Iberiabank (IBKC) 10-Q 8 Nov 19 2019 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2019	Oct. 31, 2019
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2019
Document Transition Report	false
Entity File Number	001-37532
Entity Registrant Name	IBERIABANK Corp
Entity Incorporation, State or Country Code	LA
Entity Address, Address Line One	200 West Congress Street
Entity Address, City or Town	Lafayette,
Entity Address, State or Province	LA
Entity Tax Identification Number	72-1280718
Entity Address, Postal Zip Code	70501
City Area Code	337
Local Phone Number	521-4003
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		52,267,165
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Entity Central Index Key	0000933141
Current Fiscal Year End Date	--12-31
Common Stock
Document Information [Line Items]
Title of 12(b) Security	Common Stock (par value $1.00 per share)
Trading Symbol	IBKC
Security Exchange Name	NASDAQ
Series B Preferred Stock
Document Information [Line Items]
Title of 12(b) Security	Depositary Shares, Each Representing a 1/400th Interest in
Trading Symbol	IBKCP
Security Exchange Name	NASDAQ
Series C Preferred Stock
Document Information [Line Items]
Title of 12(b) Security	Depositary Shares, Each Representing a 1/400th Interest in
Trading Symbol	IBKCO
Security Exchange Name	NASDAQ
Series D Preferred Stock
Document Information [Line Items]
Title of 12(b) Security	Depositary Shares, Each Representing a 1/400th Interest
Trading Symbol	IBKCN
Security Exchange Name	NASDAQ

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Assets
Cash and due from banks	$ 353,346	$ 294,186
Interest-bearing deposits in other banks	577,587	396,267
Total cash and cash equivalents	930,933	690,453
Securities available for sale, at fair value	4,238,082	4,783,579
Securities held to maturity (fair values of $192,586 and $204,277, respectively)	185,007	207,446
Mortgage loans held for sale, at fair value	255,276	107,734
Loans and leases, net of unearned income	23,676,537	22,519,815
Allowance for loan and lease losses	(146,235)	(140,571)
Loans and leases, net	23,530,302	22,379,244
Premises and equipment, net	298,309	300,507
Goodwill	1,235,533	1,235,533
Other intangible assets	79,143	88,736
Other assets	982,013	1,039,783
Total Assets	31,734,598	30,833,015
Deposits:
Non-interest-bearing	6,518,783	6,542,490
Interest-bearing	18,458,502	17,220,941
Total deposits	24,977,285	23,763,431
Short-term borrowings	498,049	1,482,882
Long-term debt	1,394,202	1,166,151
Other liabilities	581,762	364,274
Total Liabilities	27,451,298	26,776,738
Shareholders’ Equity
Preferred stock, $1 par value - 5,000,000 shares authorized Non-cumulative perpetual, liquidation preference $10,000 per share; 23,750 and 13,750 shares issued and outstanding, respectively, including related surplus	228,485	132,097
Common stock, $1 par value - 100,000,000 shares authorized; 52,265,887 and 54,796,231 shares issued and outstanding, respectively	52,266	54,796
Additional paid-in capital	2,680,328	2,869,416
Retained earnings	1,268,278	1,042,718
Accumulated other comprehensive income (loss)	53,943	(42,750)
Total Shareholders’ Equity	4,283,300	4,056,277
Total Liabilities and Shareholders’ Equity	$ 31,734,598	$ 30,833,015

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Securities held to maturity, fair values	$ 192,586	$ 204,277
Preferred stock, par value (in usd per share)	$ 1	$ 1
Preferred stock, shares authorized	5,000,000	5,000,000
Liquidation preference (per share)	$ 10,000	$ 10,000
Preferred stock, shares issued	23,750	13,750
Preferred stock, shares outstanding	23,750	13,750
Common stock, par value (in usd per share)	$ 1	$ 1
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	52,265,887	54,796,231
Common stock, shares outstanding	52,265,887	54,796,231

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Interest and dividend income
Loans and leases, including fees	$ 296,790	$ 283,125	$ 878,355	$ 791,670
Mortgage loans held for sale, including fees	1,936	1,037	4,578	3,027
Taxable securities	27,883	27,113	93,461	79,058
Tax-exempt securities	2,049	2,680	6,399	8,154
Other	4,520	3,112	12,436	9,524
Total interest and dividend income	333,178	317,067	995,229	891,433
Interest expense
Deposits	70,753	44,401	196,854	108,804
Short-term borrowings	3,880	4,727	14,793	10,578
Long-term debt	9,212	8,714	28,426	23,824
Total interest expense	83,845	57,842	240,073	143,206
Net interest income	249,333	259,225	755,156	748,227
Provision for credit losses	8,986	11,384	33,504	27,290
Net interest income after provision for credit losses	240,347	247,841	721,652	720,937
Non-interest income
Income from bank owned life insurance	1,760	1,744	5,307	4,287
Securities gains (losses), net	27	0	(987)	(56)
Other non-interest income	7,114	3,583	15,415	10,971
Total non-interest income	63,674	53,087	175,008	151,593
Non-interest expense
Salaries and employee benefits	103,257	101,159	304,928	313,190
Net occupancy and equipment	21,316	18,889	58,879	58,867
Communication and delivery	3,634	3,773	10,931	11,888
Marketing and business development	3,163	4,068	10,651	13,715
Computer services expense	9,638	9,036	28,178	30,738
Professional services	6,323	5,519	17,017	20,070
Credit and other loan related expense	4,532	4,830	11,532	14,313
Insurance	4,825	6,536	13,276	20,587
Travel and entertainment	2,185	1,846	7,353	7,880
Amortization of acquisition intangibles	4,410	5,382	14,205	16,595
Impairment of long-lived assets and other (gains) losses	(309)	467	1,251	24,924
Other non-interest expense	9,688	7,557	22,832	21,143
Total non-interest expense	172,662	169,062	501,033	553,910
Income before income tax expense	131,359	131,866	395,627	318,620
Income tax expense	31,509	30,401	94,048	78,410
Net income	99,850	101,465	301,579	240,210
Less: Preferred stock dividends	3,599	3,599	8,146	8,146
Net income available to common shareholders	96,251	97,866	293,433	232,064
Less: Earnings allocated to unvested restricted stock	874	908	2,806	2,341
Earnings allocated to common shareholders	$ 95,377	$ 96,958	$ 290,627	$ 229,723
Earnings per common share - Basic (in usd per share)	$ 1.83	$ 1.74	$ 5.47	$ 4.17
Earnings per common share - Diluted (in usd per share)	1.82	1.73	5.43	4.14
Cash dividends declared per common share (in usd per share)	$ 0.45	$ 0.39	$ 1.31	$ 1.15
Comprehensive income
Net income	$ 99,850	$ 101,465	$ 301,579	$ 240,210
Unrealized gains (losses) on securities:
Unrealized holding gains (losses) arising during the period (net of tax effects of $2,294, $5,906, $27,805, and $24,578, respectively)	6,975	(22,220)	93,491	(92,460)
Less: Reclassification adjustment for gains (losses) included in net income (net of tax effects of $7, $0, $244, and $12, respectively)	20	0	(743)	(44)
Unrealized gains (losses) on securities, net of tax	6,955	(22,220)	94,234	(92,416)
Fair value of derivative instruments designated as cash flow hedges:
Change in fair value of derivative instruments designated as cash flow hedges during the period (net of tax effects of $86, $217, $903, and $1,266, respectively)	(264)	818	1,992	4,762
Less: Reclassification adjustment for gains (losses) included in net income (net of tax effects of $53, $6, $154, and $47, respectively)	(162)	(22)	(467)	(178)
Fair value of derivative instruments designated as cash flow hedges, net of tax	(102)	840	2,459	4,940
Other comprehensive income (loss), net of tax	6,853	(21,380)	96,693	(87,476)
Comprehensive income	106,703	80,085	398,272	152,734
Mortgage income
Non-interest income
Non-interest income	17,432	12,729	47,725	36,045
Service charges on deposit accounts
Non-interest income
Non-interest income	13,209	13,520	38,866	39,378
Title revenue
Non-interest income
Non-interest income	7,170	6,280	19,290	18,153
Broker commissions
Non-interest income
Non-interest income	1,800	2,627	5,797	7,244
ATM and debit card fee income
Non-interest income
Non-interest income	2,948	2,470	8,562	8,028
Credit card and merchant-related income
Non-interest income
Non-interest income	3,400	3,114	10,037	9,347
Trust department income
Non-interest income
Non-interest income	4,281	3,993	12,836	11,662
Commission income
Non-interest income
Non-interest income	$ 4,533	$ 3,027	$ 12,160	$ 6,534

Consolidated Statements of Co_2

Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Unrealized holding gains (losses) arising during the period, tax expense (benefit)	$ 2,294	$ (5,906)	$ 27,805	$ (24,578)
Reclassification adjustment for gains (losses) included in net income, tax expense (benefit)	7	0	(244)	(12)
Change in fair value of derivative instruments designated as cash flow hedges, tax expense	(86)	217	903	1,266
Reclassification adjustment for gains (losses) included in net income, tax expense (benefit)	$ (53)	$ (6)	$ (154)	$ (47)

Consolidated Statements of Shar

Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Preferred Stock	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning balance (in shares) at Dec. 31, 2017		13,750	53,872,272
Beginning balance at Dec. 31, 2017	$ 3,696,791	$ 132,097	$ 53,872	$ 2,787,484	$ 769,226	$ (45,888)
Increase (Decrease) in Shareholders' Equity
Net income	240,210				240,210
Other comprehensive income (loss)	(87,476)					(87,476)
Cash dividends declared	(64,288)				(64,288)
Preferred stock dividends	(8,146)				(8,146)
Common stock issued under incentive plans, net of shares surrendered in payment (in shares)			109,983
Common stock issued under incentive plans, net of shares surrendered in payment	(3,142)		$ 110	(3,252)
Common stock issued for acquisitions (in shares)			2,787,773
Common stock issued for acquisitions	214,659		$ 2,788	211,871
Common stock repurchases (in shares)			(763,210)
Common stock repurchases	(61,046)		$ (763)	(60,283)
Share-based compensation expense	15,144			15,144
Ending balance (in shares) at Sep. 30, 2018		13,750	56,006,818
Ending balance at Sep. 30, 2018	3,942,361	$ 132,097	$ 56,007	2,950,964	936,657	(133,364)
Beginning balance (in shares) at Jun. 30, 2018		13,750	56,390,387
Beginning balance at Jun. 30, 2018	3,913,409	$ 132,097	$ 56,390	2,976,833	860,073	(111,984)
Increase (Decrease) in Shareholders' Equity
Net income	101,465				101,465
Other comprehensive income (loss)	(21,380)					(21,380)
Cash dividends declared	(21,282)				(21,282)
Preferred stock dividends	(3,599)				(3,599)
Common stock issued under incentive plans, net of shares surrendered in payment (in shares)			(20,359)
Common stock issued under incentive plans, net of shares surrendered in payment	(1,040)		$ (20)	(1,020)
Common stock repurchases (in shares)			(363,210)
Common stock repurchases	(30,376)		$ (363)	(30,013)
Share-based compensation expense	5,164			5,164
Ending balance (in shares) at Sep. 30, 2018		13,750	56,006,818
Ending balance at Sep. 30, 2018	3,942,361	$ 132,097	$ 56,007	2,950,964	936,657	(133,364)
Beginning balance (in shares) at Dec. 31, 2018		13,750	54,796,231
Beginning balance at Dec. 31, 2018	4,056,277	$ 132,097	$ 54,796	2,869,416	1,042,718	(42,750)
Increase (Decrease) in Shareholders' Equity
Net income	301,579				301,579
Other comprehensive income (loss)	96,693					96,693
Cash dividends declared	(69,720)				(69,720)
Preferred stock dividends	(8,146)				(8,146)
Common stock issued under incentive plans, net of shares surrendered in payment (in shares)			169,656
Common stock issued under incentive plans, net of shares surrendered in payment	(4,178)		$ 170	(4,348)
Common stock issued for acquisitions (in shares)		10,000
Common stock issued for acquisitions	96,388	$ 96,388
Common stock repurchases (in shares)			(2,700,000)
Common stock repurchases	(204,740)		$ (2,700)	(202,040)
Share-based compensation expense	17,300			17,300
Ending balance (in shares) at Sep. 30, 2019		23,750	52,265,887
Ending balance at Sep. 30, 2019	4,283,300	$ 228,485	$ 52,266	2,680,328	1,268,278	53,943
Beginning balance (in shares) at Jun. 30, 2019		23,750	52,805,461
Beginning balance at Jun. 30, 2019	4,238,000	$ 228,485	$ 52,805	2,714,074	1,195,546	47,090
Increase (Decrease) in Shareholders' Equity
Net income	99,850				99,850
Other comprehensive income (loss)	6,853					6,853
Cash dividends declared	(23,519)				(23,519)
Preferred stock dividends	(3,599)				(3,599)
Common stock issued under incentive plans, net of shares surrendered in payment (in shares)			12,656
Common stock issued under incentive plans, net of shares surrendered in payment	270		$ 13	257
Common stock repurchases (in shares)			(552,230)
Common stock repurchases	(40,016)		$ (552)	(39,464)
Share-based compensation expense	5,461			5,461
Ending balance (in shares) at Sep. 30, 2019		23,750	52,265,887
Ending balance at Sep. 30, 2019	$ 4,283,300	$ 228,485	$ 52,266	$ 2,680,328	$ 1,268,278	$ 53,943

Consolidated Statements of Sh_2

Consolidated Statements of Shareholders' Equity (Parenthetical) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Cash dividends declared per common share (in usd per share)	$ 0.45	$ 0.39	$ 1.31	$ 1.15

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash Flows from Operating Activities
Net income	$ 301,579	$ 240,210
Depreciation, amortization, and accretion, including amortization of purchase accounting adjustments, and market value adjustments	5,638	(1,644)
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	33,504	27,290
Share-based compensation expense - equity awards	17,300	15,144
(Gain) loss on sale of OREO and long-lived assets, net of impairment	(1,657)	6,831
Securities losses, net	987	56
(Gain) loss on early termination of FDIC loss share agreements	0	(2,708)
Cash paid for early termination of FDIC loss share agreements	0	(5,637)
Deferred income tax expense	29,407	31,348
Originations of mortgage loans held for sale	(1,443,094)	(1,139,117)
Proceeds from sales of mortgage loans held for sale	1,347,850	1,260,962
Realized and unrealized (gain) on mortgage loans held for sale, net	(52,873)	(35,244)
Other operating activities, net	200,074	(36,390)
Net Cash Provided by Operating Activities	438,715	361,101
Cash Flows from Investing Activities
Proceeds from sales of securities available for sale	299,513	18,867
Proceeds from maturities, prepayments and calls of securities available for sale	549,747	493,095
Purchases of securities available for sale, net of securities available for sale acquired	(199,321)	(711,258)
Proceeds from maturities, prepayments and calls of securities held to maturity	20,353	11,464
Purchases of equity securities, net of equity securities acquired	(15,154)	(21,090)
Proceeds from sales of equity securities	25,741	70,371
Increase in loans, net of loans acquired	(1,135,759)	(767,715)
Proceeds from sales of premises and equipment	1,149	5,698
Purchases of premises and equipment, net of premises and equipment acquired	(17,030)	(11,575)
Proceeds from dispositions of OREO	9,471	12,166
Cash paid for additional investment in tax credit entities	(6,060)	(6,059)
Cash received for acquisition of a business, net of cash paid	0	99,318
Purchase of bank owned life insurance policies	0	(50,000)
Other investing activities, net	999	595
Net Cash Used in Investing Activities	268,116	345,233
Net Cash Provided by (Used in) Investing Activities	(466,351)	(856,123)
Cash Flows from Financing Activities
Increase in deposits, net of deposits acquired	1,213,854	662,680
Net change in short-term borrowings	(984,833)	251,422
Proceeds from long-term debt, net of long-term debt acquired	500,000	927,884
Repayments of long-term debt	(271,562)	(1,361,482)
Cash dividends paid on common stock	(68,667)	(62,937)
Cash dividends paid on preferred stock	(8,146)	(8,146)
Net share-based compensation stock transactions	(4,178)	(3,142)
Payments to repurchase common stock	(204,740)	(61,046)
Net proceeds from issuance of preferred stock	96,388	0
Net Increase (Decrease) In Cash and Cash Equivalents	240,480	(149,789)
Cash and Cash Equivalents at Beginning of Period	690,453	625,724
Cash and Cash Equivalents at End of Period	930,933	475,935
Supplemental Schedule of Non-cash Activities
Acquisition of real estate in settlement of loans	6,023	13,066
Common stock issued in acquisitions	0	214,659
Supplemental Disclosures
Cash paid for interest on deposits and borrowings, net of acquired	235,888	137,727
Cash paid for income taxes	57,287	34,968
Cash received from income tax refunds	$ 178,288	$ 364

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Basis of Presentation	BASIS OF PRESENTATION IBERIABANK Corporation is a financial holding company based in Lafayette, Louisiana. The accompanying unaudited consolidated financial statements include the accounts of IBERIABANK Corporation and its consolidated subsidiaries (the "Company"). Through its subsidiaries, the Company provides a full range of commercial and consumer banking services, including private banking, small business, wealth and trust management, retail brokerage, mortgage, commercial leasing and equipment financing, and title insurance services through locations in Louisiana, Arkansas, Tennessee, Alabama, Texas, Florida, Georgia, South Carolina, North Carolina, Mississippi, Missouri, and New York. The accompanying unaudited consolidated financial statements have been prepared in accordance with GAAP for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all information and notes necessary for complete financial statements in accordance with GAAP. In the opinion of management, the accompanying unaudited consolidated financial statements contain all the significant adjustments, consisting of normal and recurring items, considered necessary for fair presentation. These interim financial statements should be read in conjunction with the Company's audited consolidated financial statements and notes in the Annual Report on Form 10-K for the year ended December 31, 2018 . Operating results for the interim period are not necessarily indicative of the results that may be expected for the full year. All significant intercompany balances and transactions have been eliminated in consolidation. Certain amounts reported in prior periods have been reclassified to conform to the current period presentation. See the Glossary of Defined Terms included in this Report for terms used herein.

Recent Accounting Pronouncement

Recent Accounting Pronouncements	9 Months Ended
	Sep. 30, 2019
Accounting Changes and Error Corrections [Abstract]
Recent Accounting Pronouncements	RECENT ACCOUNTING PRONOUNCEMENTS Pronouncements adopted during the nine months ended September 30, 2019: ASU No. 2016-02, ASU No. 2018-11, ASU No. 2018-20, and ASU 2019-01 In February 2016, the FASB issued ASU No. 2016-02, Leases (ASC 842) which requires lessees to recognize ROU assets and lease liabilities on the balance sheet for most leases, including operating leases. The lessor accounting model was relatively unchanged by this ASU. Additional quantitative and qualitative disclosures are also required. During 2018 and early 2019, the FASB issued ASU No. 2018-11, Targeted Improvements , ASU No. 2018-20, Narrow-Scope Improvements for Lessors , and ASU No. 2019-01, Codification Improvements , which clarified certain implementation issues, provided an additional optional transition method and clarified the disclosure requirements during the period of adopting ASC 842, among others. The Company adopted ASU No. 2016-02 and the related ASUs discussed above effective January 1, 2019 using the optional transition method. The Company elected the package of practical expedients that does not require the reassessment of whether expired or existing contracts contain leases, the reassessment of the lease classification for any expired or existing leases, or the reassessment of initial direct costs for existing leases. Additionally, the Company did not elect the hindsight practical expedient. The Company conducted a review of all existing lease contracts and service contracts which might contain embedded leases. Some of the Company’s leases contain variable lease payments, the majority of which depend on an index or rate, such as the Consumer Price Index. At transition, the present value of variable payments was based on the index or rate as of January 1, 2019. To determine the present value of lease payments at transition, the Company applied a portfolio approach utilizing an FHLB Advance rate based on the weighted average remaining term of the Company’s existing leases as of January 1, 2019. As a result of adopting ASC 842, the Company established an ROU asset and a lease liability as of January 1, 2019 of $94.2 million and $118.9 million , respectively. Additionally, as part of the adoption of ASC 842, $24.7 million in pre-existing liabilities were reclassified to the ROU asset on January 1, 2019. This resulted in a gross-up of the balance sheet of $94.2 million as a result of recognizing lease liabilities and corresponding right-of-use assets for operating leases. The adoption of ASC 842 also required the recognition of previously deferred gains on sale-leaseback transactions which resulted in an insignificant increase to retained earnings on January 1, 2019. The related impact on the Company’s regulatory capital ratios was not significant. The Company does not expect material changes to the recognition of lease expense in future periods as a result of the adoption of ASC 842. See Note 8, Leases, for additional disclosures required by ASC 842. ASU No. 2018-16 In October 2018, the FASB released ASU No. 2018-16, Derivatives and Hedging (ASC 815): Inclusion of the Secured Overnight Financing Rate (SOFR) Overnight Index Swap (OIS) Rate as a Benchmark Interest Rate for Hedge Accounting Purposes , which permits the use of the OIS rate based on SOFR as a U.S. benchmark interest rate for hedge accounting purposes under ASC 815 in addition to the interest rates on direct Treasury obligations of the UST, the LIBOR swap rate, the OIS Rate based on the Fed Funds Effective Rate, and the SIFMA Municipal Swap Rate. The required effective date of this ASU was dependent upon when an entity adopted the provisions of ASU No. 2017-12. The Company adopted ASU No. 2018-16 effective January 1, 2019 on a prospective basis for qualifying new or redesignated hedging relations as ASU No. 2017-12 had previously been adopted on January 1, 2018. The implementation of this ASU did not have a significant impact on the Company’s consolidated financial statements. ASU No. 2017-08 In March 2017, the FASB issued ASU No. 2017-08, Receivables-Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities, which shortens the amortization period for callable debt securities held at a premium to the earliest call date instead of the maturity date. The amendments do not require an accounting change for securities held at a discount, which will continue to be amortized to the maturity date. The Company adopted ASU No. 2017-08 effective January 1, 2019. The adoption of the ASU did not have a material impact to the Company’s consolidated financial statements. Pronouncements issued but not yet adopted: ASU No. 2016-13, ASU No. 2019-04 (portion related to ASC 326), and ASU No. 2019-05 In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (ASC 326): Measurement of Credit Losses on Financial Instruments . The guidance introduces an impairment model that is based on expected credit losses (ECL), rather than incurred losses, to estimate credit losses on certain types of financial instruments such as loans and held-to-maturity securities, including certain off-balance sheet financial instruments such as loan commitments. The measurement of ECL should consider historical information, current information, and reasonable and supportable forecasts, including estimates of prepayments, over the contractual term. Financial instruments with similar risk characteristics must be grouped together when estimating ECL. The ASU also expands credit quality disclosures. Additionally, ASU No. 2016-13 amends the current AFS security impairment model for debt securities. The new model will require an estimate of ECL when the fair value is below the amortized cost of the asset. The credit-related impairment (and subsequent recoveries) are recognized as an allowance on the balance sheet with a corresponding adjustment to the income statement. Non-credit related losses will continue to be recognized through OCI. In addition, ASU No. 2016-13 provides for a simplified accounting model for purchased financial assets with a more-than-insignificant amount of credit deterioration since their origination. The initial estimate of expected credit losses would be recognized through an ALLL with an offset (i.e., increase) to the cost basis of the related financial asset at acquisition. ASU No. 2016-13 will be effective for fiscal years beginning after December 15, 2019, including interim periods. This ASU will be applied through a modified-retrospective approach, resulting in a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective. A prospective transition approach is required for debt securities for which OTTI had been recognized before the effective date. Amounts previously recognized in AOCI as of the date of adoption that relate to improvements in cash flows expected to be collected should continue to be accreted into income over the remaining life of the asset. Recoveries of amounts previously written off relating to improvements in cash flows after the date of adoption should be recorded in earnings when received. During 2019, the FASB issued ASU No. 2019-04, Codification Improvements to Financial Instruments-Credit Losses (ASC 326), Derivatives and Hedging (ASC 815), and Financial Instruments (ASC 825), which clarified the scope of ASU No. 2016-13 and addressed various issues, including accrued interest receivable balances, recoveries, variable interest rates and prepayments, and ASU No. 2019-05, Financial Instruments-Credit Losses (Topic 326): Targeted Transition Relief , which clarified certain implementation issues. The effective date for the portion of ASU No. 2019-04 related to credit losses and ASU No. 2019-05 are the same as ASU No. 2016-13. The Company’s cross-function implementation team and engaged third-party consultants have jointly developed and continue to execute the project plan and provide implementation oversight. Significant progress has been made in implementation efforts, including model development and validation, fulfillment of additional data needs for new disclosure and reporting requirements, and drafting of accounting policies. In October 2019, user acceptance testing was completed and the Company began concurrent model runs. Implementation efforts will continue through the remainder of 2019, including continued process refinement, documentation enhancement, and finalization of the internal control framework. Based on a preliminary analysis performed in the third quarter of 2019 and forecasts of macroeconomic conditions and exposures as of September 30, 2019, the transition adjustment on January 1, 2020 is estimated to generate an ACL to loans ratio of 1.00% to 1.20% . The Company currently intends to use a blend of multiple economic forecasts to estimate expected credit losses over a one to two year reasonable and supportable forecast period and then revert to longer term historical loss experience to arrive at lifetime expected credit losses. The estimated increase in ACL is primarily due to required increases for residential mortgage and home equity loans to include the requirement to estimate lifetime expected credit losses and the remaining length of time to maturity for these loans as well as an increase in reserves on acquired non-impaired loans which had low reserve levels under the previous accounting guidance. While these ASUs are expected to increase ACL, they do not change the overall credit risk in the Company's loan and lease portfolios or the ultimate losses therein. The transition adjustment to increase ACL will primarily result in a decrease to shareholders' equity, net of income taxes, on January 1, 2020. The ultimate impact of the adoption of these ASUs will depend on the composition of the loan, lease and securities portfolios, finalization of credit loss models, and macroeconomic conditions and forecasts at the adoption date. ASU No. 2018-13 In August 2018, the FASB released ASU No. 2018-13, Fair Value Measurement (ASC 820): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement, which eliminates, adds and modifies certain disclosure requirements for fair value measurements. The ASU will be effective for fiscal years beginning after December 15, 2019, including interim periods, with early adoption permitted. The Company is currently evaluating the impact of the ASU. While adoption of this ASU will result in changes to existing disclosures, it will not have an impact on the Company’s financial position or results of operations. ASU No. 2018-17 In October 2018, the FASB released ASU No. 2018-17, Consolidation (ASC 810): Targeted Improvements to Related Party Guidance for Variable Interest Entities, which improves the consistency of the application of the variable interest entity (VIE) related party guidance for common control arrangements. This ASU requires reporting entities to consider indirect interests held through related parties under common control on a proportional basis rather than as the equivalent of a direct interest in its entirety (as currently required in GAAP) when determining whether a decision-making fee is a variable interest. ASU No. 2018-17 will be effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years, and early adoption is permitted. The guidance will be applied retrospectively with a cumulative-effect adjustment to retained earnings at the beginning of the earliest period presented. The Company is currently evaluating the impact of the ASU on the Company’s consolidated financial statements. ASU No. 2019-04 In April 2019, the FASB released ASU No. 2019-04, Codification Improvements to Financial Instruments-Credit Losses (ASC 326), Derivatives and Hedging (ASC 815), and Financial Instruments (ASC 825). The amendments in the ASU improve the Codification by eliminating inconsistencies and providing clarifications. The amendments related to the credit losses standard are discussed above under ASU 2016-13. With respect to hedge accounting, the ASU addresses partial-term fair value hedges, fair value hedge basis adjustments, and certain transition requirements, among other things. For recognizing and measuring financial instruments, the ASU addresses the scope of the guidance, the requirement for re-measurement under ASC 820 when using the measurement alternative, certain disclosure requirements and which equity securities have to be re-measured at historical exchange rates. Since the Company early adopted the guidance in ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities in 2018, the amended hedge accounting guidance in ASU No. 2019-04 will be effective as of the beginning of the first annual reporting period beginning after April 25, 2019 with early adoption permitted on any date after the issuance of this ASU. The Company is currently evaluating the impact of the ASU on the Company’s consolidated financial statements.

