC [Member] | Minimum [Member]
Debt Instrument [Line Items]
Conversion to shares | $ / shares				1.1790
LDC Funding LLC [Member] | Maximum [Member]
Debt Instrument [Line Items]
Conversion to shares | $ / shares				$ 1.4442
Peoples Gas Acquisition [Member]
Debt Instrument [Line Items]
Indebtedness			1,101,091,000
short-term debt			181,000,000
Outstanding debt			$ 920,091,000
Peoples Gas Acquisition [Member] | Minimum [Member]
Debt Instrument [Line Items]
Interest Rate			2.90%
Indebtedness			$ 920,091,000
Peoples Gas Acquisition [Member] | Maximum [Member]
Debt Instrument [Line Items]
Interest Rate			6.42%
Indebtedness			$ 181,000,000