Investment Securities (Schedule Of FHN's Available For Sale Securities) (Details) (USD $)	Mar. 31, 2013		Dec. 31, 2012	Mar. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	$ 3,110,692,000	[1]		$ 3,186,822,000	[2]
Securities available for sale, Gross Unrealized Gains	80,918,000	[1]		110,515,000	[2]
Securities available for sale, Gross Unrealized Losses	(1,391,000)	[1]		(734,000)	[2]
Securities available for sale, Fair Value	3,190,219,000	[1]	3,061,808,000	3,296,603,000	[2]
Pledged available for sale securities	2,900,000,000			2,800,000,000
Frb [Member]
Schedule of Available-for-sale Securities [Line Items]
Restricted investments	66,000,000			66,100,000
Fhlb Cincinnati Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Restricted investments	125,500,000			125,500,000
U S Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	39,992,000			40,011,000
Securities available for sale, Gross Unrealized Gains	2,000			26,000
Securities available for sale, Gross Unrealized Losses	0			0
Securities available for sale, Fair Value	39,994,000			40,037,000
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	1,009,283,000			1,352,827,000
Securities available for sale, Gross Unrealized Gains	56,649,000			74,936,000
Securities available for sale, Gross Unrealized Losses	(381,000)			(734,000)
Securities available for sale, Fair Value	1,065,551,000			1,427,029,000
Collateralized Mortgage Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	1,826,314,000			1,537,732,000
Securities available for sale, Gross Unrealized Gains	24,049,000			35,104,000
Securities available for sale, Gross Unrealized Losses	(1,010,000)			0
Securities available for sale, Fair Value	1,849,353,000			1,572,836,000
U S Government Corporations And Agencies Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	3,068,000			14,121,000
Securities available for sale, Gross Unrealized Gains	208,000			426,000
Securities available for sale, Gross Unrealized Losses	0			0
Securities available for sale, Fair Value	3,276,000			14,547,000
U S States And Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	15,255,000			18,070,000
Securities available for sale, Gross Unrealized Gains	0			0
Securities available for sale, Gross Unrealized Losses	0			0
Securities available for sale, Fair Value	15,255,000			18,070,000
Equity and other
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	216,780,000	[3]		224,061,000	[4]
Securities available for sale, Gross Unrealized Gains	10,000	[3]		23,000	[4]
Securities available for sale, Gross Unrealized Losses	0	[3]		0	[4]
Securities available for sale, Fair Value	$ 216,790,000	[3]		$ 224,084,000	[4]

[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] 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.