Acquisitions and Divestitures - Narrative (Details) $ in Millions			12 Months Ended
	Jul. 17, 2020 USD ($) branch	Jul. 01, 2020 USD ($) office state numberNewPreferredStockSeries shares	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($)	Apr. 30, 2019 USD ($)	Dec. 31, 2017 USD ($)
Business Acquisition [Line Items]
Common stock, shares issued (in shares) | shares		243,000,000	555,030,652	311,469,056
Number of new series of preferred stock | numberNewPreferredStockSeries		3
Number of states | state		12
Purchase accounting gain			$ 533	$ 0	$ 0
Goodwill			$ 1,511	$ 1,433	$ 1,433		$ 1,387
Core deposit intangibles
Business Acquisition [Line Items]
Finite-lived intangible asset, estimated useful life			10 years
Subprime Consumer Loans | Discontinued Operations, Held-for-sale
Business Acquisition [Line Items]
Loans disposed of						$ 25
IBERIABANK (IBKC)
Business Acquisition [Line Items]
Purchase accounting gain		$ 533	$ 533
Number of bank branches | branch	30
Deposits		28,232
Goodwill		(533)
SunTrust Banks, Inc. Branches
Business Acquisition [Line Items]
Number of bank branches | branch	30
Deposits	$ 2,195
Deposits premium percent	3.40%
Loans and leases	$ 423
Goodwill	$ 78		$ 78
IBERIABANK (IBKC)
Business Acquisition [Line Items]
Equity interest issued, value assigned		$ 2,500
Number of offices | office		319
NORTH CAROLINA | SunTrust Banks, Inc. Branches
Business Acquisition [Line Items]
Number of bank branches | branch	20
VIRGINIA | SunTrust Banks, Inc. Branches
Business Acquisition [Line Items]
Number of bank branches | branch	8
GEORGIA | SunTrust Banks, Inc. Branches
Business Acquisition [Line Items]
Number of bank branches | branch	2