Schedule I - Condensed Financial Information Of Parent (Statement of Cash Flows) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Condensed Financial Statements, Captions [Line Items]
Net cash flows provided by operating activities	$ 1,661	$ 1,727	$ 2,170
Cash Flows From Investing Activities:
Other	8	11	3
Net cash flows used in investing activities	(3,528)	(3,329)	(2,435)
Cash flows from financing activities:
Dividends on common stock	(565)	(494)	(472)
Short-term debt, net	55	50	(157)
Maturities of long-term debt	(8)	(442)	(580)
Issuances of long-term debt	1,997	2,183	1,527
Issuances of common stock	308	476	68
Employee payroll taxes related to stock-based compensation	(17)	(20)	(29)
Debt issuance costs	(18)	(20)	(17)
Net cash flows provided by (used in) financing activities	1,721	1,727	334
Cash, cash equivalents, and restricted cash at beginning of year	301	176	107
Cash, cash equivalents, and restricted cash at end of year	155	301	176
Noncash Investing and Financing Items [Abstract]
Noncash financing activity – Issuance of common stock for stock-based compensation	33	38	54
Parent Company
Condensed Financial Statements, Captions [Line Items]
Net cash flows provided by operating activities	79	147	491
Cash Flows From Investing Activities:
Money pool advances, net	(92)		(26)
Money pool advances, net		86
Notes receivable – ATXI	40	0	0
Investments in subsidiaries	(489)	(956)	(142)
Other	7	8	5
Net cash flows used in investing activities	(534)	(862)	(163)
Cash flows from financing activities:
Dividends on common stock	(565)	(494)	(472)
Short-term debt, net	(213)	337	(317)
Money pool borrowings, net	0	(24)	(22)
Maturities of long-term debt	0	(350)	0
Issuances of long-term debt	949	798	450
Issuances of common stock	308	476	68
Employee payroll taxes related to stock-based compensation	(17)	(20)	(29)
Debt issuance costs	(7)	(7)	(4)
Net cash flows provided by (used in) financing activities	455	716	(326)
Net change in cash, cash equivalents, and restricted cash	0	1	2
Cash, cash equivalents, and restricted cash at beginning of year	4	3	1
Cash, cash equivalents, and restricted cash at end of year	4	4	3
Cash dividends received from consolidated subsidiaries	123	105	445
Noncash Investing and Financing Items [Abstract]
Noncash financing activity – Issuance of common stock for stock-based compensation	$ 33	$ 38	$ 54

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