CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (Parenthetical) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Jun. 30, 2025		Mar. 31, 2025		Jun. 30, 2024		Mar. 31, 2024		Dec. 31, 2023
Common stock - cash dividends declared per share (in dollars per share)	$ 0.15		$ 0.15		$ 0.15		$ 0.15
Common stock repurchased under share repurchase program	$ 27	[1]	$ 365	[1]	$ 228	[2]	$ 159	[2]
Accounting Standards Update [Extensible List]									Accounting Standards Update 2023-02 [Member]
General Purchase Plan
Common stock repurchased under share repurchase program	9		$ 360		212		$ 154
Share repurchase program, authorized, amount	$ 1,000				$ 650

[1] Includes $360 million and $9 million repurchased during first and second quarter, respectively, under FHN's $1 billion general purchase program approved in October 2024 and scheduled to expire in January 2026.

[2] Includes $154 million and $212 million repurchased during first and second quarter, respectively, under FHN's $650 million general purchase program approved in January 2024 and terminated in October 2024.