Comprehensive Income (Accumulated Other Comprehensive Income (Loss), Net Of Tax) (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning	$ 5,163	$ 5,134	$ 4,678	$ 4,600	$ 5,134	$ 4,600
Net current-period other comprehensive income (loss)	9	4	4	(2)	13	2
Balance at ending	5,192	5,163	4,796	4,678	5,192	4,796
Pension And OPEB [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), net of tax	28		17		28	17	$ 23	$ 15
Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning	83	79	58	60	79	60
Net current-period other comprehensive income (loss)	9	4	4	(2)
Balance at ending	92	83	62	58	92	62
Accumulated Other Comprehensive Income [Member] | OPEB [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning		$ 79		$ 60	79	60
Other comprehensive income before reclassifications					21	6
Amounts reclassified from accumulated other comprehensive income (loss) to net loss					(8)	(4)
Net current-period other comprehensive income (loss)					13	2
Balance at ending	$ 92		$ 62		$ 92	$ 62