Investment Securities (Schedule Of FHN's Available For Sale Securities) (Details) (USD $)	Sep. 30, 2011		Dec. 31, 2010	Sep. 30, 2010
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	$ 3,197,965,000	[1]		$ 2,510,256,000	[2]
Securities available for sale, Gross Unrealized Gains	129,881,000	[1]		101,217,000	[2]
Securities available for sale, Gross Unrealized Losses				(13,000)	[2]
Securities available for sale, Fair Value	3,327,846,000	[1]	3,031,930,000	2,611,460,000	[2]
Pledged available for sale securities	3,000,000,000			2,300,000,000
U.S. Treasuries [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	40,054,000			68,252,000
Securities available for sale, Gross Unrealized Gains	135,000			333,000
Securities available for sale, Fair Value	40,189,000			68,585,000
Government Agency Issued Mortgage-Backed Securities MBS [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	1,433,636,000			945,290,000
Securities available for sale, Gross Unrealized Gains	81,324,000			54,758,000
Securities available for sale, Gross Unrealized Losses				(13,000)
Securities available for sale, Fair Value	1,514,960,000			1,000,035,000
Government Agency Issued Collateralized Mortgage Obligations CMO [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	1,462,668,000			1,124,596,000
Securities available for sale, Gross Unrealized Gains	47,507,000			37,040,000
Securities available for sale, Fair Value	1,510,175,000			1,161,636,000
Other U.S. Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	17,033,000			95,891,000
Securities available for sale, Gross Unrealized Gains	898,000			8,691,000
Securities available for sale, Fair Value	17,931,000			104,582,000
States And Municipalities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	19,365,000			41,660,000
Securities available for sale, Fair Value	19,365,000			41,660,000
Equity [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	224,698,000	[3]		234,056,000	[4]
Securities available for sale, Gross Unrealized Gains				355,000	[4]
Securities available for sale, Fair Value	224,698,000	[3]		234,411,000	[4]
Other Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	511,000			511,000
Securities available for sale, Gross Unrealized Gains	17,000			40,000
Securities available for sale, Fair Value	528,000			551,000
FHLB-Cincinnati Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Restricted Investments	125,500,000			125,500,000
Reinsurance Contract Agreement [Member]
Schedule of Available-for-sale Securities [Line Items]
Restricted Investments				9,400,000
FHN [Member]
Schedule of Available-for-sale Securities [Line Items]
Pledged available for sale securities	1,100,000,000			1,100,000,000
FRB [Member]
Schedule of Available-for-sale Securities [Line Items]
Restricted Investments	$ 66,100,000			$ 66,200,000

[1] Includes $3.0 billion of securities pledged to secure public deposits, securities sold under agreements to repurchase, and for other purposes. As of September 30, 2011, FHN had pledged $1.1 billion of the $3.0 billion pledged available for sale securities as collateral for securities sold under repurchase agreements.

[2] Includes $2.3 billion of securities pledged to secure public deposits, securities sold under agreements to repurchase, and for other purposes. As of September 30, 2010, FHN had pledged $1.1 billion of the $2.3 billion pledged available for sale securities as collateral for securities sold under repurchase agreements.

[3] Includes restricted investments in FHLB-Cincinnati stock of $125.5 million and FRB stock of $66.1 million. The remainder is money market, venture capital, and cost method investments.

[4] Includes restricted investments in FHLB-Cincinnati stock of $125.5 million and FRB stock of $66.2 million. The remainder is money market, venture capital, and cost method investments. Additionally, $9.4 million is restricted pursuant to reinsurance contract agreements.