Acqusitions and Divestitures (Schedule of Acquired Assets and Liabilities) (Details) (Mountain National Bank [Member], USD $) In Thousands, unless otherwise specified	Jun. 07, 2013
Acquired From FDIC [Member]
Assets:
Cash and cash equivalents	$ 54,872
Interest-bearing cash	26,984
Securities available-for-sale	74,640
Loans, net of unearned income	249,001
Core Deposit Intangible	0
Premises and equipment, net	9,366
Real estate acquired by foreclosure	33,294
Deferred tax asset	(286)
Other assets	2,712
Total assets acquired	450,583
Liabilities:
Deposits	362,098
Securities sold under agreements to repurchase	1,930
Federal Home Loan Bank advances	50,040
Other liabilities	4,844
Total liabilities assumed	418,912
Acquired noncontrolling interest	117
Total liabilities assumed and acquired noncontrolling interest	419,029
Excess of assets acquired over liabilities assumed	31,554
Purchase Accounting Fair Value Adjustments [Member]
Assets:
Cash and cash equivalents	0
Interest-bearing cash	0
Securities available-for-sale	(240)
Loans, net of unearned income	(34,000)
Core Deposit Intangible	2,300
Premises and equipment, net	0
Real estate acquired by foreclosure	(10,463)
Deferred tax asset	2,915
Other assets	0
Total assets acquired	(39,488)
Liabilities:
Deposits	0
Securities sold under agreements to repurchase	0
Federal Home Loan Bank advances	5,586
Other liabilities	0
Total liabilities assumed	5,586
Acquired noncontrolling interest	0
Total liabilities assumed and acquired noncontrolling interest	5,586
Aggregate purchase accounting/fair value adjustments	(45,074)
As Recorded by FHN [Member]
Assets:
Cash and cash equivalents	54,872
Interest-bearing cash	26,984
Securities available-for-sale	74,400
Loans, net of unearned income	215,001
Core Deposit Intangible	2,300
Premises and equipment, net	9,366
Real estate acquired by foreclosure	22,831
Deferred tax asset	2,629
Other assets	2,712
Total assets acquired	411,095
Liabilities:
Deposits	362,098
Securities sold under agreements to repurchase	1,930
Federal Home Loan Bank advances	55,626
Other liabilities	4,844
Total liabilities assumed	424,498
Acquired noncontrolling interest	117
Total liabilities assumed and acquired noncontrolling interest	424,615
Goodwill	$ 13,520