Long-Term Debt (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Debt Instrument
Long-term debt	$ 1,166,151	$ 1,495,835
IBERIABANK
Debt Instrument
Long-term debt	$ 1,046,041	1,375,725
IBERIABANK \| Federal Home Loan Bank Notes
Debt Instrument
Minimum FHLB advance amortization period	1 year 4 months
Maximum FHLB advance amortization period	20 years 1 month
Long-term debt	$ 986,027	1,331,579
IBERIABANK \| Federal Home Loan Bank Notes \| Blanket Floating Lien
Debt Instrument
Additional advances available from FHLB	7,000,000
IBERIABANK \| Federal Home Loan Bank Notes \| Pledge of Investment Securities
Debt Instrument
Additional advances available from FHLB	1,900,000
IBERIABANK Corporation \| Junior Subordinated Debt
Debt Instrument
Long-term debt	$ 120,110	$ 120,110
Debt Instrument term	30 years
Earliest call date after issue	5 years
Earliest interest payment deferral date (in years or 20 consecutive quarters)	5 years
Weighted Average \| IBERIABANK \| Federal Home Loan Bank Notes
Debt Instrument
Weighted average advance rate on FHLB advances	2.15%	1.48%

Period of time between issuance and earliest call date of debt instrument.

No definition available.

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- Definition

Debt Instrument, Interest Payment Deferral, Term

+ References

No definition available.

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- Definition

The minimum amortization period for Federal Home Loan Bank advances.

+ References

No definition available.

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- Definition

The maximum amortization period for Federal Home Loan Bank advances.

+ References

No definition available.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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- Definition

Amount of advances or credit lines available from the Federal Home Loan Bank (FHLB).

+ References

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- Definition

States the interest rate applicable to Federal Home Loan Bank advances outstanding as of the Balance Sheet date.

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- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

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