Acquisitions and Divestitures (Narrative) (Details) (USD $)	6 Months Ended	5 Months Ended
	Jun. 30, 2013	Jun. 07, 2013 Mountain National Bank [Member] number	Jun. 30, 2013 Mountain National Bank [Member]	Jun. 07, 2013 Mountain National Bank [Member] Acquired From FDIC [Member]
Business Acquisition [Line Items]
Acquisition date		Jun. 07, 2013
Business Acquisition, Name of Acquired Entity	Mountain National Bank
Business Acquisition, Description of Acquired Entity	Prior to the acquisition, MNB was organized as a national banking association and operated 12 branches in Sevier and Blount counties in eastern Tennessee. MNB's principal business was to accept demand and savings deposits from the general public and to make commercial, residential mortgage, and consumer loans.
Business Combination, Reason for Business Combination	The acquisition will allow FHN to expand and strengthen market share in eastern Tennessee.
Number Of Bank Branches		12
Assets acquired				$ 450,583,000
Loans acquired				249,001,000
Deposits assumed				362,098,000
Asset discount				33,000,000
Business Combination, Provisional Information, Initial Accounting Incomplete, Reasons	Because of the short time period between the June 7, 2013, closing of the transaction and the end of FHN's fiscal quarter on June 30, 2013, FHN continues to analyze the estimates of the fair value of the assets acquired and liabilities assumed, and as such the amounts recorded are provisional and are based on information that was available at the date of the acquisition. FHN believes that information provides a reasonable basis for estimating fair values. FHN expects to substantially complete the purchase price allocation by the end of 2013; however, the fair value estimates are subject to refinement for up to one year after the closing date of the acquisition as additional information relative to closing date fair values becomes available. In addition, the tax treatment is complex and subject to interpretations that may result in future adjustments of deferred taxes as of the acquisition date. Based on the timing of the acquisition occurring late in the second quarter, management may make revisions to its assessment of which loans should be classified as purchased credit impaired in accordance with ASC 310-30. This on-going assessment will be completed during third quarter 2013. FHN does not expect a change in designation to impact its estimate of fair value as of the acquisition date based on the information available.
Acquisition goodwill expected to be tax deductible			$ 7,900,000