Goodwill and Other Intangible Assets - Narrative (Details) $ in Millions		12 Months Ended
	Jul. 01, 2020 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jul. 17, 2020 USD ($) branch	Dec. 31, 2018 USD ($)
Goodwill [Line Items]
Purchase accounting gain		$ (1)	$ 533	$ 0
Goodwill		1,511	1,511	1,433		$ 1,433
Amortization expense		56	40	$ 25
IBERIABANK (IBKC)
Goodwill [Line Items]
Purchase accounting gain	$ 531		$ 533
Truist Bank Branches
Goodwill [Line Items]
Number of branches acquired | branch					30
Goodwill		$ 78			$ 78