Regulatory Matters - General Rate Cases Additional Information (Details) - USD ($) $ in Millions												12 Months Ended
	Feb. 10, 2022	Jan. 18, 2022	Jan. 14, 2022	Dec. 01, 2021	Nov. 18, 2021	Aug. 18, 2021	Apr. 30, 2021	Apr. 07, 2021	Mar. 02, 2021	Feb. 25, 2021	Jan. 15, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Jun. 28, 2021
Public Utilities, General Disclosures
General rate case authorizations												$ 115	$ 72	$ 41
California
Public Utilities, General Disclosures
General rate case authorizations												22	5	4
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
California | Water and Wastewater Services | Subsequent Event
Public Utilities, General Disclosures
General rate case authorizations, escalation increase, amount		$ 13
General rate case authorizations, Tax Cuts and Jobs Act of 2017, reduction		$ 4
Review period		45 days
Iowa
Public Utilities, General Disclosures
General rate case authorizations, approved, increase															$ 1
General rate case authorizations												1	0	0
Missouri
Public Utilities, General Disclosures
General rate case authorizations, additional annualized revenue								$ 22
Net of excess accumulated deferred income taxes, reduction in revenue								25
Net of excess accumulated deferred income taxes, protected, payable to customers								72
Net of excess accumulated deferred income taxes, unprotected, payable to customers								$ 74
Net of excess accumulated deferred income taxes, unprotected, payable to customers, period								10 years
Net of excess accumulated deferred income taxes, protected and unprotected, catch up period amount								$ 13
Net of excess accumulated deferred income taxes, payable to customers, new base rate amortization period								2 years 6 months
General rate case authorizations												22	0	0
New Jersey
Public Utilities, General Disclosures
Requested rate adjustment, amount									$ 29
General rate case authorizations												0	54	0
New Jersey | Subsequent Event
Public Utilities, General Disclosures
Requested rate increase (decrease), amount			$ 110
Pennsylvania
Public Utilities, General Disclosures
General rate case authorizations, additional annualized revenue										$ 90
General rate case authorizations, Tax Cuts and Jobs Act of 2017, reduction										51
Net of excess accumulated deferred income taxes, reduction in revenue										19
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, payable to customers, new base rate amortization period										2 years
General rate case authorizations, increase net										$ 71
General rate case authorizations										70		70	0	0
General rate case authorizations, second threshold										20
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
Illinois | Subsequent Event
Public Utilities, General Disclosures
Requested rate increase (decrease), amount	$ 71
Kentucky
Public Utilities, General Disclosures
General rate case authorizations												0	0	13
Requested rate increase (decrease), amount				$ 1
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
West Virginia
Public Utilities, General Disclosures
Net of excess accumulated deferred income taxes, reduction in revenue							$ 1
General rate case authorizations												0	0	19
Requested, general rate case for annualized revenues							32
Infrastructure changes							$ 10
Indiana
Public Utilities, General Disclosures
General rate case authorizations												$ 0	$ 13	$ 4