Derivatives (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Derivative Instruments, Gain (Loss) [Line Items]
Collateral cash receivables	$ 201,500,000	$ 163,000,000	$ 201,500,000	$ 163,000,000
Collateral cash payables	148,400,000	156,800,000	148,400,000	156,800,000
Total trading revenues	68,200,000	71,200,000	166,700,000	154,400,000
Noncallable senior debt maturing date			December 2015
Other long-term debt	2,294,224,000	2,502,517,000	2,294,224,000	2,502,517,000	2,481,660,000
Derivative liabilities related to sale	3,500,000	1,300,000	3,500,000	1,300,000
FHN [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Hedged held-to-maturity trust preferred loans principal balance	166,800,000	201,600,000	166,800,000	201,600,000
Derivative Instruments With Accelerated Termination Provisions [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Collateral received	279,500,000	247,500,000	279,500,000	247,500,000
Securities posted collateral	44,100,000	41,400,000	44,100,000	41,400,000
Net fair value of derivative assets with adjustable posting thresholds	245,700,000	198,100,000	245,700,000	198,100,000
Net fair value of derivative liabilities with adjustable posting thresholds	41,000,000	38,300,000	41,000,000	38,300,000
Long Term Debt Hedged With Fair Value Interest Rate Derivatives Using Long Haul Method [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Certain term borrowings total	500,000,000		500,000,000
Net fair value of interest rate derivatives hedging long-term debt using the long-haul method	27,900,000	11,400,000	27,900,000	11,400,000
Subordinated Debentures Subject To Mandatory Redemption Amount [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net fair value of interest rate derivatives hedging subordinated debt using long-haul method	1,100,000	12,000,000	1,100,000	12,000,000
Other long-term debt	200,000,000	200,000,000	200,000,000	200,000,000
Hedge Of Held-To-Maturity Trust Preferred Loans [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net fair value of interest rate derivatives hedging subordinated debt using long-haul method	5,000,000	13,200,000	5,000,000	13,200,000
Additional Derivative Agreements [Member] | Derivative Instruments With Adjustable Collateral Posting Thresholds [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Collateral received	279,500,000	247,500,000	279,500,000	247,500,000
Securities posted collateral	190,500,000	158,800,000	190,500,000	158,800,000
Net fair value of derivative assets with adjustable posting thresholds	247,200,000	200,200,000	247,200,000	200,200,000
Net fair value of derivative liabilities with adjustable posting thresholds	191,500,000	158,100,000	191,500,000	158,100,000
Fixed Interest Rate Swaps To Hedge [Member] | Long Term Debt Hedged With Fair Value Interest Rate Derivatives Using Shortcut Method [Member] | FHN [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Certain term borrowings total	904,000,000	904,000,000	904,000,000	904,000,000
Net fair value of interest rate derivatives hedging long-term debt using the long-haul method	$ 86,900,000	$ 101,700,000	$ 86,900,000	$ 101,700,000