Investment Securities (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011		Dec. 31, 2010
Investment Securities [Abstract]
Unrealized losses within the available for sale portfolio	$ 0	[1]	$ 7,890	[2]

[1] Includes $2.7 billion of securities pledged to secure public deposits, securities sold under agreements to repurchase, and for other purposes. As of December 31, 2011, FHN had pledged $0.8 billion of the $2.7 billion pledged available for sale securities as collateral for securities sold under repurchase agreements.

[2] Includes $2.7 billion of securities pledged to secure public deposits, securities sold under agreements to repurchase, and for other purposes. As of December 31, 2010, FHN had pledged $1.5 billion of the $2.7 billion pledged available for sale securities as collateral for securities sold under repurchase agreements.