Schedule I - Condensed Financial Information Of Parent (Balance Sheet) (Details) - USD ($) $ / shares in Units, $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Assets:
Cash and cash equivalents	$ 8	$ 139
Miscellaneous accounts and notes receivable	85	65
Other current assets	229	135
Total current assets	1,968	1,653
Other assets	891	789
Total assets	35,735	32,030
Liabilities and Shareholders' Equity:
Short-term debt	545	490
Other current liabilities	445	489
Total current liabilities	2,826	2,180
Long-term debt	12,562	11,078
Other deferred credits and liabilities	414	503
Commitments and Contingencies (Note 5)
Common stock, $.01 par value, 400.0 shares authorized – shares outstanding of 257.7 and 253.3, respectively	3	3
Other paid-in capital, principally premium on common stock	6,502	6,179
Retained earnings	3,182	2,757
Accumulated other comprehensive income (loss)	13	(1)
Total shareholders’ equity	9,829	9,080	$ 8,201
TOTAL LIABILITIES AND EQUITY	$ 35,735	$ 32,030
Common Stock, Par or Stated Value Per Share (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	400,000,000.0	400,000,000.0
Common Stock, Shares, Outstanding	257,700,000	253,300,000	246,200,000	244,500,000
Parent Company
Assets:
Cash and cash equivalents	$ 0	$ 0
Advances to money pool	108	16
Accounts receivable – affiliates	30	12
Miscellaneous accounts and notes receivable	11	15
Other current assets	4	4
Total current assets	153	47
Investments in subsidiaries	12,281	10,872
Note receivable – ATXI	35	75
Accumulated deferred income taxes, net	65	42
Other assets	184	167
Total assets	12,718	11,203
Liabilities and Shareholders' Equity:
Short-term debt	277	490
Taxes accrued	7	0
Accounts payable – affiliates	53	41
Other current liabilities	38	34
Total current liabilities	375	565
Long-term debt	2,533	1,588
Pension and other postretirement benefits	24	27
Other deferred credits and liabilities	86	85
Total liabilities	3,018	2,265
Commitments and Contingencies (Note 5)
Common stock, $.01 par value, 400.0 shares authorized – shares outstanding of 257.7 and 253.3, respectively	3	3
Other paid-in capital, principally premium on common stock	6,502	6,179
Retained earnings	3,182	2,757
Accumulated other comprehensive income (loss)	13	(1)
Total shareholders’ equity	9,700	8,938
TOTAL LIABILITIES AND EQUITY	$ 12,718	$ 11,203
Common Stock, Par or Stated Value Per Share (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	400,000,000.0	400,000,000.0
Common Stock, Shares, Outstanding	257,700,000	253,300,000