Regulatory Matters - Additional Information (Details) - USD ($) $ in Millions													3 Months Ended
	Mar. 04, 2022	Mar. 01, 2022	Feb. 24, 2022	Feb. 16, 2022	Feb. 10, 2022	Jan. 14, 2022	Dec. 01, 2021	Nov. 18, 2021	Nov. 15, 2021	Aug. 18, 2021	Mar. 02, 2021	Feb. 25, 2021	Mar. 31, 2022	Mar. 31, 2021	Apr. 01, 2022
Public Utilities, General Disclosures
General rate case authorizations													$ 48	$ 92
Pennsylvania
Public Utilities, General Disclosures
General rate case authorizations, additional annualized revenue												$ 90
Net of excess accumulated deferred income taxes, reduction in revenue												19
General rate case authorizations, increase net												71
General rate case authorizations												70	20	70
General rate case authorizations, Tax Cuts And Jobs Act Of 2017												51
General rate case authorizations, second threshold												20
Net of excess accumulated deferred income taxes, protected, payable to customers												200
Net of excess accumulated deferred income taxes, unprotected, payable to customers												$ 116
Net of excess accumulated deferred income taxes, unprotected, payable to customers, period												20 years
Net of excess accumulated deferred income taxes, protected and unprotected, payable to customers												$ 19
Net of excess accumulated deferred income taxes, payable to customers, bill credit												$ 11
Net of excess accumulated deferred income taxes, payable to customers, bill credit period												2 years
Net of excess accumulated deferred income taxes, payable to customers, new base rate amortization period												2 years
Pennsylvania | Subsequent Event
Public Utilities, General Disclosures
Implemented infrastructure surcharge for annualized incremental revenues															$ 2
West Virginia
Public Utilities, General Disclosures
General rate case authorizations, additional annualized revenue			$ 15
General rate case authorizations, excess of accumulated deferred income taxes, reduction in revenue			2
General rate case authorizations, infrastructure surcharges			$ 10
General rate case authorizations													15	0
California
Public Utilities, General Disclosures
General rate case authorizations													$ 13	$ 22
California | Water and Wastewater Services
Public Utilities, General Disclosures
General rate case authorizations, additional annualized revenue								$ 22
General rate case authorizations, excess of accumulated deferred income taxes, reduction in revenue								$ 4
Approved rate increase (decrease), amount				$ 13
General rate case authorizations, Tax Cuts and Jobs Act of 2017, reduction				$ 4
New Jersey
Public Utilities, General Disclosures
Requested rate adjustment, amount											$ 29
Requested rate increase (decrease), amount						$ 110
Illinois
Public Utilities, General Disclosures
Requested rate increase (decrease), amount					$ 71
Kentucky
Public Utilities, General Disclosures
Requested rate increase (decrease), amount							$ 1
Operating ratio, percentage							88.00%
Requested, infrastructure surcharge for annualized revenues, additional		$ 3
Kentucky | June 1, 2022 | Maximum
Public Utilities, General Disclosures
Requested rate increase (decrease), amount							$ 1
Kentucky | June 1, 2023 | Maximum
Public Utilities, General Disclosures
Requested rate increase (decrease), amount							1
Kentucky | June 1, 2024 | Maximum
Public Utilities, General Disclosures
Requested rate increase (decrease), amount							1
Kentucky | June 1, 2025 | Maximum
Public Utilities, General Disclosures
Requested rate increase (decrease), amount							$ 1
Virginia
Public Utilities, General Disclosures
Requested rate increase (decrease), amount									$ 15
Hawaii
Public Utilities, General Disclosures
Requested rate increase (decrease), amount										$ 2
Missouri
Public Utilities, General Disclosures
Requested, infrastructure surcharge for annualized revenues, additional	$ 19