CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($)	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Current Assets:
Cash and cash equivalents	$ 230,000,000	$ 147,000,000
Accounts receivable	690,000,000	676,000,000
Bad debt reserve	44,000,000	52,000,000
Prepaid expense and other current assets ($19 and $15 related to VIEs, respectively)	132,000,000	121,000,000
Other Assets [Abstract]
Regulatory assets ($420 and $633 related to VIEs, respectively)	$ 2,321,000,000	$ 2,094,000,000
Shareholders’ Equity:
Cumulative preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Cumulative preferred stock, authorized (in shares)	20,000,000	20,000,000	20,000,000
Cumulative preferred stock, outstanding (in shares)	800,000	2,402,400	1,777,500
Cumulative preferred stock, aggregate liquidation preference	$ 800	$ 2,402
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01	$ 0.01
Common stock, authorized (in shares)	1,000,000,000	1,000,000,000	1,000,000,000
Common stock, outstanding (in shares)	628,923,534	551,355,861
Variable Interest Entity, Primary Beneficiary
Current Assets:
Cash and cash equivalents	$ 92,000,000	$ 139,000,000
Accounts receivable	29,000,000	23,000,000
Prepaid expense and other current assets ($19 and $15 related to VIEs, respectively)	19,000,000	15,000,000
Other Assets [Abstract]
Regulatory assets ($420 and $633 related to VIEs, respectively)	$ 420,000,000	$ 633,000,000