Investment Securities

Investment Securities	9 Months Ended
	Sep. 30, 2019
Investments, Debt and Equity Securities [Abstract]
Investment Securities	INVESTMENT SECURITIES The amortized cost and fair values of investment securities, with gross unrealized gains and losses, consisted of the following: September 30, 2019 (in thousands) Amortized Gross Gross Estimated Securities available for sale: U.S. Government-sponsored enterprise obligations $ 39,887 $ 294 $ — $ 40,181 Obligations of state and political subdivisions 166,034 7,333 — 173,367 Mortgage-backed securities: Residential agency 3,135,619 31,354 (3,930 ) 3,163,043 Commercial agency 732,669 24,239 (179 ) 756,729 Other securities 101,324 3,543 (105 ) 104,762 Total securities available for sale $ 4,175,533 $ 66,763 $ (4,214 ) $ 4,238,082 Securities held to maturity: Obligations of state and political subdivisions $ 167,888 $ 7,725 $ — $ 175,613 Mortgage-backed securities: Residential agency 17,119 50 (196 ) 16,973 Total securities held to maturity $ 185,007 $ 7,775 $ (196 ) $ 192,586 December 31, 2018 (in thousands) Amortized Gross Gross Estimated Securities available for sale: U.S. Government-sponsored enterprise obligations $ 995 $ 3 $ — $ 998 Obligations of state and political subdivisions 177,566 2,045 (723 ) 178,888 Mortgage-backed securities: Residential agency 3,837,584 8,886 (57,073 ) 3,789,397 Commercial agency 730,148 2,363 (14,799 ) 717,712 Other securities 97,020 351 (787 ) 96,584 Total securities available for sale $ 4,843,313 $ 13,648 $ (73,382 ) $ 4,783,579 Securities held to maturity: Obligations of state and political subdivisions $ 188,684 $ 309 $ (2,497 ) $ 186,496 Mortgage-backed securities: Residential agency 18,762 30 (1,011 ) 17,781 Total securities held to maturity $ 207,446 $ 339 $ (3,508 ) $ 204,277 Securities with carrying values of $2.1 billion and $2.4 billion were pledged to support repurchase transactions, public funds deposits, and certain long-term borrowings at September 30, 2019 and December 31, 2018 , respectively. Information pertaining to securities with gross unrealized losses, aggregated by investment category and length of time that individual securities have been in a continuous loss position, was as follows: September 30, 2019 Less Than Twelve Months Twelve Months or More Total (in thousands) Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Securities available for sale: Mortgage-backed securities: Residential agency $ (1,829 ) $ 447,333 $ (2,101 ) $ 299,396 $ (3,930 ) $ 746,729 Commercial agency (83 ) 8,961 (96 ) 10,994 (179 ) 19,955 Other securities (6 ) 13,368 (99 ) 4,802 (105 ) 18,170 Total securities available for sale $ (1,918 ) $ 469,662 $ (2,296 ) $ 315,192 $ (4,214 ) $ 784,854 Securities held to maturity: Mortgage-backed securities: Residential agency $ (2 ) $ 924 $ (194 ) $ 9,551 $ (196 ) $ 10,475 Total securities held to maturity $ (2 ) $ 924 $ (194 ) $ 9,551 $ (196 ) $ 10,475 December 31, 2018 Less Than Twelve Months Twelve Months or More Total (in thousands) Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Securities available for sale: Obligations of state and political subdivisions $ (9 ) $ 4,112 $ (714 ) $ 30,268 $ (723 ) $ 34,380 Mortgage-backed securities: Residential agency (816 ) 197,057 (56,257 ) 2,193,862 (57,073 ) 2,390,919 Commercial agency (43 ) 18,190 (14,756 ) 483,565 (14,799 ) 501,755 Other securities (94 ) 18,025 (693 ) 32,577 (787 ) 50,602 Total securities available for sale $ (962 ) $ 237,384 $ (72,420 ) $ 2,740,272 $ (73,382 ) $ 2,977,656 Securities held to maturity: Obligations of state and political subdivisions $ (3 ) $ 2,059 $ (2,494 ) $ 151,699 $ (2,497 ) $ 153,758 Mortgage-backed securities: Residential agency — — (1,011 ) 17,478 (1,011 ) 17,478 Total securities held to maturity $ (3 ) $ 2,059 $ (3,505 ) $ 169,177 $ (3,508 ) $ 171,236 The Company held certain investment securities where amortized cost exceeded fair value, resulting in unrealized loss positions, as shown in the tables above. Management evaluates securities for other-than-temporary impairment on at least a quarterly basis, and more frequently when economic or market concerns warrant such evaluation. Impairment is considered to be other-than-temporary if the Company (1) intends to sell the security, (2) more likely than not will be required to sell the security before recovering its cost, or (3) does not expect to recover the security's entire amortized cost basis. As of September 30, 2019 , the Company did not intend to sell any of these securities, did not expect to be required to sell these securities, and expected to recover the entire amortized cost of all these securities. At September 30, 2019 , 107 debt securities had unrealized losses of 0.55% of the securities’ amortized cost basis. At December 31, 2018 , 488 debt securities had unrealized losses of 2.38% of the securities’ amortized cost basis. The unrealized losses for each of the securities related to market interest rate changes and not credit concerns of the issuers. Additional information on securities that were in a continuous loss position for over twelve months at September 30, 2019 and December 31, 2018 is presented in the following table. (in thousands) September 30, 2019 December 31, 2018 Number of securities Mortgage-backed securities: Residential agency 66 302 Commercial agency 6 72 Obligations of state and political subdivisions — 60 Other securities 4 7 76 441 Amortized Cost Basis Mortgage-backed securities: Residential agency $ 311,242 $ 2,268,608 Commercial agency 11,090 498,321 Obligations of state and political subdivisions — 185,175 Other securities 4,901 33,270 $ 327,233 $ 2,985,374 Unrealized Loss Mortgage-backed securities: Residential agency $ 2,295 $ 57,268 Commercial agency 96 14,756 Obligations of state and political subdivisions — 3,208 Other securities 99 693 $ 2,490 $ 75,925 The amortized cost and estimated fair value of investment securities by maturity at September 30, 2019 are presented in the following table. Securities are classified according to their contractual maturities without consideration of principal amortization, potential prepayments or call options. Accordingly, actual maturities may differ from contractual maturities. Weighted average yields are calculated on the basis of the yield to maturity based on the amortized cost of each security. Securities Available for Sale Securities Held to Maturity (in thousands) Weighted Amortized Estimated Weighted Amortized Estimated Within one year or less 2.55 % $ 10,720 $ 10,787 2.33 % $ 948 $ 949 One through five years 2.62 123,447 125,721 2.63 4,483 4,518 After five through ten years 2.76 760,325 786,040 2.35 43,085 44,653 Over ten years 2.67 3,281,041 3,315,534 2.58 136,491 142,466 2.68 % $ 4,175,533 $ 4,238,082 2.53 % $ 185,007 $ 192,586 The following is a summary of realized gains and losses from the sale of securities classified as available for sale. Gains or losses on securities sold are recorded on the trade date, using the specific identification method. Three Months Ended September 30, Nine Months Ended September 30, (in thousands) 2019 2018 2019 2018 Realized gains $ 27 $ — $ 1,324 $ 39 Realized losses — — (2,311 ) (95 ) $ 27 $ — $ (987 ) $ (56 ) In addition to the gains above, the Company realized certain gains on calls of securities held to maturity that were not significant to the consolidated financial statements. Other Equity Securities The Company accounts for the following securities at cost less impairment plus or minus any observable price changes, which approximates fair value, with the exception of CRA and Community Development Investment Funds, which are recorded at fair value. Other equity securities, which are presented in other assets on the consolidated balance sheets, were as follows: (in thousands) September 30, 2019 December 31, 2018 Federal Home Loan Bank stock $ 87,156 $ 95,213 Federal Reserve Bank stock 85,630 85,630 CRA and Community Development Investment Funds 1,962 1,884 Other investments 21,023 9,709 $ 195,771 $ 192,436

Loans and Leases

Loans and Leases	9 Months Ended
	Sep. 30, 2019
Receivables [Abstract]
Loans and Leases	LOANS AND LEASES Loans and leases by portfolio segment and class consisted of the following for the periods indicated: (in thousands) September 30, 2019 December 31, 2018 Commercial loans and leases: Real estate - construction $ 1,330,014 $ 1,196,366 Real estate - owner-occupied 2,468,061 2,395,822 Real estate - non-owner-occupied 6,011,681 5,796,117 Commercial and industrial (1) 6,490,125 5,737,017 Total commercial loans and leases 16,299,881 15,125,322 Residential mortgage loans 4,649,745 4,359,156 Consumer and other loans: Home equity 2,053,588 2,304,694 Other 673,323 730,643 Total consumer and other loans 2,726,911 3,035,337 Total loans and leases $ 23,676,537 $ 22,519,815 (1) Includes equipment financing leases Net deferred loan origination fees were $37.8 million and $30.2 million at September 30, 2019 and December 31, 2018 , respectively. Total net discount on the Company's loans was $97.8 million and $136.8 million at September 30, 2019 and December 31, 2018 , respectively, of which $61.8 million and $81.6 million was related to non-impaired loans. In addition to loans issued in the normal course of business, the Company considers overdrafts on customer deposit accounts to be loans and reclassifies these overdrafts as loans in its consolidated balance sheets. At September 30, 2019 and December 31, 2018 , overdrafts of $7.0 million and $9.2 million , respectively, had been reclassified to loans. Loans with carrying values of $8.5 billion and $7.6 billion were pledged as collateral for borrowings at September 30, 2019 and December 31, 2018 , respectively. Aging Analysis The following tables provide an analysis of the aging of loans and leases as of September 30, 2019 and December 31, 2018 . Past due and non-accrual loan amounts exclude acquired impaired loans, even if contractually past due or if the Company does not expect to receive payment in full, as the Company is currently accreting interest income over the expected life of the loans. For additional information on the determination of past due status and the Company's policies for recording payments received, placing loans and leases on non-accrual status, and the resumption of interest accrual on non-accruing loans and leases, see Note 1, Summary of Significant Accounting Policies, in the 2018 10-K. September 30, 2019 Accruing (in thousands) Current or Less Than 30 days Past Due 30-59 days 60-89 days > 90 days Total Past Due Non-accrual (1) Acquired Impaired Total Real estate- construction $ 1,307,793 $ 3,851 $ — $ — $ 3,851 $ 1,381 $ 16,989 $ 1,330,014 Real estate- owner-occupied 2,389,631 2,294 1,031 — 3,325 17,158 57,947 2,468,061 Real estate- non-owner-occupied 5,930,480 2,093 2,672 426 5,191 20,201 55,809 6,011,681 Commercial and industrial 6,417,203 3,614 1,769 2,696 8,079 43,494 21,349 6,490,125 Residential mortgage 4,502,109 1,252 13,463 1,668 16,383 50,439 80,814 4,649,745 Consumer - home equity 1,967,342 10,448 6,792 — 17,240 18,311 50,695 2,053,588 Consumer - other 663,561 2,839 2,500 — 5,339 2,129 2,294 673,323 Total $ 23,178,119 $ 26,391 $ 28,227 $ 4,790 $ 59,408 $ 153,113 $ 285,897 $ 23,676,537 (1) Of the total non-accrual loans at September 30, 2019 , $10.7 million were past due 30-59 days, $4.5 million were past due 60-89 days, and $73.4 million were past due more than 90 days. December 31, 2018 Accruing (in thousands) Current or Less Than 30 days Past Due 30-59 days 60-89 days > 90 days Total Past Due Non-accrual (1) Acquired Impaired Total Real estate- construction $ 1,167,795 $ 1,054 $ — $ — $ 1,054 $ 1,094 $ 26,423 $ 1,196,366 Real estate- owner-occupied 2,305,743 7,167 — — 7,167 10,260 72,652 2,395,822 Real estate- non-owner-occupied 5,703,131 7,473 360 — 7,833 15,898 69,255 5,796,117 Commercial and industrial 5,645,304 5,139 1,320 553 7,012 57,860 26,841 5,737,017 Residential mortgage 4,218,146 2,768 13,063 1,575 17,406 30,396 93,208 4,359,156 Consumer - home equity 2,200,517 10,283 2,409 — 12,692 18,830 72,655 2,304,694 Consumer - other 719,122 4,695 1,601 — 6,296 2,846 2,379 730,643 Total $ 21,959,758 $ 38,579 $ 18,753 $ 2,128 $ 59,460 $ 137,184 $ 363,413 $ 22,519,815 (1) Of the total non-accrual loans at December 31, 2018 , $7.0 million were past due 30-59 days, $3.7 million were past due 60-89 days, and $66.9 million were past due more than 90 days. Acquired Loans The Company acquired certain loans from Sabadell United to customers with addresses outside of the United States. Foreign loans, denominated in U.S. dollars, totaled $194.6 million and $202.6 million at September 30, 2019 and December 31, 2018 , respectively. The following is a summary of changes in the accretable difference for all loans accounted for under ASC 310-30 during the nine months ended September 30 : (in thousands) 2019 2018 Balance at beginning of period $ 133,342 $ 152,623 Additions — 2,371 Transfers from non-accretable difference to accretable yield (1,740 ) (4 ) Accretion (29,506 ) (37,115 ) Changes in expected cash flows not affecting non-accretable differences (1) (2,927 ) 21,092 Balance at end of period $ 99,169 $ 138,967 (1) Includes changes in cash flows expected to be collected due to the impact of changes in actual or expected timing of liquidation events, modifications, changes in interest rates and changes in prepayment assumptions. Troubled Debt Restructurings Information about the Company’s TDRs at September 30, 2019 and 2018 is presented in the following tables. Modifications of loans that are accounted for within a pool under ASC Topic 310-30 are excluded as TDRs. Accordingly, such modifications do not result in the removal of those loans from the pool, even if the modification of those loans would otherwise be considered a TDR. As a result, all such acquired loans that would otherwise meet the criteria for classification as a TDR are excluded from the tables below. TDRs totaling $61.0 million and $46.0 million occurred during the nine months ended September 30, 2019 and 2018, respectively, through modification of the original loan terms. The following table provides information on how the TDRs were modified during the periods indicated: Three Months Ended September 30, Nine Months Ended September 30, (in thousands) 2019 2018 2019 2018 Extended maturities $ 2,476 $ 3,658 $ 13,097 $ 10,020 Maturity and interest rate adjustment 288 267 715 368 Movement to or extension of interest-rate only payments 48 — 1,827 48 Interest rate adjustment — — 71 101 Forbearance 22,202 802 25,068 14,386 Other concession(s) (1) 3,724 1,810 20,250 21,031 Total $ 28,738 $ 6,537 $ 61,028 $ 45,954 (1) Other concessions may include covenant waivers, forgiveness of principal or interest associated with a customer bankruptcy, or a combination of any of the above concessions. Of the $61.0 million of TDRs occurring during the nine months ended September 30, 2019 , $25.5 million were on accrual status and $35.5 million were on non-accrual status. Of the $46.0 million of TDRs occurring during the nine months ended September 30 2018 , $20.2 million were on accrual status and $25.8 million were on non-accrual status. The following table presents the end of period balance for loans modified in a TDR during the periods indicated: Three Months Ended September 30, 2019 2018 (in thousands, except number of loans) Number of Loans Pre-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment Number of Loans Pre-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment Real estate- construction 1 $ 6,331 $ 7,602 — $ — $ — Real estate- owner-occupied 7 8,936 8,691 1 2,312 2,312 Real estate- non-owner-occupied 6 1,553 1,210 6 1,818 1,790 Commercial and industrial 14 1,954 1,952 9 829 804 Residential mortgage 10 7,210 6,870 3 257 255 Consumer - home equity 19 2,375 2,237 15 1,152 1,124 Consumer - other 17 202 176 11 352 252 Total 74 $ 28,561 $ 28,738 45 $ 6,720 $ 6,537 Nine Months Ended September 30, 2019 2018 (in thousands, except number of loans) Number of Loans Pre-modification Outstanding Recorded Investment Post-modification Outstanding Recorded Investment Number of Loans Pre-modification Outstanding Recorded Investment Post-modification Outstanding Recorded Investment Real estate- construction 1 $ 6,331 $ 7,602 1 $ 1,950 $ 976 Real estate- owner-occupied 11 10,153 9,869 8 15,233 13,373 Real estate- non-owner-occupied 16 7,931 7,233 13 3,228 3,064 Commercial and industrial 48 29,156 19,594 32 32,827 22,769 Residential mortgage 28 8,897 8,524 9 898 837 Consumer - home equity 69 7,629 7,268 47 4,130 4,047 Consumer - other 63 1,065 938 53 1,056 888 Total 236 $ 71,162 $ 61,028 163 $ 59,322 $ 45,954 Information detailing TDRs that defaulted during the three-month and nine-month periods ended September 30, 2019 and 2018 , and were modified in the previous twelve months (i.e., the twelve months prior to the default) is presented in the following tables. The Company has defined a default as any loan with a payment that is currently past due greater than 30 days , or was past due greater than 30 days at any point during the respective periods, or since the date of modification, whichever is shorter. Three Months Ended September 30, 2019 2018 (in thousands, except number of loans) Number of Loans Recorded Investment Number of Loans Recorded Investment Real estate- owner-occupied — $ — 1 $ 929 Real estate- non-owner-occupied 2 2,460 1 7 Commercial and industrial 8 1,429 2 127 Residential mortgage 1 101 — — Consumer - home equity 1 64 4 380 Consumer - other 5 57 6 86 Total 17 $ 4,111 14 $ 1,529 Nine Months Ended September 30, 2019 2018 (in thousands, except number of loans) Number of Loans Recorded Investment Number of Loans Recorded Investment Real estate- owner-occupied 6 $ 1,225 6 $ 10,101 Real estate- non-owner-occupied 16 5,176 6 1,084 Commercial and industrial 25 6,859 12 3,632 Residential mortgage 18 1,394 8 912 Consumer - home equity 21 1,873 17 1,978 Consumer - other 38 557 39 488 Total 124 $ 17,084 88 $ 18,195

Allowance for Credit Losses and

Allowance for Credit Losses and Credit Quality	9 Months Ended
	Sep. 30, 2019
Receivables [Abstract]
Allowance for Credit Losses and Credit Quality	ALLOWANCE FOR CREDIT LOSSES AND CREDIT QUALITY Allowance for Credit Losses Activity A summary of changes in the allowance for credit losses for the nine months ended September 30 was as follows: (in thousands) 2019 2018 Allowance for loan and lease losses at beginning of period $ 140,571 $ 140,891 Provision for loan and lease losses 32,190 26,678 Transfer of balance to OREO and other (2,696 ) (5,709 ) Charge-offs (29,971 ) (34,740 ) Recoveries 6,141 9,830 Allowance for loan and lease losses at end of period $ 146,235 $ 136,950 Reserve for unfunded commitments at beginning of period $ 14,830 $ 13,208 Balance created in acquisition accounting — 900 Provision for unfunded lending commitments 1,314 613 Reserve for unfunded commitments at end of period $ 16,144 $ 14,721 Allowance for credit losses at end of period $ 162,379 $ 151,671 A summary of changes in the allowance for credit losses, by loan portfolio type, for the nine months ended September 30 was as follows: 2019 (in thousands) Commercial Real Estate Commercial and Industrial Residential Mortgage Consumer and Other Total Allowance for loan and lease losses at beginning of period $ 51,806 $ 54,096 $ 12,998 $ 21,671 $ 140,571 Provision for (Reversal of) loan and lease losses 9,205 15,819 (152 ) 7,318 32,190 Transfer of balance to OREO and other (309 ) 236 (2,879 ) 256 (2,696 ) Charge-offs (2,179 ) (17,799 ) (219 ) (9,774 ) (29,971 ) Recoveries 474 3,163 169 2,335 6,141 Allowance for loan and lease losses at end of period $ 58,997 $ 55,515 $ 9,917 $ 21,806 $ 146,235 Reserve for unfunded commitments at beginning of period $ 4,869 $ 6,198 $ 866 $ 2,897 $ 14,830 Provision for (Reversal of) unfunded commitments 357 493 (216 ) 680 1,314 Reserve for unfunded commitments at end of period $ 5,226 $ 6,691 $ 650 $ 3,577 $ 16,144 Allowance on loans individually evaluated for impairment $ 2,721 $ 7,974 $ 281 $ 3,039 $ 14,015 Allowance on loans collectively evaluated for impairment 50,809 45,990 5,393 18,630 120,822 Allowance on loans acquired with deteriorated credit quality 5,467 1,551 4,243 137 11,398 Loans and leases, net of unearned income: Balance at end of period $ 9,809,756 $ 6,490,125 $ 4,649,745 $ 2,726,911 $ 23,676,537 Balance at end of period individually evaluated for impairment 73,715 51,350 42,423 37,907 205,395 Balance at end of period collectively evaluated for impairment 9,605,296 6,417,426 4,526,508 2,636,015 23,185,245 Balance at end of period acquired with deteriorated credit quality 130,745 21,349 80,814 52,989 285,897 2018 (in thousands) Commercial Real Estate Commercial and Industrial Residential Mortgage Consumer and Other Total Allowance for loan and lease losses at beginning of period $ 54,201 $ 53,916 $ 9,117 $ 23,657 $ 140,891 Provision for (Reversal of) loan and lease losses (4,020 ) 20,372 2,318 8,008 26,678 Transfer of balance to OREO and other (1,556 ) (814 ) (45 ) (3,294 ) (5,709 ) Charge-offs (1,281 ) (22,447 ) (365 ) (10,647 ) (34,740 ) Recoveries 1,019 5,665 53 3,093 9,830 Allowance for loan and lease losses at end of period $ 48,363 $ 56,692 $ 11,078 $ 20,817 $ 136,950 Reserve for unfunded commitments at beginning of period $ 4,531 $ 5,309 $ 555 $ 2,813 $ 13,208 Balance created in acquisition accounting 129 81 — 690 900 Provision for (Reversal of) unfunded commitments (134 ) 169 246 332 613 Reserve for unfunded commitments at end of period $ 4,526 $ 5,559 $ 801 $ 3,835 $ 14,721 Allowance on loans individually evaluated for impairment $ 2,650 $ 10,471 $ 154 $ 2,973 $ 16,248 Allowance on loans collectively evaluated for impairment 40,519 44,727 5,063 17,661 107,970 Allowance on loans acquired with deteriorated credit quality 5,194 1,494 5,861 183 12,732 Loans and leases, net of unearned income: Balance at end of period $ 9,381,883 $ 5,581,040 $ 4,300,163 $ 3,080,820 $ 22,343,906 Balance at end of period individually evaluated for impairment 73,469 75,625 6,230 33,863 189,187 Balance at end of period collectively evaluated for impairment 9,126,653 5,478,377 4,174,524 2,970,301 21,749,855 Balance at end of period acquired with deteriorated credit quality 181,761 27,038 119,409 76,656 404,864 Portfolio Segment Risk Factors Commercial real estate loans include loans to commercial customers for medium-term financing of land and buildings or for land development or construction of a building. These loans are repaid from revenues through operations of the businesses, rents of properties, sales of properties and refinances. Commercial and industrial loans and leases represent loans to commercial customers to finance general working capital needs, equipment purchases and leases and other projects where repayment is derived from cash flows resulting from business operations. The Company originates commercial and industrial loans on a secured and, to a lesser extent, unsecured basis. Residential mortgage loans consist of loans to consumers to finance a primary residence. The vast majority of the residential mortgage loan portfolio is comprised of non-conforming 1-4 family mortgage loans secured by properties located in the Company's market areas and originated under terms and documentation that permit their sale in a secondary market. Consumer loans are offered by the Company in order to provide a full range of retail financial services to its customers and include home equity, credit card and other direct consumer installment loans. The Company originates substantially all of its consumer loans in its primary market areas. Loans in the consumer segment are sensitive to unemployment and other key consumer economic measures. Credit Quality Indicators For commercial loans and leases, the Company utilizes regulatory classification ratings to monitor credit quality. Loans with a "pass" rating are those that the Company believes will be fully repaid in accordance with the contractual loan terms. Commercial loans and leases that are "criticized" are those that have some weakness or potential weakness that indicate an increased probability of future loss. "Criticized" loans are grouped into three categories: "special mention", "substandard", and "doubtful". Special mention loans have potential weaknesses that, if left uncorrected, may result in deterioration of the Company's credit position at some future date. Substandard commercial loans have well-defined weaknesses and are characterized by the distinct possibility that the Company will sustain some loss if the deficiencies are not corrected. Doubtful commercial loans have the same weaknesses as substandard loans with the added characteristics that the probability of loss is high and collection of the full amount is improbable. Substandard and doubtful loans are collectively referred to as "classified" loans. For residential mortgage loans and consumer loans, the Company primarily uses the loan's payment and delinquency status to monitor credit quality. These credit quality indicators are continually updated and monitored. The recorded investment in loans and leases by credit quality indicator is presented in the following tables. Asset risk classifications for commercial loans and leases reflect the classification as of September 30, 2019 and December 31, 2018 . Credit quality information in the tables below includes total loans acquired (including acquired impaired loans) at the net loan balance, after the application of premiums and discounts. Loan premiums and discounts represent the adjustment of acquired loans to fair value at the acquisition date, as adjusted for income accretion and changes in cash flow estimates in subsequent periods. September 30, 2019 December 31, 2018 (in thousands) Pass Special Mention Sub- Doubtful Loss Total Pass Special Mention Sub- Doubtful Total Real estate - construction $ 1,300,847 $ 19,631 $ 9,536 $ — $ — $ 1,330,014 $ 1,182,554 $ 1,062 $ 12,740 $ 10 $ 1,196,366 Real estate - owner-occupied 2,409,221 19,786 38,214 840 — 2,468,061 2,328,999 25,526 41,297 — 2,395,822 Real estate - non-owner-occupied 5,926,537 47,494 37,193 447 10 6,011,681 5,687,963 78,009 26,512 3,633 5,796,117 Commercial and industrial 6,340,738 71,431 63,303 14,653 — 6,490,125 5,586,482 52,632 73,853 24,050 5,737,017 Total $ 15,977,343 $ 158,342 $ 148,246 $ 15,940 $ 10 $ 16,299,881 $ 14,785,998 $ 157,229 $ 154,402 $ 27,693 $ 15,125,322 September 30, 2019 December 31, 2018 (in thousands) Current 30+ Days Past Due Total Current 30+ Days Past Due Total Residential mortgage $ 4,567,633 $ 82,112 $ 4,649,745 $ 4,290,152 $ 69,004 $ 4,359,156 Consumer - home equity 2,011,913 41,675 2,053,588 2,258,659 46,035 2,304,694 Consumer - other 665,702 7,621 673,323 721,231 9,412 730,643 Total $ 7,245,248 $ 131,408 $ 7,376,656 $ 7,270,042 $ 124,451 $ 7,394,493 Impaired Loans Information on the Company’s investment in impaired loans, which include all TDRs and all other non-accrual loans evaluated or measured individually for impairment for purposes of determining the ALLL, is presented in the following tables as of and for the periods indicated. September 30, 2019 December 31, 2018 Unpaid Principal Balance Recorded Investment Related Allowance Unpaid Principal Balance Recorded Investment Related Allowance (in thousands) With no related allowance recorded: Real estate - construction $ 9,540 $ 8,531 $ — $ 10,261 $ 9,262 $ — Real estate - owner-occupied 33,985 33,590 — 25,037 19,044 — Real estate - non-owner-occupied 23,964 22,652 — 15,265 14,288 — Commercial and industrial 21,813 17,771 — 55,554 43,886 — Residential mortgage 36,182 35,089 — 1,244 1,221 — Consumer - home equity 4,736 4,734 — 4,183 4,176 — With an allowance recorded: Real estate - construction 98 85 (1 ) 228 140 (11 ) Real estate - owner-occupied 5,135 4,921 (2,529 ) 5,032 4,773 (520 ) Real estate - non-owner-occupied 4,149 3,936 (191 ) 6,445 6,398 (105 ) Commercial and industrial 45,409 33,579 (7,974 ) 46,387 27,915 (12,646 ) Residential mortgage 8,010 7,334 (281 ) 5,870 5,358 (145 ) Consumer - home equity 29,773 29,124 (2,577 ) 29,284 28,818 (2,427 ) Consumer - other 4,308 4,049 (462 ) 4,956 4,446 (488 ) Total $ 227,102 $ 205,395 $ (14,015 ) $ 209,746 $ 169,725 $ (16,342 ) Total commercial loans and leases $ 144,093 $ 125,065 $ (10,695 ) $ 164,209 $ 125,706 $ (13,282 ) Total residential mortgage loans 44,192 42,423 (281 ) 7,114 6,579 (145 ) Total consumer and other loans 38,817 37,907 (3,039 ) 38,423 37,440 (2,915 ) Three Months Ended September 30, 2019 Three Months Ended September 30, 2018 Nine Months Ended September 30, 2019 Nine Months Ended September 30, 2018 Average Interest Average Interest Average Recorded Investment Interest Income Recognized Average Recorded Investment Interest Income Recognized (in thousands) With no related allowance recorded: Real estate - construction $ 7,333 $ 82 $ 10,806 $ 164 $ 7,145 $ 242 $ 10,371 $ 460 Real estate - owner-occupied 33,895 355 34,118 209 34,437 1,235 34,505 903 Real estate - non-owner-occupied 22,794 72 22,091 249 22,910 301 22,988 746 Commercial and industrial 20,594 108 43,409 523 20,727 401 40,564 1,543 Residential mortgage 35,896 136 1,254 9 31,315 391 1,271 36 Consumer - home equity 4,736 47 705 2 4,613 137 708 16 With an allowance recorded: Real estate - construction 87 — 148 — 93 — 151 1 Real estate - owner-occupied 4,952 10 4,006 83 5,050 113 4,044 102 Real estate - non-owner-occupied 4,155 46 2,398 20 4,090 137 2,442 76 Commercial and industrial 36,824 173 40,357 150 36,765 582 47,098 720 Residential mortgage 7,414 74 5,014 50 7,502 232 5,066 149 Consumer - home equity 29,200 298 28,577 305 28,982 890 27,905 892 Consumer - other 4,175 59 4,710 65 4,326 184 4,884 208 Total $ 212,055 $ 1,460 $ 197,593 $ 1,829 $ 207,955 $ 4,845 $ 201,997 $ 5,852 Total commercial loans and leases $ 130,634 $ 846 $ 157,333 $ 1,398 $ 131,217 $ 3,011 $ 162,163 $ 4,551 Total residential mortgage loans 43,310 210 6,268 59 38,817 623 6,337 185 Total consumer and other loans 38,111 404 33,992 372 37,921 1,211 33,497 1,116 As of September 30, 2019 and December 31, 2018 , the Company was not committed to lend a material amount of additional funds to any customer whose loan was classified as impaired or as a TDR.

