Consolidated Condensed Statements of Income (Parenthetical) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2013	Jun. 30, 2013
Consolidated Condensed Statements Of Income [Abstract]
Pension and post-retirement plans expense reclassified from accumulated other comprehensive income	$ 2.9	$ 5.4
Income tax benefit reclassified from accumulated other comprehensive income	$ 1.1	$ 2.1

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