Significant Accounting Policies (Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ 11,055	$ 10,401	$ 8,713
Other comprehensive income (loss) before reclassifications	37	(9)
Amounts reclassified from Accumulated other comprehensive loss	4	4
Other comprehensive income (loss)	41	(5)	50
Ending balance	11,704	11,055	10,401
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(67)	(62)	(112)
Other comprehensive income (loss)	41	(5)	50
Ending balance	(26)	(67)	(62)
Net Unrealized Gain (Loss) on Derivatives
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(17)	(4)
Other comprehensive income (loss) before reclassifications	47	(14)
Amounts reclassified from Accumulated other comprehensive loss	0	1
Other comprehensive income (loss)	47	(13)
Ending balance	30	(17)	(4)
Benefit Obligations
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(52)	(58)
Other comprehensive income (loss) before reclassifications	(3)	3
Amounts reclassified from Accumulated other comprehensive loss	4	3
Other comprehensive income (loss)	1	6
Ending balance	(51)	(52)	(58)
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	2	0
Other comprehensive income (loss) before reclassifications	(7)	2
Amounts reclassified from Accumulated other comprehensive loss	0	0
Other comprehensive income (loss)	(7)	2
Ending balance	$ (5)	$ 2	$ 0