Fair Value Measurements - Changes in Level 3 Financial Assets and Financial Liabilities Carried at Fair Value (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2025	Mar. 31, 2024
Transfers into / (out of) Level 3
Change in unrealized gain or (loss) included in Other comprehensive loss for assets held at the end of the reporting period	$ 3	$ (4)
Debt securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance, including held for sale assets	417	447
Losses included in Shareholders' net income (loss)	(10)	(21)
Gains (losses) included in Other comprehensive loss	7	(3)
Purchases, sales and settlements
Purchases	2	0
Settlements	(31)	(14)
Total purchases, sales and settlements	(29)	(14)
Transfers into / (out of) Level 3
Transfers into Level 3	18	16
Transfers out of Level 3	(30)	(3)
Total transfers into / (out of) Level 3	(12)	13
Ending balance	373
Ending balance, including held for sale assets		422
Total losses included in Shareholders' net income (loss) attributable to instruments held at the reporting date	$ (13)	$ (21)

This element represents total gains or losses for the period (realized and unrealized), arising from assets included in income attributable to instruments held at the reporting date, measured at fair value on a recurring basis using unobservable inputs (Level 3), which are included in earnings or resulted in a change in asset value.

No definition available.