Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($)	Jun. 30, 2022	Dec. 31, 2021
Cash and cash equivalents	$ 555,000,000	$ 230,000,000
Accounts receivable, less allowance for credit losses	783,000,000	690,000,000
Allowance for credit losses	41,000,000	44,000,000
Accrued unbilled revenues, allowance for credit losses	2,000,000	6,000,000
Prepaid expenses and other current assets	116,000,000	132,000,000
Regulatory assets	$ 2,229,000,000	$ 2,321,000,000
Preferred Stock [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, authorized (in shares)	20,000,000	20,000,000
Preferred stock, outstanding (in shares)	800,000	800,000
Preferred stock aggregate liquidation preference	$ 800	$ 800
Common Stock [Abstract]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, authorized (in shares)	1,000,000,000	1,000,000,000
Common stock, outstanding (in shares)	629,490,422	628,923,534
Variable Interest Entity, Primary Beneficiary
Cash and cash equivalents	$ 78,000,000	$ 92,000,000
Accounts receivable, less allowance for credit losses	37,000,000	29,000,000
Prepaid expenses and other current assets	18,000,000	19,000,000
Regulatory assets	$ 318,000,000	$ 420,000,000