LOANS AND LEASES - Summary of Loans and Leases Portfolio (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 125,713	$ 119,088
Loans held for sale, at fair value	3,631	1,946
Other loans held for sale	1,362	1,384
SBA Loans Serviced For Others \| CBNA and Other Subsidiaries
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	45	33
Mortgage loans serviced for others \| CBNA and Other Subsidiaries
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	79,900	77,500
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	64,930	57,538
Commercial \| Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	48,017	41,479
Commercial \| Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	14,485	13,522
Commercial \| Leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	2,428	2,537
Commercial \| SBA Guaranteed PPP Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	4,700
Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	60,783	61,550
Retail \| Residential mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	19,245	19,083
Retail \| Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	12,541	13,154
Retail \| Automobile
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	12,028	12,120
Retail \| Education
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	10,591	10,347
Retail \| Other retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 6,378	$ 6,846

The amount of other loans receivable that will be sold to other entities.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

The face amount of loans that will be sold to other entities.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
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- Definition

Amount, before allowance for credit loss, of financing receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919230-210447

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