LOANS - Corporate Loans Credit Quality Indicators (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Loans receivable
Loans, net of unearned income	$ 672,938	$ 667,034
Loans at fair value	4,536	4,374
Corporate
Loans receivable
Loans, net of unearned income	347,854	333,378
Total non-accrual	1,668	1,942
Loans at fair value	4,513	4,349
Corporate \| Commercial and industrial
Loans receivable
Loans, net of unearned income	151,727	141,322
Total non-accrual	1,260	1,506
Corporate \| Financial institutions
Loans receivable
Loans, net of unearned income	75,012	73,757
Total non-accrual	87	92
Corporate \| Mortgage and real estate
Loans receivable
Loans, net of unearned income	53,109	51,964
Total non-accrual	192	195
Corporate \| Lease financing
Loans receivable
Loans, net of unearned income	1,629	1,655
Total non-accrual	43	46
Corporate \| Other
Loans receivable
Loans, net of unearned income	61,864	60,331
Total non-accrual	86	103
Corporate \| Private bank loans managed on a delinquency basis
Loans receivable
Loans, net of unearned income	25,860	25,674
Corporate \| Investment grade
Loans receivable
Loans, net of unearned income	253,720	242,326
Corporate \| Investment grade \| Commercial and industrial
Loans receivable
Loans, net of unearned income	108,881	101,313
Corporate \| Investment grade \| Financial institutions
Loans receivable
Loans, net of unearned income	62,082	60,404
Corporate \| Investment grade \| Mortgage and real estate
Loans receivable
Loans, net of unearned income	23,831	23,213
Corporate \| Investment grade \| Lease financing
Loans receivable
Loans, net of unearned income	1,063	1,090
Corporate \| Investment grade \| Other
Loans receivable
Loans, net of unearned income	57,863	56,306
Corporate \| Non-investment grade
Loans receivable
Loans, net of unearned income	63,761	61,029
Corporate \| Non-investment grade \| Commercial and industrial
Loans receivable
Loans, net of unearned income	41,586	38,503
Total non-accrual	1,260	1,506
Corporate \| Non-investment grade \| Financial institutions
Loans receivable
Loans, net of unearned income	12,843	13,261
Total non-accrual	87	92
Corporate \| Non-investment grade \| Mortgage and real estate
Loans receivable
Loans, net of unearned income	3,226	2,881
Total non-accrual	192	195
Corporate \| Non-investment grade \| Lease financing
Loans receivable
Loans, net of unearned income	523	518
Total non-accrual	43	46
Corporate \| Non-investment grade \| Other
Loans receivable
Loans, net of unearned income	3,915	3,924
Total non-accrual	$ 86	$ 103

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No definition available.

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- Definition

Recorded investment in financing receivables that are on nonaccrual status as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5111-111524

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- Definition

Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes 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 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5074-111524

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- Definition

Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-URI http://asc.fasb.org/subtopic&trid=2196772

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