Loans and Allowance for Loan Losses - Loans in Consumer Portfolio Segment and Purchased Credit Impaired Loans Segment (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Consumer portfolio loans
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	$ 423	$ 603
Nonaccrual	328	421
Loans held for investment	88,213	86,507
Consumer \| Other Consumer Loans [Member]
Consumer portfolio loans
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	2	1
Accrual	4,449	2,694
Nonaccrual	1	1
Loans held for investment	4,450	2,695
Consumer \| residential mortgage and home equity [Member]
Consumer portfolio loans
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	187	205
Accrual	37,878	40,532
Nonaccrual	137	139
Loans held for investment	38,018	40,677
Commercial \| Commercial mortgage
Consumer portfolio loans
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	7	25
Nonaccrual	15	12
Loans held for investment	16,895	15,354
Notes Receivable [Member] \| Consumer \| Residential mortgage
Consumer portfolio loans
Loans held for investment	36,000
Notes Receivable [Member] \| Commercial \| Commercial mortgage
Consumer portfolio loans
Loans held for investment	18,000
Financial and Insurance [Member] \| Notes Receivable [Member] \| Commercial
Consumer portfolio loans
Loans held for investment	8,000
Power and Utilities [Member] \| Notes Receivable [Member] \| Commercial
Consumer portfolio loans
Loans held for investment	3,000
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
Consumer Portfolio Segment [Member]
Consumer portfolio loans
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	189	206
Accrual	42,327	43,226
Nonaccrual	138	140
Loans held for investment	42,468	43,372
Total	42,465	43,366
Consumer Portfolio Segment [Member] \| residential mortgage and home equity [Member]
Consumer portfolio loans
Total	38,015	40,671
Consumer Portfolio Segment [Member] \| Other Consumer Loans [Member]
Consumer portfolio loans
Total	4,450	2,695
Commercial Portfolio Segment [Member]
Consumer portfolio loans
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	234	397
Nonaccrual	190	281
Loans held for investment	45,745	43,135
Commercial Portfolio Segment [Member] \| Construction
Consumer portfolio loans
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	$ 0	$ 0

Financing receivable recorded investment accrual status.

No definition available.

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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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- 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

Amount of financing receivable on nonaccrual status.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5111-111524

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 16
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919258-210447

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- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (a)(4)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5212-111524

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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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