Variable Interest Entities (Summary Of VIE Not Consolidated By FHN) (Details) (USD $)	Sep. 30, 2012		Dec. 31, 2011	Sep. 30, 2011		Dec. 31, 2010
Variable Interest Entity [Line Items]
Loans, net of unearned income	$ 16,523,783,000	[1],[2]	$ 16,397,127,000	$ 16,241,402,000	[1],[2]
Term borrowings	2,263,238,000		2,481,660,000	2,509,804,000
Trading securities	1,204,366,000		988,217,000	1,227,197,000
Total MSR recognized by FHN	120,537,000		144,069,000	150,803,000		207,319,000
Custodial balances	4,569,113,000		4,613,014,000	4,412,375,000
Securities available for sale, Fair Value	3,123,629,000	[3]	3,066,272,000	3,327,846,000	[4]
Low Income Housing Partnerships [Member]
Variable Interest Entity [Line Items]
Maximum Loss Exposure	57,030,000	[5],[6]		76,607,000	[5],[7]
Maximum loss exposure, contractual funding commitments	500,000			1,500,000
Liability Recognized	0	[5],[6]		0	[5],[7]
Low Income Housing Partnerships [Member] | Other Assets Related To Vie [Member]
Variable Interest Entity [Line Items]
Maximum loss exposure, current investments	56,500,000			75,100,000
New Market Tax Credit Llcs [Member]
Variable Interest Entity [Line Items]
Maximum Loss Exposure	20,312,000	[5],[8]
Liability Recognized	0	[5],[8]
New Market Tax Credit Llcs [Member] | Current Investment Funded By Borrowings [Member]
Variable Interest Entity [Line Items]
Maximum loss exposure, current investments	15,300,000
Small Issuer Trust Preferred Holdings [Member]
Variable Interest Entity [Line Items]
Maximum Loss Exposure	446,045,000	[9]		457,156,000	[9]
Liability Recognized	0	[9]		0	[9]
On Balance Sheet Trust Preferred Securitization [Member]
Variable Interest Entity [Line Items]
Maximum Loss Exposure	60,662,000	[10]		62,253,000	[11]
Liability Recognized	53,511,000	[10]		51,908,000	[11]
Loans, net of unearned income	112,500,000			112,500,000
Term borrowings	53,500,000			51,900,000
Trading securities	1,700,000			1,700,000
Proprietary Trust Preferred Issuances [Member]
Variable Interest Entity [Line Items]
Liability Recognized	206,186,000	[12]		206,186,000	[12]
Proprietary Agency Residential Mortgage Securitizations [Member]
Variable Interest Entity [Line Items]
Maximum Loss Exposure	425,741,000	[13]		476,329,000	[14]
Liability Recognized	0	[13]		0	[14]
Proprietary Agency Residential Mortgage Securitizations [Member] | Other Assets Related To Vie [Member]
Variable Interest Entity [Line Items]
Aggregate servicing advances	300,600,000			317,100,000
On Balance Sheet Consumer Loan Securitizations [Member]
Variable Interest Entity [Line Items]
Maximum Loss Exposure	6,654,000	[15]
Liability Recognized	302,633,000	[15]
Loans, net of unearned income	309,300,000
Term borrowings	302,600,000
Holdings Of Agency Mortgage Backed Securities [Member]
Variable Interest Entity [Line Items]
Maximum Loss Exposure	3,462,956,000	[16],[9]		3,588,871,000	[17],[9]
Liability Recognized	0	[16],[9]		0	[17],[9]
Trading securities	636,800,000			563,700,000
Securities available for sale, Fair Value	2,800,000,000			3,000,000,000
Short Positions In Agency Mortgage Backed Securities [Member]
Variable Interest Entity [Line Items]
Liability Recognized	13,221,000	[12]		1,617,000	[12]
Commercial Loan Troubled Debt Restructurings [Member]
Variable Interest Entity [Line Items]
Maximum Loss Exposure	95,681,000	[18],[19]		98,977,000	[18],[20]
Maximum loss exposure, contractual funding commitments	1,400,000			600,000
Liability Recognized	0	[18],[19]		0	[18],[20]
Loans, net of unearned income	94,300,000			98,400,000
Managed Discretionary Trusts [Member]
Variable Interest Entity [Line Items]
Maximum Loss Exposure	0	[12]			[12]
Liability Recognized	0	[12]			[12]
Proprietary Residential Mortgage Securitizations [Member]
Variable Interest Entity [Line Items]
Trading securities	8,400,000			12,200,000
Total MSR recognized by FHN	71,500,000			80,900,000
Agency Residential Mortgage Securitizations [Member]
Variable Interest Entity [Line Items]
Trading securities	10,800,000			15,500,000
Total MSR recognized by FHN	$ 34,400,000			$ 50,600,000

[1] Balances as of September 30, 2012 and 2011 include $14.7 million and $26.9 million of reserves, respectively, and $417.0 million and $623.3 million of balances in restricted consumer real estate loans and secured borrowings, respectively.

[2] Balances as of September 30, 2012 and 2011 include $.6 million and $5.5 million of reserves, respectively, and $14.2 million and $42.4 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, $.6 billion was pledged as collateral for securities sold under repurchase agreements.

[4] Includes $3.0 billion of securities pledged to secure public deposits, securities sold under agreements to repurchase, and for other purposes. Of this amount, $1.1 billion was pledged as collateral for securities sold under repurchase agreements.

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

[6] Maximum loss exposure represents $56.5 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 $75.1 million of current investments and $1.5 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 $53.5 million classified as Term borrowings.

[11] Includes $112.5 million classified as Loans, net of unearned income, and $1.7 million classified as Trading securities which are offset by $51.9 million classified as Term borrowings.

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

[13] Includes $71.5 million and $34.4 million classified as MSR and $8.4 million and $10.8 million classified as Trading securities related to proprietary and agency residential mortgage securitizations, respectively. Aggregate servicing advances of $300.6 million are classified as Other assets.

[14] Includes $80.9 million and $50.6 million classified as MSR and $12.2 million and $15.5 million classified as Trading securities related to proprietary and agency residential mortgage securitizations, respectively. Aggregate servicing advances of $317.1 million are classified as Other assets.

[15] Includes $309.3 million classified as Loans, net of unearned income which are offset by $302.6 million classified as Term borrowings.

[16] Includes $636.8 million classified as Trading securities and $2.8 billion classified as Securities available for sale.

[17] Includes $563.7 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 $94.3 million of current receivables and $1.4 million of contractual funding commitments on loans related to commercial borrowers involved in a troubled debt restructuring.

[20] Maximum loss exposure represents $98.4 million of current receivables and $.6 million of contractual funding commitments on loans related to commercial borrowers involved in a troubled debt restructuring.