Loans and Allowance for Loan Losses - Loans in Consumer Portfolio an Purchased credit-impaired loans (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Loans disclosures
Nonaccrual	$ 323	$ 328
Consumer
Loans disclosures
Loans covered by FDIC loss share agreements		3
Accrual		42,327
Nonaccrual	149	138
Total loans held for investment, before purchased credit-impaired loans		42,465
Consumer \| Other Consumer Loans [Member]
Loans disclosures
Total loans held for investment, before purchased credit-impaired loans		4,450
Consumer \| residential mortgage and home equity [Member]
Loans disclosures
Total loans held for investment, before purchased credit-impaired loans		38,015
Other Consumer Loans [Member] \| Consumer Loans Portfolio Segment [Member]
Loans disclosures
Accrual		4,449
Nonaccrual	3	1
residential mortgage and home equity [Member] \| Consumer Loans Portfolio Segment [Member]
Loans disclosures
Accrual		37,878
Nonaccrual	$ 146	$ 137

Financing receivable recorded investment accrual status.

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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

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+ 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

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.

+ 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
-URI http://asc.fasb.org/extlink&oid=118952595&loc=d3e4428-111522

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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