Securities Purchased Under Agreements To Resell And Collateral Pledged By Company (Details) - USD ($)	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014
Securities Purchased under Agreements to Resell [Abstract]
Gross amounts of recognized assets	$ 793,098,000		$ 561,802,000
Gross amounts offset in the Statement of Condition	0		0
Net amounts of assets presented in the Statement of Condition	793,098,000	$ 659,154,000	561,802,000
Offsetting securities sold under agreements to repurchase	(2,909,000)		(53,382,000)
Securities collateral (not recognized on FHN's Statement of Condition)	(782,844,000)		(500,659,000)
Net amount	$ 7,345,000		$ 7,761,000