Variable Interest Entities - Schedule of VIEs Consolidated by FHN (Details) - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025
Assets
Other assets	$ 3,906	$ 3,888
Liabilities:
Other liabilities	2,045	2,076
Rabbi Trusts used for Deferred Compensation Plans
Assets
Other assets	208	202
Liabilities:
Other liabilities	$ 187	$ 176

Amount of assets classified as other.

Amount of liabilities classified as other.

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+ Details