Business Segment Information (Amounts Of Consolidated Revenue, Expense, Tax And Assets) (Details) (USD $)	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Segment Reporting Information [Line Items]
Net interest income	$ 156,866,000us-gaap_InterestIncomeExpenseNet	$ 152,359,000us-gaap_InterestIncomeExpenseNet
Provision/(provision credit) for loan losses	5,000,000	10,000,000
Noninterest income	129,689,000us-gaap_NoninterestIncome	145,730,000us-gaap_NoninterestIncome
Noninterest expense	376,221,000us-gaap_NoninterestExpense	218,044,000us-gaap_NoninterestExpense
Income/(loss) before income taxes	(94,666,000)	70,045,000
Provision/(benefit) for income taxes	(22,261,000)us-gaap_IncomeTaxExpenseBenefit	20,066,000us-gaap_IncomeTaxExpenseBenefit
Net income/(loss)	(72,405,000)us-gaap_ProfitLoss	49,979,000us-gaap_ProfitLoss
Average assets	25,644,604,000fhn_SegmentReportingAverageAssets	23,910,853,000fhn_SegmentReportingAverageAssets
Regional Banking [Member]
Segment Reporting Information [Line Items]
Net interest income	154,409,000	142,026,000
Provision/(provision credit) for loan losses	4,915,000	12,990,000
Noninterest income	60,204,000	59,992,000
Noninterest expense	135,780,000	132,543,000
Income/(loss) before income taxes	73,918,000	56,485,000
Provision/(benefit) for income taxes	26,381,000	20,083,000
Net income/(loss)	47,537,000	36,402,000
Average assets	14,228,116,000	12,615,394,000
Capital Markets [Member]
Segment Reporting Information [Line Items]
Net interest income	4,323,000	3,476,000
Noninterest income	61,565,000	56,759,000
Noninterest expense	54,683,000	52,598,000
Income/(loss) before income taxes	11,205,000	7,637,000
Provision/(benefit) for income taxes	4,167,000	2,843,000
Net income/(loss)	7,038,000	4,794,000
Average assets	2,446,267,000	2,038,368,000
Corporate [Member]
Segment Reporting Information [Line Items]
Net interest income	(16,084,000)	(9,923,000)
Noninterest income	5,385,000	13,215,000
Noninterest expense	14,169,000	17,327,000
Income/(loss) before income taxes	(24,868,000)	(14,035,000)
Provision/(benefit) for income taxes	(11,640,000)	(10,628,000)
Net income/(loss)	(13,228,000)	(3,407,000)
Average assets	6,414,745,000	5,852,792,000
Non Strategic [Member]
Segment Reporting Information [Line Items]
Net interest income	14,218,000	16,780,000
Provision/(provision credit) for loan losses	85,000	(2,990,000)
Noninterest income	2,535,000	15,764,000
Noninterest expense	171,589,000	15,576,000
Income/(loss) before income taxes	(154,921,000)	19,958,000
Provision/(benefit) for income taxes	(41,169,000)	7,768,000
Net income/(loss)	(113,752,000)	12,190,000
Average assets	$ 2,555,476,000	$ 3,404,299,000

Amount of average assets attributed to the reportable segment.

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Sum of operating profit and nonoperating income or expense before Income or Loss from equity method investments, income taxes, extraordinary items, and noncontrolling interest.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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The net amount of operating interest income (expense).

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Total aggregate amount of all noninterest expense.

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The total amount of noninterest income which may be derived from: (1) fees and commissions; (2) premiums earned; (3) insurance policy charges; (4) the sale or disposal of assets; and (5) other sources not otherwise specified.

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The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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Amount of expense related loan transactions, lease transactions, credit loss from transactions other than loan and lease transactions, and other loss based on assessment of uncollectability from the counterparty to reduce the account to their net realizable value.

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