Loans and Allowance for Loan Losses - Loans in Consumer Portfolio Segment and Purchased Credit Impaired Loans Segment (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Consumer portfolio loans
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	$ 603	$ 645
Nonaccrual	421	465
Loans held for investment	86,507	80,014
Total	86,507	80,014
Consumer
Consumer portfolio loans
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	206	264
Accrual	43,226	38,971
Nonaccrual	140	126
Loans held for investment	43,372	39,105
Total	43,372	39,105
Consumer \| Residential mortgage
Consumer portfolio loans
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	184	234
Accrual	38,314	35,534
Nonaccrual	121	104
Total	38,439	35,643
Consumer \| Home equity and other consumer loans
Consumer portfolio loans
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	22	30
Accrual	4,912	3,437
Nonaccrual	19	22
Total	4,933	3,462
Commercial
Consumer portfolio loans
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	397	381
Nonaccrual	281	339
Loans held for investment	43,135	40,909
Total	43,135	40,909
Commercial \| Commercial mortgage
Consumer portfolio loans
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	25	33
Nonaccrual	12	20
Total	15,354	14,320
Excluding Loans Covered by FDIC Loss Share Agreements [Member] \| Consumer
Consumer portfolio loans
Total	43,366	39,097
Excluding Loans Covered by FDIC Loss Share Agreements [Member] \| Consumer \| Residential mortgage
Consumer portfolio loans
Total	38,435	35,638
Excluding Loans Covered by FDIC Loss Share Agreements [Member] \| Consumer \| Home equity and other consumer loans
Consumer portfolio loans
Total	4,931	3,459
Notes Receivable [Member] \| Consumer \| Residential mortgage
Consumer portfolio loans
Loans held for investment	38,000
Notes Receivable [Member] \| Commercial \| Commercial mortgage
Consumer portfolio loans
Loans held for investment	16,000
Financial and Insurance [Member] \| Notes Receivable [Member] \| Commercial
Consumer portfolio loans
Loans held for investment	7,000
Power and Utilities [Member] \| Notes Receivable [Member] \| Commercial
Consumer portfolio loans
Loans held for investment	4,000
Oil and Gas [Member] \| Notes Receivable [Member] \| Commercial
Consumer portfolio loans
Loans held for investment	3,000
Manufacturing Sector [Member] \| Notes Receivable [Member] \| Commercial
Consumer portfolio loans
Loans held for investment	4,000
Commercial Portfolio Segment [Member] \| Construction
Consumer portfolio loans
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	$ 0	$ 0

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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 purchased credit impaired loans.

+ References

No definition available.

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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
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-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5111-111524

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Unpaid principal balance of impaired financing receivables for which there is a related allowance for credit losses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
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-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

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+ 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 210.9-03.10(3))
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