Fair Values - Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis (Details) - Nonrecurring - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Assets at fair value
Loans	$ 7,561		$ 7,561		$ 8,747
Other assets—Other investments					4
Other assets—ROU assets					23
Total	7,561		7,561		8,774
Liabilities
Other liabilities and accrued expenses—Lending commitments	122		122		170
Total	122		122		170
Assets
Fair Value Adjustment Disclosure
Gains (losses) from fair value remeasurements	(146)	$ (32)	(209)	$ (129)
Loans
Fair Value Adjustment Disclosure
Gains (losses) from fair value remeasurements	(136)	(35)	(190)	(117)
Other assets—Other investments
Fair Value Adjustment Disclosure
Gains (losses) from fair value remeasurements	0	5	(7)	4
Other assets - Premises, equipement and software
Fair Value Adjustment Disclosure
Gains (losses) from fair value remeasurements	(10)	(2)	(12)	(6)
Other assets - ROU assets
Fair Value Adjustment Disclosure
Gains (losses) from fair value remeasurements	0	0	0	(10)
Liabilities
Fair Value Adjustment Disclosure
Gains (losses) from fair value remeasurements	(2)	7	8	38
Other liabilities and accrued expenses—Lending commitments
Fair Value Adjustment Disclosure
Gains (losses) from fair value remeasurements	(2)	$ 7	8	$ 38
Level 2
Assets at fair value
Loans	1,991		1,991		4,215
Other assets—Other investments					0
Other assets—ROU assets					23
Total	1,991		1,991		4,238
Liabilities
Other liabilities and accrued expenses—Lending commitments	62		62		110
Total	62		62		110
Level 3
Assets at fair value
Loans	5,570		5,570		4,532
Other assets—Other investments					4
Other assets—ROU assets					0
Total	5,570		5,570		4,536
Liabilities
Other liabilities and accrued expenses—Lending commitments	60		60		60
Total	$ 60		$ 60		$ 60