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	9 Months Ended
	Sep. 30, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	GOODWILL AND OTHER INTANGIBLE ASSETS Goodwill Changes to the carrying amount of goodwill by reporting unit for the nine months ended September 30, 2019 , and the year ended December 31, 2018 are provided in the following table: (in thousands) IBERIABANK Mortgage LTC Total Balance, December 31, 2017 $ 1,160,559 $ 23,178 $ 5,165 $ 1,188,902 Goodwill acquired and adjustments during the year 43,251 — 3,380 46,631 Balance, December 31, 2018 $ 1,203,810 $ 23,178 $ 8,545 $ 1,235,533 Goodwill acquired and adjustments during the year — — — — Balance, September 30, 2019 $ 1,203,810 $ 23,178 $ 8,545 $ 1,235,533 The goodwill acquired and adjustments made during 2018 were the result of the Sabadell United, Gibraltar, and SolomonParks acquisitions. There were no changes to goodwill during the nine months ended September 30, 2019 . The Company performed the required annual goodwill impairment test as of October 1, 2018. The Company’s annual impairment test did not indicate impairment in any of the Company’s reporting units as of the testing date. Following the testing date, management evaluated the events and changes that could indicate that goodwill might be impaired and concluded that a subsequent interim test was not necessary. The Company is currently in the process of performing its annual impairment test as of October 1, 2019. Mortgage Servicing Rights Mortgage servicing rights are recorded at the lower of cost or market value in other intangible assets on the Company's consolidated balance sheets and amortized over the remaining servicing life of the loans, with consideration given to prepayment assumptions. Mortgage servicing rights had the following carrying values as of the periods indicated: September 30, 2019 December 31, 2018 Gross Carrying Amount Valuation Allowance Accumulated Amortization Net Carrying Amount Gross Carrying Amount Valuation Allowance Accumulated Amortization Net Carrying Amount (in thousands) Mortgage servicing rights $ 19,517 $ (195 ) $ (5,994 ) $ 13,328 $ 13,612 $ — $ (4,806 ) $ 8,806 Title Plant The Company held title plant assets recorded in other intangible assets on the Company's consolidated balance sheets totaling $6.8 million at both September 30, 2019 and December 31, 2018 . No events or changes in circumstances occurred during the nine months ended September 30, 2019 to suggest the carrying value of the title plant was not recoverable. Intangible assets subject to amortization Definite-lived intangible assets had the following carrying values included in other intangible assets on the Company’s consolidated balance sheets as of the periods indicated: September 30, 2019 December 31, 2018 (in thousands) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Core deposit intangible assets $ 136,183 $ (77,256 ) $ 58,927 $ 136,183 $ (63,213 ) $ 72,970 Customer relationship intangible asset 1,385 (1,363 ) 22 1,385 (1,323 ) 62 Non-compete agreement 206 (102 ) 104 206 (72 ) 134 Total $ 137,774 $ (78,721 ) $ 59,053 $ 137,774 $ (64,608 ) $ 73,166

Derivative Instruments and Othe

Derivative Instruments and Other Hedging Activities	9 Months Ended
	Sep. 30, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments and Other Hedging Activities	DERIVATIVE INSTRUMENTS AND OTHER HEDGING ACTIVITIES The Company enters into derivative financial instruments to manage interest rate risk, exposures related to liquidity and credit risk, and to facilitate customer transactions. The primary types of derivatives utilized by the Company for its risk management strategies include interest rate swap agreements, interest rate collars, interest rate floors, foreign exchange contracts, interest rate lock commitments, forward sales commitments, written and purchased options, and credit derivatives. All derivative instruments are recognized on the consolidated balance sheets as other assets or other liabilities at fair value, regardless of whether a right of offset exists. Cash flow hedge relationships mitigate exposure to the variability of future cash flows or other forecasted transactions. The Company enters into interest rate swap agreements in a cash flow hedge to convert forecasted variable interest payments to a fixed rate on its junior subordinated debt. In addition, the Company has entered into interest rate collars and interest rate floors and designated the instruments as cash flow hedges of the risk of fluctuations in interest rates, thereby reducing the Company's exposure to variability in cash flows from variable-rate loans. For cash flow hedges, the effective and ineffective portions of the gain or loss related to the derivative instrument is initially reported as a component of other comprehensive income and subsequently reclassified into earnings when the forecasted transaction affects earnings or when the hedge is terminated. In applying hedge accounting for derivatives, the Company establishes and documents a method for assessing the effectiveness of the hedging derivative and a measurement approach for determining the ineffective aspect of the hedge upon the inception of the hedge. For derivative instruments that are not designated as hedging instruments, changes in the fair value of the derivatives are recognized in earnings immediately. Information pertaining to outstanding derivative instruments was as follows: Derivative Assets - Fair Value Derivative Liabilities - Fair Value (in thousands) September 30, 2019 December 31, 2018 September 30, 2019 December 31, 2018 Derivatives designated as hedging instruments: Interest rate contracts $ 23,339 $ 3,469 $ — $ — Total derivatives designated as hedging instruments $ 23,339 $ 3,469 $ — $ — Derivatives not designated as hedging instruments: Interest rate contracts: Customer swaps - upstream $ 12 $ 474 $ 6,104 $ 191 Customer swaps - downstream 104,779 16,946 206 17,812 Foreign exchange contracts — 18 — 18 Forward sales contracts 485 630 654 750 Written and purchased options 7,549 5,490 3,695 3,310 Other contracts 71 21 192 43 Total derivatives not designated as hedging instruments $ 112,896 $ 23,579 $ 10,851 $ 22,124 Total $ 136,235 $ 27,048 $ 10,851 $ 22,124 Derivative Assets - Notional Amount Derivative Liabilities - Notional Amount (in thousands) September 30, 2019 December 31, 2018 September 30, 2019 December 31, 2018 Derivatives designated as hedging instruments: Interest rate contracts $ 800,000 $ 408,500 $ 108,500 $ — Total derivatives designated as hedging instruments $ 800,000 $ 408,500 $ 108,500 $ — Derivatives not designated as hedging instruments: Interest rate contracts: Customer swaps - upstream $ 142,425 $ 919,653 $ 2,259,248 $ 701,257 Customer swaps - downstream 2,259,248 701,257 142,425 919,653 Foreign exchange contracts — 1,202 — 1,202 Forward sales contracts 144,368 1,140 211,049 143,179 Written and purchased options 339,569 229,333 128,150 140,645 Other contracts 74,085 50,527 145,443 85,623 Total derivatives not designated as hedging instruments $ 2,959,695 $ 1,903,112 $ 2,886,315 $ 1,991,559 Total $ 3,759,695 $ 2,311,612 $ 2,994,815 $ 1,991,559 The Company has entered into risk participation agreements with counterparties to transfer or assume credit exposures related to interest rate derivatives. The notional amounts of risk participation agreements sold were $145.4 million and $85.6 million at September 30, 2019 and December 31, 2018 , respectively. Assuming all underlying third party customers referenced in the swap contracts defaulted at September 30, 2019 and December 31, 2018 , the exposure from these agreements would not be material based on the fair value of the underlying swaps. The Company is party to collateral agreements with certain derivative counterparties. Such agreements require that the Company maintain collateral based on the fair values of individual derivative transactions. In the event of default by the Company, the counterparty would be entitled to the collateral. At September 30, 2019 and December 31, 2018 , the Company was not required to post collateral due to the Company's derivative position at the balance sheet date. At September 30, 2019 and December 31, 2018 , the Company was required to post $106.5 million and $35.8 million , respectively, in variation margin payments for its derivative transactions, which is required to be netted against the fair value of the derivatives in other assets or other liabilities on the consolidated balance sheets. The Company does not anticipate additional assets will be required to be posted as collateral, nor does it believe additional assets would be required to settle its derivative instruments immediately if contingent features were triggered at September 30, 2019 . The Company’s master netting agreements represent written, legally enforceable bilateral agreements that (1) create a single legal obligation for all individual transactions covered by the master agreement and (2) in the event of default, provide the non-defaulting counterparty the right to accelerate, terminate, and close-out on a net basis all transactions under the agreement and to promptly liquidate or set-off collateral posted by the defaulting counterparty. As permitted by GAAP, the Company does not offset fair value amounts recognized for the right to reclaim cash collateral or the obligation to return cash collateral against recognized fair value amounts of derivatives executed with the same counterparty under a master netting agreement. The following table reconciles the gross amounts presented in the consolidated balance sheets to the net amounts that would result in the event of offset. September 30, 2019 Gross Amounts Presented in the Balance Sheet Gross Amounts Not Offset in the Balance Sheet Net (in thousands) Derivatives Collateral Derivatives subject to master netting arrangements Derivative assets Interest rate contracts designated as hedging instruments $ 23,338 $ — $ — $ 23,338 Interest rate contracts not designated as hedging instruments 104,791 (6,119 ) — 98,672 Written and purchased options 3,581 — — 3,581 Total derivative assets subject to master netting arrangements $ 131,710 $ (6,119 ) $ — $ 125,591 Derivative liabilities Interest rate contracts not designated as hedging instruments $ 6,310 $ (6,119 ) $ — $ 191 Written and purchased options 3,581 — — 3,581 Total derivative liabilities subject to master netting arrangements $ 9,891 $ (6,119 ) $ — $ 3,772 December 31, 2018 Gross Amounts Presented in the Balance Sheet Gross Amounts Not Offset in the Balance Sheet Net (in thousands) Derivatives Collateral Derivatives subject to master netting arrangements Derivative assets Interest rate contracts designated as hedging instruments $ 3,469 $ — $ — $ 3,469 Interest rate contracts not designated as hedging instruments 17,420 (619 ) — 16,801 Written and purchased options 3,285 — — 3,285 Total derivative assets subject to master netting arrangements $ 24,174 $ (619 ) $ — $ 23,555 Derivative liabilities Interest rate contracts not designated as hedging instruments $ 18,003 $ (619 ) $ — $ 17,384 Written and purchased options 3,285 — — 3,285 Total derivative liabilities subject to master netting arrangements $ 21,288 $ (619 ) $ — $ 20,669 During the three and nine months ended September 30, 2019 and 2018 , the Company did not reclassify into earnings any gain or loss as a result of the discontinuance of cash flow hedges because it was probable the original forecasted transaction would not occur by the end of the originally specified term. At September 30, 2019 , the Company did not expect to reclassify a material amount from accumulated other comprehensive income into interest income over the next twelve months for derivatives that will be settled. At September 30, 2019 and 2018 , and for the three and nine months then ended, information pertaining to the effect of the hedging instruments on the consolidated financial statements was as follows: Amount of Gain (Loss) Recognized in OCI, net of taxes Location of Gain (Loss) Reclassified from AOCI into Income Amount of Gain (Loss) Reclassified from AOCI into Income, net of taxes Location of Gain (Loss) Recognized in Income on Derivatives (Amount Excluded from Effectiveness Testing) Amount of Gain (Loss) Recognized in Income on Derivatives (Amount Excluded from Effectiveness Testing) Total Including Component Excluding Component Total Including Component Excluding Component Total Including Component Excluding Component (in thousands) For the Three Months Ended September 30, Derivatives in Cash Flow Hedging Relationships 2019 2019 2019 Interest rate contracts $ (264 ) $ 312 $ (576 ) Interest expense $ (162 ) $ 102 $ (264 ) Interest expense $ — $ — $ — 2018 2018 2018 Interest rate contracts $ 818 $ 818 $ — Interest expense $ (22 ) $ (22 ) $ — Interest expense $ — $ — $ — Amount of Gain (Loss) Recognized in OCI, net of taxes Location of Gain (Loss) Reclassified from AOCI into Income Amount of Gain (Loss) Reclassified from AOCI into Income, net of taxes Location of Gain (Loss) Recognized in Income on Derivatives (Amount Excluded from Effectiveness Testing) Amount of Gain (Loss) Recognized in Income on Derivatives (Amount Excluded from Effectiveness Testing) Total Including Component Excluding Component Total Including Component Excluding Component Total Including Component Excluding Component (in thousands) For the Nine Months Ended September 30, Derivatives in Cash Flow Hedging Relationships 2019 2019 2019 Interest rate contracts $ 1,992 $ 3,196 $ (1,204 ) Interest expense $ (467 ) $ 212 $ (679 ) Interest expense $ — $ — $ — 2018 2018 2018 Interest rate contracts $ 4,762 $ 4,762 $ — Interest expense $ (178 ) $ (178 ) $ — Interest expense $ — $ — $ — Information pertaining to the effect of derivatives not designated as hedging instruments on the consolidated financial statements as of September 30, was as follows: Location of Gain (Loss) Recognized in Income on Derivatives Amount of Gain (Loss) Recognized in Income on Derivatives For the Three Months Ended September 30, For the Nine Months Ended September 30, (in thousands) 2019 2018 2019 2018 Interest rate contracts (1) Commission income $ 4,067 $ 2,586 $ 10,761 $ 5,093 Foreign exchange contracts Other income 8 7 14 17 Forward sales contracts Mortgage income (1,765 ) 948 (8,085 ) 4,563 Written and purchased options Mortgage income (1,848 ) (692 ) 1,675 473 Other contracts Other income (72 ) 1 (99 ) (4 ) Total $ 390 $ 2,850 $ 4,266 $ 10,142 (1) Includes fees associated with customer interest rate contracts.

Leases

Leases	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Leases	LEASES IBERIABANK as Lessee The Company leases certain branch and corporate offices, land and ATM facilities through operating leases with terms ranging from less than one year to 44 years . The Company has no financing leases (formerly capital leases). As discussed in Note 2, Recent Accounting Pronouncements, the Company adopted new guidance for leases on January 1, 2019 which requires leases, whether classified as operating leases or financing leases, to be accounted for as the acquisition of a right-of-use asset (ROU asset) and a related lease liability recorded at the present value of the lease payments less any lease incentives. The ROU asset represents the Company’s right to use an underlying asset for the lease term and is included in other assets on the Company’s consolidated balance sheets. The lease liability represents the Company’s obligation to make lease payments and is included in other liabilities in the Company’s consolidated balance sheets. The cost of the lease is recognized on a straight-line basis over the lease term as lease expense. Prior to January 1, 2019, operating leases were not recorded on the balance sheet. See Note 2, Recent Accounting Pronouncements, for further discussion of the adoption on this new guidance. Subsequent to the adoption of ASC 842 on January 1, 2019, the Company reviews new lease and service contracts to determine if the contracts contain an embedded lease. For leases that do not provide an implicit rate, the Company uses the corresponding FHLB Advance rate based on the lease term at commencement in determining the present value of lease payments. For leases with variable lease payments, the present value is determined using the index at the lease commencement date. Changes in variable rent payments due to subsequent changes in the index or rate do not result in a re-measurement of the ROU asset or lease liability, but are recognized as expense in the period in which they occur. Certain of the Company’s leases contain options to either renew, extend or terminate the lease. During the third quarter of 2019, the exercise of existing renewal options became reasonably certain for several of the Company’s leases with current noncancelable terms ending in 2020. These renewal options have varying term lengths ranging from 1 to 5 years , and the payments associated with the renewal options were included in the measurement of the lease liability and ROU asset as of September 30, 2019. The Company also has lease agreements with lease and non-lease components, which are generally accounted for separately. Non-lease components, which primarily consist of common area maintenance, utilities, and janitorial services, are based on the stand-alone price of the services and expensed as incurred. Operating lease expense for the three and nine months ended September 30, 2019 totaled $6.9 million and $20.5 million , respectively. During the three and nine months ended September 30, 2019 , the Company paid $6.7 million and $21.1 million , respectively, for amounts included in the measurement of lease liabilities and $18.1 million and $31.3 million , respectively, to obtain ROU assets. The following summarizes the ROU asset and lease liabilities as of September 30, 2019 : (in thousands) September 30, 2019 Right-of-use assets $ 112,156 Lease liabilities 131,800 Weighted average remaining lease term 7.95 Weighted average discount rate 3.14 % Maturities of operating lease liabilities as of September 30, 2019 were as follows: (in thousands) 2019 $ 6,732 2020 25,895 2021 23,847 2022 21,414 2023 16,659 2024 and thereafter 55,296 Total operating lease payments $ 149,843 Less: Imputed interest 18,043 Total lease liabilities $ 131,800 As of September 30, 2019 , the Company had not entered into any material leases that had not yet commenced. IBERIABANK as Lessor As a lessor, the Company engages in the leasing of equipment to commercial customers primarily through direct financing and sales-type leases. Direct financing and sales-type leases are similar to other forms of installment lending in that lessors generally do not retain benefits and risks incidental to ownership of the property subject to leases. Such arrangements are essentially financing transactions that permit lessees to acquire and use property. The new guidance on leases discussed above did not have a significant impact on the lessor model of accounting. As lessor, the sum of all minimum lease payments over the lease term and the estimated residual value, less unearned interest income, is recorded as the net investment in the lease on the commencement date and is included in loans and leases, net of unearned income in the consolidated balance sheets. Interest income is accrued as earned over the term of the lease based on the net investment in leases. Fees incurred to originate the lease are deferred on the commencement date and recognized as an adjustment of the yield on the lease. The Company’s portfolio of direct financing and sales-type leases contains terms of 3 to 20 years . Some of these leases contain options to extend the leases for up to 12 months and/or to terminate the lease within one year . These direct financing and sales-type leases typically include a payment structure set at lease inception and do not provide any additional services. Expenses associated with the leased equipment, such as maintenance and insurance, are paid by the lessee directly to third parties. The lease agreement typically contains an option for the purchase of the leased property by the lessee at the end of the lease term at either the property’s residual value or a specified price. In all cases, the Company expects to sell or re-lease the equipment at the end of the lease term. Due to the nature and structure of the Company’s direct financing and sales-type leases, there is no selling profit or loss on these transactions. At a lease’s inception, the Company determines the expected residual value of the leased property at the end of the lease term based on the type of equipment leased, location and usage, as well as the contractual return provisions in the lease agreement. Additionally, the Company utilizes multiple market sources of data to establish equipment values and in many cases engages certified appraisers to provide valuation analyses. In order to manage the risk associated with the residual value of its leased assets, lease agreements typically include various provisions designed to protect the value of the leased property, such as contractual equipment maintenance, use and return provisions, remarketing agreements, and lessee guarantees. In a few cases, the Company also obtains third-party guarantees to further manage residual risk in the portfolio. On an annual basis, leased properties with material residual values are reviewed for impairment. The components of the Company’s net investment in leases were as follows: (in thousands) September 30, 2019 Lease payment receivable $ 363,224 Unguaranteed residual assets 34,991 Total net investment in leases $ 398,215 For the three and nine months ended September 30, 2019 , interest income for direct financing or sales-type leases totaled $3.1 million and $7.4 million . During the three and nine months ended September 30, 2019 , there was no profit or loss recognized at the commencement date for direct financing or sales-type leases. Maturities of the Company's lease receivables as of September 30, 2019 were as follows: (in thousands) 2019 $ 21,480 2020 82,993 2021 68,163 2022 62,809 2023 48,670 2024 and thereafter 90,277 Total future minimum lease payments $ 374,392 Less: Imputed interest 11,168 Lease receivables $ 363,224
Leases	LEASES IBERIABANK as Lessee The Company leases certain branch and corporate offices, land and ATM facilities through operating leases with terms ranging from less than one year to 44 years . The Company has no financing leases (formerly capital leases). As discussed in Note 2, Recent Accounting Pronouncements, the Company adopted new guidance for leases on January 1, 2019 which requires leases, whether classified as operating leases or financing leases, to be accounted for as the acquisition of a right-of-use asset (ROU asset) and a related lease liability recorded at the present value of the lease payments less any lease incentives. The ROU asset represents the Company’s right to use an underlying asset for the lease term and is included in other assets on the Company’s consolidated balance sheets. The lease liability represents the Company’s obligation to make lease payments and is included in other liabilities in the Company’s consolidated balance sheets. The cost of the lease is recognized on a straight-line basis over the lease term as lease expense. Prior to January 1, 2019, operating leases were not recorded on the balance sheet. See Note 2, Recent Accounting Pronouncements, for further discussion of the adoption on this new guidance. Subsequent to the adoption of ASC 842 on January 1, 2019, the Company reviews new lease and service contracts to determine if the contracts contain an embedded lease. For leases that do not provide an implicit rate, the Company uses the corresponding FHLB Advance rate based on the lease term at commencement in determining the present value of lease payments. For leases with variable lease payments, the present value is determined using the index at the lease commencement date. Changes in variable rent payments due to subsequent changes in the index or rate do not result in a re-measurement of the ROU asset or lease liability, but are recognized as expense in the period in which they occur. Certain of the Company’s leases contain options to either renew, extend or terminate the lease. During the third quarter of 2019, the exercise of existing renewal options became reasonably certain for several of the Company’s leases with current noncancelable terms ending in 2020. These renewal options have varying term lengths ranging from 1 to 5 years , and the payments associated with the renewal options were included in the measurement of the lease liability and ROU asset as of September 30, 2019. The Company also has lease agreements with lease and non-lease components, which are generally accounted for separately. Non-lease components, which primarily consist of common area maintenance, utilities, and janitorial services, are based on the stand-alone price of the services and expensed as incurred. Operating lease expense for the three and nine months ended September 30, 2019 totaled $6.9 million and $20.5 million , respectively. During the three and nine months ended September 30, 2019 , the Company paid $6.7 million and $21.1 million , respectively, for amounts included in the measurement of lease liabilities and $18.1 million and $31.3 million , respectively, to obtain ROU assets. The following summarizes the ROU asset and lease liabilities as of September 30, 2019 : (in thousands) September 30, 2019 Right-of-use assets $ 112,156 Lease liabilities 131,800 Weighted average remaining lease term 7.95 Weighted average discount rate 3.14 % Maturities of operating lease liabilities as of September 30, 2019 were as follows: (in thousands) 2019 $ 6,732 2020 25,895 2021 23,847 2022 21,414 2023 16,659 2024 and thereafter 55,296 Total operating lease payments $ 149,843 Less: Imputed interest 18,043 Total lease liabilities $ 131,800 As of September 30, 2019 , the Company had not entered into any material leases that had not yet commenced. IBERIABANK as Lessor As a lessor, the Company engages in the leasing of equipment to commercial customers primarily through direct financing and sales-type leases. Direct financing and sales-type leases are similar to other forms of installment lending in that lessors generally do not retain benefits and risks incidental to ownership of the property subject to leases. Such arrangements are essentially financing transactions that permit lessees to acquire and use property. The new guidance on leases discussed above did not have a significant impact on the lessor model of accounting. As lessor, the sum of all minimum lease payments over the lease term and the estimated residual value, less unearned interest income, is recorded as the net investment in the lease on the commencement date and is included in loans and leases, net of unearned income in the consolidated balance sheets. Interest income is accrued as earned over the term of the lease based on the net investment in leases. Fees incurred to originate the lease are deferred on the commencement date and recognized as an adjustment of the yield on the lease. The Company’s portfolio of direct financing and sales-type leases contains terms of 3 to 20 years . Some of these leases contain options to extend the leases for up to 12 months and/or to terminate the lease within one year . These direct financing and sales-type leases typically include a payment structure set at lease inception and do not provide any additional services. Expenses associated with the leased equipment, such as maintenance and insurance, are paid by the lessee directly to third parties. The lease agreement typically contains an option for the purchase of the leased property by the lessee at the end of the lease term at either the property’s residual value or a specified price. In all cases, the Company expects to sell or re-lease the equipment at the end of the lease term. Due to the nature and structure of the Company’s direct financing and sales-type leases, there is no selling profit or loss on these transactions. At a lease’s inception, the Company determines the expected residual value of the leased property at the end of the lease term based on the type of equipment leased, location and usage, as well as the contractual return provisions in the lease agreement. Additionally, the Company utilizes multiple market sources of data to establish equipment values and in many cases engages certified appraisers to provide valuation analyses. In order to manage the risk associated with the residual value of its leased assets, lease agreements typically include various provisions designed to protect the value of the leased property, such as contractual equipment maintenance, use and return provisions, remarketing agreements, and lessee guarantees. In a few cases, the Company also obtains third-party guarantees to further manage residual risk in the portfolio. On an annual basis, leased properties with material residual values are reviewed for impairment. The components of the Company’s net investment in leases were as follows: (in thousands) September 30, 2019 Lease payment receivable $ 363,224 Unguaranteed residual assets 34,991 Total net investment in leases $ 398,215 For the three and nine months ended September 30, 2019 , interest income for direct financing or sales-type leases totaled $3.1 million and $7.4 million . During the three and nine months ended September 30, 2019 , there was no profit or loss recognized at the commencement date for direct financing or sales-type leases. Maturities of the Company's lease receivables as of September 30, 2019 were as follows: (in thousands) 2019 $ 21,480 2020 82,993 2021 68,163 2022 62,809 2023 48,670 2024 and thereafter 90,277 Total future minimum lease payments $ 374,392 Less: Imputed interest 11,168 Lease receivables $ 363,224
Leases	LEASES IBERIABANK as Lessee The Company leases certain branch and corporate offices, land and ATM facilities through operating leases with terms ranging from less than one year to 44 years . The Company has no financing leases (formerly capital leases). As discussed in Note 2, Recent Accounting Pronouncements, the Company adopted new guidance for leases on January 1, 2019 which requires leases, whether classified as operating leases or financing leases, to be accounted for as the acquisition of a right-of-use asset (ROU asset) and a related lease liability recorded at the present value of the lease payments less any lease incentives. The ROU asset represents the Company’s right to use an underlying asset for the lease term and is included in other assets on the Company’s consolidated balance sheets. The lease liability represents the Company’s obligation to make lease payments and is included in other liabilities in the Company’s consolidated balance sheets. The cost of the lease is recognized on a straight-line basis over the lease term as lease expense. Prior to January 1, 2019, operating leases were not recorded on the balance sheet. See Note 2, Recent Accounting Pronouncements, for further discussion of the adoption on this new guidance. Subsequent to the adoption of ASC 842 on January 1, 2019, the Company reviews new lease and service contracts to determine if the contracts contain an embedded lease. For leases that do not provide an implicit rate, the Company uses the corresponding FHLB Advance rate based on the lease term at commencement in determining the present value of lease payments. For leases with variable lease payments, the present value is determined using the index at the lease commencement date. Changes in variable rent payments due to subsequent changes in the index or rate do not result in a re-measurement of the ROU asset or lease liability, but are recognized as expense in the period in which they occur. Certain of the Company’s leases contain options to either renew, extend or terminate the lease. During the third quarter of 2019, the exercise of existing renewal options became reasonably certain for several of the Company’s leases with current noncancelable terms ending in 2020. These renewal options have varying term lengths ranging from 1 to 5 years , and the payments associated with the renewal options were included in the measurement of the lease liability and ROU asset as of September 30, 2019. The Company also has lease agreements with lease and non-lease components, which are generally accounted for separately. Non-lease components, which primarily consist of common area maintenance, utilities, and janitorial services, are based on the stand-alone price of the services and expensed as incurred. Operating lease expense for the three and nine months ended September 30, 2019 totaled $6.9 million and $20.5 million , respectively. During the three and nine months ended September 30, 2019 , the Company paid $6.7 million and $21.1 million , respectively, for amounts included in the measurement of lease liabilities and $18.1 million and $31.3 million , respectively, to obtain ROU assets. The following summarizes the ROU asset and lease liabilities as of September 30, 2019 : (in thousands) September 30, 2019 Right-of-use assets $ 112,156 Lease liabilities 131,800 Weighted average remaining lease term 7.95 Weighted average discount rate 3.14 % Maturities of operating lease liabilities as of September 30, 2019 were as follows: (in thousands) 2019 $ 6,732 2020 25,895 2021 23,847 2022 21,414 2023 16,659 2024 and thereafter 55,296 Total operating lease payments $ 149,843 Less: Imputed interest 18,043 Total lease liabilities $ 131,800 As of September 30, 2019 , the Company had not entered into any material leases that had not yet commenced. IBERIABANK as Lessor As a lessor, the Company engages in the leasing of equipment to commercial customers primarily through direct financing and sales-type leases. Direct financing and sales-type leases are similar to other forms of installment lending in that lessors generally do not retain benefits and risks incidental to ownership of the property subject to leases. Such arrangements are essentially financing transactions that permit lessees to acquire and use property. The new guidance on leases discussed above did not have a significant impact on the lessor model of accounting. As lessor, the sum of all minimum lease payments over the lease term and the estimated residual value, less unearned interest income, is recorded as the net investment in the lease on the commencement date and is included in loans and leases, net of unearned income in the consolidated balance sheets. Interest income is accrued as earned over the term of the lease based on the net investment in leases. Fees incurred to originate the lease are deferred on the commencement date and recognized as an adjustment of the yield on the lease. The Company’s portfolio of direct financing and sales-type leases contains terms of 3 to 20 years . Some of these leases contain options to extend the leases for up to 12 months and/or to terminate the lease within one year . These direct financing and sales-type leases typically include a payment structure set at lease inception and do not provide any additional services. Expenses associated with the leased equipment, such as maintenance and insurance, are paid by the lessee directly to third parties. The lease agreement typically contains an option for the purchase of the leased property by the lessee at the end of the lease term at either the property’s residual value or a specified price. In all cases, the Company expects to sell or re-lease the equipment at the end of the lease term. Due to the nature and structure of the Company’s direct financing and sales-type leases, there is no selling profit or loss on these transactions. At a lease’s inception, the Company determines the expected residual value of the leased property at the end of the lease term based on the type of equipment leased, location and usage, as well as the contractual return provisions in the lease agreement. Additionally, the Company utilizes multiple market sources of data to establish equipment values and in many cases engages certified appraisers to provide valuation analyses. In order to manage the risk associated with the residual value of its leased assets, lease agreements typically include various provisions designed to protect the value of the leased property, such as contractual equipment maintenance, use and return provisions, remarketing agreements, and lessee guarantees. In a few cases, the Company also obtains third-party guarantees to further manage residual risk in the portfolio. On an annual basis, leased properties with material residual values are reviewed for impairment. The components of the Company’s net investment in leases were as follows: (in thousands) September 30, 2019 Lease payment receivable $ 363,224 Unguaranteed residual assets 34,991 Total net investment in leases $ 398,215 For the three and nine months ended September 30, 2019 , interest income for direct financing or sales-type leases totaled $3.1 million and $7.4 million . During the three and nine months ended September 30, 2019 , there was no profit or loss recognized at the commencement date for direct financing or sales-type leases. Maturities of the Company's lease receivables as of September 30, 2019 were as follows: (in thousands) 2019 $ 21,480 2020 82,993 2021 68,163 2022 62,809 2023 48,670 2024 and thereafter 90,277 Total future minimum lease payments $ 374,392 Less: Imputed interest 11,168 Lease receivables $ 363,224

