Commitments, Guarantees and Contingencies - Commitments (Details) $ in Millions	Mar. 31, 2021 USD ($)
Commitment, Fiscal Year Maturity
Less than 1 (year)	$ 108,875
1-3 (years)	48,579
3-5 (years)	42,867
Over 5 (years)	13,860
Total	214,181
Forward-starting secured financing receivables
Commitment, Fiscal Year Maturity
Less than 1 (year)	73,016
1-3 (years)	0
3-5 (years)	0
Over 5 (years)	0
Total	73,016
Forward-starting secured financing receivables settled within three business days	61,198
Central counterparty
Commitment, Fiscal Year Maturity
Less than 1 (year)	300
1-3 (years)	0
3-5 (years)	0
Over 5 (years)	6,404
Total	6,704
Underwriting
Commitment, Fiscal Year Maturity
Less than 1 (year)	234
1-3 (years)	0
3-5 (years)	0
Over 5 (years)	0
Total	234
Investment activities
Commitment, Fiscal Year Maturity
Less than 1 (year)	811
1-3 (years)	267
3-5 (years)	62
Over 5 (years)	337
Total	1,477
Letters of credit and other financial guarantees
Commitment, Fiscal Year Maturity
Less than 1 (year)	30
1-3 (years)	0
3-5 (years)	0
Over 5 (years)	3
Total	33
Corporate lending
Commitment, Fiscal Year Maturity
Less than 1 (year)	16,895
1-3 (years)	38,987
3-5 (years)	40,975
Over 5 (years)	6,091
Total	102,948
Lending commitments participated to third parties	8,703
Secured lending facilities
Commitment, Fiscal Year Maturity
Less than 1 (year)	5,806
1-3 (years)	5,967
3-5 (years)	1,552
Over 5 (years)	269
Total	13,594
Commercial and Residential real estate lending
Commitment, Fiscal Year Maturity
Less than 1 (year)	435
1-3 (years)	129
3-5 (years)	19
Over 5 (years)	247
Total	830
Securities-based lending and Other
Commitment, Fiscal Year Maturity
Less than 1 (year)	11,348
1-3 (years)	3,229
3-5 (years)	259
Over 5 (years)	509
Total	$ 15,345