Investment Securities (Schedule Of FHN's Available For Sale Securities) (Details) (USD $)	Sep. 30, 2012		Dec. 31, 2011	Sep. 30, 2011
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	$ 3,019,009,000	[1]		$ 3,197,965,000	[2]
Securities available for sale, Gross Unrealized Gains	105,516,000	[1]		129,881,000	[2]
Securities available for sale, Gross Unrealized Losses	(896,000)	[1]		0	[2]
Securities available for sale, Fair Value	3,123,629,000	[1]	3,066,272,000	3,327,846,000	[2]
Pledged available for sale securities	2,800,000,000			3,000,000,000
Parent Company [Member]
Schedule of Available-for-sale Securities [Line Items]
Pledged available for sale securities	600,000,000			1,100,000,000
Frb [Member]
Schedule of Available-for-sale Securities [Line Items]
Restricted investments	66,000,000			66,100,000
U S Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	54,995,000			40,054,000
Securities available for sale, Gross Unrealized Gains	1,000			135,000
Securities available for sale, Gross Unrealized Losses	0			0
Securities available for sale, Fair Value	54,996,000			40,189,000
Mortgage Backed Securities Issued By U S Government Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	1,191,811,000			1,433,636,000
Securities available for sale, Gross Unrealized Gains	79,639,000			81,324,000
Securities available for sale, Gross Unrealized Losses	0			0
Securities available for sale, Fair Value	1,271,450,000			1,514,960,000
Fhlb Cincinnati Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Restricted investments	125,500,000			125,500,000
Collateralized Mortgage Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	1,530,075,000			1,462,668,000
Securities available for sale, Gross Unrealized Gains	25,562,000			47,507,000
Securities available for sale, Gross Unrealized Losses	(896,000)			0
Securities available for sale, Fair Value	1,554,741,000			1,510,175,000
U S Government Corporations And Agencies Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	3,911,000			17,033,000
Securities available for sale, Gross Unrealized Gains	291,000			898,000
Securities available for sale, Gross Unrealized Losses	0			0
Securities available for sale, Fair Value	4,202,000			17,931,000
U S States And Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	17,970,000			19,365,000
Securities available for sale, Gross Unrealized Gains	0			0
Securities available for sale, Gross Unrealized Losses	0			0
Securities available for sale, Fair Value	17,970,000			19,365,000
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	219,737,000	[3]		224,698,000	[4]
Securities available for sale, Gross Unrealized Gains	16,000	[3]		0	[4]
Securities available for sale, Gross Unrealized Losses	0	[3]		0	[4]
Securities available for sale, Fair Value	219,753,000	[3]		224,698,000	[4]
Other Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	510,000			511,000
Securities available for sale, Gross Unrealized Gains	7,000			17,000
Securities available for sale, Gross Unrealized Losses	0			0
Securities available for sale, Fair Value	$ 517,000			$ 528,000

[1] 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.

[2] 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.

[3] Includes restricted investments in FHLB-Cincinnati stock of $125.5 million and FRB stock of $66.0 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 $66.1 million. The remainder is money market, venture capital, and cost method investments.