ALLOWANCE FOR CREDIT LOSSES, NONPERFORMING ASSETS, AND CONCENTRATIONS OF CREDIT RISK - Summary of Changes in Allowance for Credit Losses (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
Sep. 30, 2014	Sep. 30, 2013
Allowance for Loan and Lease Losses [Roll Forward]
Allowance for loan and lease losses / Reserve for unfunded lending commitments	$ 1,221
Provision for credit losses	247	347
Allowance for loan and lease losses / Reserve for unfunded lending commitments	1,201
Allowance for loan and lease losses
Allowance for Loan and Lease Losses [Roll Forward]
Allowance for loan and lease losses / Reserve for unfunded lending commitments	1,221	1,255
Charge-offs	(374)	(542)
Recoveries	131	156
Net recoveries (charge-offs)	(243)	(386)
Provision for credit losses	223	(350)
Allowance for loan and lease losses / Reserve for unfunded lending commitments	1,201	1,219
Allowance for loan and lease losses \| Commercial
Allowance for Loan and Lease Losses [Roll Forward]
Allowance for loan and lease losses / Reserve for unfunded lending commitments	498	509
Charge-offs	(30)	(72)
Recoveries	47	69
Net recoveries (charge-offs)	17	(3)
Provision for credit losses	27	(51)
Allowance for loan and lease losses / Reserve for unfunded lending commitments	542	455
Allowance for loan and lease losses \| Retail
Allowance for Loan and Lease Losses [Roll Forward]
Allowance for loan and lease losses / Reserve for unfunded lending commitments	723	657
Charge-offs	(344)	(470)
Recoveries	84	87
Net recoveries (charge-offs)	(260)	(383)
Provision for credit losses	196	(329)
Allowance for loan and lease losses / Reserve for unfunded lending commitments	659	603
Allowance for loan and lease losses \| Unallocated
Allowance for Loan and Lease Losses [Roll Forward]
Allowance for loan and lease losses / Reserve for unfunded lending commitments		89
Charge-offs		0
Recoveries		0
Net recoveries (charge-offs)		0
Provision for credit losses		(72)
Allowance for loan and lease losses / Reserve for unfunded lending commitments		161
Reserve for unfunded lending commitments
Allowance for Loan and Lease Losses [Roll Forward]
Allowance for loan and lease losses / Reserve for unfunded lending commitments	39	40
Provision for Other Credit Losses	(24)	3
Allowance for loan and lease losses / Reserve for unfunded lending commitments	63	37
Reserve for unfunded lending commitments \| Commercial
Allowance for Loan and Lease Losses [Roll Forward]
Allowance for loan and lease losses / Reserve for unfunded lending commitments	39	40
Provision for Other Credit Losses	(24)	3
Allowance for loan and lease losses / Reserve for unfunded lending commitments	63	37
Reserve for unfunded lending commitments \| Retail
Allowance for Loan and Lease Losses [Roll Forward]
Allowance for loan and lease losses / Reserve for unfunded lending commitments	0	0
Provision for Other Credit Losses	0	0
Allowance for loan and lease losses / Reserve for unfunded lending commitments	0	0
Reserve for unfunded lending commitments \| Unallocated
Allowance for Loan and Lease Losses [Roll Forward]
Allowance for loan and lease losses / Reserve for unfunded lending commitments		0
Provision for Other Credit Losses		0
Allowance for loan and lease losses / Reserve for unfunded lending commitments		0
Allowance for loan and lease losses and reserve for off-balance sheet activities. Total
Allowance for Loan and Lease Losses [Roll Forward]
Allowance for loan and lease losses / Reserve for unfunded lending commitments	1,264	1,256
Allowance for loan and lease losses and reserve for off-balance sheet activities. Total \| Commercial
Allowance for Loan and Lease Losses [Roll Forward]
Allowance for loan and lease losses / Reserve for unfunded lending commitments	605	492
Allowance for loan and lease losses and reserve for off-balance sheet activities. Total \| Retail
Allowance for Loan and Lease Losses [Roll Forward]
Allowance for loan and lease losses / Reserve for unfunded lending commitments	659	603
Allowance for loan and lease losses and reserve for off-balance sheet activities. Total \| Unallocated
Allowance for Loan and Lease Losses [Roll Forward]
Allowance for loan and lease losses / Reserve for unfunded lending commitments		$ 161

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Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.

+ References

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- Definition

Amount, after recoveries, of loans and leases that have been written-off.

+ References

No definition available.

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- Definition

Amount of recovery of loans and lease receivables which had previously been fully or partially written-off as bad debts.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (c)(4)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953423-111524

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- Definition

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.7(d))

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 7

-Subparagraph d

-Article 9

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (g)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953423-111524

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-Section 50

-Paragraph 11B

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953423-111524

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 30

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-Paragraph 2

-Subparagraph (b)(1)(ii)

-URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 6

-Section L

-Subsection 1

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- Definition

Amount of expense related to estimated loss from loan and lease transactions.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 11

-Article 9

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-04.11)

-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

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-Section 50

-Paragraph 11B

-Subparagraph (c)(2)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953423-111524

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- Definition

Amount of expense related to credit loss from transactions other than loan and lease transactions.

+ References

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