Comprehensive Income (Accumulated Other Comprehensive Income (Loss), Net Of Tax) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022	Dec. 31, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning	$ 5,134	$ 4,600
Net current-period other comprehensive income (loss)	4	(2)
Balance at ending	5,163	4,678
Pension And OPEB [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), net of tax	25	15	$ 23	$ 15
Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning	79	60
Net current-period other comprehensive income (loss)	4	(2)
Balance at ending	83	58
Accumulated Other Comprehensive Income [Member] | OPEB [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning	79	60
Other comprehensive income before reclassifications	8	1
Amounts reclassified from accumulated other comprehensive income (loss) to net loss	(4)	(3)
Net current-period other comprehensive income (loss)	4	(2)
Balance at ending	$ 83	$ (58)