Acquisitions and Divestitures - Narrative (Details) $ in Thousands			3 Months Ended		9 Months Ended
	Jul. 17, 2020 USD ($) branch	Jul. 01, 2020 USD ($) numberNewPreferredStockSeries office state shares	Sep. 30, 2020 USD ($) shares	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) shares	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($) shares	Apr. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)
Business Acquisition [Line Items]
Number of common stock issued | shares		243,000,000	554,787,728		554,787,728		311,469,056
Number of new series of preferred stock | numberNewPreferredStockSeries		3
Assets			$ 83,029,579		$ 83,029,579		$ 43,310,900
Total loans, net of unearned income and allowance for loan losses			58,718,429		58,718,429		30,860,804
Securities available for sale at fair value			7,995,872		7,995,872		4,445,403
Deposits			68,408,907		68,408,907		32,429,535
Goodwill			1,510,431	$ 1,432,787	1,510,431	$ 1,432,787	$ 1,432,787		$ 1,432,787
Purchase accounting gain			532,150	$ 0	$ 532,150	$ 0
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								$ 25,000
IBERIABANK (IBKC)
Business Acquisition [Line Items]
Deposits			28,231,609		$ 28,231,609
Goodwill			(532,150)		(532,150)
Purchase accounting gain		$ 532,200
SunTrust Banks, Inc. Branches
Business Acquisition [Line Items]
Number of bank branches | branch	30
Loans and leases (a)	$ 423,400
Deposits	$ 2,200,000		2,194,870		2,194,870
Deposits premium percent	3.40%
Goodwill			$ 77,644		$ 77,644
IBERIABANK (IBKC)
Business Acquisition [Line Items]
Equity interest issued, value assigned		$ 2,500,000
Number of offices | office		319
Number of states | state		12
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