Significant Accounting Policies (Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ 10,401	$ 8,713	$ 12,589
Other comprehensive income (loss)	(5)	50	15
Ending balance	11,055	10,401	8,713
AOCI including portion attributable to noncontrolling interest
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(62)	(112)
Other comprehensive income (loss) before reclassifications	(9)	5
Amounts reclassified from Accumulated other comprehensive loss	4	45
Other comprehensive income (loss)	(5)	50
Ending balance	(67)	(62)	(112)
Net Unrealized Gain (Loss) on Derivatives
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(4)	(11)
Other comprehensive income (loss) before reclassifications	(14)	5
Amounts reclassified from Accumulated other comprehensive loss	1	2
Other comprehensive income (loss)	(13)	7
Ending balance	(17)	(4)	(11)
Benefit Obligations
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(58)	(101)
Other comprehensive income (loss) before reclassifications	3	0
Amounts reclassified from Accumulated other comprehensive loss	3	43
Other comprehensive income (loss)	6	43
Ending balance	(52)	(58)	(101)
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	0	0
Other comprehensive income (loss) before reclassifications	2	0
Amounts reclassified from Accumulated other comprehensive loss	0	0
Other comprehensive income (loss)	2	0
Ending balance	$ 2	$ 0	$ 0