Fair Value Measurements - Narrative (Details) - USD ($)		3 Months Ended			12 Months Ended
	Apr. 01, 2020	Sep. 30, 2021	Sep. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill impairment		$ 0	$ 0		$ 0	$ 185,000,000	$ 0
Infrastructure Services Disposal Group
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill impairment						82,000,000
Energy Services Disposal Group
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill impairment						62,000,000
Indiana Electric Integrated
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill impairment				$ 185,000,000		185,000,000
Level 2 | Infrastructure Services Disposal Group
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of disposal group				864,000,000
Level 2 | Energy Services Disposal Group
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of disposal group				402,000,000
Enable Midstream Partners
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Reduction of dividend or distribution amount (as a percent)	50.00%
Equity method investment, impairment					0	1,541,000,000	0
Equity method investment, fair value				848,000,000
Goodwill impairment					$ 0	28,000,000	$ 86,000,000
Enable Midstream Partners | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity method investment, impairment						$ 1,541,000,000
Equity method investment, fair value				$ 848,000,000