Consolidated Statements of Changes in Equity (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Equity, Class of Treasury Stock [Line Items]
Common stock - cash dividends declared per share (in dollars per share)	$ 0.60	$ 0.60	$ 0.60
First Horizon Share Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Common stock repurchased under share repurchase programs			$ 401
Preferred Stock
Equity, Class of Treasury Stock [Line Items]
Number of shares issued in transaction (in shares)		4,936	1,500
Preferred stock issuance, net of offering cost (in dollars per share)		$ 100,000	$ 100,000