Fair Value Option - Aggregate differences (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Long-term beneficial interests
Performing loans - 90 days or more outstanding	$ 0	$ 0
Other guarantees and commitments
Long-term beneficial interests
Other guarantees and commitments, contractual amount	5,580,000,000	5,720,000,000
Guarantor obligations, current carrying value	(116,000,000)	(121,000,000)
Letters of credit hedged by derivative transactions \| Other guarantees and commitments
Long-term beneficial interests
Other guarantees and commitments, contractual amount	4,400,000,000	4,500,000,000
Guarantor obligations, current carrying value	(139,000,000)	(147,000,000)
Carrying value
Loans
Nonaccrual loans	3,725,000,000	3,854,000,000
Total loans	38,819,000,000	43,859,000,000
Carrying value \| Trading assets
Loans
Nonaccrual loans	3,718,000,000	3,847,000,000
All other performing loans	32,983,000,000	37,608,000,000
Carrying value \| Loans
Loans
Nonaccrual loans	7,000,000	7,000,000
All other performing loans	2,111,000,000	2,397,000,000
Carrying value \| Principal-protected debt
Long-term debt
Long-term debt	14,613,000,000	14,660,000,000
Estimate of Fair Value
Loans
Nonaccrual loans	865,000,000	912,000,000
Total loans	34,120,000,000	38,763,000,000
Long-term debt
Long-term debt	30,633,000,000	30,226,000,000
Long-term beneficial interests
Total long-term beneficial interests	1,281,000,000	2,162,000,000
Estimate of Fair Value \| Trading assets
Loans
Nonaccrual loans	858,000,000	905,000,000
All other performing loans	31,151,000,000	35,462,000,000
Estimate of Fair Value \| Loans
Loans
Nonaccrual loans	7,000,000	7,000,000
All other performing loans	2,104,000,000	2,389,000,000
Estimate of Fair Value \| Principal-protected debt
Long-term debt
Long-term debt	15,357,000,000	15,484,000,000
Estimate of Fair Value \| Nonprincipal-protected debt
Long-term debt
Long-term debt	15,276,000,000	14,742,000,000
Long-term beneficial interests
Total long-term beneficial interests	1,281,000,000	2,162,000,000
Change During Period
Loans
Nonaccrual loans	(2,860,000,000)	(2,942,000,000)
Total loans	(4,699,000,000)	(5,096,000,000)
Change During Period \| Trading assets
Loans
Nonaccrual loans	(2,860,000,000)	(2,942,000,000)
All other performing loans	(1,832,000,000)	(2,146,000,000)
Change During Period \| Loans
Loans
Nonaccrual loans	0	0
All other performing loans	(7,000,000)	(8,000,000)
Change During Period \| Principal-protected debt
Long-term debt
Long-term debt	$ 744,000,000	$ 824,000,000

Represents the portion of loans held as assets for which the fair value option has been elected, valued at fair value.

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- Definition

Fair Value Options Other Performing Loans.

+ References

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- Definition

Long Term Beneficial Interests.

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No definition available.

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- Definition

This item represents the aggregate fair value of loans held as assets that are in nonaccrual status for which the fair value option has been elected, if the entity's policy is to recognize interest income separately from other changes in fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 28

-Subparagraph (e)(2)

-URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14064-108612

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- Definition

For loans held as assets for which the fair value option has been elected, this item represents the difference between the aggregate fair value and the aggregate unpaid principal balance of those loans that are 90 days or more past due, in nonaccrual status, or both.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 28

-Subparagraph (e)(3)

-URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14064-108612

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- Definition

The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 460

-SubTopic 10

-Section 50

-Paragraph 4

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12069-110248

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- Definition

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 460

-SubTopic 10

-Section 50

-Paragraph 4

-Subparagraph (b)(1)

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- Definition

Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 7

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22)

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-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.16)

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 9

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-Number 210

-Section 02

-Paragraph 20, 22

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-Publisher FASB

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-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

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