Variable Interest Entities - Summary of VIE Consolidated By FHN (Details) - USD ($) $ in Thousands	Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017	Dec. 31, 2016
Assets:
Cash and due from banks	$ 633,728		$ 781,291
Loans, net of unearned income	31,061,111	[1]	27,535,532	[1]	$ 27,658,929
Less: Allowance for loan losses	200,307		180,424		$ 189,555	$ 202,068
Total net loans	30,860,804		27,355,108
Other assets	2,046,338		1,802,939
Total assets	43,310,900		40,832,258
Liabilities:
Term borrowings	791,368		1,170,963
Other liabilities	873,079		580,335
Total liabilities	38,234,892		36,046,878
On-Balance Sheet Consumer Loan Securitization
Assets:
Cash and due from banks	0		0
Loans, net of unearned income	0		16,213
Less: Allowance for loan losses	0		0
Total net loans	0		16,213
Other assets	0		35
Total assets	0		16,248
Liabilities:
Term borrowings	0		2,981
Other liabilities	0		0
Total liabilities	0		2,981
Rabbi Trusts Used for Deferred Compensation Plans
Assets:
Other assets	91,873		78,446
Total assets	91,873		78,446
Liabilities:
Other liabilities	70,830		56,700
Total liabilities	$ 70,830		$ 56,700

[1] December 31, 2019 and 2018 include $18.8 million and $28.6 million, respectively, of held-to-maturity consumer mortgage loans secured by residential real estate in process of foreclosure.