Variable Interest Entities (Summary Of VIE Not Consolidated By FHN) (Details) (USD $)	Mar. 31, 2013		Dec. 31, 2012	Mar. 31, 2012		Dec. 31, 2011
Variable Interest Entity [Line Items]
Loans, net of unearned income	$ 15,889,670,000		$ 16,708,582,000	$ 15,971,330,000
Term borrowings	2,197,864,000		2,226,482,000	2,340,706,000
Trading securities	1,397,746,000		1,262,720,000	1,238,041,000
Total MSR recognized by FHN	109,102,000		114,311,000	142,956,000		144,069,000
Custodial balances	4,454,045,000		4,602,472,000	4,969,597,000
Securities available for sale, Fair Value	3,190,219,000	[1]	3,061,808,000	3,296,603,000	[2]
Low Income Housing Partnerships [Member]
Variable Interest Entity [Line Items]
Maximum Loss Exposure	52,528,000	[3],[4]		66,524,000	[3],[5]
Maximum loss exposure, contractual funding commitments	1,900,000			500,000
Liability Recognized	0	[3],[4]		0	[3],[5]
Low Income Housing Partnerships [Member] | Other Assets Related To Vie [Member]
Variable Interest Entity [Line Items]
Maximum loss exposure, current investments	50,600,000			66,100,000
New Market Tax Credit Llcs [Member]
Variable Interest Entity [Line Items]
Maximum Loss Exposure	23,494,000	[3],[6]		20,726,000	[3],[7]
Liability Recognized	0	[3],[6]		0	[3],[7]
New Market Tax Credit Llcs [Member] | Current Investment Funded By Borrowings [Member]
Variable Interest Entity [Line Items]
Maximum loss exposure, current investments	18,000,000			15,300,000
Small Issuer Trust Preferred Holdings [Member]
Variable Interest Entity [Line Items]
Maximum Loss Exposure	418,404,000	[8]		447,156,000	[8]
Liability Recognized	0	[8]		0	[8]
On Balance Sheet Trust Preferred Securitization [Member]
Variable Interest Entity [Line Items]
Maximum Loss Exposure	54,577,000	[9]		61,723,000	[10]
Liability Recognized	59,597,000	[9]		52,451,000	[10]
Loans, net of unearned income	112,500,000			112,500,000
Term borrowings	59,600,000			52,500,000
Trading securities	1,700,000			1,700,000
Proprietary Trust Preferred Issuances [Member]
Variable Interest Entity [Line Items]
Liability Recognized	206,186,000	[11]		206,186,000	[11]
Proprietary Agency Residential Mortgage Securitizations [Member]
Variable Interest Entity [Line Items]
Maximum Loss Exposure	416,648,000	[12]		480,107,000	[13]
Liability Recognized	0	[12]		0	[13]
Proprietary Agency Residential Mortgage Securitizations [Member] | Other Assets Related To Vie [Member]
Variable Interest Entity [Line Items]
Aggregate servicing advances	304,800,000			330,900,000
On Balance Sheet Consumer Loan Securitizations [Member]
Variable Interest Entity [Line Items]
Maximum Loss Exposure	14,477,000	[14]		11,646,000	[15]
Liability Recognized	270,385,000	[14]		338,817,000	[15]
Loans, net of unearned income	284,900,000			350,500,000
Term borrowings	270,400,000			338,800,000
Holdings Of Agency Mortgage Backed Securities [Member]
Variable Interest Entity [Line Items]
Maximum Loss Exposure	3,584,187,000	[16],[8]		3,626,034,000	[17],[8]
Liability Recognized	0	[16],[8]		0	[17],[8]
Trading securities	669,300,000			626,200,000
Securities available for sale, Fair Value	2,900,000,000			3,000,000,000
Short Positions In Agency Mortgage Backed Securities [Member]
Variable Interest Entity [Line Items]
Liability Recognized	51,108,000	[11]		0	[11]
Commercial Loan Troubled Debt Restructurings [Member]
Variable Interest Entity [Line Items]
Maximum Loss Exposure	68,921,000	[18],[19]		83,746,000	[18],[20]
Maximum loss exposure, contractual funding commitments	3,200,000			1,100,000
Liability Recognized	0	[18],[19]		0	[18],[20]
Loans, net of unearned income	65,700,000			82,700,000
Managed Discretionary Trusts [Member]
Variable Interest Entity [Line Items]
Maximum Loss Exposure	0	[11]			[11]
Liability Recognized	0	[11]			[11]
Proprietary Residential Mortgage Securitizations [Member]
Variable Interest Entity [Line Items]
Trading securities	7,600,000			11,200,000
Total MSR recognized by FHN	66,600,000			81,100,000
Agency Residential Mortgage Securitizations [Member]
Variable Interest Entity [Line Items]
Trading securities	8,800,000			13,400,000
Total MSR recognized by FHN	$ 28,700,000			$ 43,500,000

[1] Includes $2.9 billion of securities pledged to secure public deposits, securities sold under agreements to repurchase, and for other purposes.

[2] Includes $2.8 billion of securities pledged to secure public deposits, securities sold under agreements to repurchase, and for other purposes.

[3] A liability is not recognized as investments are written down over the life of the related tax credit.

[4] Maximum loss exposure represents $50.6 million of current investments and $1.9 million of contractual funding commitments. Only the current investment amount is included in Other assets.

[5] Maximum loss exposure represents $66.1 million of current investments and $.5 million of contractual funding commitments. Only the current investment amount is included in Other assets.

[6] Maximum loss exposure represents current investment balance. Of the initial investment, $18.0 million was funded through loans from community development enterprises.

[7] Maximum loss exposure represents current investment balance. Of the initial investment $15.3 million was funded through loans from community development enterprises.

[8] Maximum loss exposure represents the value of current investments. A liability is not recognized as FHN is solely a holder of the trusts’ securities.

[9] Includes $112.5 million classified as Loans, net of unearned income, and $1.7 million classified as Trading securities which are offset by $59.6 million classified as Term borrowings.

[10] Includes $112.5 million classified as Loans, net of unearned income, and $1.7 million classified as Trading securities which are offset by $52.5 million classified as Term borrowings.

[11] No exposure to loss due to the nature of FHN’s involvement.

[12] Includes $66.6 million and $28.7 million classified as MSR and $7.6 million and $8.8 million classified as Trading securities related to proprietary and agency residential mortgage securitizations, respectively. Aggregate servicing advances of $304.8 million are classified as Other assets.

[13] Includes $81.1 million and $43.5 million classified as MSR and $11.2 million and $13.4 million classified as Trading securities related to proprietary and agency residential mortgage securitizations, respectively. Aggregate servicing advances of $330.9 million are classified as Other assets.

[14] Includes $284.9 million classified as Loans, net of unearned income which are offset by $270.4 million classified as Term borrowings.

[15] Includes $350.5 million as Loans, net of unearned income which are offset by $338.8 million classified as Term borrowings.

[16] Includes $669.3 million classified as Trading securities and $2.9 billion classified as Securities available for sale.

[17] Includes $626.2 million classified as Trading securities and $3.0 billion classified as Securities available for sale.

[18] A liability is not recognized as the loans are the only variable interests held in the troubled commercial borrowers’ operations.

[19] Maximum loss exposure represents $65.7 million of current receivables and $3.2 million of contractual funding commitments on loans related to commercial borrowers involved in a troubled debt restructuring.

[20] Maximum loss exposure represents $82.7 million of current receivables and $1.1 million of contractual funding commitments on loans related to commercial borrowers involved in a troubled debt restructuring.