Variable Interest Entities (Summary Of VIE Not Consolidated By FHN) (Details) (USD $)	Mar. 31, 2012		Dec. 31, 2011	Mar. 31, 2011		Dec. 31, 2010
Variable Interest Entity [Line Items]
Loans, net of unearned income	$ 15,971,330,000	[1],[2]	$ 16,397,127,000	$ 15,972,372,000	[1],[2]
Term borrowings	2,340,706,000		2,481,660,000	2,514,754,000
Trading securities	1,238,041,000		988,217,000	924,854,000
Total MSR recognized by FHN	142,956,000		144,069,000	207,748,000		207,319,000
Custodial balances	4,969,597,000		4,613,014,000	4,480,413,000
Securities available for sale, Fair Value	3,296,603,000	[3]	3,066,272,000	3,085,478,000	[4]
Low Income Housing Partnerships [Member]
Variable Interest Entity [Line Items]
Maximum loss exposure, contractual funding commitments	500,000			900,000
Low Income Housing Partnerships [Member] | Other Assets [Member]
Variable Interest Entity [Line Items]
Maximum Loss Exposure	66,524,000	[5],[6]		84,231,000	[5],[7]
Maximum loss exposure, current investments	66,100,000			83,300,000
Liability Recognized		[5],[6]			[5],[7]
New Market Tax Credit LLCs [Member] | Other Assets [Member]
Variable Interest Entity [Line Items]
Maximum Loss Exposure	20,726,000	[5],[8]
Maximum loss exposure, current investments	15,300,000
Liability Recognized		[5],[8]
Small Issuer Trust Preferred Holdings [Member] | Loans, Net Of Unearned Income [Member]
Variable Interest Entity [Line Items]
Maximum Loss Exposure	447,156,000	[9]		465,157,000	[9]
Liability Recognized		[9]			[9]
On-Balance Sheet Trust Preferred Securitization [Member]
Variable Interest Entity [Line Items]
Maximum Loss Exposure	61,723,000	[10]		62,684,000	[10]
Liability Recognized	52,451,000	[10]		51,477,000	[10]
Loans, net of unearned income	112,500,000			112,500,000
Term borrowings	52,500,000			51,500,000
Trading securities	1,700,000			1,700,000
Proprietary Trust Preferred Issuances [Member] | Term Borrowings [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	480,107,000	[12]		404,562,000	[13]
Liability Recognized		[12]			[13]
Custodial balances				91,500,000
Proprietary & Agency Residential Mortgage Securitizations [Member] | Other Assets [Member]
Variable Interest Entity [Line Items]
Aggregate servicing advances	330,900,000			286,000,000
On-Balance Sheet Consumer Loan Securitizations [Member]
Variable Interest Entity [Line Items]
Maximum Loss Exposure	11,646,000	[14]
Liability Recognized	338,817,000	[14]
Loans, net of unearned income	350,500,000
Term borrowings	338,800,000
Holdings Of Agency Mortgage-Backed Securities [Member]
Variable Interest Entity [Line Items]
Maximum Loss Exposure	3,626,034,000	[15],[9]		3,226,263,000	[16],[9]
Liability Recognized		[15],[9]			[16],[9]
Trading securities	626,200,000
Securities available for sale, Fair Value	3,000,000,000			2,800,000,000
Holdings Of Agency Mortgage-Backed Securities [Member] | Trading Securities [Member]
Variable Interest Entity [Line Items]
Trading securities				475,300,000
Short Positions In Agency Mortgage-Backed Securities [Member] | Trading Liabilities [Member]
Variable Interest Entity [Line Items]
Maximum Loss Exposure		[11]
Liability Recognized		[11]		12,789,000
Commercial Loan Troubled Debt Restructurings [Member]
Variable Interest Entity [Line Items]
Maximum Loss Exposure	82,700,000			101,300,000
Maximum loss exposure, contractual funding commitments	1,100,000			2,800,000
Commercial Loan Troubled Debt Restructurings [Member] | Loans, Net Of Unearned Income [Member]
Variable Interest Entity [Line Items]
Maximum Loss Exposure	83,746,000	[17],[18]		104,069,000	[13],[5],[9]
Liability Recognized		[17],[18]			[13],[5],[9]
Managed Discretionary Trusts [Member]
Variable Interest Entity [Line Items]
Maximum Loss Exposure		[11]			[19],[20]
Liability Recognized		[11]			[19],[20]
Proprietary Residential Mortgage Securitizations [Member]
Variable Interest Entity [Line Items]
Trading securities	11,200,000			13,400,000
Total MSR recognized by FHN	81,100,000			100,300,000
Agency Residential Mortgage Securitizations [Member]
Variable Interest Entity [Line Items]
Trading securities	13,400,000			20,700,000
Total MSR recognized by FHN	$ 43,500,000			$ 75,600,000

[1] Balances as of March 31, 2012 and 2011 include $20.1 million and $36.5 million of reserves, respectively, and $467.0 million and $672.4 million of balances in restricted consumer real estate loans and secured borrowings, respectively.

[2] Balances as of March 31, 2012 and 2011 include $5.4 million and $3.3 million of reserves, respectively, and $38.0 million and $49.9 million of balances in restricted permanent mortgage loans and secured borrowings, respectively.

[3] Includes $2.8 billion of securities pledged to secure public deposits, securities sold under agreements to repurchase, and for other purposes. Of this amount, $.4 billion was pledged as collateral for securities sold under repurchase agreements.

[4] Includes $2.8 billion of securities pledged to secure public deposits, securities sold under agreements to repurchase, and for other purposes. Of this amount, $.9 bilion was pledged as collateral for securities sold under repurchase agreements.

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

[6] 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.

[7] Maximum loss exposure represents $83.3 million of current investments and $.9 million of contractual funding commitments. Only the current investment amount is included in Other Assets.

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

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

[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 $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.

[13] Includes $100.3 million and $75.6 million classified as Mortgage servicing rights and $13.4 million and $20.7 million classified as Trading securities related to proprietary and agency residential mortgage securitizations, respectively. Aggregate servicing advances of $286.0 million are classified as Other assets and is offset by aggregate custodial balances of $91.5 million classified as Noninterest-bearing deposits.

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

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

[16] Includes $475.3 million classified as Trading securities and $2.8 billion classified as Securities available for sale.

[17] 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.

[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 $101.3 million of current receivables and $2.8 million of contractual funding commitments on loans related to commercial borrowers involved in a troubled debt restructuring.

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