Organization, Consolidation and Presentation of Financial Statements - Immaterial Revision of Prior Period (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Retained Earnings (Accumulated Deficit)	$ (9,861)		$ (9,861)		$ (11,054)
Assets	(22,169)		(22,169)		(22,838)
Net Income (Loss)	$ 1,357	$ (113)	$ 1,184	$ (383)
Revision of Prior Period, Adjustment [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Retained Earnings (Accumulated Deficit)					46
Total liabilities					27
Assets					19
Revision of Prior Period, Adjustment [Member] | Maximum
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net Income (Loss)		$ 14		$ 14	$ 14	$ 14	$ 14	$ 14