Securities Purchased Under Agreements To Resell And Collateral Pledged By Company (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Securities Purchased under Agreements to Resell [Abstract]
Gross amounts of recognized assets	$ 881,732		$ 816,991
Gross amounts offset in the Statement of Condition	0		0
Net amounts of assets presented in the Statement of Condition	881,732	$ 615,773	816,991
Offsetting securities sold under agreements to repurchase	(2,137)		(3,605)
Securities collateral (not recognized on FHN's Statement of Condition)	(870,795)		(805,178)
Net amount	$ 8,800		$ 8,208