Other Assets - Schedule of Equity Securities without Readily Determinable Fair Value (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Other Assets [Abstract]
FRB stock	$ 442,000,000		$ 442,000,000		$ 440,000,000
FHLB stock	310,000,000		310,000,000		258,000,000
Equity investments without a readily determinable fair value
Cost basis	91,000,000		91,000,000		74,000,000
Upward adjustments	53,000,000		53,000,000		53,000,000
Downward adjustments (including impairment)	(38,000,000)		(38,000,000)		(36,000,000)
Carrying amount, equity investments without a readily determinable fair value	106,000,000		106,000,000		91,000,000
Nonmarketable equity investments	858,000,000		858,000,000		$ 789,000,000
Upward adjustments	0	$ 1,000,000	0	$ 2,000,000
Downward adjustments (including impairment)	0	(5,000,000)	(2,000,000)	(19,000,000)
Impairment of FHLB and FRB stock	$ 0	$ 0	$ 0	$ 0