Deposits (Narrative) (Details) - USD ($) $ in Billions	Dec. 31, 2019	Dec. 31, 2018
Deposits [Abstract]
Time Deposits, $250,000 or More	$ 1.7	$ 1.7

The aggregate amount of domestic and foreign time deposit liabilities (including certificates of deposits, individual retirement accounts and open accounts) in denominations of $250,000 or more.

No definition available.

Name:	rf_TimeDeposits250000orMore
Namespace Prefix:	rf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant