Fair Value Option - Aggregate Differences (Details) - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Long-term beneficial interests
Performing loans, ninety days or more past due	$ 0	$ 0
Lending-related commitments, fair value option elected
Long-term beneficial interests
Contractual amount of lending-related commitments	9,100,000,000	7,400,000,000
Contractual lending-related commitments, fair value	(53,000,000)	(76,000,000)
Contractual principal outstanding
Loans
Nonaccrual loans	4,171,000,000	4,258,000,000
Total loans	49,196,000,000	44,954,000,000
Contractual principal outstanding \| Principal-protected debt
Long-term debt
Total long-term debt	31,858,000,000	26,297,000,000
Contractual principal outstanding \| Loans reported as trading assets
Loans
Nonaccrual loans	4,171,000,000	4,219,000,000
All other performing loans	41,986,000,000	38,157,000,000
Contractual principal outstanding \| Loans
Loans
Nonaccrual loans	0	39,000,000
All other performing loans	3,039,000,000	2,539,000,000
Fair value
Loans
Nonaccrual loans	1,189,000,000	1,371,000,000
Total loans	44,571,000,000	40,469,000,000
Long-term debt
Total long-term debt	54,112,000,000	47,519,000,000
Long-term beneficial interests
Total long-term beneficial interests	17,000,000	45,000,000
Fair value \| Principal-protected debt
Long-term debt
Total long-term debt	27,518,000,000	23,848,000,000
Fair value \| Nonprincipal-protected debt
Long-term debt
Total long-term debt	26,594,000,000	23,671,000,000
Long-term beneficial interests
Total long-term beneficial interests	17,000,000	45,000,000
Fair value \| Loans reported as trading assets
Loans
Nonaccrual loans	1,189,000,000	1,371,000,000
All other performing loans	40,395,000,000	36,590,000,000
Fair value \| Loans
Loans
Nonaccrual loans	0	0
All other performing loans	2,987,000,000	2,508,000,000
Fair value over/(under) contractual principal outstanding
Loans
Nonaccrual loans, Fair value over/(under) contractual principal outstanding	(2,982,000,000)	(2,887,000,000)
Total loans	(4,625,000,000)	(4,485,000,000)
Fair value over/(under) contractual principal outstanding \| Principal-protected debt
Long-term debt
Long-term debt, Fair value over/(under) contractual principal outstanding	(4,340,000,000)	(2,449,000,000)
Fair value over/(under) contractual principal outstanding \| Loans reported as trading assets
Loans
Nonaccrual loans, Fair value over/(under) contractual principal outstanding	(2,982,000,000)	(2,848,000,000)
All other performing loans	(1,591,000,000)	(1,567,000,000)
Fair value over/(under) contractual principal outstanding \| Loans
Loans
Nonaccrual loans, Fair value over/(under) contractual principal outstanding	0	(39,000,000)
All other performing loans	$ (52,000,000)	$ (31,000,000)

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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Fair Value Options Other Performing Loans.

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Guarantor Obligations, Net of Other Commitments, Current Carrying Value

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Long Term Beneficial Interests.

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Long term beneficial interests.

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- Definition

This item represents the difference between the aggregate fair value and the aggregate unpaid principal balance of long-term debt instruments that have contractual principal amounts and for which the fair value option has been elected.

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-Publisher FASB
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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.

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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 in nonaccrual status.

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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.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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