Commitments, Guarantees and Contingencies (Commitments) (Details) $ in Millions	Mar. 31, 2018 USD ($)
Commitment, Fiscal Year Maturity
Less than 1 (year)	$ 107,698
1-3 (years)	44,079
3-5 (years)	46,747
Over 5 (years)	9,164
Total	207,688
Corporate Lending
Commitment, Fiscal Year Maturity
Commitments participated to third parties	6,877
Forward-starting Secured Financing Receivables
Commitment, Fiscal Year Maturity
Less than 1 (year)	85,399
1-3 (years)	0
3-5 (years)	0
Over 5 (years)	1,177
Total	86,576
Commitments settled within three business days	72,754
Underwriting
Commitment, Fiscal Year Maturity
Less than 1 (year)	344
1-3 (years)	0
3-5 (years)	0
Over 5 (years)	0
Total	344
Investment Activities
Commitment, Fiscal Year Maturity
Less than 1 (year)	527
1-3 (years)	96
3-5 (years)	62
Over 5 (years)	230
Total	915
Letters of Credit and Other Financial Guarantees
Commitment, Fiscal Year Maturity
Less than 1 (year)	195
1-3 (years)	0
3-5 (years)	1
Over 5 (years)	41
Total	237
Lending Commitments \| Corporate Lending
Commitment, Fiscal Year Maturity
Less than 1 (year)	14,447
1-3 (years)	43,086
3-5 (years)	46,618
Over 5 (years)	7,454
Total	111,605
Lending Commitments \| Consumer Lending
Commitment, Fiscal Year Maturity
Less than 1 (year)	6,598
1-3 (years)	0
3-5 (years)	8
Over 5 (years)	3
Total	6,609
Lending Commitments \| Residential Real Estate Lending
Commitment, Fiscal Year Maturity
Less than 1 (year)	5
1-3 (years)	64
3-5 (years)	33
Over 5 (years)	259
Total	361
Lending Commitments \| Wholesale Real Estate Lending
Commitment, Fiscal Year Maturity
Less than 1 (year)	183
1-3 (years)	833
3-5 (years)	25
Over 5 (years)	0
Total	$ 1,041

Commitments participated to third parties.

No definition available.

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Minimum amount of other commitment maturing in the next three business days following the latest fiscal year for commitments not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in this taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

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Minimum amount of other commitment not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in the taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

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- Definition

Minimum amount of other commitment maturing after the fifth fiscal year following the latest fiscal year for commitments not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in this taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

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Minimum amount of other commitment maturing in the fourth and fifth fiscal years following the latest fiscal year for commitments not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in this taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

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Minimum amount of other commitment maturing in the next fiscal year following the latest fiscal year for commitments not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in this taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

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No definition available.

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Minimum amount of other commitment maturing in the second and third fiscal years following the latest fiscal year for commitments not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in this taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

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