Acquisitions and Divestitures - Narrative (Details) $ in Thousands	Jul. 17, 2020 USD ($) branch	Jul. 01, 2020 USD ($) office state shares	Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)	Apr. 30, 2019 USD ($)
Business Acquisition [Line Items]
Assets			$ 48,644,659	$ 43,310,900
Total loans, net of unearned income and allowance for loan losses			32,171,056	30,860,804
Securities available-for-sale			5,476,156	4,445,403
Deposits			$ 37,759,351	$ 32,429,535
Subprime Consumer Loans | Discontinued Operations, Held-for-sale
Business Acquisition [Line Items]
Loans disposed of					$ 25,000
Subsequent Event | SunTrust Banks, Inc. Branches
Business Acquisition [Line Items]
Number of bank branches | branch	30
Loans	$ 423,700
Deposits	$ 2,200,000
Deposits premium percent	3.40%
Subsequent Event | IBERIABANK (IBKC)
Business Acquisition [Line Items]
Equity interest issued, number of shares (in shares) | shares		242,000,000
Equity interest issued, value assigned		$ 2,500,000
Number of offices | office		319
Number of states | state		12
Assets		$ 34,700,000
Total loans, net of unearned income and allowance for loan losses		26,100,000
Securities available-for-sale		3,500,000
Deposits		$ 28,300,000
Subsequent Event | NORTH CAROLINA | SunTrust Banks, Inc. Branches
Business Acquisition [Line Items]
Number of bank branches | branch	20
Subsequent Event | VIRGINIA | SunTrust Banks, Inc. Branches
Business Acquisition [Line Items]
Number of bank branches | branch	8
Subsequent Event | GEORGIA | SunTrust Banks, Inc. Branches
Business Acquisition [Line Items]
Number of bank branches | branch	2