Loans - Wholesale Loan Portfolio, Geographic Distribution and Delinquency (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022
Financing Receivable, Past Due [Line Items]
Retained loans	$ 1,265,941	$ 1,089,598	$ 1,068,073
Wholesale
Financing Receivable, Past Due [Line Items]
Retained loans	671,952	603,670	$ 596,208
Wholesale | Criticized nonaccrual
Financing Receivable, Past Due [Line Items]
Retained loans	2,907	1,963
Wholesale | Current and less than 30 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Retained loans	666,850	599,009
Wholesale | 30–89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Retained loans	2,054	2,544
Wholesale | 90 or more days past due and still accruing
Financing Receivable, Past Due [Line Items]
Retained loans	141	154
Wholesale | Total U.S.
Financing Receivable, Past Due [Line Items]
Retained loans	549,853	479,589
Wholesale | Total non-U.S.
Financing Receivable, Past Due [Line Items]
Retained loans	122,099	124,081
Wholesale | Secured by real estate
Financing Receivable, Past Due [Line Items]
Retained loans	161,877	126,732
Wholesale | Secured by real estate | Criticized nonaccrual
Financing Receivable, Past Due [Line Items]
Retained loans	490	246
Wholesale | Secured by real estate | Current and less than 30 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Retained loans	160,861	126,083
Wholesale | Secured by real estate | 30–89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Retained loans	507	402
Wholesale | Secured by real estate | 90 or more days past due and still accruing
Financing Receivable, Past Due [Line Items]
Retained loans	19	1
Wholesale | Secured by real estate | Total U.S.
Financing Receivable, Past Due [Line Items]
Retained loans	159,200	123,740
Wholesale | Secured by real estate | Total non-U.S.
Financing Receivable, Past Due [Line Items]
Retained loans	2,677	2,992
Wholesale | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Retained loans	166,177	167,660
Wholesale | Commercial and industrial | Criticized nonaccrual
Financing Receivable, Past Due [Line Items]
Retained loans	1,320	1,018
Wholesale | Commercial and industrial | Current and less than 30 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Retained loans	164,179	165,415
Wholesale | Commercial and industrial | 30–89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Retained loans	598	1,127
Wholesale | Commercial and industrial | 90 or more days past due and still accruing
Financing Receivable, Past Due [Line Items]
Retained loans	80	100
Wholesale | Commercial and industrial | Total U.S.
Financing Receivable, Past Due [Line Items]
Retained loans	125,997	125,324
Wholesale | Commercial and industrial | Total non-U.S.
Financing Receivable, Past Due [Line Items]
Retained loans	40,180	42,336
Wholesale | Other
Financing Receivable, Past Due [Line Items]
Retained loans	343,898	309,278
Wholesale | Other | Criticized nonaccrual
Financing Receivable, Past Due [Line Items]
Retained loans	1,097	699
Wholesale | Other | Current and less than 30 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Retained loans	341,810	307,511
Wholesale | Other | 30–89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Retained loans	949	1,015
Wholesale | Other | 90 or more days past due and still accruing
Financing Receivable, Past Due [Line Items]
Retained loans	42	53
Wholesale | Other | Total U.S.
Financing Receivable, Past Due [Line Items]
Retained loans	264,656	230,525
Wholesale | Other | Total non-U.S.
Financing Receivable, Past Due [Line Items]
Retained loans	$ 79,242	$ 78,753