Commitments and Contingencies - Summary (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Investments in affordable housing projects:
Carrying amount	$ 2,018	$ 1,948
Amount of future funding commitments included in carrying amount	935	928
Lending exposure	526	561
Tax credits subject to recapture	455	471
Private equity investments	469	471
Future funding commitments to private equity investments	$ 134	$ 143

Future funding commitments to consolidated private equity funds

No definition available.

Name:	bbt_FutureFundingCommitmentsToConsolidatedPrivateEquityFunds
Namespace Prefix:	bbt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Outstanding loan commitments to affordable housing investments

+ References

No definition available.

+ Details

Name:	bbt_OutstandingLoanCommitmentsToTheseAffordableHousingInvestments
Namespace Prefix:	bbt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Tax Credits Subject To Recapture Related To Affordable Housing Projects

+ References

No definition available.

+ Details

Name:	bbt_TaxCreditsSubjectToRecaptureRelatedToAffordableHousingProjects
Namespace Prefix:	bbt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of investment in qualified affordable housing projects.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 740
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=64813897&loc=SL49122993-202985

+ Details

Name:	us-gaap_AmortizationMethodQualifiedAffordableHousingProjectInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_OtherCommitmentsAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of commitment or contingent commitments to qualified affordable housing project investments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 740
-Section 50
-Paragraph 2
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=64813897&loc=SL49122993-202985

+ Details

Name:	us-gaap_QualifiedAffordableHousingProjectInvestmentsCommitment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Aggregate carrying value of owned private equity or other securities for which a quoted market price is not readily determinable, the value of which has been determined by management based upon fair value methods, including pricing of similar securities and valuation techniques and is included in the schedule of financial condition or the balance sheet.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Rule 15c3-1
-Number 240
-Section 15c3-1

+ Details

Name:	us-gaap_SecuritiesOwnedNotReadilyMarketable
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant