Variable Interest Entities - Summary Of VIE Consolidated By FHN (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Assets:
Other assets	$ 2,209,235	$ 2,046,338
Total assets	48,644,659	43,310,900
Liabilities:
Other liabilities	900,884	873,079
Total liabilities	43,436,274	38,234,892
Rabbi Trusts Used for Deferred Compensation Plans
Assets:
Other assets	93,212	91,873
Total assets	93,212	91,873
Liabilities:
Other liabilities	71,783	70,830
Total liabilities	$ 71,783	$ 70,830