Loan Portfolio - Loans by Category (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Residential — prime loans:
Total loans	$ 88,222	$ 86,405
Commercial lease financing includes receivables held as collateral for secured borrowing	16	24
Loans	87,335	85,528
Commercial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and industrial	44,569	41,859
Commercial real estate:
Commercial mortgage	14,162	14,088
Construction	1,736	1,960
Total commercial real estate loans	15,898	16,048
Commercial lease financing	4,509	4,826
Total commercial/consumer loans	64,976	62,733
Residential — prime loans:
Total loans		62,733
Consumer Portfolio Segment [Member]
Commercial real estate:
Total commercial/consumer loans	23,246	23,672
Residential — prime loans:
Real estate — residential mortgage	5,452	5,483
Home equity loans	11,519	12,028
Total residential — prime loans	16,971	17,511
Consumer direct loans	1,785	1,794
Credit cards	1,094	1,106
Consumer indirect loans	3,396	3,261
Total loans		23,672
Commercial Credit Card [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and industrial	128	119
Education Lending [Member] \| Discontinued Operations [Member]
Residential — prime loans:
Loans	$ 1,200	$ 1,300

Loans and leases receivable consumer direct loans.

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Loans and leases receivable consumer indirect loans.

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Amount before allowance of commercial leases and leveraged lease transactions where the entity is long-term creditor. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes leases covered under loss sharing agreements.

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Amount, before allowance and fees, of loans and leases receivable. Excludes loans and leases covered under loss sharing agreements.

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Reflects the aggregate value of loans, trade receivables, securities and financial instruments that serve as collateral for obligations arising from a transfer of financial assets recorded as a secured borrowing.

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Amount before allowance of revolving, open-end loan, extended under a line of credit and secured by the borrower's residential property. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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Amount before allowance of consumer mortgage. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes subordinated loans such as home equity lines of credit and loans and leases covered under loss sharing agreements.

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Amount before allowance of consumer real estate loans. Includes, but not limited to, construction financing, residential mortgage loans, and home equity lines of credit. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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Amount before allowance of credit card loans issued to individuals. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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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.

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Amount after allowance and 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 and loans held for sale.

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Amount before allowance of commercial construction loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans covered under loss sharing agreements.

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Amount before allowance of loans issued to agricultural, commercial and industrial, and financial institutions. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans covered under loss sharing agreements.

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Amount before allowance of mortgage loans on existing land or building. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans covered under loss sharing agreements.

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