Variable Interest Entities - Summary Of VIE Consolidated By FHN (Details) - USD ($) $ in Thousands	Jun. 30, 2019		Mar. 31, 2019	Dec. 31, 2018		Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Assets:
Cash and due from banks	$ 596,081			$ 781,291
Loans, net of unearned income	29,712,810	[1]		27,535,532	[1]	$ 27,701,740
Less: Allowance for loan losses	192,749		$ 184,911	180,424		$ 185,462	$ 187,194	$ 189,555
Total net loans	29,520,061			27,355,108
Total assets	1,885,116			1,802,939
Total assets	42,171,770			40,832,258
Liabilities:
Term borrowings	1,186,646			1,170,963
Other liabilities	741,862			580,335
Total liabilities	37,245,689			36,046,878
On-Balance Sheet Consumer Loan Securitization
Assets:
Cash and due from banks	0			0
Loans, net of unearned income	13,483			16,213
Less: Allowance for loan losses	0			0
Total net loans	13,483			16,213
Total assets	29			35
Total assets	13,512			16,248
Liabilities:
Term borrowings	1,801			2,981
Other liabilities	0			0
Total liabilities	1,801			2,981
Rabbi Trusts Used for Deferred Compensation Plans
Assets:
Total assets	87,222			78,446
Total assets	87,222			78,446
Liabilities:
Other liabilities	65,867			56,700
Total liabilities	$ 65,867			$ 56,700

[1] June 30, 2019 and December 31, 2018 include $17.3 million and $28.6 million, respectively, of held-to-maturity consumer mortgage loans secured by residential real estate in process of foreclosure.