Consolidated Condensed Statements of Income (Parenthetical) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2013
Consolidated Condensed Statements Of Income [Abstract]
Employee compensation, incentives, and benefits (quarter ended March 31, 2013 includes $2.5 million of expense associated with pension and post-retirement plans reclassifed from accumulated other comprehensive income)	$ (2.5)
Reclassification From Accumulated Other Comprehensive Income Current Period Tax	$ (1.0)

Amount before tax of reclassification adjustment from accumulated other comprehensive (income) loss related to net period benefit cost (credit) for pension and other postretirement defined benefit plans.

No definition available.

Name:	fhn_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAociPensionAndOtherPostretirementBenefitPlansBeforeTax
Namespace Prefix:	fhn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration