Components of Other Comprehensive Income/(loss) (Schedule of Changes in AOCI) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017		Jun. 30, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ (249,958)	$ (170,441)	$ (247,654)		$ (214,192)
Net unrealized gains/(losses)	12,247	17,637	9,649		61,656
Amounts reclassifed from AOCI	249	470	543		202
Other comprehensive income/(loss)	12,496	18,107	10,192	[1]	61,858	[1]
Ending Balance	(237,462)	(152,334)	(237,462)		(152,334)
Securities AFS
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(18,795)	42,554	(17,232)		3,394
Net unrealized gains/(losses)	9,188	16,037	7,652		56,217
Amounts reclassifed from AOCI	(250)	0	(277)		(1,020)
Other comprehensive income/(loss)	8,938	16,037	7,375		55,197
Ending Balance	(9,857)	58,591	(9,857)		58,591
Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(3,179)	3,465	(1,265)		0
Net unrealized gains/(losses)	3,059	1,600	1,997		5,439
Amounts reclassifed from AOCI	(904)	(374)	(1,756)		(748)
Other comprehensive income/(loss)	2,155	1,226	241		4,691
Ending Balance	(1,024)	4,691	(1,024)		4,691
Pension and Postretirement Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(227,984)	(216,460)	(229,157)		(217,586)
Net unrealized gains/(losses)	0	0	0		0
Amounts reclassifed from AOCI	1,403	844	2,576		1,970
Other comprehensive income/(loss)	1,403	844	2,576		1,970
Ending Balance	$ (226,581)	$ (215,616)	$ (226,581)		$ (215,616)

[1] Due to the nature of the preferred stock issued by FHN and its subsidiaries, all components of Other comprehensive income/(loss) have been attributed solely to FHN as the controlling interest holder.