Components of Other Comprehensive Income/(loss) (Schedule of Changes in AOCI) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017		Sep. 30, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ (237,462)	$ (152,334)	$ (247,654)		$ (214,192)
Net unrealized gains/(losses)	4,317	(9,098)	13,966		52,558
Amounts reclassified from AOCI	761	604	1,304		806
Other comprehensive income/(loss)	5,078	(8,494)	15,270	[1]	53,364	[1]
Ending Balance	(232,384)	(160,828)	(232,384)		(160,828)
Securities AFS
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(9,857)	58,591	(17,232)		3,394
Net unrealized gains/(losses)	3,918	(7,887)	11,570		48,330
Amounts reclassified from AOCI	(1)	0	(278)		(1,020)
Other comprehensive income/(loss)	3,917	(7,887)	11,292		47,310
Ending Balance	(5,940)	50,704	(5,940)		50,704
Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(1,024)	4,691	(1,265)		0
Net unrealized gains/(losses)	(91)	(1,211)	1,906		4,228
Amounts reclassified from AOCI	(643)	(359)	(2,399)		(1,107)
Other comprehensive income/(loss)	(734)	(1,570)	(493)		3,121
Ending Balance	(1,758)	3,121	(1,758)		3,121
Pension and Postretirement Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(226,581)	(215,616)	(229,157)		(217,586)
Net unrealized gains/(losses)	490	0	490		0
Amounts reclassified from AOCI	1,405	963	3,981		2,933
Other comprehensive income/(loss)	1,895	963	4,471		2,933
Ending Balance	$ (224,686)	$ (214,653)	$ (224,686)		$ (214,653)

[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.