Investment Securities - Schedule of Cost/Amortized, Unrealized Gains/Losses & Fair Value on Available-for-sale Securities (Details) - USD ($) $ in Millions	Sep. 30, 2026	Dec. 31, 2025
Debt Securities, Available-for-sale [Line Items]
Cost/ Amortized Cost	$ 1,601	$ 1,584
Unrealized Gains	2	13
Unrealized Losses	(113)	(65)
Fair Value	1,490	1,532
U.S. government and government sponsored entities
Debt Securities, Available-for-sale [Line Items]
Cost/ Amortized Cost	13	13
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	13	13
Obligations of states, municipalities, and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Cost/ Amortized Cost	55	59
Unrealized Gains	0	0
Unrealized Losses	(4)	(3)
Fair Value	51	56
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Cost/ Amortized Cost	42	0
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	42	0
Non-U.S. government and government sponsored entities
Debt Securities, Available-for-sale [Line Items]
Cost/ Amortized Cost	133	159
Unrealized Gains	0	1
Unrealized Losses	(5)	(3)
Fair Value	128	157
Corporate debt
Debt Securities, Available-for-sale [Line Items]
Cost/ Amortized Cost	1,070	1,057
Unrealized Gains	2	11
Unrealized Losses	(72)	(38)
Fair Value	1,000	1,030
RMBS
Debt Securities, Available-for-sale [Line Items]
Cost/ Amortized Cost	207	206
Unrealized Gains	0	1
Unrealized Losses	(27)	(17)
Fair Value	180	190
CMBS
Debt Securities, Available-for-sale [Line Items]
Cost/ Amortized Cost	19	24
Unrealized Gains	0	0
Unrealized Losses	(2)	(2)
Fair Value	17	22
CDO/ABS
Debt Securities, Available-for-sale [Line Items]
Cost/ Amortized Cost	62	66
Unrealized Gains	0	0
Unrealized Losses	(3)	(2)
Fair Value	$ 59	$ 64

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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