Shareholders' Equity, Capital R

Shareholders' Equity, Capital Ratios and Other Regulatory Matters	9 Months Ended
	Sep. 30, 2019
Banking and Thrift [Abstract]
Shareholders' Equity, Capital Ratios and Other Regulatory Matters	SHAREHOLDERS' EQUITY, CAPITAL RATIOS AND OTHER REGULATORY MATTERS Preferred Stock On April 4, 2019, the Company issued and sold an aggregate of 4,000,000 depositary shares (the “Series D Depositary Shares”), each representing a 1/400th ownership interest in a share of the Company’s 6.100% Fixed-to-Floating Non-Cumulative Perpetual Preferred Stock, Series D, par value $1.00 per share, (“Series D Preferred Stock”), with a liquidation preference of $10,000 per share of Series D Preferred Stock (equivalent to $25 per depositary share), which represents $100 million in aggregate liquidation preference. Dividends will accrue and be payable on the Series D Preferred Stock, if declared by the Company's Board of Directors, and (i) will be paid semi-annually on May 1 and November 1, in arrears, at an annual rate equal to 6.100% for each period from the issuance date to May 1, 2024 and (ii) will be paid quarterly on February 1, May 1, August 1, and November 1 at an annual rate equal to three-month LIBOR plus 3.859% for each period on or after August 1, 2024. The Company may redeem the Series D Preferred Stock at its option, subject to regulatory approval, as described in the Company’s Registration Statement on Form 8-A, filed with the Securities and Exchange Commission on April 4, 2019. The following table presents a summary of the Company's non-cumulative perpetual preferred stock: September 30, 2019 December 31, 2018 Issuance Date Earliest Redemption Date Annual Dividend Rate Liquidation Amount Carrying Amount Carrying Amount (in thousands) Series B Preferred Stock 8/5/2015 8/1/2025 6.625 % $ 80,000 $ 76,812 $ 76,812 Series C Preferred Stock 5/9/2016 5/1/2026 6.600 % 57,500 55,285 55,285 Series D Preferred Stock 4/4/2019 5/1/2024 6.100 % 100,000 96,388 — $ 237,500 $ 228,485 $ 132,097 Common Stock In 2018, the Company's Board of Directors authorized the repurchase of up to 2,765,000 shares of IBERIABANK Corporation's outstanding common stock. The remaining 117,230 shares available under this plan were repurchased during the third quarter of 2019. Also during the third quarter of 2019, the Company announced a new Board-approved share repurchase program for up to 1,600,000 shares, or approximately 3% of total common shares outstanding at the time of the announcement. Stock repurchases under this program will be made from time to time, on the open market or in privately negotiated transactions. The timing of these repurchases will depend on market conditions and other requirements. The share repurchase program does not obligate the Company to repurchase any dollar amount or number of shares, and expires during the third quarter of 2021. The program may be extended, modified, suspended, or discontinued at any time. During the third quarter of 2019, the Company repurchased 552,230 common shares for approximately $40.0 million at a weighted average cost of $72.46 per share. During the third quarter of 2018, the Company repurchased 363,210 common shares for approximately $30.4 million at a weighted average cost of $83.63 . During the nine months ended September 30, 2019 , the Company repurchased 2,700,000 common shares for approximately $204.7 million at a weighted average cost of $75.83 per share. During the nine months ended September 30, 2018 , the Company repurchased 763,210 common shares for approximately $61.0 million at a weighted average cost of $79.99 per share. At September 30, 2019 , the remaining number of common shares that could be repurchased under the new plan was 1,165,000 shares. Regulatory Capital The Company and IBERIABANK are subject to various regulatory capital requirements administered by federal and state banking agencies. Failure to meet minimum capital requirements can initiate certain mandatory and possibly additional discretionary actions by regulators that, if undertaken, could have a direct material effect on the Company’s consolidated financial statements. Under capital adequacy regulations and the regulatory framework for prompt corrective action, the Company and IBERIABANK, as applicable, must meet specific capital guidelines that involve quantitative measures of their assets, liabilities and certain off-balance sheet items as calculated under regulatory accounting practices. The capital amounts and classification are also subject to qualitative judgments by the regulators about components, risk weightings and other factors. As of September 30, 2019 , the Company and IBERIABANK met all capital adequacy requirements to which they are subject. As of September 30, 2019 , the most recent notification from the FRB categorized IBERIABANK as well-capitalized under the regulatory framework for prompt corrective action (the prompt corrective action requirements are not applicable to the Company). To be categorized as well-capitalized, an institution must maintain minimum total risk-based, Tier 1 risk-based, Common Equity Tier 1, and Tier 1 leverage ratios as set forth in the following table. There are no conditions or events since the notification that management believes have changed that categorization. The Company’s and IBERIABANK’s actual capital amounts and ratios as of September 30, 2019 and December 31, 2018 are presented in the following tables: (in thousands) September 30, 2019 Minimum Well-Capitalized Actual Amount Ratio Amount Ratio Amount Ratio Tier 1 Leverage Consolidated $ 1,208,894 4.00 % N/A N/A $ 2,955,775 9.78 % IBERIABANK 1,206,257 4.00 1,507,821 5.00 2,861,883 9.49 Common Equity Tier 1 (CET1) Consolidated $ 1,179,356 4.50 % N/A N/A $ 2,727,290 10.41 % IBERIABANK 1,175,984 4.50 1,698,643 6.50 2,861,883 10.95 Tier 1 Risk-Based Capital Consolidated $ 1,572,475 6.00 % N/A N/A $ 2,955,775 11.28 % IBERIABANK 1,567,978 6.00 2,090,638 8.00 2,861,883 10.95 Total Risk-Based Capital Consolidated $ 2,096,633 8.00 % N/A N/A $ 3,234,654 12.34 % IBERIABANK 2,090,638 8.00 2,613,297 10.00 3,024,262 11.57 (in thousands) December 31, 2018 Minimum Well-Capitalized Actual Amount Ratio Amount Ratio Amount Ratio Tier 1 Leverage Consolidated $ 1,168,343 4.00 % N/A N/A $ 2,812,863 9.63 % IBERIABANK 1,165,537 4.00 1,456,921 5.00 2,733,099 9.38 Common Equity Tier 1 (CET1) Consolidated $ 1,125,405 4.50 % N/A N/A $ 2,680,766 10.72 % IBERIABANK 1,122,712 4.50 1,621,695 6.50 2,733,099 10.95 Tier 1 Risk-Based Capital Consolidated $ 1,500,540 6.00 % N/A N/A $ 2,812,863 11.25 % IBERIABANK 1,496,949 6.00 1,995,932 8.00 2,733,099 10.95 Total Risk-Based Capital Consolidated $ 2,000,720 8.00 % N/A N/A $ 3,084,764 12.33 % IBERIABANK 1,995,932 8.00 2,494,915 10.00 2,888,500 11.58 Minimum capital ratios are subject to a capital conservation buffer. In order to avoid limitations on distributions, including dividend payments, and certain discretionary bonus payments to executive officers, an institution must hold a capital conservation buffer above its minimum risk-based capital requirements. This capital conservation buffer is calculated as the lowest of the differences between the actual CET1 ratio, Tier 1 Risk-Based Capital Ratio, and Total Risk-Based Capital ratio and the corresponding minimum ratios. At September 30, 2019 , the required minimum capital conservation buffer was 2.50% . At September 30, 2019 , the capital conservation buffers of the Company and IBERIABANK were 4.34% and 3.57% , respectively.

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Earnings Per Share	EARNINGS PER SHARE The computations of basic and diluted earnings per share were as follows: Three Months Ended September 30, Nine Months Ended September 30, (in thousands, except per share data) 2019 2018 2019 2018 Earnings Per Common Share - Basic: Net income $ 99,850 $ 101,465 $ 301,579 $ 240,210 Less: Preferred stock dividends 3,599 3,599 8,146 8,146 Less: Dividends and undistributed earnings allocated to unvested restricted shares 874 908 2,806 2,341 Earnings allocated to common shareholders - basic $ 95,377 $ 96,958 $ 290,627 $ 229,723 Weighted average common shares outstanding 51,984 55,571 53,160 55,047 Earnings per common share - basic $ 1.83 $ 1.74 $ 5.47 $ 4.17 Earnings Per Common Share - Diluted: Earnings allocated to common shareholders - basic $ 95,377 $ 96,958 $ 290,627 $ 229,723 Adjustment for undistributed earnings allocated to unvested restricted shares (17 ) (25 ) (37 ) (49 ) Earnings allocated to common shareholders - diluted $ 95,360 $ 96,933 $ 290,590 $ 229,674 Weighted average common shares outstanding 51,984 55,571 53,160 55,047 Dilutive potential common shares 308 374 333 360 Weighted average common shares outstanding - diluted 52,292 55,945 53,493 55,407 Earnings per common share - diluted $ 1.82 $ 1.73 $ 5.43 $ 4.14 For the three months ended September 30, 2019 and 2018 , the calculations for basic shares outstanding excluded weighted average shares owned by the RRP of 491,977 and 542,796 , respectively. For the nine months ended September 30, 2019 and 2018 , the calculations for basic shares outstanding excluded weighted average shares owned by the RRP of 525,652 and 581,397 , respectively. The effects from the assumed exercises of 152,991 and 60,931 stock options were not included in the computation of diluted earnings per share for the three months ended September 30, 2019 and 2018 , respectively, because they were antidilutive. For the nine months ended September 30, 2019 and 2018 , the effects from the assumed exercises of 152,991 and 147,834

Share-Based Compensation

Share-Based Compensation	9 Months Ended
	Sep. 30, 2019
Share-based Payment Arrangement [Abstract]
Share-Based Compensation	SHARE-BASED COMPENSATION The Company has various types of share-based compensation plans that permit the granting of awards in the form of stock options, restricted stock, restricted share units and phantom stock. These plans are administered by the Compensation Committee of the Board of Directors, which selects persons eligible to receive awards and determines the terms, conditions and other provisions of the awards. At September 30, 2019, awards of 3,450,647 shares could be made under approved incentive compensation plans. The Company issues shares to fulfill stock option exercises and restricted share units and restricted stock awards vesting from available authorized common shares. At September 30, 2019, the Company believes there are adequate authorized shares to satisfy anticipated stock option exercises and restricted share unit and restricted stock award vesting. Stock option awards The Company issues stock options under various plans to directors, officers and other key employees. The option exercise price cannot be less than the fair value of the underlying common stock as of the date of the option grant and the maximum option term cannot exceed ten years . The following table represents the activity related to stock options during the periods indicated: Number of Shares Weighted Average Exercise Price Outstanding options, December 31, 2017 686,366 $ 58.24 Granted 97,620 82.02 Exercised (41,697 ) 53.12 Forfeited or expired (27,328 ) 68.19 Outstanding options, September 30, 2018 714,961 $ 61.41 Exercisable options, September 30, 2018 500,349 $ 56.70 Outstanding options, December 31, 2018 714,420 $ 61.41 Granted 127,090 70.34 Exercised (50,375 ) 52.99 Forfeited or expired (12,227 ) 72.79 Outstanding options, September 30, 2019 778,908 $ 63.23 Exercisable options, September 30, 2019 533,784 $ 58.60 The Company uses the Black-Scholes option pricing model to estimate the fair value of stock option awards. The following weighted-average assumptions were used for option awards issued during the following periods: For the Nine Months Ended September 30, 2019 2018 Expected dividends 2.3 % 1.8 % Expected volatility 24.5 % 24.3 % Risk-free interest rate 2.5 % 2.7 % Expected term (in years) 5.7 5.8 Weighted-average grant-date fair value $ 14.44 $ 18.48 The assumptions above are based on multiple factors, including historical stock option exercise patterns and post-vesting employment termination behaviors, expected future exercise patterns and the expected volatility of the Company’s stock price. The following table represents the compensation expense that is included in non-interest expense and related income tax benefits in the accompanying consolidated statements of comprehensive income related to stock options for the following periods: For the Three Months Ended September 30, For the Nine Months Ended September 30, (in thousands) 2019 2018 2019 2018 Compensation expense related to stock options $ 373 $ 321 $ 1,058 $ 952 Income tax benefit related to stock options 28 23 78 70 At September 30, 2019 , there was $2.4 million of unrecognized compensation expense related to stock options that is expected to be recognized over a weighted-average period of 2.7 years . Restricted stock awards The Company issues restricted stock under various plans for certain officers and directors. The restricted stock awards may not be sold or otherwise transferred until certain restrictions have lapsed. The holders of the restricted stock receive dividends and have the right to vote the shares. The compensation expense for these awards is determined based on the market price of the Company's common stock at the date of grant applied to the total number of shares granted and is recognized over the vesting period (generally three to five years). As of September 30, 2019 and 2018, unrecognized share-based compensation expense associated with these awards totaled $24.3 million and $30.9 million , respectively. The unrecognized compensation expense related to restricted stock awards at September 30, 2019 is expected to be recognized over a weighted-average period of 1.3 years . Restricted share units The Company issues restricted share units to certain of its executive officers. Restricted share units vest after the end of a three year performance period, based on satisfaction of the market and performance conditions set forth in the restricted share unit agreements. Recipients do not possess voting or investment power over the common stock underlying such units until vesting. The grant date fair value of these restricted share units is the same as the value of the corresponding number of shares of common stock, adjusted for assumptions surrounding the market-based conditions contained in the respective agreements. See Note 1, Summary of Significant Accounting Policies, in the 2018 Annual Report on Form 10-K for the year ended December 31, 2018, for further discussion of restricted share units with market or performance conditions. The following table represents the compensation expense that was included in non-interest expense and related income tax benefits in the accompanying consolidated statements of comprehensive income related to restricted stock awards and restricted share units for the periods indicated: For the Three Months Ended September 30, For the Nine Months Ended September 30, (in thousands) 2019 2018 2019 2018 Compensation expense related to restricted stock awards and restricted share units $ 5,088 $ 4,843 $ 16,242 $ 14,192 Income tax benefit related to restricted stock awards and restricted share units 1,068 1,017 3,411 2,980 The following table represents unvested restricted stock award and restricted share unit activity for the following periods: For the Nine Months Ended September 30, 2019 2018 Number of shares at beginning of period 700,628 738,187 Granted 217,078 229,181 Forfeited (18,955 ) (70,981 ) Vested (248,047 ) (192,217 ) Number of shares at end of period 650,704 704,170 Phantom stock awards The Company issues phantom stock awards to certain key officers and employees. The awards are subject to a vesting period of five years and are paid out in cash upon vesting. The amount paid per vesting period is calculated as the number of vested “share equivalents” multiplied by the closing market price of a share of the Company’s common stock on the vesting date. Share equivalents are calculated on the date of grant as the total award’s dollar value divided by the closing market price of a share of the Company’s common stock on the grant date. The following table represents compensation expense recorded for phantom stock based on the number of share equivalents vested at September 30 of the periods indicated and the current market price of the Company’s stock at that time: For the Three Months Ended September 30, For the Nine Months Ended September 30, (in thousands) 2019 2018 2019 2018 Compensation expense related to phantom stock $ 2,257 $ 2,375 $ 7,902 $ 7,388 The following table represents phantom stock award activity during the periods indicated: (in thousands) Number of share equivalents (1) Value of share equivalents (2) Balance, December 31, 2017 393,844 $ 30,523 Granted 151,908 12,358 Forfeited share equivalents (59,550 ) 4,844 Vested share equivalents (130,497 ) 10,871 Balance, September 30, 2018 355,705 $ 28,937 Balance, December 31, 2018 353,407 $ 22,717 Granted 183,879 13,890 Forfeited share equivalents (30,283 ) 2,288 Vested share equivalents (107,592 ) 8,116 Balance, September 30, 2019 399,411 $ 30,171 (1) Number of share equivalents includes all reinvested dividend equivalents for the periods indicated. (2) Except for share equivalents at the beginning of each period, which are based on the value at that time, and vested share payments, which are based on the cash paid at the time of vesting, the value of share equivalents is calculated based on the market price of the Company’s stock at the end of the respective periods. The market price of the Company’s stock was $75.54 and $81.35 on September 30, 2019 , and 2018, respectively.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS Recurring fair value measurements The following table presents information about the Company's assets and liabilities that are measured at fair value on a recurring basis as of September 30, 2019 and December 31, 2018 and their classification within the fair value hierarchy. See Note 1, Summary of Significant Accounting Policies, in the Annual Report on Form 10-K for the year ended December 31, 2018 , for a description of how fair value measurements are determined. September 30, 2019 (in thousands) Level 1 Level 2 Level 3 Total Assets Securities available for sale $ — $ 4,238,082 $ — $ 4,238,082 Mortgage loans held for sale — 255,276 — 255,276 Mortgage loans held for investment, at fair value option — — 4,138 4,138 Derivative instruments — 136,235 — 136,235 Total $ — $ 4,629,593 $ 4,138 $ 4,633,731 Liabilities Derivative instruments $ — $ 10,851 $ — $ 10,851 Total $ — $ 10,851 $ — $ 10,851 December 31, 2018 Level 1 Level 2 Level 3 Total Assets Securities available for sale $ — $ 4,783,579 $ — $ 4,783,579 Mortgage loans held for sale — 107,734 — 107,734 Mortgage loans held for investment, at fair value option — — 3,143 3,143 Derivative instruments — 27,048 — 27,048 Total $ — $ 4,918,361 $ 3,143 $ 4,921,504 Liabilities Derivative instruments $ — $ 22,124 $ — $ 22,124 Total $ — $ 22,124 $ — $ 22,124 During the nine months ended September 30, 2019 , there were no transfers between the Level 1 and Level 2 fair value categories. Non-recurring fair value measurements The Company holds certain assets that are measured at fair value only in certain circumstances, such as impairment. The following table presents information about the Company's assets that are measured at fair value and still held as of September 30, 2019 and December 31, 2018 for which a non-recurring fair value adjustment was recorded during the periods then ended. See Note 1, Summary of Significant Accounting Policies, in the Annual Report on Form 10-K for the year ended December 31, 2018 , for a description of how fair value measurements are determined. September 30, 2019 (in thousands) Level 1 Level 2 Level 3 Total Assets Impaired loans $ — $ — $ 79,442 $ 79,442 OREO, net — — 4,008 4,008 Total $ — $ — $ 83,450 $ 83,450 December 31, 2018 (in thousands) Level 1 Level 2 Level 3 Total Assets Impaired loans $ — $ — $ 65,914 $ 65,914 OREO, net — — 6,433 6,433 Total $ — $ — $ 72,347 $ 72,347 The tables above exclude the initial measurement of assets and liabilities that were acquired as part of business combinations. These assets and liabilities were recorded at their fair value upon acquisition in accordance with GAAP and were not re-measured during the periods presented unless specifically required by GAAP. Acquisition date fair values represent either Level 2 fair value measurements (investment securities, deposits, and premises and equipment) or Level 3 fair value measurements (loans, core deposit intangible assets, and debt). Refer to Note 3, Acquisition Activity, in the Annual Report on Form 10-K for the year ended December 31, 2018 , for further detail. The Company did not record any liabilities at fair value for which measurement of the fair value was made on a non-recurring basis as of September 30, 2019 and December 31, 2018 . Fair value option The Company has elected the fair value option for originated residential mortgage loans held for sale, which allows for a more effective offset of the changes in fair values of the loans and the derivative instruments used to hedge them without the burden of complying with the requirements for hedge accounting. The Company also has a portion of mortgage loans held for investment for which the fair value option was elected upon origination and which continue to be accounted for at fair value at September 30, 2019 and December 31, 2018 , respectively. The following table summarizes the difference between the aggregate fair value and the aggregate unpaid principal balance for mortgage loans held for sale and mortgage loans held for investment measured at fair value: September 30, 2019 December 31, 2018 (in thousands) Aggregate Fair Value Aggregate Unpaid Principal Aggregate Fair Value Less Unpaid Principal Aggregate Fair Value Aggregate Unpaid Principal Aggregate Fair Value Less Unpaid Principal Mortgage loans held for sale, at fair value $ 255,276 $ 248,256 $ 7,020 $ 107,734 $ 104,345 $ 3,389 Mortgage loans held for investment, at fair value 4,138 4,306 (168 ) 3,143 3,595 (452 ) Interest income on mortgage loans held for sale and mortgage loans held for investment at fair value option is recognized based on contractual rates and is reflected in interest income on loans held for sale in the consolidated statements of comprehensive income. The following table details net gains (losses) resulting from the change in fair value of loans that were recorded in mortgage income in the consolidated statements of comprehensive income for the three and nine months ended September 30, 2019 and 2018. The changes in fair value are mostly offset by economic hedging activities, with an insignificant portion of these changes attributable to changes in instrument-specific credit risk. Net Gains (Losses) Resulting From Changes in Fair Value For the Three Months Ended September 30, For the Nine Months Ended September 30, (in thousands) 2019 2018 2019 2018 Fair value option Mortgage loans held for sale, at fair value $ 100 $ (1,041 ) $ 3,631 $ (2,513 ) Mortgage loans held for investment, at fair value (14 ) (296 ) 73 (1,217 )

Fair Value of Financial Instrum

Fair Value of Financial Instruments	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	FAIR VALUE OF FINANCIAL INSTRUMENTS The estimated fair value of a financial instrument is the current amount that would be exchanged between willing parties, other than in a forced liquidation. Fair value is best determined based upon quoted market prices. However, in many instances, there are no quoted market prices for the Company’s various financial instruments. In cases where quoted market prices are not available, fair values are based on estimates using present value or other valuation techniques. Those techniques are significantly affected by the assumptions used, including the discount rate and estimates of future cash flows. Accordingly, the fair value estimates may not be realized in an immediate settlement of the instrument. ASC Topic 825, Financial Instruments , excludes certain financial instruments and all non-financial instruments from its disclosure requirements. Consequently, the aggregate fair value amounts presented may not necessarily represent the underlying fair value of the Company. The carrying amount and estimated fair values of the Company’s financial instruments, as well as the level within the fair value hierarchy, are included in the tables below. See Note 1, Summary of Significant Accounting Policies, and Note 2, Recent Accounting Pronouncements, in the Annual Report on Form 10-K for the year ended December 31, 2018 , for a description of how fair value measurements are determined. September 30, 2019 (in thousands) Carrying Amount Fair Value Level 1 Level 2 Level 3 Measurement Category Fair Value Financial Assets Securities available for sale $ 4,238,082 $ 4,238,082 $ — $ 4,238,082 $ — Mortgage loans held for sale 255,276 255,276 — 255,276 — Mortgage loans held for investment, at fair value option 4,138 4,138 — — 4,138 Derivative instruments 136,235 136,235 — 136,235 — Financial Liabilities Derivative instruments 10,851 10,851 — 10,851 — Amortized Cost Financial Assets Cash and cash equivalents $ 930,933 $ 930,933 $ 930,933 $ — $ — Securities held to maturity 185,007 192,586 — 192,586 — Loans and leases, carried at amortized cost, net of unearned income and allowance for loan and lease losses 23,526,164 23,290,286 — — 23,290,286 Financial Liabilities Deposits 24,977,285 24,985,510 — 24,985,510 — Short-term borrowings 498,049 498,049 223,049 275,000 — Long-term debt 1,394,202 1,391,857 — — 1,391,857 December 31, 2018 (in thousands) Carrying Amount Fair Value Level 1 Level 2 Level 3 Measurement Category Fair Value Financial Assets Securities available for sale $ 4,783,579 $ 4,783,579 $ — $ 4,783,579 $ — Mortgage loans held for sale 107,734 107,734 — 107,734 — Mortgage loans held for investment, at fair value option 3,143 3,143 — — 3,143 Derivative instruments 27,048 27,048 — 27,048 — Financial Liabilities Derivative instruments 22,124 22,124 — 22,124 — Amortized Cost Financial Assets Cash and cash equivalents $ 690,453 $ 690,453 $ 690,453 $ — $ — Securities held to maturity 207,446 204,277 — 204,277 — Loans and leases, carried at amortized cost, net of unearned income and allowance for loan and lease losses 22,376,101 22,088,236 — — 22,088,236 Financial Liabilities Deposits 23,763,431 23,752,139 — 23,752,139 — Short-term borrowings 1,482,882 1,482,882 315,882 1,167,000 — Long-term debt 1,166,151 1,154,062 — — 1,154,062 The fair value estimates presented herein are based upon pertinent information available to management as of September 30, 2019 and December 31, 2018 . Although management is not aware of any factors that would significantly affect the estimated fair value amounts, such amounts have not been comprehensively revalued for purposes of these financial statements since these dates and, therefore, current estimates of fair value may differ significantly from the amounts presented herein.

Business Segments

Business Segments	9 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
Business Segments	BUSINESS SEGMENTS Each of the Company’s reportable operating segments serves the specific needs of the Company’s customers based on the products and services it offers. The reportable segments are based upon those revenue-producing components for which separate financial information is produced internally and primarily reflect the manner in which resources are allocated and performance is assessed. Further, the reportable operating segments are also determined based on the quantitative thresholds prescribed within ASC Topic 280, Segment Reporting , and consideration of the usefulness of the information to the users of the consolidated financial statements. The Company reports the results of its operations through three reportable segments: IBERIABANK, Mortgage, and LTC. The IBERIABANK segment represents the Company’s commercial and retail banking functions, including its lending, investment, and deposit activities. IBERIABANK also includes the Company’s wealth management, capital markets, and other corporate functions. The Mortgage segment represents the Company’s origination, funding, and subsequent sale of one-to-four family residential mortgage loans. The LTC segment represents the Company’s title insurance and loan closing services. Certain expenses not directly attributable to a specific reportable segment are allocated to segments based on pre-determined methods that reflect utilization. Also within IBERIABANK are certain reconciling items that translate reportable segment results into consolidated results. The following tables present certain information regarding operations by reportable segment, including a reconciliation of segment results to reported consolidated results for the periods presented. Reconciling items between segment results and reported results include: • Elimination of interest income and interest expense representing interest earned by IBERIABANK on interest-bearing checking accounts held by related companies, as well as the elimination of the related deposit balances at the IBERIABANK segment; • Elimination of investment in subsidiary balances on certain operating segments included in total and average segment assets; and • Elimination of intercompany due to and due from balances on certain operating segments that are included in total and average segment assets. Three Months Ended September 30, 2019 (in thousands) IBERIABANK Mortgage LTC Consolidated Interest and dividend income $ 330,896 $ 2,282 $ — $ 333,178 Interest expense 83,845 — — 83,845 Net interest income 247,051 2,282 — 249,333 Provision for (reversal of) credit losses 8,974 12 — 8,986 Mortgage income — 17,432 — 17,432 Title revenue — — 7,170 7,170 Other non-interest income (expense) 35,881 3,194 (3 ) 39,072 Allocated expenses (income) (4,068 ) 2,991 1,077 — Non-interest expense 152,988 14,676 4,998 172,662 Income before income tax expense 125,038 5,229 1,092 131,359 Income tax expense 29,938 1,282 289 31,509 Net income $ 95,100 $ 3,947 $ 803 $ 99,850 Total loans, leases, and loans held for sale, net of unearned income $ 23,650,057 $ 281,756 $ — $ 23,931,813 Total assets 31,386,350 320,994 27,254 31,734,598 Total deposits 24,946,708 30,577 — 24,977,285 Average assets 31,256,216 271,817 26,258 31,554,291 Three Months Ended September 30, 2018 (in thousands) IBERIABANK Mortgage LTC Consolidated Interest and dividend income $ 315,467 $ 1,599 $ 1 $ 317,067 Interest expense 57,842 — — 57,842 Net interest income 257,625 1,599 1 259,225 Provision for (reversal of) credit losses 11,386 (2 ) — 11,384 Mortgage income — 12,729 — 12,729 Title revenue — — 6,280 6,280 Other non-interest income (expense) 33,594 (16 ) 500 34,078 Allocated expenses (income) (3,691 ) 2,680 1,011 — Non-interest expense 154,000 10,223 4,839 169,062 Income before income tax expense 129,524 1,411 931 131,866 Income tax expense 29,765 386 250 30,401 Net income $ 99,759 $ 1,025 $ 681 $ 101,465 Total loans, leases, and loans held for sale, net of unearned income $ 22,302,679 $ 84,203 $ — $ 22,386,882 Total assets 29,974,065 119,322 25,000 30,118,387 Total deposits 23,179,549 13,897 — 23,193,446 Average assets 29,863,742 158,464 24,025 30,046,231 Nine Months Ended September 30, 2019 (in thousands) IBERIABANK Mortgage LTC Consolidated Interest and dividend income $ 989,595 $ 5,633 $ 1 $ 995,229 Interest expense 240,073 — — 240,073 Net interest income 749,522 5,633 1 755,156 Provision for (reversal of) credit losses 33,539 (35 ) — 33,504 Mortgage income — 47,725 — 47,725 Title revenue — — 19,290 19,290 Other non-interest income (expense) 104,840 3,172 (19 ) 107,993 Allocated expenses (income) (10,515 ) 7,741 2,774 — Non-interest expense 447,882 38,807 14,344 501,033 Income before income tax expense 383,456 10,017 2,154 395,627 Income tax expense 91,047 2,425 576 94,048 Net income $ 292,409 $ 7,592 $ 1,578 $ 301,579 Total loans, leases, and loans held for sale, net of unearned income $ 23,650,057 $ 281,756 $ — $ 23,931,813 Total assets 31,386,350 320,994 27,254 31,734,598 Total deposits 24,946,708 30,577 — 24,977,285 Average assets 30,981,906 215,306 25,299 31,222,511 Nine Months Ended September 30, 2018 (in thousands) IBERIABANK Mortgage LTC Consolidated Interest and dividend income $ 886,629 $ 4,802 $ 2 $ 891,433 Interest expense 143,206 — — 143,206 Net interest income 743,423 4,802 2 748,227 Provision for (reversal of) credit losses 27,316 (26 ) — 27,290 Mortgage income — 36,045 — 36,045 Title revenue — — 18,153 18,153 Other non-interest income (expense) 96,981 (83 ) 497 97,395 Allocated expenses (income) (9,043 ) 6,714 2,329 — Non-interest expense 505,423 34,105 14,382 553,910 Income (loss) before income tax expense 316,708 (29 ) 1,941 318,620 Income tax expense (benefit) 78,516 (7 ) (99 ) 78,410 Net income (loss) $ 238,192 $ (22 ) $ 2,040 $ 240,210 Total loans, leases, and loans held for sale, net of unearned income $ 22,302,679 $ 84,203 $ — $ 22,386,882 Total assets 29,974,065 119,322 25,000 30,118,387 Total deposits 23,179,549 13,897 — 23,193,446 Average assets 29,136,369 164,039 23,037 29,323,445

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES Off-balance sheet commitments In the normal course of business, to meet the financing needs of its customers, the Company is a party to credit-related financial instruments, with risk not reflected in the consolidated financial statements. These financial instruments include commitments to extend credit, standby letters of credit, and commercial letters of credit. Such commitments involve, to varying degrees, elements of credit and interest rate risk in excess of the amount recognized in the consolidated balance sheets. The credit policies used for these commitments are consistent with those used for on-balance sheet instruments. The Company’s exposure to credit loss in the event of non-performance by its customers under such commitments or letters of credit represents the contractual amount of the financial instruments as indicated in the table below. At September 30, 2019 and December 31, 2018 , the fair value of guarantees under commercial and standby letters of credit was $2.2 million and $2.4 million , respectively. This fair value will decrease as the existing commercial and standby letters of credit approach their expiration dates. At September 30, 2019 and December 31, 2018 , respectively, the Company had the following financial instruments outstanding and related reserves, whose contract amounts represent credit risk: (in thousands) September 30, 2019 December 31, 2018 Commitments to extend credit $ 883,615 $ 642,162 Unfunded commitments under lines of credit 7,252,052 6,883,963 Commercial and standby letters of credit 215,664 240,436 Reserve for unfunded lending commitments 16,144 14,830 Commitments to extend credit are agreements to lend to a customer as long as there is no violation of any condition established in the contract. Commitments generally have fixed expiration dates or other termination clauses and may require payment of a fee by the borrower. Since many of the commitments are expected to be drawn upon, the total commitment amounts generally represent future cash requirements. The Company evaluates each customer’s creditworthiness on a case-by-case basis. The amount of collateral, if any, is based on management’s credit evaluation of the customer. Unfunded commitments under commercial lines of credit, revolving credit lines, and overdraft protection agreements are commitments for possible future extensions of credit to existing customers. Many of these types of commitments do not contain a specified maturity date and may not be drawn upon to the total extent to which the Company is committed. See Note 5, Allowance for Credit Losses and Credit Quality, for additional information related to the Company’s reserve for unfunded lending commitments. Commercial and standby letters of credit are conditional commitments issued by the Company to guarantee the performance of a customer to a third party. These guarantees are primarily issued to support public and private borrowing arrangements, including commercial paper issuance, bond financing, and similar transactions. The credit risk involved in issuing letters of credit is essentially the same as that involved in extending loan facilities to customers. When necessary, they are collateralized, generally in the form of marketable securities and cash equivalents. Legal proceedings The nature of the business of the Company’s banking and other subsidiaries ordinarily results in a certain amount of claims, litigation, investigations, and legal and administrative cases and proceedings, which are considered incidental to the normal conduct of business. Some of these claims are against entities or assets of which the Company is a successor or acquired in business acquisitions. The Company has asserted defenses to these claims and, with respect to such legal proceedings, intends to continue to defend itself vigorously, litigating or settling cases according to management’s judgment as to what is in the best interest of the Company and its shareholders. In July of 2016, the Company received a subpoena from the Office of Inspector General of the U.S. Department of Housing and Urban Development (“HUD”) requesting information on certain previously originated loans insured by the Federal Housing Administration ("FHA") as well as other documents regarding the Company's FHA-related policies and practices. After the Company complied with the subpoena, attorneys from the Department of Justice (“DOJ”) informed the Company in late March of 2017 that a civil qui tam suit had been filed against the Company in federal court involving the subject matter of the HUD subpoena. The HUD lawsuit was settled on December 11, 2017 in the amount of $11.7 million . On February 2, 2018, IBERIABANK filed a lawsuit in the United States District Court for the Eastern District of Louisiana (New Orleans) against Illinois Union Insurance Company and Travelers Casualty and Surety Company of America in an effort to recover the $11.7 million it paid to settle the HUD matter. IBERIABANK filed that lawsuit to recover the insurance proceeds to which it claims to be entitled under certain Bankers’ Professional Liability insurance policies issued by defendants Illinois Union and Travelers. More specifically, IBERIABANK alleges that the insurers have failed to honor their obligations under the policies to pay IBERIABANK’s losses in connection with the $11.7 million settlement of disputed allegations relating to IBERIABANK’s professional services in connection with certain mortgage loans insured by the FHA. The judge in the federal lawsuit granted motion for summary judgment thereby dismissing the case. The Company has appealed that decision to the United States Court of Appeals for the Fifth Circuit. The appeal seeks reversal of the summary judgment such that the case can be remanded to the district court in an effort to recover the $11.7 million . The Company assesses its liabilities and contingencies in connection with outstanding legal proceedings utilizing the latest information available. Where it is probable that the Company will incur a loss and the amount of the loss can be reasonably estimated, the Company records a liability in its consolidated financial statements. These legal reserves may be increased or decreased to reflect any relevant developments on a quarterly basis. Where a loss is not probable or the amount of loss is not estimable, the Company does not accrue legal reserves. While the outcome of legal proceedings is inherently uncertain, based on information currently available and available insurance coverage, the Company’s management believes that it has established appropriate legal reserves. Any incremental liabilities arising from pending legal proceedings are not expected to have a material adverse effect on the Company’s consolidated financial position, consolidated results of operations, or consolidated cash flows. However, it is possible that the ultimate resolution of these matters, if unfavorable, may be material to the Company’s consolidated financial position, consolidated results of operations, or consolidated cash flows. As of the date of this filing, the Company believes the amount of losses associated with legal proceedings that is reasonably possible to incur above amounts already accrued and reported as of September 30, 2019 is not material.

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2019
Related Party Transactions [Abstract]
Related Party Transactions	RELATED PARTY TRANSACTIONS In the ordinary course of business, the Company may execute transactions with various related parties. Examples of such transactions may include lending or deposit arrangements, transfers of financial assets, services for administrative support, and other miscellaneous items. The Company has granted loans to executive officers and directors and their affiliates. These loans, including the related principal additions, principal payments, and unfunded commitments are not material to the consolidated financial statements at September 30, 2019 and December 31, 2018 . There were no outstanding loans to such related parties classified as non-accrual, past due, or troubled debt restructurings at September 30, 2019 . Deposits from related parties held by the Company were not material at September 30, 2019 and December 31, 2018 .

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2019
Subsequent Events [Abstract]
Subsequent Events	SUBSEQUENT EVENTS On November 3, 2019, the Company entered into a definitive agreement with First Horizon National Corporation (“First Horizon”) under which the companies will combine in an all-stock merger of equals. As a result of the merger, each share of the Company's common stock will be exchanged for 4.584 shares of First Horizon common stock. Under the terms of the agreement, which was unanimously approved by the Boards of Directors of both companies, the combined organization will operate under the First Horizon name and will be headquartered in Memphis, Tennessee. The merger is expected to close in the second quarter of 2020, subject to satisfaction of customary closing conditions, including receipt of customary regulatory approvals and approval by the shareholders of each company.

Basis of Presentation (Policies

Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Principles of Consolidation	All significant intercompany balances and transactions have been eliminated in consolidation.
Reclassification	Certain amounts reported in prior periods have been reclassified to conform to the current period presentation.
Recent Accounting Pronouncements	RECENT ACCOUNTING PRONOUNCEMENTS Pronouncements adopted during the nine months ended September 30, 2019: ASU No. 2016-02, ASU No. 2018-11, ASU No. 2018-20, and ASU 2019-01 In February 2016, the FASB issued ASU No. 2016-02, Leases (ASC 842) which requires lessees to recognize ROU assets and lease liabilities on the balance sheet for most leases, including operating leases. The lessor accounting model was relatively unchanged by this ASU. Additional quantitative and qualitative disclosures are also required. During 2018 and early 2019, the FASB issued ASU No. 2018-11, Targeted Improvements , ASU No. 2018-20, Narrow-Scope Improvements for Lessors , and ASU No. 2019-01, Codification Improvements , which clarified certain implementation issues, provided an additional optional transition method and clarified the disclosure requirements during the period of adopting ASC 842, among others. The Company adopted ASU No. 2016-02 and the related ASUs discussed above effective January 1, 2019 using the optional transition method. The Company elected the package of practical expedients that does not require the reassessment of whether expired or existing contracts contain leases, the reassessment of the lease classification for any expired or existing leases, or the reassessment of initial direct costs for existing leases. Additionally, the Company did not elect the hindsight practical expedient. The Company conducted a review of all existing lease contracts and service contracts which might contain embedded leases. Some of the Company’s leases contain variable lease payments, the majority of which depend on an index or rate, such as the Consumer Price Index. At transition, the present value of variable payments was based on the index or rate as of January 1, 2019. To determine the present value of lease payments at transition, the Company applied a portfolio approach utilizing an FHLB Advance rate based on the weighted average remaining term of the Company’s existing leases as of January 1, 2019. As a result of adopting ASC 842, the Company established an ROU asset and a lease liability as of January 1, 2019 of $94.2 million and $118.9 million , respectively. Additionally, as part of the adoption of ASC 842, $24.7 million in pre-existing liabilities were reclassified to the ROU asset on January 1, 2019. This resulted in a gross-up of the balance sheet of $94.2 million as a result of recognizing lease liabilities and corresponding right-of-use assets for operating leases. The adoption of ASC 842 also required the recognition of previously deferred gains on sale-leaseback transactions which resulted in an insignificant increase to retained earnings on January 1, 2019. The related impact on the Company’s regulatory capital ratios was not significant. The Company does not expect material changes to the recognition of lease expense in future periods as a result of the adoption of ASC 842. See Note 8, Leases, for additional disclosures required by ASC 842. ASU No. 2018-16 In October 2018, the FASB released ASU No. 2018-16, Derivatives and Hedging (ASC 815): Inclusion of the Secured Overnight Financing Rate (SOFR) Overnight Index Swap (OIS) Rate as a Benchmark Interest Rate for Hedge Accounting Purposes , which permits the use of the OIS rate based on SOFR as a U.S. benchmark interest rate for hedge accounting purposes under ASC 815 in addition to the interest rates on direct Treasury obligations of the UST, the LIBOR swap rate, the OIS Rate based on the Fed Funds Effective Rate, and the SIFMA Municipal Swap Rate. The required effective date of this ASU was dependent upon when an entity adopted the provisions of ASU No. 2017-12. The Company adopted ASU No. 2018-16 effective January 1, 2019 on a prospective basis for qualifying new or redesignated hedging relations as ASU No. 2017-12 had previously been adopted on January 1, 2018. The implementation of this ASU did not have a significant impact on the Company’s consolidated financial statements. ASU No. 2017-08 In March 2017, the FASB issued ASU No. 2017-08, Receivables-Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities, which shortens the amortization period for callable debt securities held at a premium to the earliest call date instead of the maturity date. The amendments do not require an accounting change for securities held at a discount, which will continue to be amortized to the maturity date. The Company adopted ASU No. 2017-08 effective January 1, 2019. The adoption of the ASU did not have a material impact to the Company’s consolidated financial statements. Pronouncements issued but not yet adopted: ASU No. 2016-13, ASU No. 2019-04 (portion related to ASC 326), and ASU No. 2019-05 In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (ASC 326): Measurement of Credit Losses on Financial Instruments . The guidance introduces an impairment model that is based on expected credit losses (ECL), rather than incurred losses, to estimate credit losses on certain types of financial instruments such as loans and held-to-maturity securities, including certain off-balance sheet financial instruments such as loan commitments. The measurement of ECL should consider historical information, current information, and reasonable and supportable forecasts, including estimates of prepayments, over the contractual term. Financial instruments with similar risk characteristics must be grouped together when estimating ECL. The ASU also expands credit quality disclosures. Additionally, ASU No. 2016-13 amends the current AFS security impairment model for debt securities. The new model will require an estimate of ECL when the fair value is below the amortized cost of the asset. The credit-related impairment (and subsequent recoveries) are recognized as an allowance on the balance sheet with a corresponding adjustment to the income statement. Non-credit related losses will continue to be recognized through OCI. In addition, ASU No. 2016-13 provides for a simplified accounting model for purchased financial assets with a more-than-insignificant amount of credit deterioration since their origination. The initial estimate of expected credit losses would be recognized through an ALLL with an offset (i.e., increase) to the cost basis of the related financial asset at acquisition. ASU No. 2016-13 will be effective for fiscal years beginning after December 15, 2019, including interim periods. This ASU will be applied through a modified-retrospective approach, resulting in a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective. A prospective transition approach is required for debt securities for which OTTI had been recognized before the effective date. Amounts previously recognized in AOCI as of the date of adoption that relate to improvements in cash flows expected to be collected should continue to be accreted into income over the remaining life of the asset. Recoveries of amounts previously written off relating to improvements in cash flows after the date of adoption should be recorded in earnings when received. During 2019, the FASB issued ASU No. 2019-04, Codification Improvements to Financial Instruments-Credit Losses (ASC 326), Derivatives and Hedging (ASC 815), and Financial Instruments (ASC 825), which clarified the scope of ASU No. 2016-13 and addressed various issues, including accrued interest receivable balances, recoveries, variable interest rates and prepayments, and ASU No. 2019-05, Financial Instruments-Credit Losses (Topic 326): Targeted Transition Relief , which clarified certain implementation issues. The effective date for the portion of ASU No. 2019-04 related to credit losses and ASU No. 2019-05 are the same as ASU No. 2016-13. The Company’s cross-function implementation team and engaged third-party consultants have jointly developed and continue to execute the project plan and provide implementation oversight. Significant progress has been made in implementation efforts, including model development and validation, fulfillment of additional data needs for new disclosure and reporting requirements, and drafting of accounting policies. In October 2019, user acceptance testing was completed and the Company began concurrent model runs. Implementation efforts will continue through the remainder of 2019, including continued process refinement, documentation enhancement, and finalization of the internal control framework. Based on a preliminary analysis performed in the third quarter of 2019 and forecasts of macroeconomic conditions and exposures as of September 30, 2019, the transition adjustment on January 1, 2020 is estimated to generate an ACL to loans ratio of 1.00% to 1.20% . The Company currently intends to use a blend of multiple economic forecasts to estimate expected credit losses over a one to two year reasonable and supportable forecast period and then revert to longer term historical loss experience to arrive at lifetime expected credit losses. The estimated increase in ACL is primarily due to required increases for residential mortgage and home equity loans to include the requirement to estimate lifetime expected credit losses and the remaining length of time to maturity for these loans as well as an increase in reserves on acquired non-impaired loans which had low reserve levels under the previous accounting guidance. While these ASUs are expected to increase ACL, they do not change the overall credit risk in the Company's loan and lease portfolios or the ultimate losses therein. The transition adjustment to increase ACL will primarily result in a decrease to shareholders' equity, net of income taxes, on January 1, 2020. The ultimate impact of the adoption of these ASUs will depend on the composition of the loan, lease and securities portfolios, finalization of credit loss models, and macroeconomic conditions and forecasts at the adoption date. ASU No. 2018-13 In August 2018, the FASB released ASU No. 2018-13, Fair Value Measurement (ASC 820): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement, which eliminates, adds and modifies certain disclosure requirements for fair value measurements. The ASU will be effective for fiscal years beginning after December 15, 2019, including interim periods, with early adoption permitted. The Company is currently evaluating the impact of the ASU. While adoption of this ASU will result in changes to existing disclosures, it will not have an impact on the Company’s financial position or results of operations. ASU No. 2018-17 In October 2018, the FASB released ASU No. 2018-17, Consolidation (ASC 810): Targeted Improvements to Related Party Guidance for Variable Interest Entities, which improves the consistency of the application of the variable interest entity (VIE) related party guidance for common control arrangements. This ASU requires reporting entities to consider indirect interests held through related parties under common control on a proportional basis rather than as the equivalent of a direct interest in its entirety (as currently required in GAAP) when determining whether a decision-making fee is a variable interest. ASU No. 2018-17 will be effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years, and early adoption is permitted. The guidance will be applied retrospectively with a cumulative-effect adjustment to retained earnings at the beginning of the earliest period presented. The Company is currently evaluating the impact of the ASU on the Company’s consolidated financial statements. ASU No. 2019-04 In April 2019, the FASB released ASU No. 2019-04, Codification Improvements to Financial Instruments-Credit Losses (ASC 326), Derivatives and Hedging (ASC 815), and Financial Instruments (ASC 825). The amendments in the ASU improve the Codification by eliminating inconsistencies and providing clarifications. The amendments related to the credit losses standard are discussed above under ASU 2016-13. With respect to hedge accounting, the ASU addresses partial-term fair value hedges, fair value hedge basis adjustments, and certain transition requirements, among other things. For recognizing and measuring financial instruments, the ASU addresses the scope of the guidance, the requirement for re-measurement under ASC 820 when using the measurement alternative, certain disclosure requirements and which equity securities have to be re-measured at historical exchange rates. Since the Company early adopted the guidance in ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities in 2018, the amended hedge accounting guidance in ASU No. 2019-04 will be effective as of the beginning of the first annual reporting period beginning after April 25, 2019 with early adoption permitted on any date after the issuance of this ASU. The Company is currently evaluating the impact of the ASU on the Company’s consolidated financial statements.

Investment Securities (Tables)

Investment Securities (Tables)	9 Months Ended
	Sep. 30, 2019
Investments, Debt and Equity Securities [Abstract]
Available-for-sale Securities	Information pertaining to securities with gross unrealized losses, aggregated by investment category and length of time that individual securities have been in a continuous loss position, was as follows: September 30, 2019 Less Than Twelve Months Twelve Months or More Total (in thousands) Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Securities available for sale: Mortgage-backed securities: Residential agency $ (1,829 ) $ 447,333 $ (2,101 ) $ 299,396 $ (3,930 ) $ 746,729 Commercial agency (83 ) 8,961 (96 ) 10,994 (179 ) 19,955 Other securities (6 ) 13,368 (99 ) 4,802 (105 ) 18,170 Total securities available for sale $ (1,918 ) $ 469,662 $ (2,296 ) $ 315,192 $ (4,214 ) $ 784,854 Securities held to maturity: Mortgage-backed securities: Residential agency $ (2 ) $ 924 $ (194 ) $ 9,551 $ (196 ) $ 10,475 Total securities held to maturity $ (2 ) $ 924 $ (194 ) $ 9,551 $ (196 ) $ 10,475 December 31, 2018 Less Than Twelve Months Twelve Months or More Total (in thousands) Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Securities available for sale: Obligations of state and political subdivisions $ (9 ) $ 4,112 $ (714 ) $ 30,268 $ (723 ) $ 34,380 Mortgage-backed securities: Residential agency (816 ) 197,057 (56,257 ) 2,193,862 (57,073 ) 2,390,919 Commercial agency (43 ) 18,190 (14,756 ) 483,565 (14,799 ) 501,755 Other securities (94 ) 18,025 (693 ) 32,577 (787 ) 50,602 Total securities available for sale $ (962 ) $ 237,384 $ (72,420 ) $ 2,740,272 $ (73,382 ) $ 2,977,656 Securities held to maturity: Obligations of state and political subdivisions $ (3 ) $ 2,059 $ (2,494 ) $ 151,699 $ (2,497 ) $ 153,758 Mortgage-backed securities: Residential agency — — (1,011 ) 17,478 (1,011 ) 17,478 Total securities held to maturity $ (3 ) $ 2,059 $ (3,505 ) $ 169,177 $ (3,508 ) $ 171,236 The amortized cost and fair values of investment securities, with gross unrealized gains and losses, consisted of the following: September 30, 2019 (in thousands) Amortized Gross Gross Estimated Securities available for sale: U.S. Government-sponsored enterprise obligations $ 39,887 $ 294 $ — $ 40,181 Obligations of state and political subdivisions 166,034 7,333 — 173,367 Mortgage-backed securities: Residential agency 3,135,619 31,354 (3,930 ) 3,163,043 Commercial agency 732,669 24,239 (179 ) 756,729 Other securities 101,324 3,543 (105 ) 104,762 Total securities available for sale $ 4,175,533 $ 66,763 $ (4,214 ) $ 4,238,082 Securities held to maturity: Obligations of state and political subdivisions $ 167,888 $ 7,725 $ — $ 175,613 Mortgage-backed securities: Residential agency 17,119 50 (196 ) 16,973 Total securities held to maturity $ 185,007 $ 7,775 $ (196 ) $ 192,586 December 31, 2018 (in thousands) Amortized Gross Gross Estimated Securities available for sale: U.S. Government-sponsored enterprise obligations $ 995 $ 3 $ — $ 998 Obligations of state and political subdivisions 177,566 2,045 (723 ) 178,888 Mortgage-backed securities: Residential agency 3,837,584 8,886 (57,073 ) 3,789,397 Commercial agency 730,148 2,363 (14,799 ) 717,712 Other securities 97,020 351 (787 ) 96,584 Total securities available for sale $ 4,843,313 $ 13,648 $ (73,382 ) $ 4,783,579 Securities held to maturity: Obligations of state and political subdivisions $ 188,684 $ 309 $ (2,497 ) $ 186,496 Mortgage-backed securities: Residential agency 18,762 30 (1,011 ) 17,781 Total securities held to maturity $ 207,446 $ 339 $ (3,508 ) $ 204,277
Held-to-maturity Securities	The amortized cost and fair values of investment securities, with gross unrealized gains and losses, consisted of the following: September 30, 2019 (in thousands) Amortized Gross Gross Estimated Securities available for sale: U.S. Government-sponsored enterprise obligations $ 39,887 $ 294 $ — $ 40,181 Obligations of state and political subdivisions 166,034 7,333 — 173,367 Mortgage-backed securities: Residential agency 3,135,619 31,354 (3,930 ) 3,163,043 Commercial agency 732,669 24,239 (179 ) 756,729 Other securities 101,324 3,543 (105 ) 104,762 Total securities available for sale $ 4,175,533 $ 66,763 $ (4,214 ) $ 4,238,082 Securities held to maturity: Obligations of state and political subdivisions $ 167,888 $ 7,725 $ — $ 175,613 Mortgage-backed securities: Residential agency 17,119 50 (196 ) 16,973 Total securities held to maturity $ 185,007 $ 7,775 $ (196 ) $ 192,586 December 31, 2018 (in thousands) Amortized Gross Gross Estimated Securities available for sale: U.S. Government-sponsored enterprise obligations $ 995 $ 3 $ — $ 998 Obligations of state and political subdivisions 177,566 2,045 (723 ) 178,888 Mortgage-backed securities: Residential agency 3,837,584 8,886 (57,073 ) 3,789,397 Commercial agency 730,148 2,363 (14,799 ) 717,712 Other securities 97,020 351 (787 ) 96,584 Total securities available for sale $ 4,843,313 $ 13,648 $ (73,382 ) $ 4,783,579 Securities held to maturity: Obligations of state and political subdivisions $ 188,684 $ 309 $ (2,497 ) $ 186,496 Mortgage-backed securities: Residential agency 18,762 30 (1,011 ) 17,781 Total securities held to maturity $ 207,446 $ 339 $ (3,508 ) $ 204,277 Information pertaining to securities with gross unrealized losses, aggregated by investment category and length of time that individual securities have been in a continuous loss position, was as follows: September 30, 2019 Less Than Twelve Months Twelve Months or More Total (in thousands) Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Securities available for sale: Mortgage-backed securities: Residential agency $ (1,829 ) $ 447,333 $ (2,101 ) $ 299,396 $ (3,930 ) $ 746,729 Commercial agency (83 ) 8,961 (96 ) 10,994 (179 ) 19,955 Other securities (6 ) 13,368 (99 ) 4,802 (105 ) 18,170 Total securities available for sale $ (1,918 ) $ 469,662 $ (2,296 ) $ 315,192 $ (4,214 ) $ 784,854 Securities held to maturity: Mortgage-backed securities: Residential agency $ (2 ) $ 924 $ (194 ) $ 9,551 $ (196 ) $ 10,475 Total securities held to maturity $ (2 ) $ 924 $ (194 ) $ 9,551 $ (196 ) $ 10,475 December 31, 2018 Less Than Twelve Months Twelve Months or More Total (in thousands) Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Gross Unrealized Losses Estimated Fair Value Securities available for sale: Obligations of state and political subdivisions $ (9 ) $ 4,112 $ (714 ) $ 30,268 $ (723 ) $ 34,380 Mortgage-backed securities: Residential agency (816 ) 197,057 (56,257 ) 2,193,862 (57,073 ) 2,390,919 Commercial agency (43 ) 18,190 (14,756 ) 483,565 (14,799 ) 501,755 Other securities (94 ) 18,025 (693 ) 32,577 (787 ) 50,602 Total securities available for sale $ (962 ) $ 237,384 $ (72,420 ) $ 2,740,272 $ (73,382 ) $ 2,977,656 Securities held to maturity: Obligations of state and political subdivisions $ (3 ) $ 2,059 $ (2,494 ) $ 151,699 $ (2,497 ) $ 153,758 Mortgage-backed securities: Residential agency — — (1,011 ) 17,478 (1,011 ) 17,478 Total securities held to maturity $ (3 ) $ 2,059 $ (3,505 ) $ 169,177 $ (3,508 ) $ 171,236
Additional Information on Securities in a Continuous Loss Position	Additional information on securities that were in a continuous loss position for over twelve months at September 30, 2019 and December 31, 2018 is presented in the following table. (in thousands) September 30, 2019 December 31, 2018 Number of securities Mortgage-backed securities: Residential agency 66 302 Commercial agency 6 72 Obligations of state and political subdivisions — 60 Other securities 4 7 76 441 Amortized Cost Basis Mortgage-backed securities: Residential agency $ 311,242 $ 2,268,608 Commercial agency 11,090 498,321 Obligations of state and political subdivisions — 185,175 Other securities 4,901 33,270 $ 327,233 $ 2,985,374 Unrealized Loss Mortgage-backed securities: Residential agency $ 2,295 $ 57,268 Commercial agency 96 14,756 Obligations of state and political subdivisions — 3,208 Other securities 99 693 $ 2,490 $ 75,925
Schedule of Amortized Cost and Estimated Fair Value of Investment Securities by Maturity	The amortized cost and estimated fair value of investment securities by maturity at September 30, 2019 are presented in the following table. Securities are classified according to their contractual maturities without consideration of principal amortization, potential prepayments or call options. Accordingly, actual maturities may differ from contractual maturities. Weighted average yields are calculated on the basis of the yield to maturity based on the amortized cost of each security. Securities Available for Sale Securities Held to Maturity (in thousands) Weighted Amortized Estimated Weighted Amortized Estimated Within one year or less 2.55 % $ 10,720 $ 10,787 2.33 % $ 948 $ 949 One through five years 2.62 123,447 125,721 2.63 4,483 4,518 After five through ten years 2.76 760,325 786,040 2.35 43,085 44,653 Over ten years 2.67 3,281,041 3,315,534 2.58 136,491 142,466 2.68 % $ 4,175,533 $ 4,238,082 2.53 % $ 185,007 $ 192,586
Schedule of Realized Gains and Losses from Sale of Securities Classified as Available for Sale	The following is a summary of realized gains and losses from the sale of securities classified as available for sale. Gains or losses on securities sold are recorded on the trade date, using the specific identification method. Three Months Ended September 30, Nine Months Ended September 30, (in thousands) 2019 2018 2019 2018 Realized gains $ 27 $ — $ 1,324 $ 39 Realized losses — — (2,311 ) (95 ) $ 27 $ — $ (987 ) $ (56 )
Schedule of Securities in Other Assets on Company's Consolidated Balance Sheets	The Company accounts for the following securities at cost less impairment plus or minus any observable price changes, which approximates fair value, with the exception of CRA and Community Development Investment Funds, which are recorded at fair value. Other equity securities, which are presented in other assets on the consolidated balance sheets, were as follows: (in thousands) September 30, 2019 December 31, 2018 Federal Home Loan Bank stock $ 87,156 $ 95,213 Federal Reserve Bank stock 85,630 85,630 CRA and Community Development Investment Funds 1,962 1,884 Other investments 21,023 9,709 $ 195,771 $ 192,436

Loans and Leases (Tables)

Loans and Leases (Tables)	9 Months Ended
	Sep. 30, 2019
Receivables [Abstract]
Schedule of Non-Covered and Covered Loans	Loans and leases by portfolio segment and class consisted of the following for the periods indicated: (in thousands) September 30, 2019 December 31, 2018 Commercial loans and leases: Real estate - construction $ 1,330,014 $ 1,196,366 Real estate - owner-occupied 2,468,061 2,395,822 Real estate - non-owner-occupied 6,011,681 5,796,117 Commercial and industrial (1) 6,490,125 5,737,017 Total commercial loans and leases 16,299,881 15,125,322 Residential mortgage loans 4,649,745 4,359,156 Consumer and other loans: Home equity 2,053,588 2,304,694 Other 673,323 730,643 Total consumer and other loans 2,726,911 3,035,337 Total loans and leases $ 23,676,537 $ 22,519,815 (1) Includes equipment financing leases
Schedule of Aging of Loans	The following tables provide an analysis of the aging of loans and leases as of September 30, 2019 and December 31, 2018 . Past due and non-accrual loan amounts exclude acquired impaired loans, even if contractually past due or if the Company does not expect to receive payment in full, as the Company is currently accreting interest income over the expected life of the loans. For additional information on the determination of past due status and the Company's policies for recording payments received, placing loans and leases on non-accrual status, and the resumption of interest accrual on non-accruing loans and leases, see Note 1, Summary of Significant Accounting Policies, in the 2018 10-K. September 30, 2019 Accruing (in thousands) Current or Less Than 30 days Past Due 30-59 days 60-89 days > 90 days Total Past Due Non-accrual (1) Acquired Impaired Total Real estate- construction $ 1,307,793 $ 3,851 $ — $ — $ 3,851 $ 1,381 $ 16,989 $ 1,330,014 Real estate- owner-occupied 2,389,631 2,294 1,031 — 3,325 17,158 57,947 2,468,061 Real estate- non-owner-occupied 5,930,480 2,093 2,672 426 5,191 20,201 55,809 6,011,681 Commercial and industrial 6,417,203 3,614 1,769 2,696 8,079 43,494 21,349 6,490,125 Residential mortgage 4,502,109 1,252 13,463 1,668 16,383 50,439 80,814 4,649,745 Consumer - home equity 1,967,342 10,448 6,792 — 17,240 18,311 50,695 2,053,588 Consumer - other 663,561 2,839 2,500 — 5,339 2,129 2,294 673,323 Total $ 23,178,119 $ 26,391 $ 28,227 $ 4,790 $ 59,408 $ 153,113 $ 285,897 $ 23,676,537 (1) Of the total non-accrual loans at September 30, 2019 , $10.7 million were past due 30-59 days, $4.5 million were past due 60-89 days, and $73.4 million were past due more than 90 days. December 31, 2018 Accruing (in thousands) Current or Less Than 30 days Past Due 30-59 days 60-89 days > 90 days Total Past Due Non-accrual (1) Acquired Impaired Total Real estate- construction $ 1,167,795 $ 1,054 $ — $ — $ 1,054 $ 1,094 $ 26,423 $ 1,196,366 Real estate- owner-occupied 2,305,743 7,167 — — 7,167 10,260 72,652 2,395,822 Real estate- non-owner-occupied 5,703,131 7,473 360 — 7,833 15,898 69,255 5,796,117 Commercial and industrial 5,645,304 5,139 1,320 553 7,012 57,860 26,841 5,737,017 Residential mortgage 4,218,146 2,768 13,063 1,575 17,406 30,396 93,208 4,359,156 Consumer - home equity 2,200,517 10,283 2,409 — 12,692 18,830 72,655 2,304,694 Consumer - other 719,122 4,695 1,601 — 6,296 2,846 2,379 730,643 Total $ 21,959,758 $ 38,579 $ 18,753 $ 2,128 $ 59,460 $ 137,184 $ 363,413 $ 22,519,815 (1) Of the total non-accrual loans at December 31, 2018 , $7.0 million were past due 30-59 days, $3.7 million were past due 60-89 days, and $66.9 million were past due more than 90 days.
Summary of Changes in Accretable Yields of Acquired Loans	The following is a summary of changes in the accretable difference for all loans accounted for under ASC 310-30 during the nine months ended September 30 : (in thousands) 2019 2018 Balance at beginning of period $ 133,342 $ 152,623 Additions — 2,371 Transfers from non-accretable difference to accretable yield (1,740 ) (4 ) Accretion (29,506 ) (37,115 ) Changes in expected cash flows not affecting non-accretable differences (1) (2,927 ) 21,092 Balance at end of period $ 99,169 $ 138,967 (1) Includes changes in cash flows expected to be collected due to the impact of changes in actual or expected timing of liquidation events, modifications, changes in interest rates and changes in prepayment assumptions.
Schedule of Modified TDRs	The following table provides information on how the TDRs were modified during the periods indicated: Three Months Ended September 30, Nine Months Ended September 30, (in thousands) 2019 2018 2019 2018 Extended maturities $ 2,476 $ 3,658 $ 13,097 $ 10,020 Maturity and interest rate adjustment 288 267 715 368 Movement to or extension of interest-rate only payments 48 — 1,827 48 Interest rate adjustment — — 71 101 Forbearance 22,202 802 25,068 14,386 Other concession(s) (1) 3,724 1,810 20,250 21,031 Total $ 28,738 $ 6,537 $ 61,028 $ 45,954 (1) Other concessions may include covenant waivers, forgiveness of principal or interest associated with a customer bankruptcy, or a combination of any of the above concessions.
Schedule of Subsequently Defaulted TDRs	The following table presents the end of period balance for loans modified in a TDR during the periods indicated: Three Months Ended September 30, 2019 2018 (in thousands, except number of loans) Number of Loans Pre-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment Number of Loans Pre-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment Real estate- construction 1 $ 6,331 $ 7,602 — $ — $ — Real estate- owner-occupied 7 8,936 8,691 1 2,312 2,312 Real estate- non-owner-occupied 6 1,553 1,210 6 1,818 1,790 Commercial and industrial 14 1,954 1,952 9 829 804 Residential mortgage 10 7,210 6,870 3 257 255 Consumer - home equity 19 2,375 2,237 15 1,152 1,124 Consumer - other 17 202 176 11 352 252 Total 74 $ 28,561 $ 28,738 45 $ 6,720 $ 6,537 Nine Months Ended September 30, 2019 2018 (in thousands, except number of loans) Number of Loans Pre-modification Outstanding Recorded Investment Post-modification Outstanding Recorded Investment Number of Loans Pre-modification Outstanding Recorded Investment Post-modification Outstanding Recorded Investment Real estate- construction 1 $ 6,331 $ 7,602 1 $ 1,950 $ 976 Real estate- owner-occupied 11 10,153 9,869 8 15,233 13,373 Real estate- non-owner-occupied 16 7,931 7,233 13 3,228 3,064 Commercial and industrial 48 29,156 19,594 32 32,827 22,769 Residential mortgage 28 8,897 8,524 9 898 837 Consumer - home equity 69 7,629 7,268 47 4,130 4,047 Consumer - other 63 1,065 938 53 1,056 888 Total 236 $ 71,162 $ 61,028 163 $ 59,322 $ 45,954 Information detailing TDRs that defaulted during the three-month and nine-month periods ended September 30, 2019 and 2018 , and were modified in the previous twelve months (i.e., the twelve months prior to the default) is presented in the following tables. The Company has defined a default as any loan with a payment that is currently past due greater than 30 days , or was past due greater than 30 days at any point during the respective periods, or since the date of modification, whichever is shorter. Three Months Ended September 30, 2019 2018 (in thousands, except number of loans) Number of Loans Recorded Investment Number of Loans Recorded Investment Real estate- owner-occupied — $ — 1 $ 929 Real estate- non-owner-occupied 2 2,460 1 7 Commercial and industrial 8 1,429 2 127 Residential mortgage 1 101 — — Consumer - home equity 1 64 4 380 Consumer - other 5 57 6 86 Total 17 $ 4,111 14 $ 1,529 Nine Months Ended September 30, 2019 2018 (in thousands, except number of loans) Number of Loans Recorded Investment Number of Loans Recorded Investment Real estate- owner-occupied 6 $ 1,225 6 $ 10,101 Real estate- non-owner-occupied 16 5,176 6 1,084 Commercial and industrial 25 6,859 12 3,632 Residential mortgage 18 1,394 8 912 Consumer - home equity 21 1,873 17 1,978 Consumer - other 38 557 39 488 Total 124 $ 17,084 88 $ 18,195

Allowance for Credit Losses a_2

Allowance for Credit Losses and Credit Quality (Tables)	9 Months Ended
	Sep. 30, 2019
Receivables [Abstract]
Schedule of Allowance for Loan Losses for Covered and Non-Covered Loan Portfolios	A summary of changes in the allowance for credit losses for the nine months ended September 30 was as follows: (in thousands) 2019 2018 Allowance for loan and lease losses at beginning of period $ 140,571 $ 140,891 Provision for loan and lease losses 32,190 26,678 Transfer of balance to OREO and other (2,696 ) (5,709 ) Charge-offs (29,971 ) (34,740 ) Recoveries 6,141 9,830 Allowance for loan and lease losses at end of period $ 146,235 $ 136,950 Reserve for unfunded commitments at beginning of period $ 14,830 $ 13,208 Balance created in acquisition accounting — 900 Provision for unfunded lending commitments 1,314 613 Reserve for unfunded commitments at end of period $ 16,144 $ 14,721 Allowance for credit losses at end of period $ 162,379 $ 151,671 A summary of changes in the allowance for credit losses, by loan portfolio type, for the nine months ended September 30 was as follows: 2019 (in thousands) Commercial Real Estate Commercial and Industrial Residential Mortgage Consumer and Other Total Allowance for loan and lease losses at beginning of period $ 51,806 $ 54,096 $ 12,998 $ 21,671 $ 140,571 Provision for (Reversal of) loan and lease losses 9,205 15,819 (152 ) 7,318 32,190 Transfer of balance to OREO and other (309 ) 236 (2,879 ) 256 (2,696 ) Charge-offs (2,179 ) (17,799 ) (219 ) (9,774 ) (29,971 ) Recoveries 474 3,163 169 2,335 6,141 Allowance for loan and lease losses at end of period $ 58,997 $ 55,515 $ 9,917 $ 21,806 $ 146,235 Reserve for unfunded commitments at beginning of period $ 4,869 $ 6,198 $ 866 $ 2,897 $ 14,830 Provision for (Reversal of) unfunded commitments 357 493 (216 ) 680 1,314 Reserve for unfunded commitments at end of period $ 5,226 $ 6,691 $ 650 $ 3,577 $ 16,144 Allowance on loans individually evaluated for impairment $ 2,721 $ 7,974 $ 281 $ 3,039 $ 14,015 Allowance on loans collectively evaluated for impairment 50,809 45,990 5,393 18,630 120,822 Allowance on loans acquired with deteriorated credit quality 5,467 1,551 4,243 137 11,398 Loans and leases, net of unearned income: Balance at end of period $ 9,809,756 $ 6,490,125 $ 4,649,745 $ 2,726,911 $ 23,676,537 Balance at end of period individually evaluated for impairment 73,715 51,350 42,423 37,907 205,395 Balance at end of period collectively evaluated for impairment 9,605,296 6,417,426 4,526,508 2,636,015 23,185,245 Balance at end of period acquired with deteriorated credit quality 130,745 21,349 80,814 52,989 285,897 2018 (in thousands) Commercial Real Estate Commercial and Industrial Residential Mortgage Consumer and Other Total Allowance for loan and lease losses at beginning of period $ 54,201 $ 53,916 $ 9,117 $ 23,657 $ 140,891 Provision for (Reversal of) loan and lease losses (4,020 ) 20,372 2,318 8,008 26,678 Transfer of balance to OREO and other (1,556 ) (814 ) (45 ) (3,294 ) (5,709 ) Charge-offs (1,281 ) (22,447 ) (365 ) (10,647 ) (34,740 ) Recoveries 1,019 5,665 53 3,093 9,830 Allowance for loan and lease losses at end of period $ 48,363 $ 56,692 $ 11,078 $ 20,817 $ 136,950 Reserve for unfunded commitments at beginning of period $ 4,531 $ 5,309 $ 555 $ 2,813 $ 13,208 Balance created in acquisition accounting 129 81 — 690 900 Provision for (Reversal of) unfunded commitments (134 ) 169 246 332 613 Reserve for unfunded commitments at end of period $ 4,526 $ 5,559 $ 801 $ 3,835 $ 14,721 Allowance on loans individually evaluated for impairment $ 2,650 $ 10,471 $ 154 $ 2,973 $ 16,248 Allowance on loans collectively evaluated for impairment 40,519 44,727 5,063 17,661 107,970 Allowance on loans acquired with deteriorated credit quality 5,194 1,494 5,861 183 12,732 Loans and leases, net of unearned income: Balance at end of period $ 9,381,883 $ 5,581,040 $ 4,300,163 $ 3,080,820 $ 22,343,906 Balance at end of period individually evaluated for impairment 73,469 75,625 6,230 33,863 189,187 Balance at end of period collectively evaluated for impairment 9,126,653 5,478,377 4,174,524 2,970,301 21,749,855 Balance at end of period acquired with deteriorated credit quality 181,761 27,038 119,409 76,656 404,864
Investment in Legacy and Acquired Loans by Credit Quality Indicator	The recorded investment in loans and leases by credit quality indicator is presented in the following tables. Asset risk classifications for commercial loans and leases reflect the classification as of September 30, 2019 and December 31, 2018 . Credit quality information in the tables below includes total loans acquired (including acquired impaired loans) at the net loan balance, after the application of premiums and discounts. Loan premiums and discounts represent the adjustment of acquired loans to fair value at the acquisition date, as adjusted for income accretion and changes in cash flow estimates in subsequent periods. September 30, 2019 December 31, 2018 (in thousands) Pass Special Mention Sub- Doubtful Loss Total Pass Special Mention Sub- Doubtful Total Real estate - construction $ 1,300,847 $ 19,631 $ 9,536 $ — $ — $ 1,330,014 $ 1,182,554 $ 1,062 $ 12,740 $ 10 $ 1,196,366 Real estate - owner-occupied 2,409,221 19,786 38,214 840 — 2,468,061 2,328,999 25,526 41,297 — 2,395,822 Real estate - non-owner-occupied 5,926,537 47,494 37,193 447 10 6,011,681 5,687,963 78,009 26,512 3,633 5,796,117 Commercial and industrial 6,340,738 71,431 63,303 14,653 — 6,490,125 5,586,482 52,632 73,853 24,050 5,737,017 Total $ 15,977,343 $ 158,342 $ 148,246 $ 15,940 $ 10 $ 16,299,881 $ 14,785,998 $ 157,229 $ 154,402 $ 27,693 $ 15,125,322 September 30, 2019 December 31, 2018 (in thousands) Current 30+ Days Past Due Total Current 30+ Days Past Due Total Residential mortgage $ 4,567,633 $ 82,112 $ 4,649,745 $ 4,290,152 $ 69,004 $ 4,359,156 Consumer - home equity 2,011,913 41,675 2,053,588 2,258,659 46,035 2,304,694 Consumer - other 665,702 7,621 673,323 721,231 9,412 730,643 Total $ 7,245,248 $ 131,408 $ 7,376,656 $ 7,270,042 $ 124,451 $ 7,394,493
Schedule of Investment in Legacy Impaired Loans	Information on the Company’s investment in impaired loans, which include all TDRs and all other non-accrual loans evaluated or measured individually for impairment for purposes of determining the ALLL, is presented in the following tables as of and for the periods indicated. September 30, 2019 December 31, 2018 Unpaid Principal Balance Recorded Investment Related Allowance Unpaid Principal Balance Recorded Investment Related Allowance (in thousands) With no related allowance recorded: Real estate - construction $ 9,540 $ 8,531 $ — $ 10,261 $ 9,262 $ — Real estate - owner-occupied 33,985 33,590 — 25,037 19,044 — Real estate - non-owner-occupied 23,964 22,652 — 15,265 14,288 — Commercial and industrial 21,813 17,771 — 55,554 43,886 — Residential mortgage 36,182 35,089 — 1,244 1,221 — Consumer - home equity 4,736 4,734 — 4,183 4,176 — With an allowance recorded: Real estate - construction 98 85 (1 ) 228 140 (11 ) Real estate - owner-occupied 5,135 4,921 (2,529 ) 5,032 4,773 (520 ) Real estate - non-owner-occupied 4,149 3,936 (191 ) 6,445 6,398 (105 ) Commercial and industrial 45,409 33,579 (7,974 ) 46,387 27,915 (12,646 ) Residential mortgage 8,010 7,334 (281 ) 5,870 5,358 (145 ) Consumer - home equity 29,773 29,124 (2,577 ) 29,284 28,818 (2,427 ) Consumer - other 4,308 4,049 (462 ) 4,956 4,446 (488 ) Total $ 227,102 $ 205,395 $ (14,015 ) $ 209,746 $ 169,725 $ (16,342 ) Total commercial loans and leases $ 144,093 $ 125,065 $ (10,695 ) $ 164,209 $ 125,706 $ (13,282 ) Total residential mortgage loans 44,192 42,423 (281 ) 7,114 6,579 (145 ) Total consumer and other loans 38,817 37,907 (3,039 ) 38,423 37,440 (2,915 ) Three Months Ended September 30, 2019 Three Months Ended September 30, 2018 Nine Months Ended September 30, 2019 Nine Months Ended September 30, 2018 Average Interest Average Interest Average Recorded Investment Interest Income Recognized Average Recorded Investment Interest Income Recognized (in thousands) With no related allowance recorded: Real estate - construction $ 7,333 $ 82 $ 10,806 $ 164 $ 7,145 $ 242 $ 10,371 $ 460 Real estate - owner-occupied 33,895 355 34,118 209 34,437 1,235 34,505 903 Real estate - non-owner-occupied 22,794 72 22,091 249 22,910 301 22,988 746 Commercial and industrial 20,594 108 43,409 523 20,727 401 40,564 1,543 Residential mortgage 35,896 136 1,254 9 31,315 391 1,271 36 Consumer - home equity 4,736 47 705 2 4,613 137 708 16 With an allowance recorded: Real estate - construction 87 — 148 — 93 — 151 1 Real estate - owner-occupied 4,952 10 4,006 83 5,050 113 4,044 102 Real estate - non-owner-occupied 4,155 46 2,398 20 4,090 137 2,442 76 Commercial and industrial 36,824 173 40,357 150 36,765 582 47,098 720 Residential mortgage 7,414 74 5,014 50 7,502 232 5,066 149 Consumer - home equity 29,200 298 28,577 305 28,982 890 27,905 892 Consumer - other 4,175 59 4,710 65 4,326 184 4,884 208 Total $ 212,055 $ 1,460 $ 197,593 $ 1,829 $ 207,955 $ 4,845 $ 201,997 $ 5,852 Total commercial loans and leases $ 130,634 $ 846 $ 157,333 $ 1,398 $ 131,217 $ 3,011 $ 162,163 $ 4,551 Total residential mortgage loans 43,310 210 6,268 59 38,817 623 6,337 185 Total consumer and other loans 38,111 404 33,992 372 37,921 1,211 33,497 1,116

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Carrying Amount of Goodwill	Changes to the carrying amount of goodwill by reporting unit for the nine months ended September 30, 2019 , and the year ended December 31, 2018 are provided in the following table: (in thousands) IBERIABANK Mortgage LTC Total Balance, December 31, 2017 $ 1,160,559 $ 23,178 $ 5,165 $ 1,188,902 Goodwill acquired and adjustments during the year 43,251 — 3,380 46,631 Balance, December 31, 2018 $ 1,203,810 $ 23,178 $ 8,545 $ 1,235,533 Goodwill acquired and adjustments during the year — — — — Balance, September 30, 2019 $ 1,203,810 $ 23,178 $ 8,545 $ 1,235,533
Schedule of Mortgage Servicing Rights	Mortgage servicing rights had the following carrying values as of the periods indicated: September 30, 2019 December 31, 2018 Gross Carrying Amount Valuation Allowance Accumulated Amortization Net Carrying Amount Gross Carrying Amount Valuation Allowance Accumulated Amortization Net Carrying Amount (in thousands) Mortgage servicing rights $ 19,517 $ (195 ) $ (5,994 ) $ 13,328 $ 13,612 $ — $ (4,806 ) $ 8,806
Schedule of Definite-Lived Intangible Assets	Definite-lived intangible assets had the following carrying values included in other intangible assets on the Company’s consolidated balance sheets as of the periods indicated: September 30, 2019 December 31, 2018 (in thousands) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Core deposit intangible assets $ 136,183 $ (77,256 ) $ 58,927 $ 136,183 $ (63,213 ) $ 72,970 Customer relationship intangible asset 1,385 (1,363 ) 22 1,385 (1,323 ) 62 Non-compete agreement 206 (102 ) 104 206 (72 ) 134 Total $ 137,774 $ (78,721 ) $ 59,053 $ 137,774 $ (64,608 ) $ 73,166

Derivative Instruments and Ot_2

Derivative Instruments and Other Hedging Activities (Tables)	9 Months Ended
	Sep. 30, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Outstanding Derivative Instruments	Information pertaining to outstanding derivative instruments was as follows: Derivative Assets - Fair Value Derivative Liabilities - Fair Value (in thousands) September 30, 2019 December 31, 2018 September 30, 2019 December 31, 2018 Derivatives designated as hedging instruments: Interest rate contracts $ 23,339 $ 3,469 $ — $ — Total derivatives designated as hedging instruments $ 23,339 $ 3,469 $ — $ — Derivatives not designated as hedging instruments: Interest rate contracts: Customer swaps - upstream $ 12 $ 474 $ 6,104 $ 191 Customer swaps - downstream 104,779 16,946 206 17,812 Foreign exchange contracts — 18 — 18 Forward sales contracts 485 630 654 750 Written and purchased options 7,549 5,490 3,695 3,310 Other contracts 71 21 192 43 Total derivatives not designated as hedging instruments $ 112,896 $ 23,579 $ 10,851 $ 22,124 Total $ 136,235 $ 27,048 $ 10,851 $ 22,124 Derivative Assets - Notional Amount Derivative Liabilities - Notional Amount (in thousands) September 30, 2019 December 31, 2018 September 30, 2019 December 31, 2018 Derivatives designated as hedging instruments: Interest rate contracts $ 800,000 $ 408,500 $ 108,500 $ — Total derivatives designated as hedging instruments $ 800,000 $ 408,500 $ 108,500 $ — Derivatives not designated as hedging instruments: Interest rate contracts: Customer swaps - upstream $ 142,425 $ 919,653 $ 2,259,248 $ 701,257 Customer swaps - downstream 2,259,248 701,257 142,425 919,653 Foreign exchange contracts — 1,202 — 1,202 Forward sales contracts 144,368 1,140 211,049 143,179 Written and purchased options 339,569 229,333 128,150 140,645 Other contracts 74,085 50,527 145,443 85,623 Total derivatives not designated as hedging instruments $ 2,959,695 $ 1,903,112 $ 2,886,315 $ 1,991,559 Total $ 3,759,695 $ 2,311,612 $ 2,994,815 $ 1,991,559
Offsetting Assets	The following table reconciles the gross amounts presented in the consolidated balance sheets to the net amounts that would result in the event of offset. September 30, 2019 Gross Amounts Presented in the Balance Sheet Gross Amounts Not Offset in the Balance Sheet Net (in thousands) Derivatives Collateral Derivatives subject to master netting arrangements Derivative assets Interest rate contracts designated as hedging instruments $ 23,338 $ — $ — $ 23,338 Interest rate contracts not designated as hedging instruments 104,791 (6,119 ) — 98,672 Written and purchased options 3,581 — — 3,581 Total derivative assets subject to master netting arrangements $ 131,710 $ (6,119 ) $ — $ 125,591 Derivative liabilities Interest rate contracts not designated as hedging instruments $ 6,310 $ (6,119 ) $ — $ 191 Written and purchased options 3,581 — — 3,581 Total derivative liabilities subject to master netting arrangements $ 9,891 $ (6,119 ) $ — $ 3,772 December 31, 2018 Gross Amounts Presented in the Balance Sheet Gross Amounts Not Offset in the Balance Sheet Net (in thousands) Derivatives Collateral Derivatives subject to master netting arrangements Derivative assets Interest rate contracts designated as hedging instruments $ 3,469 $ — $ — $ 3,469 Interest rate contracts not designated as hedging instruments 17,420 (619 ) — 16,801 Written and purchased options 3,285 — — 3,285 Total derivative assets subject to master netting arrangements $ 24,174 $ (619 ) $ — $ 23,555 Derivative liabilities Interest rate contracts not designated as hedging instruments $ 18,003 $ (619 ) $ — $ 17,384 Written and purchased options 3,285 — — 3,285 Total derivative liabilities subject to master netting arrangements $ 21,288 $ (619 ) $ — $ 20,669
Offsetting Liabilities	The following table reconciles the gross amounts presented in the consolidated balance sheets to the net amounts that would result in the event of offset. September 30, 2019 Gross Amounts Presented in the Balance Sheet Gross Amounts Not Offset in the Balance Sheet Net (in thousands) Derivatives Collateral Derivatives subject to master netting arrangements Derivative assets Interest rate contracts designated as hedging instruments $ 23,338 $ — $ — $ 23,338 Interest rate contracts not designated as hedging instruments 104,791 (6,119 ) — 98,672 Written and purchased options 3,581 — — 3,581 Total derivative assets subject to master netting arrangements $ 131,710 $ (6,119 ) $ — $ 125,591 Derivative liabilities Interest rate contracts not designated as hedging instruments $ 6,310 $ (6,119 ) $ — $ 191 Written and purchased options 3,581 — — 3,581 Total derivative liabilities subject to master netting arrangements $ 9,891 $ (6,119 ) $ — $ 3,772 December 31, 2018 Gross Amounts Presented in the Balance Sheet Gross Amounts Not Offset in the Balance Sheet Net (in thousands) Derivatives Collateral Derivatives subject to master netting arrangements Derivative assets Interest rate contracts designated as hedging instruments $ 3,469 $ — $ — $ 3,469 Interest rate contracts not designated as hedging instruments 17,420 (619 ) — 16,801 Written and purchased options 3,285 — — 3,285 Total derivative assets subject to master netting arrangements $ 24,174 $ (619 ) $ — $ 23,555 Derivative liabilities Interest rate contracts not designated as hedging instruments $ 18,003 $ (619 ) $ — $ 17,384 Written and purchased options 3,285 — — 3,285 Total derivative liabilities subject to master netting arrangements $ 21,288 $ (619 ) $ — $ 20,669
Effect of Derivatives on the Consolidated Financial Statements	At September 30, 2019 and 2018 , and for the three and nine months then ended, information pertaining to the effect of the hedging instruments on the consolidated financial statements was as follows: Amount of Gain (Loss) Recognized in OCI, net of taxes Location of Gain (Loss) Reclassified from AOCI into Income Amount of Gain (Loss) Reclassified from AOCI into Income, net of taxes Location of Gain (Loss) Recognized in Income on Derivatives (Amount Excluded from Effectiveness Testing) Amount of Gain (Loss) Recognized in Income on Derivatives (Amount Excluded from Effectiveness Testing) Total Including Component Excluding Component Total Including Component Excluding Component Total Including Component Excluding Component (in thousands) For the Three Months Ended September 30, Derivatives in Cash Flow Hedging Relationships 2019 2019 2019 Interest rate contracts $ (264 ) $ 312 $ (576 ) Interest expense $ (162 ) $ 102 $ (264 ) Interest expense $ — $ — $ — 2018 2018 2018 Interest rate contracts $ 818 $ 818 $ — Interest expense $ (22 ) $ (22 ) $ — Interest expense $ — $ — $ — Amount of Gain (Loss) Recognized in OCI, net of taxes Location of Gain (Loss) Reclassified from AOCI into Income Amount of Gain (Loss) Reclassified from AOCI into Income, net of taxes Location of Gain (Loss) Recognized in Income on Derivatives (Amount Excluded from Effectiveness Testing) Amount of Gain (Loss) Recognized in Income on Derivatives (Amount Excluded from Effectiveness Testing) Total Including Component Excluding Component Total Including Component Excluding Component Total Including Component Excluding Component (in thousands) For the Nine Months Ended September 30, Derivatives in Cash Flow Hedging Relationships 2019 2019 2019 Interest rate contracts $ 1,992 $ 3,196 $ (1,204 ) Interest expense $ (467 ) $ 212 $ (679 ) Interest expense $ — $ — $ — 2018 2018 2018 Interest rate contracts $ 4,762 $ 4,762 $ — Interest expense $ (178 ) $ (178 ) $ — Interest expense $ — $ — $ — Information pertaining to the effect of derivatives not designated as hedging instruments on the consolidated financial statements as of September 30, was as follows: Location of Gain (Loss) Recognized in Income on Derivatives Amount of Gain (Loss) Recognized in Income on Derivatives For the Three Months Ended September 30, For the Nine Months Ended September 30, (in thousands) 2019 2018 2019 2018 Interest rate contracts (1) Commission income $ 4,067 $ 2,586 $ 10,761 $ 5,093 Foreign exchange contracts Other income 8 7 14 17 Forward sales contracts Mortgage income (1,765 ) 948 (8,085 ) 4,563 Written and purchased options Mortgage income (1,848 ) (692 ) 1,675 473 Other contracts Other income (72 ) 1 (99 ) (4 ) Total $ 390 $ 2,850 $ 4,266 $ 10,142 (1) Includes fees associated with customer interest rate contracts.

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Assets And Liabilities, Leases	The following summarizes the ROU asset and lease liabilities as of September 30, 2019 : (in thousands) September 30, 2019 Right-of-use assets $ 112,156 Lease liabilities 131,800 Weighted average remaining lease term 7.95 Weighted average discount rate 3.14 %
Lessee, Operating Lease, Liability, Maturity	Maturities of operating lease liabilities as of September 30, 2019 were as follows: (in thousands) 2019 $ 6,732 2020 25,895 2021 23,847 2022 21,414 2023 16,659 2024 and thereafter 55,296 Total operating lease payments $ 149,843 Less: Imputed interest 18,043 Total lease liabilities $ 131,800
Lessor, Net Investment in in Leases	The components of the Company’s net investment in leases were as follows: (in thousands) September 30, 2019 Lease payment receivable $ 363,224 Unguaranteed residual assets 34,991 Total net investment in leases $ 398,215
Sales-type and Direct Financing Leases, Lease Receivable, Maturity	Maturities of the Company's lease receivables as of September 30, 2019 were as follows: (in thousands) 2019 $ 21,480 2020 82,993 2021 68,163 2022 62,809 2023 48,670 2024 and thereafter 90,277 Total future minimum lease payments $ 374,392 Less: Imputed interest 11,168 Lease receivables $ 363,224

Shareholders' Equity, Capital_2

Shareholders' Equity, Capital Ratios and Other Regulatory Matters (Tables)	9 Months Ended
	Sep. 30, 2019
Banking and Thrift [Abstract]
Schedule of Preferred Stock	The following table presents a summary of the Company's non-cumulative perpetual preferred stock: September 30, 2019 December 31, 2018 Issuance Date Earliest Redemption Date Annual Dividend Rate Liquidation Amount Carrying Amount Carrying Amount (in thousands) Series B Preferred Stock 8/5/2015 8/1/2025 6.625 % $ 80,000 $ 76,812 $ 76,812 Series C Preferred Stock 5/9/2016 5/1/2026 6.600 % 57,500 55,285 55,285 Series D Preferred Stock 4/4/2019 5/1/2024 6.100 % 100,000 96,388 — $ 237,500 $ 228,485 $ 132,097
Actual Capital Amounts and Ratios	The Company’s and IBERIABANK’s actual capital amounts and ratios as of September 30, 2019 and December 31, 2018 are presented in the following tables: (in thousands) September 30, 2019 Minimum Well-Capitalized Actual Amount Ratio Amount Ratio Amount Ratio Tier 1 Leverage Consolidated $ 1,208,894 4.00 % N/A N/A $ 2,955,775 9.78 % IBERIABANK 1,206,257 4.00 1,507,821 5.00 2,861,883 9.49 Common Equity Tier 1 (CET1) Consolidated $ 1,179,356 4.50 % N/A N/A $ 2,727,290 10.41 % IBERIABANK 1,175,984 4.50 1,698,643 6.50 2,861,883 10.95 Tier 1 Risk-Based Capital Consolidated $ 1,572,475 6.00 % N/A N/A $ 2,955,775 11.28 % IBERIABANK 1,567,978 6.00 2,090,638 8.00 2,861,883 10.95 Total Risk-Based Capital Consolidated $ 2,096,633 8.00 % N/A N/A $ 3,234,654 12.34 % IBERIABANK 2,090,638 8.00 2,613,297 10.00 3,024,262 11.57 (in thousands) December 31, 2018 Minimum Well-Capitalized Actual Amount Ratio Amount Ratio Amount Ratio Tier 1 Leverage Consolidated $ 1,168,343 4.00 % N/A N/A $ 2,812,863 9.63 % IBERIABANK 1,165,537 4.00 1,456,921 5.00 2,733,099 9.38 Common Equity Tier 1 (CET1) Consolidated $ 1,125,405 4.50 % N/A N/A $ 2,680,766 10.72 % IBERIABANK 1,122,712 4.50 1,621,695 6.50 2,733,099 10.95 Tier 1 Risk-Based Capital Consolidated $ 1,500,540 6.00 % N/A N/A $ 2,812,863 11.25 % IBERIABANK 1,496,949 6.00 1,995,932 8.00 2,733,099 10.95 Total Risk-Based Capital Consolidated $ 2,000,720 8.00 % N/A N/A $ 3,084,764 12.33 % IBERIABANK 1,995,932 8.00 2,494,915 10.00 2,888,500 11.58

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Schedule of Calculation of Basic and Diluted Earnings Per Share	The computations of basic and diluted earnings per share were as follows: Three Months Ended September 30, Nine Months Ended September 30, (in thousands, except per share data) 2019 2018 2019 2018 Earnings Per Common Share - Basic: Net income $ 99,850 $ 101,465 $ 301,579 $ 240,210 Less: Preferred stock dividends 3,599 3,599 8,146 8,146 Less: Dividends and undistributed earnings allocated to unvested restricted shares 874 908 2,806 2,341 Earnings allocated to common shareholders - basic $ 95,377 $ 96,958 $ 290,627 $ 229,723 Weighted average common shares outstanding 51,984 55,571 53,160 55,047 Earnings per common share - basic $ 1.83 $ 1.74 $ 5.47 $ 4.17 Earnings Per Common Share - Diluted: Earnings allocated to common shareholders - basic $ 95,377 $ 96,958 $ 290,627 $ 229,723 Adjustment for undistributed earnings allocated to unvested restricted shares (17 ) (25 ) (37 ) (49 ) Earnings allocated to common shareholders - diluted $ 95,360 $ 96,933 $ 290,590 $ 229,674 Weighted average common shares outstanding 51,984 55,571 53,160 55,047 Dilutive potential common shares 308 374 333 360 Weighted average common shares outstanding - diluted 52,292 55,945 53,493 55,407 Earnings per common share - diluted $ 1.82 $ 1.73 $ 5.43 $ 4.14

Share-Based Compensation (Table

Share-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2019
Share-based Payment Arrangement [Abstract]
Schedule of Share-based Compensation Arrangements by Share-based Payment Award	The following table represents the activity related to stock options during the periods indicated: Number of Shares Weighted Average Exercise Price Outstanding options, December 31, 2017 686,366 $ 58.24 Granted 97,620 82.02 Exercised (41,697 ) 53.12 Forfeited or expired (27,328 ) 68.19 Outstanding options, September 30, 2018 714,961 $ 61.41 Exercisable options, September 30, 2018 500,349 $ 56.70 Outstanding options, December 31, 2018 714,420 $ 61.41 Granted 127,090 70.34 Exercised (50,375 ) 52.99 Forfeited or expired (12,227 ) 72.79 Outstanding options, September 30, 2019 778,908 $ 63.23 Exercisable options, September 30, 2019 533,784 $ 58.60 The following table represents unvested restricted stock award and restricted share unit activity for the following periods: For the Nine Months Ended September 30, 2019 2018 Number of shares at beginning of period 700,628 738,187 Granted 217,078 229,181 Forfeited (18,955 ) (70,981 ) Vested (248,047 ) (192,217 ) Number of shares at end of period 650,704 704,170 The following table represents phantom stock award activity during the periods indicated: (in thousands) Number of share equivalents (1) Value of share equivalents (2) Balance, December 31, 2017 393,844 $ 30,523 Granted 151,908 12,358 Forfeited share equivalents (59,550 ) 4,844 Vested share equivalents (130,497 ) 10,871 Balance, September 30, 2018 355,705 $ 28,937 Balance, December 31, 2018 353,407 $ 22,717 Granted 183,879 13,890 Forfeited share equivalents (30,283 ) 2,288 Vested share equivalents (107,592 ) 8,116 Balance, September 30, 2019 399,411 $ 30,171 (1) Number of share equivalents includes all reinvested dividend equivalents for the periods indicated. (2) Except for share equivalents at the beginning of each period, which are based on the value at that time, and vested share payments, which are based on the cash paid at the time of vesting, the value of share equivalents is calculated based on the market price of the Company’s stock at the end of the respective periods. The market price of the Company’s stock was $75.54 and $81.35 on September 30, 2019 , and 2018, respectively.
Schedule of Valuation Assumptions	The following weighted-average assumptions were used for option awards issued during the following periods: For the Nine Months Ended September 30, 2019 2018 Expected dividends 2.3 % 1.8 % Expected volatility 24.5 % 24.3 % Risk-free interest rate 2.5 % 2.7 % Expected term (in years) 5.7 5.8 Weighted-average grant-date fair value $ 14.44 $ 18.48
Schedule of Allocation for Share-based Compensation Expense	The following table represents compensation expense recorded for phantom stock based on the number of share equivalents vested at September 30 of the periods indicated and the current market price of the Company’s stock at that time: For the Three Months Ended September 30, For the Nine Months Ended September 30, (in thousands) 2019 2018 2019 2018 Compensation expense related to phantom stock $ 2,257 $ 2,375 $ 7,902 $ 7,388 The following table represents the compensation expense that is included in non-interest expense and related income tax benefits in the accompanying consolidated statements of comprehensive income related to stock options for the following periods: For the Three Months Ended September 30, For the Nine Months Ended September 30, (in thousands) 2019 2018 2019 2018 Compensation expense related to stock options $ 373 $ 321 $ 1,058 $ 952 Income tax benefit related to stock options 28 23 78 70 The following table represents the compensation expense that was included in non-interest expense and related income tax benefits in the accompanying consolidated statements of comprehensive income related to restricted stock awards and restricted share units for the periods indicated: For the Three Months Ended September 30, For the Nine Months Ended September 30, (in thousands) 2019 2018 2019 2018 Compensation expense related to restricted stock awards and restricted share units $ 5,088 $ 4,843 $ 16,242 $ 14,192 Income tax benefit related to restricted stock awards and restricted share units 1,068 1,017 3,411 2,980

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Financial Asset and Liabilities Measured at Fair Value on Recurring Basis	The following table presents information about the Company's assets and liabilities that are measured at fair value on a recurring basis as of September 30, 2019 and December 31, 2018 and their classification within the fair value hierarchy. See Note 1, Summary of Significant Accounting Policies, in the Annual Report on Form 10-K for the year ended December 31, 2018 , for a description of how fair value measurements are determined. September 30, 2019 (in thousands) Level 1 Level 2 Level 3 Total Assets Securities available for sale $ — $ 4,238,082 $ — $ 4,238,082 Mortgage loans held for sale — 255,276 — 255,276 Mortgage loans held for investment, at fair value option — — 4,138 4,138 Derivative instruments — 136,235 — 136,235 Total $ — $ 4,629,593 $ 4,138 $ 4,633,731 Liabilities Derivative instruments $ — $ 10,851 $ — $ 10,851 Total $ — $ 10,851 $ — $ 10,851 December 31, 2018 Level 1 Level 2 Level 3 Total Assets Securities available for sale $ — $ 4,783,579 $ — $ 4,783,579 Mortgage loans held for sale — 107,734 — 107,734 Mortgage loans held for investment, at fair value option — — 3,143 3,143 Derivative instruments — 27,048 — 27,048 Total $ — $ 4,918,361 $ 3,143 $ 4,921,504 Liabilities Derivative instruments $ — $ 22,124 $ — $ 22,124 Total $ — $ 22,124 $ — $ 22,124
Financial Asset and Liabilities Measured at Fair Value on Nonrecurring Basis	The Company holds certain assets that are measured at fair value only in certain circumstances, such as impairment. The following table presents information about the Company's assets that are measured at fair value and still held as of September 30, 2019 and December 31, 2018 for which a non-recurring fair value adjustment was recorded during the periods then ended. See Note 1, Summary of Significant Accounting Policies, in the Annual Report on Form 10-K for the year ended December 31, 2018 , for a description of how fair value measurements are determined. September 30, 2019 (in thousands) Level 1 Level 2 Level 3 Total Assets Impaired loans $ — $ — $ 79,442 $ 79,442 OREO, net — — 4,008 4,008 Total $ — $ — $ 83,450 $ 83,450 December 31, 2018 (in thousands) Level 1 Level 2 Level 3 Total Assets Impaired loans $ — $ — $ 65,914 $ 65,914 OREO, net — — 6,433 6,433 Total $ — $ — $ 72,347 $ 72,347
Summary of Difference Between the Aggregate Fair Value and the Aggregate Unpaid Principal Balance for Mortgage Loans Held for Sale	The following table summarizes the difference between the aggregate fair value and the aggregate unpaid principal balance for mortgage loans held for sale and mortgage loans held for investment measured at fair value: September 30, 2019 December 31, 2018 (in thousands) Aggregate Fair Value Aggregate Unpaid Principal Aggregate Fair Value Less Unpaid Principal Aggregate Fair Value Aggregate Unpaid Principal Aggregate Fair Value Less Unpaid Principal Mortgage loans held for sale, at fair value $ 255,276 $ 248,256 $ 7,020 $ 107,734 $ 104,345 $ 3,389 Mortgage loans held for investment, at fair value 4,138 4,306 (168 ) 3,143 3,595 (452 )
Fair Value Option, Disclosures	The following table details net gains (losses) resulting from the change in fair value of loans that were recorded in mortgage income in the consolidated statements of comprehensive income for the three and nine months ended September 30, 2019 and 2018. The changes in fair value are mostly offset by economic hedging activities, with an insignificant portion of these changes attributable to changes in instrument-specific credit risk. Net Gains (Losses) Resulting From Changes in Fair Value For the Three Months Ended September 30, For the Nine Months Ended September 30, (in thousands) 2019 2018 2019 2018 Fair value option Mortgage loans held for sale, at fair value $ 100 $ (1,041 ) $ 3,631 $ (2,513 ) Mortgage loans held for investment, at fair value (14 ) (296 ) 73 (1,217 )

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Estimated Fair Values and Carrying Amounts of Financial Instruments	The carrying amount and estimated fair values of the Company’s financial instruments, as well as the level within the fair value hierarchy, are included in the tables below. See Note 1, Summary of Significant Accounting Policies, and Note 2, Recent Accounting Pronouncements, in the Annual Report on Form 10-K for the year ended December 31, 2018 , for a description of how fair value measurements are determined. September 30, 2019 (in thousands) Carrying Amount Fair Value Level 1 Level 2 Level 3 Measurement Category Fair Value Financial Assets Securities available for sale $ 4,238,082 $ 4,238,082 $ — $ 4,238,082 $ — Mortgage loans held for sale 255,276 255,276 — 255,276 — Mortgage loans held for investment, at fair value option 4,138 4,138 — — 4,138 Derivative instruments 136,235 136,235 — 136,235 — Financial Liabilities Derivative instruments 10,851 10,851 — 10,851 — Amortized Cost Financial Assets Cash and cash equivalents $ 930,933 $ 930,933 $ 930,933 $ — $ — Securities held to maturity 185,007 192,586 — 192,586 — Loans and leases, carried at amortized cost, net of unearned income and allowance for loan and lease losses 23,526,164 23,290,286 — — 23,290,286 Financial Liabilities Deposits 24,977,285 24,985,510 — 24,985,510 — Short-term borrowings 498,049 498,049 223,049 275,000 — Long-term debt 1,394,202 1,391,857 — — 1,391,857 December 31, 2018 (in thousands) Carrying Amount Fair Value Level 1 Level 2 Level 3 Measurement Category Fair Value Financial Assets Securities available for sale $ 4,783,579 $ 4,783,579 $ — $ 4,783,579 $ — Mortgage loans held for sale 107,734 107,734 — 107,734 — Mortgage loans held for investment, at fair value option 3,143 3,143 — — 3,143 Derivative instruments 27,048 27,048 — 27,048 — Financial Liabilities Derivative instruments 22,124 22,124 — 22,124 — Amortized Cost Financial Assets Cash and cash equivalents $ 690,453 $ 690,453 $ 690,453 $ — $ — Securities held to maturity 207,446 204,277 — 204,277 — Loans and leases, carried at amortized cost, net of unearned income and allowance for loan and lease losses 22,376,101 22,088,236 — — 22,088,236 Financial Liabilities Deposits 23,763,431 23,752,139 — 23,752,139 — Short-term borrowings 1,482,882 1,482,882 315,882 1,167,000 — Long-term debt 1,166,151 1,154,062 — — 1,154,062

Business Segments (Tables)

Business Segments (Tables)	9 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
Schedule of Segment Reporting Information	The following tables present certain information regarding operations by reportable segment, including a reconciliation of segment results to reported consolidated results for the periods presented. Reconciling items between segment results and reported results include: • Elimination of interest income and interest expense representing interest earned by IBERIABANK on interest-bearing checking accounts held by related companies, as well as the elimination of the related deposit balances at the IBERIABANK segment; • Elimination of investment in subsidiary balances on certain operating segments included in total and average segment assets; and • Elimination of intercompany due to and due from balances on certain operating segments that are included in total and average segment assets. Three Months Ended September 30, 2019 (in thousands) IBERIABANK Mortgage LTC Consolidated Interest and dividend income $ 330,896 $ 2,282 $ — $ 333,178 Interest expense 83,845 — — 83,845 Net interest income 247,051 2,282 — 249,333 Provision for (reversal of) credit losses 8,974 12 — 8,986 Mortgage income — 17,432 — 17,432 Title revenue — — 7,170 7,170 Other non-interest income (expense) 35,881 3,194 (3 ) 39,072 Allocated expenses (income) (4,068 ) 2,991 1,077 — Non-interest expense 152,988 14,676 4,998 172,662 Income before income tax expense 125,038 5,229 1,092 131,359 Income tax expense 29,938 1,282 289 31,509 Net income $ 95,100 $ 3,947 $ 803 $ 99,850 Total loans, leases, and loans held for sale, net of unearned income $ 23,650,057 $ 281,756 $ — $ 23,931,813 Total assets 31,386,350 320,994 27,254 31,734,598 Total deposits 24,946,708 30,577 — 24,977,285 Average assets 31,256,216 271,817 26,258 31,554,291 Three Months Ended September 30, 2018 (in thousands) IBERIABANK Mortgage LTC Consolidated Interest and dividend income $ 315,467 $ 1,599 $ 1 $ 317,067 Interest expense 57,842 — — 57,842 Net interest income 257,625 1,599 1 259,225 Provision for (reversal of) credit losses 11,386 (2 ) — 11,384 Mortgage income — 12,729 — 12,729 Title revenue — — 6,280 6,280 Other non-interest income (expense) 33,594 (16 ) 500 34,078 Allocated expenses (income) (3,691 ) 2,680 1,011 — Non-interest expense 154,000 10,223 4,839 169,062 Income before income tax expense 129,524 1,411 931 131,866 Income tax expense 29,765 386 250 30,401 Net income $ 99,759 $ 1,025 $ 681 $ 101,465 Total loans, leases, and loans held for sale, net of unearned income $ 22,302,679 $ 84,203 $ — $ 22,386,882 Total assets 29,974,065 119,322 25,000 30,118,387 Total deposits 23,179,549 13,897 — 23,193,446 Average assets 29,863,742 158,464 24,025 30,046,231 Nine Months Ended September 30, 2019 (in thousands) IBERIABANK Mortgage LTC Consolidated Interest and dividend income $ 989,595 $ 5,633 $ 1 $ 995,229 Interest expense 240,073 — — 240,073 Net interest income 749,522 5,633 1 755,156 Provision for (reversal of) credit losses 33,539 (35 ) — 33,504 Mortgage income — 47,725 — 47,725 Title revenue — — 19,290 19,290 Other non-interest income (expense) 104,840 3,172 (19 ) 107,993 Allocated expenses (income) (10,515 ) 7,741 2,774 — Non-interest expense 447,882 38,807 14,344 501,033 Income before income tax expense 383,456 10,017 2,154 395,627 Income tax expense 91,047 2,425 576 94,048 Net income $ 292,409 $ 7,592 $ 1,578 $ 301,579 Total loans, leases, and loans held for sale, net of unearned income $ 23,650,057 $ 281,756 $ — $ 23,931,813 Total assets 31,386,350 320,994 27,254 31,734,598 Total deposits 24,946,708 30,577 — 24,977,285 Average assets 30,981,906 215,306 25,299 31,222,511 Nine Months Ended September 30, 2018 (in thousands) IBERIABANK Mortgage LTC Consolidated Interest and dividend income $ 886,629 $ 4,802 $ 2 $ 891,433 Interest expense 143,206 — — 143,206 Net interest income 743,423 4,802 2 748,227 Provision for (reversal of) credit losses 27,316 (26 ) — 27,290 Mortgage income — 36,045 — 36,045 Title revenue — — 18,153 18,153 Other non-interest income (expense) 96,981 (83 ) 497 97,395 Allocated expenses (income) (9,043 ) 6,714 2,329 — Non-interest expense 505,423 34,105 14,382 553,910 Income (loss) before income tax expense 316,708 (29 ) 1,941 318,620 Income tax expense (benefit) 78,516 (7 ) (99 ) 78,410 Net income (loss) $ 238,192 $ (22 ) $ 2,040 $ 240,210 Total loans, leases, and loans held for sale, net of unearned income $ 22,302,679 $ 84,203 $ — $ 22,386,882 Total assets 29,974,065 119,322 25,000 30,118,387 Total deposits 23,179,549 13,897 — 23,193,446 Average assets 29,136,369 164,039 23,037 29,323,445

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Summary of Financial Instruments Outstanding	At September 30, 2019 and December 31, 2018 , respectively, the Company had the following financial instruments outstanding and related reserves, whose contract amounts represent credit risk: (in thousands) September 30, 2019 December 31, 2018 Commitments to extend credit $ 883,615 $ 642,162 Unfunded commitments under lines of credit 7,252,052 6,883,963 Commercial and standby letters of credit 215,664 240,436 Reserve for unfunded lending commitments 16,144 14,830

Recent Accounting Pronounceme_2

Recent Accounting Pronouncements (Details) - USD ($) $ in Thousands	Jan. 01, 2019	Sep. 30, 2019
Accounting Changes and Error Corrections [Abstract]
Right-of-use assets	$ 94,200	$ 112,156
Lease liability	118,900	$ 131,800
Liabilities reclassed to right-of-used assets	$ 24,700
Ratio of ACL to all loans		1.20%

Investment Securities - Schedul

Investment Securities - Schedule of Amortized Cost and Fair Values of Investment Securities, with Gross Unrealized Gains and Losses (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Schedule of Available-for-sale Securities
Amortized Cost	$ 4,175,533	$ 4,843,313
Gross Unrealized Gains	66,763	13,648
Gross Unrealized Losses	(4,214)	(73,382)
Estimated Fair Value	4,238,082	4,783,579
Schedule of Held-to-maturity Securities
Amortized Cost	185,007	207,446
Gross Unrealized Gains	7,775	339
Gross Unrealized Losses	(196)	(3,508)
Estimated Fair Value	192,586	204,277
Fair value of securities held as collateral	2,100,000	2,400,000
U.S. Government-sponsored enterprise obligations
Schedule of Available-for-sale Securities
Amortized Cost	39,887	995
Gross Unrealized Gains	294	3
Gross Unrealized Losses	0	0
Estimated Fair Value	40,181	998
Obligations of state and political subdivisions
Schedule of Available-for-sale Securities
Amortized Cost	166,034	177,566
Gross Unrealized Gains	7,333	2,045
Gross Unrealized Losses	0	(723)
Estimated Fair Value	173,367	178,888
Schedule of Held-to-maturity Securities
Amortized Cost	167,888	188,684
Gross Unrealized Gains	7,725	309
Gross Unrealized Losses	0	(2,497)
Estimated Fair Value	175,613	186,496
Mortgage-backed securities: Residential agency
Schedule of Available-for-sale Securities
Amortized Cost	3,135,619	3,837,584
Gross Unrealized Gains	31,354	8,886
Gross Unrealized Losses	(3,930)	(57,073)
Estimated Fair Value	3,163,043	3,789,397
Schedule of Held-to-maturity Securities
Amortized Cost	17,119	18,762
Gross Unrealized Gains	50	30
Gross Unrealized Losses	(196)	(1,011)
Estimated Fair Value	16,973	17,781
Mortgage-backed securities: Commercial agency
Schedule of Available-for-sale Securities
Amortized Cost	732,669	730,148
Gross Unrealized Gains	24,239	2,363
Gross Unrealized Losses	(179)	(14,799)
Estimated Fair Value	756,729	717,712
Other securities
Schedule of Available-for-sale Securities
Amortized Cost	101,324	97,020
Gross Unrealized Gains	3,543	351
Gross Unrealized Losses	(105)	(787)
Estimated Fair Value	$ 104,762	$ 96,584

Investment Securities - Sched_2

Investment Securities - Schedule of Securities with Gross Unrealized Losses Aggregated by Investment Category (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Gross Unrealized Losses
Less Than Twelve Months	$ (1,918)	$ (962)
Twelve Months or More	(2,296)	(72,420)
Total	(4,214)	(73,382)
Estimated Fair Value
Less Than Twelve Months	469,662	237,384
Twelve Months or More	315,192	2,740,272
Total	784,854	2,977,656
Gross Unrealized Losses
Less than twelve months	(2)	(3)
Over twelve months	(194)	(3,505)
Total	(196)	(3,508)
Estimated Fair Value
Less than twelve months	924	2,059
Over twelve months	9,551	169,177
Total	10,475	171,236
Obligations of state and political subdivisions
Gross Unrealized Losses
Less Than Twelve Months		(9)
Twelve Months or More		(714)
Total		(723)
Estimated Fair Value
Less Than Twelve Months		4,112
Twelve Months or More		30,268
Total		34,380
Gross Unrealized Losses
Less than twelve months		(3)
Over twelve months		(2,494)
Total		(2,497)
Estimated Fair Value
Less than twelve months		2,059
Over twelve months		151,699
Total		153,758
Mortgage-backed securities: Residential agency
Gross Unrealized Losses
Less Than Twelve Months	(1,829)	(816)
Twelve Months or More	(2,101)	(56,257)
Total	(3,930)	(57,073)
Estimated Fair Value
Less Than Twelve Months	447,333	197,057
Twelve Months or More	299,396	2,193,862
Total	746,729	2,390,919
Gross Unrealized Losses
Less than twelve months	(2)	0
Over twelve months	(194)	(1,011)
Total	(196)	(1,011)
Estimated Fair Value
Less than twelve months	924	0
Over twelve months	9,551	17,478
Total	10,475	17,478
Mortgage-backed securities: Commercial agency
Gross Unrealized Losses
Less Than Twelve Months	(83)	(43)
Twelve Months or More	(96)	(14,756)
Total	(179)	(14,799)
Estimated Fair Value
Less Than Twelve Months	8,961	18,190
Twelve Months or More	10,994	483,565
Total	19,955	501,755
Other securities
Gross Unrealized Losses
Less Than Twelve Months	(6)	(94)
Twelve Months or More	(99)	(693)
Total	(105)	(787)
Estimated Fair Value
Less Than Twelve Months	13,368	18,025
Twelve Months or More	4,802	32,577
Total	$ 18,170	$ 50,602

Investment Securities - Additio

Investment Securities - Additional Information on Securities in a Continuous Loss Position (Detail) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2019USD ($)Security	Dec. 31, 2018USD ($)Security
Schedule of Available-for-sale Securities
Number of debt securities with unrealized losses | Security	107	488
Debt securities with unrealized losses (percentage of amortized cost)	0.55%	2.38%
Number of securities | Security	76	441
Amortized cost basis	$ 327,233	$ 2,985,374
Unrealized loss	$ 2,490	$ 75,925
Mortgage-backed securities: Residential agency
Schedule of Available-for-sale Securities
Number of securities | Security	66	302
Amortized cost basis	$ 311,242	$ 2,268,608
Unrealized loss	$ 2,295	$ 57,268
Mortgage-backed securities: Commercial agency
Schedule of Available-for-sale Securities
Number of securities | Security	6	72
Amortized cost basis	$ 11,090	$ 498,321
Unrealized loss	$ 96	$ 14,756
Obligations of state and political subdivisions
Schedule of Available-for-sale Securities
Number of securities | Security	0	60
Amortized cost basis	$ 0	$ 185,175
Unrealized loss	$ 0	$ 3,208
Other securities
Schedule of Available-for-sale Securities
Number of securities | Security	4	7
Amortized cost basis	$ 4,901	$ 33,270
Unrealized loss	$ 99	$ 693

Investment Securities - Sched_3

Investment Securities - Schedule of Amortized Cost and Estimated Fair Value of Investment Securities by Maturity (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Weighted Average Yield
Within one year or less	2.55%
One through five years	2.62%
After five through ten years	2.76%
Over ten years	2.67%
Weighted average yield	2.68%
Amortized Cost
Within one year or less	$ 10,720
One through five years	123,447
After five through ten years	760,325
Over ten years	3,281,041
Amortized Cost	4,175,533	$ 4,843,313
Estimated Fair Value
Within one year or less	10,787
One through five years	125,721
After five through ten years	786,040
Over ten years	3,315,534
Estimated fair value	$ 4,238,082	4,783,579
Weighted Average Yield
Within one year or less	2.33%
One through five years	2.63%
After five through ten years	2.35%
Over ten years	2.58%
Weighted average yield	2.53%
Amortized Cost
Within one year or less	$ 948
One through five years	4,483
After five through ten years	43,085
Over ten years	136,491
Amortized Cost	185,007	207,446
Estimated Fair Value
Within one year or less	949
One through five years	4,518
After five through ten years	44,653
Over ten years	142,466
Estimated fair value	$ 192,586	$ 204,277

Investment Securities - Sched_4

Investment Securities - Schedule of Realized Gains and Losses from Sale of Securities Classified as Available for Sale (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Realized gains	$ 27	$ 0	$ 1,324	$ 39
Realized losses	0	0	(2,311)	(95)
Realized gains (losses)	$ 27	$ 0	$ (987)	$ (56)

Investment Securities - Sched_5

Investment Securities - Schedule of Securities in Other Assets on Company's Consolidated Balance Sheets (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Federal Home Loan Bank (FHLB) stock	$ 87,156	$ 95,213
Federal Reserve Bank Stock	85,630	85,630
CRA and Community Development Investment Funds	1,962	1,884
Other Investments	21,023	9,709
Marketable Securities	$ 195,771	$ 192,436

Loans and Leases - Schedule of

Loans and Leases - Schedule of Non-Covered Loans (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable
Loans and leases, net of unearned income	$ 23,676,537	$ 22,519,815
Commercial loans and leases
Accounts, Notes, Loans and Financing Receivable
Loans and leases, net of unearned income	16,299,881	15,125,322
Commercial loans and leases | Real estate - construction
Accounts, Notes, Loans and Financing Receivable
Loans and leases, net of unearned income	1,330,014	1,196,366
Commercial loans and leases | Real estate - owner-occupied
Accounts, Notes, Loans and Financing Receivable
Loans and leases, net of unearned income	2,468,061	2,395,822
Commercial loans and leases | Real estate - non-owner-occupied
Accounts, Notes, Loans and Financing Receivable
Loans and leases, net of unearned income	6,011,681	5,796,117
Commercial loans and leases | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable
Loans and leases, net of unearned income	6,490,125	5,737,017
Residential mortgage loans
Accounts, Notes, Loans and Financing Receivable
Loans and leases, net of unearned income	4,649,745	4,359,156
Consumer and other loans
Accounts, Notes, Loans and Financing Receivable
Loans and leases, net of unearned income	2,726,911	3,035,337
Consumer and other loans | Home equity
Accounts, Notes, Loans and Financing Receivable
Loans and leases, net of unearned income	2,053,588	2,304,694
Consumer and other loans | Other
Accounts, Notes, Loans and Financing Receivable
Loans and leases, net of unearned income	$ 673,323	$ 730,643

Loans and Leases - Loans (Detai

Loans and Leases - Loans (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable
Net deferred loan origination fees	$ 37,800		$ 37,800		$ 30,200
Net discount	97,800		97,800		136,800
Deposit liabilities reclassified as loans receivable	7,000		7,000		9,200
Loans with carrying value pledged to secure public deposits and other borrowings	8,500,000		8,500,000		7,600,000
Acquired Loans
Accounts, Notes, Loans and Financing Receivable
Net discount	61,800		61,800		81,600
Sabadell United | Non-US
Accounts, Notes, Loans and Financing Receivable
Covered loans acquired	194,600		194,600		$ 202,600
TDRs Occurring during the Period | TDRs
Accounts, Notes, Loans and Financing Receivable
TDRs during period	$ 28,738	$ 6,537	61,028	$ 45,954
TDRs during period on accrual status			25,500	20,200
TDRs during period on non-accrual status			$ 35,500	$ 25,800

Loans and Leases - Schedule o_2

Loans and Leases - Schedule of Aging of Loans (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable
Accruing	$ 59,408	$ 59,460
Non-accrual Loans	153,113	137,184
Acquired Impaired Loans	205,395	169,725
Total Loans	23,676,537	22,519,815
Non-accrual loans 30-59 days past due	10,700	7,000
Non-accrual loans past due 60-89 days	4,500	3,700
Non-accrual loans over 90 days past due	73,400	66,900
Commercial Loans
Accounts, Notes, Loans and Financing Receivable
Acquired Impaired Loans	125,065	125,706
Total Loans	16,299,881	15,125,322
Commercial Loans | Real estate - construction
Accounts, Notes, Loans and Financing Receivable
Accruing	3,851	1,054
Non-accrual Loans	1,381	1,094
Total Loans	1,330,014	1,196,366
Commercial Loans | Real estate - owner-occupied
Accounts, Notes, Loans and Financing Receivable
Accruing	3,325	7,167
Non-accrual Loans	17,158	10,260
Total Loans	2,468,061	2,395,822
Commercial Loans | Real estate - non-owner-occupied
Accounts, Notes, Loans and Financing Receivable
Accruing	5,191	7,833
Non-accrual Loans	20,201	15,898
Total Loans	6,011,681	5,796,117
Commercial Loans | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable
Accruing	8,079	7,012
Non-accrual Loans	43,494	57,860
Total Loans	6,490,125	5,737,017
Residential mortgage loans
Accounts, Notes, Loans and Financing Receivable
Acquired Impaired Loans	42,423	6,579
Residential mortgage loans | Residential mortgage
Accounts, Notes, Loans and Financing Receivable
Current	4,567,633	4,290,152
Accruing	16,383	17,406
Non-accrual Loans	50,439	30,396
Total Loans	4,649,745	4,359,156
Consumer and Other Loans
Accounts, Notes, Loans and Financing Receivable
Acquired Impaired Loans	37,907	37,440
Consumer and Other Loans | Consumer - Home equity
Accounts, Notes, Loans and Financing Receivable
Current	2,011,913	2,258,659
Accruing	17,240	12,692
Non-accrual Loans	18,311	18,830
Total Loans	2,053,588	2,304,694
Consumer and Other Loans | Consumer - Other
Accounts, Notes, Loans and Financing Receivable
Current	665,702	721,231
Accruing	5,339	6,296
Non-accrual Loans	2,129	2,846
Total Loans	673,323	730,643
Current or Less Than 30 days past due
Accounts, Notes, Loans and Financing Receivable
Current	23,178,119	21,959,758
Current or Less Than 30 days past due | Commercial Loans | Real estate - construction
Accounts, Notes, Loans and Financing Receivable
Current	1,307,793	1,167,795
Current or Less Than 30 days past due | Commercial Loans | Real estate - owner-occupied
Accounts, Notes, Loans and Financing Receivable
Current	2,389,631	2,305,743
Current or Less Than 30 days past due | Commercial Loans | Real estate - non-owner-occupied
Accounts, Notes, Loans and Financing Receivable
Current	5,930,480	5,703,131
Current or Less Than 30 days past due | Commercial Loans | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable
Current	6,417,203	5,645,304
Current or Less Than 30 days past due | Residential mortgage loans | Residential mortgage
Accounts, Notes, Loans and Financing Receivable
Current	4,502,109	4,218,146
Current or Less Than 30 days past due | Consumer and Other Loans | Consumer - Home equity
Accounts, Notes, Loans and Financing Receivable
Current	1,967,342	2,200,517
Current or Less Than 30 days past due | Consumer and Other Loans | Consumer - Other
Accounts, Notes, Loans and Financing Receivable
Current	663,561	719,122
30-59 days
Accounts, Notes, Loans and Financing Receivable
Accruing	26,391	38,579
30-59 days | Commercial Loans | Real estate - construction
Accounts, Notes, Loans and Financing Receivable
Accruing	3,851	1,054
30-59 days | Commercial Loans | Real estate - owner-occupied
Accounts, Notes, Loans and Financing Receivable
Accruing	2,294	7,167
30-59 days | Commercial Loans | Real estate - non-owner-occupied
Accounts, Notes, Loans and Financing Receivable
Accruing	2,093	7,473
30-59 days | Commercial Loans | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable
Accruing	3,614	5,139
30-59 days | Residential mortgage loans | Residential mortgage
Accounts, Notes, Loans and Financing Receivable
Accruing	1,252	2,768
30-59 days | Consumer and Other Loans | Consumer - Home equity
Accounts, Notes, Loans and Financing Receivable
Accruing	10,448	10,283
30-59 days | Consumer and Other Loans | Consumer - Other
Accounts, Notes, Loans and Financing Receivable
Accruing	2,839	4,695
60-89 days
Accounts, Notes, Loans and Financing Receivable
Accruing	28,227	18,753
60-89 days | Commercial Loans | Real estate - construction
Accounts, Notes, Loans and Financing Receivable
Accruing	0	0
60-89 days | Commercial Loans | Real estate - owner-occupied
Accounts, Notes, Loans and Financing Receivable
Accruing	1,031	0
60-89 days | Commercial Loans | Real estate - non-owner-occupied
Accounts, Notes, Loans and Financing Receivable
Accruing	2,672	360
60-89 days | Commercial Loans | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable
Accruing	1,769	1,320
60-89 days | Residential mortgage loans | Residential mortgage
Accounts, Notes, Loans and Financing Receivable
Accruing	13,463	13,063
60-89 days | Consumer and Other Loans | Consumer - Home equity
Accounts, Notes, Loans and Financing Receivable
Accruing	6,792	2,409
60-89 days | Consumer and Other Loans | Consumer - Other
Accounts, Notes, Loans and Financing Receivable
Accruing	2,500	1,601
Greater than 90 days
Accounts, Notes, Loans and Financing Receivable
Accruing	4,790	2,128
Greater than 90 days | Commercial Loans | Real estate - construction
Accounts, Notes, Loans and Financing Receivable
Accruing	0	0
Greater than 90 days | Commercial Loans | Real estate - owner-occupied
Accounts, Notes, Loans and Financing Receivable
Accruing	0	0
Greater than 90 days | Commercial Loans | Real estate - non-owner-occupied
Accounts, Notes, Loans and Financing Receivable
Accruing	426	0
Greater than 90 days | Commercial Loans | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable
Accruing	2,696	553
Greater than 90 days | Residential mortgage loans | Residential mortgage
Accounts, Notes, Loans and Financing Receivable
Accruing	1,668	1,575
Greater than 90 days | Consumer and Other Loans | Consumer - Home equity
Accounts, Notes, Loans and Financing Receivable
Accruing	0	0
Greater than 90 days | Consumer and Other Loans | Consumer - Other
Accounts, Notes, Loans and Financing Receivable
Accruing	0	0
Acquired Loans
Accounts, Notes, Loans and Financing Receivable
Acquired Impaired Loans	285,897	363,413
Acquired Loans | Commercial Loans | Real estate - construction
Accounts, Notes, Loans and Financing Receivable
Acquired Impaired Loans	16,989	26,423
Acquired Loans | Commercial Loans | Real estate - owner-occupied
Accounts, Notes, Loans and Financing Receivable
Acquired Impaired Loans	57,947	72,652
Acquired Loans | Commercial Loans | Real estate - non-owner-occupied
Accounts, Notes, Loans and Financing Receivable
Acquired Impaired Loans	55,809	69,255
Acquired Loans | Commercial Loans | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable
Acquired Impaired Loans	21,349	26,841
Acquired Loans | Residential mortgage loans | Residential mortgage
Accounts, Notes, Loans and Financing Receivable
Acquired Impaired Loans	80,814	93,208
Acquired Loans | Consumer and Other Loans | Consumer - Home equity
Accounts, Notes, Loans and Financing Receivable
Acquired Impaired Loans	50,695	72,655
Acquired Loans | Consumer and Other Loans | Consumer - Other
Accounts, Notes, Loans and Financing Receivable
Acquired Impaired Loans	$ 2,294	$ 2,379

Loans and Leases - Schedule o_3

Loans and Leases - Schedule of Carrying Amount of Loans Acquired (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
Accounts, Notes, Loans and Financing Receivable
Expected losses and foregone interest	$ (162,379)		$ (151,671)
Loans acquired with no evidence of deteriorated credit quality	4,138	$ 3,143
Related allowance	$ (14,015)	$ (16,342)

Loans and Leases - Summary of C

Loans and Leases - Summary of Changes in Accretable Yields of Acquired Loans (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Balance at beginning of period	$ 133,342	$ 152,623
Additions	0	2,371
Transfers from non-accretable difference to accretable yield	(1,740)	(4)
Accretion	(29,506)	(37,115)
Changes in expected cash flows not affecting non-accretable differences	(2,927)	21,092
Balance at end of period	$ 99,169	$ 138,967

Loans and Leases - Schedule o_4

Loans and Leases - Schedule of Modified TDRs (Detail) - TDRs Occurring during the Period - TDRs $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019USD ($)SecurityLoan	Sep. 30, 2018USD ($)SecurityLoan	Sep. 30, 2019USD ($)SecurityLoan	Sep. 30, 2018USD ($)SecurityLoan
Financing Receivable, Modifications
Number of Loans | SecurityLoan	74	45	236	163
Pre-modification Outstanding Recorded Investment	$ 28,561	$ 6,720	$ 71,162	$ 59,322
Recorded investment	$ 4,111	$ 1,529	$ 17,084	$ 18,195
Number of loans | SecurityLoan	17	14	124	88
Extended maturities	$ 2,476	$ 3,658	$ 13,097	$ 10,020
Maturity and interest rate adjustment	288	267	715	368
Movement to or extension of interest-rate only payments	48	0	1,827	48
Interest rate adjustment	0	0	71	101
Financing Receivable Modifications Forbearance	22,202	802	25,068	14,386
Other concession(s)	3,724	1,810	20,250	21,031
TDRs during period	$ 28,738	$ 6,537	$ 61,028	$ 45,954
Commercial Loans | Real estate - construction
Financing Receivable, Modifications
Number of Loans | SecurityLoan	1	0	1	1
Pre-modification Outstanding Recorded Investment	$ 6,331	$ 0	$ 6,331	$ 1,950
TDRs during period	$ 7,602	$ 0	$ 7,602	$ 976
Commercial Loans | Real estate - owner-occupied
Financing Receivable, Modifications
Number of Loans | SecurityLoan	7	1	11	8
Pre-modification Outstanding Recorded Investment	$ 8,936	$ 2,312	$ 10,153	$ 15,233
Recorded investment	$ 0	$ 929	$ 1,225	$ 10,101
Number of loans | SecurityLoan	0	1	6	6
TDRs during period	$ 8,691	$ 2,312	$ 9,869	$ 13,373
Commercial Loans | Real estate - non-owner-occupied
Financing Receivable, Modifications
Number of Loans | SecurityLoan	6	6	16	13
Pre-modification Outstanding Recorded Investment	$ 1,553	$ 1,818	$ 7,931	$ 3,228
Recorded investment	$ 2,460	$ 7	$ 5,176	$ 1,084
Number of loans | SecurityLoan	2	1	16	6
TDRs during period	$ 1,210	$ 1,790	$ 7,233	$ 3,064
Commercial Loans | Commercial and industrial
Financing Receivable, Modifications
Number of Loans | SecurityLoan	14	9	48	32
Pre-modification Outstanding Recorded Investment	$ 1,954	$ 829	$ 29,156	$ 32,827
Recorded investment	$ 1,429	$ 127	$ 6,859	$ 3,632
Number of loans | SecurityLoan	8	2	25	12
TDRs during period	$ 1,952	$ 804	$ 19,594	$ 22,769
Residential mortgage loans | Residential mortgage
Financing Receivable, Modifications
Number of Loans | SecurityLoan	10	3	28	9
Pre-modification Outstanding Recorded Investment	$ 7,210	$ 257	$ 8,897	$ 898
Recorded investment	$ 101	$ 0	$ 1,394	$ 912
Number of loans | SecurityLoan	1	0	18	8
TDRs during period	$ 6,870	$ 255	$ 8,524	$ 837
Consumer and Other Loans | Consumer - Home equity
Financing Receivable, Modifications
Number of Loans | SecurityLoan	19	15	69	47
Pre-modification Outstanding Recorded Investment	$ 2,375	$ 1,152	$ 7,629	$ 4,130
Recorded investment	$ 64	$ 380	$ 1,873	$ 1,978
Number of loans | SecurityLoan	1	4	21	17
TDRs during period	$ 2,237	$ 1,124	$ 7,268	$ 4,047
Consumer and Other Loans | Consumer - Other
Financing Receivable, Modifications
Number of Loans | SecurityLoan	17	11	63	53
Pre-modification Outstanding Recorded Investment	$ 202	$ 352	$ 1,065	$ 1,056
Recorded investment	$ 57	$ 86	$ 557	$ 488
Number of loans | SecurityLoan	5	6	38	39
TDRs during period	$ 176	$ 252	$ 938	$ 888

Loans and Leases - Schedule o_5

Loans and Leases - Schedule of Subsequently Defaulted TDRs (Detail) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019USD ($)SecurityLoan	Sep. 30, 2018USD ($)SecurityLoan	Sep. 30, 2019USD ($)SecurityLoan	Sep. 30, 2018USD ($)SecurityLoan
Accounts, Notes, Loans and Financing Receivable
Threshold period for loans in default (in days)			30 days
TDRs | TDRs Occurring during the Period
Accounts, Notes, Loans and Financing Receivable
Number of Loans | SecurityLoan	74	45	236	163
Pre-modification Outstanding Recorded Investment	$ 28,561	$ 6,720	$ 71,162	$ 59,322
Post-modification Outstanding Recorded Investment	$ 28,738	$ 6,537	$ 61,028	$ 45,954
Number of loans | SecurityLoan	17	14	124	88
Recorded investment	$ 4,111	$ 1,529	$ 17,084	$ 18,195
TDRs | Commercial Loans | Real estate - construction | TDRs Occurring during the Period
Accounts, Notes, Loans and Financing Receivable
Number of Loans | SecurityLoan	1	0	1	1
Pre-modification Outstanding Recorded Investment	$ 6,331	$ 0	$ 6,331	$ 1,950
Post-modification Outstanding Recorded Investment	$ 7,602	$ 0	$ 7,602	$ 976
TDRs | Commercial Loans | Real estate - owner-occupied | TDRs Occurring during the Period
Accounts, Notes, Loans and Financing Receivable
Number of Loans | SecurityLoan	7	1	11	8
Pre-modification Outstanding Recorded Investment	$ 8,936	$ 2,312	$ 10,153	$ 15,233
Post-modification Outstanding Recorded Investment	$ 8,691	$ 2,312	$ 9,869	$ 13,373
Number of loans | SecurityLoan	0	1	6	6
Recorded investment	$ 0	$ 929	$ 1,225	$ 10,101
TDRs | Commercial Loans | Real estate - non-owner-occupied | TDRs Occurring during the Period
Accounts, Notes, Loans and Financing Receivable
Number of Loans | SecurityLoan	6	6	16	13
Pre-modification Outstanding Recorded Investment	$ 1,553	$ 1,818	$ 7,931	$ 3,228
Post-modification Outstanding Recorded Investment	$ 1,210	$ 1,790	$ 7,233	$ 3,064
Number of loans | SecurityLoan	2	1	16	6
Recorded investment	$ 2,460	$ 7	$ 5,176	$ 1,084
TDRs | Commercial Loans | Commercial and industrial | TDRs Occurring during the Period
Accounts, Notes, Loans and Financing Receivable
Number of Loans | SecurityLoan	14	9	48	32
Pre-modification Outstanding Recorded Investment	$ 1,954	$ 829	$ 29,156	$ 32,827
Post-modification Outstanding Recorded Investment	$ 1,952	$ 804	$ 19,594	$ 22,769
Number of loans | SecurityLoan	8	2	25	12
Recorded investment	$ 1,429	$ 127	$ 6,859	$ 3,632
TDRs | Residential mortgage loans | Residential mortgage | TDRs Occurring during the Period
Accounts, Notes, Loans and Financing Receivable
Number of Loans | SecurityLoan	10	3	28	9
Pre-modification Outstanding Recorded Investment	$ 7,210	$ 257	$ 8,897	$ 898
Post-modification Outstanding Recorded Investment	$ 6,870	$ 255	$ 8,524	$ 837
Number of loans | SecurityLoan	1	0	18	8
Recorded investment	$ 101	$ 0	$ 1,394	$ 912
TDRs | Consumer and Other Loans | Consumer - Home equity | TDRs Occurring during the Period
Accounts, Notes, Loans and Financing Receivable
Number of Loans | SecurityLoan	19	15	69	47
Pre-modification Outstanding Recorded Investment	$ 2,375	$ 1,152	$ 7,629	$ 4,130
Post-modification Outstanding Recorded Investment	$ 2,237	$ 1,124	$ 7,268	$ 4,047
Number of loans | SecurityLoan	1	4	21	17
Recorded investment	$ 64	$ 380	$ 1,873	$ 1,978
TDRs | Consumer and Other Loans | Consumer - Other | TDRs Occurring during the Period
Accounts, Notes, Loans and Financing Receivable
Number of Loans | SecurityLoan	17	11	63	53
Pre-modification Outstanding Recorded Investment	$ 202	$ 352	$ 1,065	$ 1,056
Post-modification Outstanding Recorded Investment	$ 176	$ 252	$ 938	$ 888
Number of loans | SecurityLoan	5	6	38	39
Recorded investment	$ 57	$ 86	$ 557	$ 488

Allowance for Credit Losses a_3

Allowance for Credit Losses and Credit Quality - Schedule of Allowance for Loan Losses for Covered and Non-Covered Loan Portfolios (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Allowance for credit losses
Allowance for loan and lease losses at beginning of period	$ 140,571	$ 140,891
Provision for loan and lease losses	32,190	26,678
Transfer of balance to OREO and other	(2,696)	(5,709)
Charge-offs	(29,971)	(34,740)
Recoveries	6,141	9,830
Allowance for loan and lease losses at end of period	146,235	136,950
Reserve For Unfunded Commitments
Reserve for unfunded commitments at beginning of period	14,830	13,208
Balance created in acquisition accounting	0	900
Provision for unfunded lending commitments	1,314	613
Reserve for unfunded commitments at end of period	16,144	14,721
Allowance for credit losses at end of period	$ 162,379	$ 151,671

Allowance for Credit Losses a_4

Allowance for Credit Losses and Credit Quality - Schedule of Allowance for Loan Losses for Legacy and Acquired Loans, by Loan Portfolio (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Financing Receivable, Allowance for Credit Losses
Allowance for loan and lease losses at beginning of period	$ 140,571	$ 140,891
Provision for (Reversal of) loan and lease losses	32,190	26,678
Transfer of balance to OREO and other	(2,696)	(5,709)
Charge-offs	(29,971)	(34,740)
Recoveries	6,141	9,830
Allowance for loan and lease losses at end of period	146,235	136,950
Financing Receivable, Reserve For Unfunded Commitments
Reserve for unfunded commitments at beginning of period	14,830	13,208
Balance created in acquisition accounting		900
Provision for (Reversal of) unfunded commitments	1,314	613
Reserve for unfunded commitments at end of period	16,144	14,721
Allowance on loans individually evaluated for impairment	14,015	16,248
Allowance on loans collectively evaluated for impairment	120,822	107,970
Allowance on loans acquired with deteriorated credit quality	162,379	151,671
Loans and leases, net of unearned income:
Balance at end of period	23,676,537	22,343,906
Balance at end of period individually evaluated for impairment	205,395	189,187
Balance at end of period collectively evaluated for impairment	23,185,245	21,749,855
Commercial Loans | Real Estate
Financing Receivable, Allowance for Credit Losses
Allowance for loan and lease losses at beginning of period	51,806	54,201
Provision for (Reversal of) loan and lease losses	9,205	(4,020)
Transfer of balance to OREO and other	(309)	(1,556)
Charge-offs	(2,179)	(1,281)
Recoveries	474	1,019
Allowance for loan and lease losses at end of period	58,997	48,363
Financing Receivable, Reserve For Unfunded Commitments
Reserve for unfunded commitments at beginning of period	4,869	4,531
Balance created in acquisition accounting		129
Provision for (Reversal of) unfunded commitments	357	(134)
Reserve for unfunded commitments at end of period	5,226	4,526
Allowance on loans individually evaluated for impairment	2,721	2,650
Allowance on loans collectively evaluated for impairment	50,809	40,519
Loans and leases, net of unearned income:
Balance at end of period	9,809,756	9,381,883
Balance at end of period individually evaluated for impairment	73,715	73,469
Balance at end of period collectively evaluated for impairment	9,605,296	9,126,653
Commercial Loans | Commercial and industrial
Financing Receivable, Allowance for Credit Losses
Allowance for loan and lease losses at beginning of period	54,096	53,916
Provision for (Reversal of) loan and lease losses	15,819	20,372
Transfer of balance to OREO and other	236	(814)
Charge-offs	(17,799)	(22,447)
Recoveries	3,163	5,665
Allowance for loan and lease losses at end of period	55,515	56,692
Financing Receivable, Reserve For Unfunded Commitments
Reserve for unfunded commitments at beginning of period	6,198	5,309
Balance created in acquisition accounting		81
Provision for (Reversal of) unfunded commitments	493	169
Reserve for unfunded commitments at end of period	6,691	5,559
Allowance on loans individually evaluated for impairment	7,974	10,471
Allowance on loans collectively evaluated for impairment	45,990	44,727
Loans and leases, net of unearned income:
Balance at end of period	6,490,125	5,581,040
Balance at end of period individually evaluated for impairment	51,350	75,625
Balance at end of period collectively evaluated for impairment	6,417,426	5,478,377
Residential mortgage loans
Financing Receivable, Allowance for Credit Losses
Allowance for loan and lease losses at beginning of period	12,998	9,117
Provision for (Reversal of) loan and lease losses	(152)	2,318
Transfer of balance to OREO and other	(2,879)	(45)
Charge-offs	(219)	(365)
Recoveries	169	53
Allowance for loan and lease losses at end of period	9,917	11,078
Financing Receivable, Reserve For Unfunded Commitments
Reserve for unfunded commitments at beginning of period	866	555
Balance created in acquisition accounting		0
Provision for (Reversal of) unfunded commitments	(216)	246
Reserve for unfunded commitments at end of period	650	801
Allowance on loans individually evaluated for impairment	281	154
Allowance on loans collectively evaluated for impairment	5,393	5,063
Loans and leases, net of unearned income:
Balance at end of period	4,649,745	4,300,163
Balance at end of period individually evaluated for impairment	42,423	6,230
Balance at end of period collectively evaluated for impairment	4,526,508	4,174,524
Consumer and Other Loans
Financing Receivable, Allowance for Credit Losses
Allowance for loan and lease losses at beginning of period	21,671	23,657
Provision for (Reversal of) loan and lease losses	7,318	8,008
Transfer of balance to OREO and other	256	(3,294)
Charge-offs	(9,774)	(10,647)
Recoveries	2,335	3,093
Allowance for loan and lease losses at end of period	21,806	20,817
Financing Receivable, Reserve For Unfunded Commitments
Reserve for unfunded commitments at beginning of period	2,897	2,813
Balance created in acquisition accounting		690
Provision for (Reversal of) unfunded commitments	680	332
Reserve for unfunded commitments at end of period	3,577	3,835
Allowance on loans individually evaluated for impairment	3,039	2,973
Allowance on loans collectively evaluated for impairment	18,630	17,661
Loans and leases, net of unearned income:
Balance at end of period	2,726,911	3,080,820
Balance at end of period individually evaluated for impairment	37,907	33,863
Balance at end of period collectively evaluated for impairment	2,636,015	2,970,301
Receivables Acquired with Deteriorated Credit Quality
Financing Receivable, Reserve For Unfunded Commitments
Allowance on loans acquired with deteriorated credit quality	11,398	12,732
Loans and leases, net of unearned income:
Balance at end of period acquired with deteriorated credit quality	285,897	404,864
Receivables Acquired with Deteriorated Credit Quality | Commercial Loans | Real Estate
Financing Receivable, Reserve For Unfunded Commitments
Allowance on loans acquired with deteriorated credit quality	5,467	5,194
Loans and leases, net of unearned income:
Balance at end of period acquired with deteriorated credit quality	130,745	181,761
Receivables Acquired with Deteriorated Credit Quality | Commercial Loans | Commercial and industrial
Financing Receivable, Reserve For Unfunded Commitments
Allowance on loans acquired with deteriorated credit quality	1,551	1,494
Loans and leases, net of unearned income:
Balance at end of period acquired with deteriorated credit quality	21,349	27,038
Receivables Acquired with Deteriorated Credit Quality | Residential mortgage loans
Financing Receivable, Reserve For Unfunded Commitments
Allowance on loans acquired with deteriorated credit quality	4,243	5,861
Loans and leases, net of unearned income:
Balance at end of period acquired with deteriorated credit quality	80,814	119,409
Receivables Acquired with Deteriorated Credit Quality | Consumer and Other Loans
Financing Receivable, Reserve For Unfunded Commitments
Allowance on loans acquired with deteriorated credit quality	137	183
Loans and leases, net of unearned income:
Balance at end of period acquired with deteriorated credit quality	$ 52,989	$ 76,656

Allowance for Credit Losses a_5

Allowance for Credit Losses and Credit Quality - Investment in Legacy and Acquired Loans by Credit Quality Indicator (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Financing Receivable, Allowance for Credit Losses
Total Loans	$ 23,676,537	$ 22,519,815
Commercial Loans
Financing Receivable, Allowance for Credit Losses
Total Loans	16,299,881	15,125,322
Commercial Loans | Real estate - construction
Financing Receivable, Allowance for Credit Losses
Total Loans	1,330,014	1,196,366
Commercial Loans | Real estate - owner-occupied
Financing Receivable, Allowance for Credit Losses
Total Loans	2,468,061	2,395,822
Commercial Loans | Real estate - non-owner-occupied
Financing Receivable, Allowance for Credit Losses
Total Loans	6,011,681	5,796,117
Commercial Loans | Commercial and industrial
Financing Receivable, Allowance for Credit Losses
Total Loans	6,490,125	5,737,017
Residential and Consumer Portfolio
Financing Receivable, Allowance for Credit Losses
Current	7,245,248	7,270,042
30 or more days past due	131,408	124,451
Total Loans	7,376,656	7,394,493
Residential mortgage loans | Residential mortgage
Financing Receivable, Allowance for Credit Losses
Current	4,567,633	4,290,152
30 or more days past due	82,112	69,004
Total Loans	4,649,745	4,359,156
Consumer and Other Loans | Consumer - Home equity
Financing Receivable, Allowance for Credit Losses
Current	2,011,913	2,258,659
30 or more days past due	41,675	46,035
Total Loans	2,053,588	2,304,694
Consumer and Other Loans | Consumer - Other
Financing Receivable, Allowance for Credit Losses
Current	665,702	721,231
30 or more days past due	7,621	9,412
Total Loans	673,323	730,643
Pass | Commercial Loans
Financing Receivable, Allowance for Credit Losses
Gross loans and leases receivable	15,977,343	14,785,998
Pass | Commercial Loans | Real estate - construction
Financing Receivable, Allowance for Credit Losses
Gross loans and leases receivable	1,300,847	1,182,554
Pass | Commercial Loans | Real estate - owner-occupied
Financing Receivable, Allowance for Credit Losses
Gross loans and leases receivable	2,409,221	2,328,999
Pass | Commercial Loans | Real estate - non-owner-occupied
Financing Receivable, Allowance for Credit Losses
Gross loans and leases receivable	5,926,537	5,687,963
Pass | Commercial Loans | Commercial and industrial
Financing Receivable, Allowance for Credit Losses
Gross loans and leases receivable	6,340,738	5,586,482
Special Mention | Commercial Loans
Financing Receivable, Allowance for Credit Losses
Gross loans and leases receivable	158,342	157,229
Special Mention | Commercial Loans | Real estate - construction
Financing Receivable, Allowance for Credit Losses
Gross loans and leases receivable	19,631	1,062
Special Mention | Commercial Loans | Real estate - owner-occupied
Financing Receivable, Allowance for Credit Losses
Gross loans and leases receivable	19,786	25,526
Special Mention | Commercial Loans | Real estate - non-owner-occupied
Financing Receivable, Allowance for Credit Losses
Gross loans and leases receivable	47,494	78,009
Special Mention | Commercial Loans | Commercial and industrial
Financing Receivable, Allowance for Credit Losses
Gross loans and leases receivable	71,431	52,632
Substandard | Commercial Loans
Financing Receivable, Allowance for Credit Losses
Gross loans and leases receivable	148,246	154,402
Substandard | Commercial Loans | Real estate - construction
Financing Receivable, Allowance for Credit Losses
Gross loans and leases receivable	9,536	12,740
Substandard | Commercial Loans | Real estate - owner-occupied
Financing Receivable, Allowance for Credit Losses
Gross loans and leases receivable	38,214	41,297
Substandard | Commercial Loans | Real estate - non-owner-occupied
Financing Receivable, Allowance for Credit Losses
Gross loans and leases receivable	37,193	26,512
Substandard | Commercial Loans | Commercial and industrial
Financing Receivable, Allowance for Credit Losses
Gross loans and leases receivable	63,303	73,853
Doubtful | Commercial Loans
Financing Receivable, Allowance for Credit Losses
Gross loans and leases receivable	15,940	27,693
Doubtful | Commercial Loans | Real estate - construction
Financing Receivable, Allowance for Credit Losses
Gross loans and leases receivable	0	10
Doubtful | Commercial Loans | Real estate - owner-occupied
Financing Receivable, Allowance for Credit Losses
Gross loans and leases receivable	840	0
Doubtful | Commercial Loans | Real estate - non-owner-occupied
Financing Receivable, Allowance for Credit Losses
Gross loans and leases receivable	447	3,633
Doubtful | Commercial Loans | Commercial and industrial
Financing Receivable, Allowance for Credit Losses
Gross loans and leases receivable	14,653	$ 24,050
Loss | Commercial and industrial
Financing Receivable, Allowance for Credit Losses
Gross loans and leases receivable	0
Loss | Commercial Loans
Financing Receivable, Allowance for Credit Losses
Gross loans and leases receivable	10
Loss | Commercial Loans | Real estate - construction
Financing Receivable, Allowance for Credit Losses
Gross loans and leases receivable	0
Loss | Commercial Loans | Real estate - owner-occupied
Financing Receivable, Allowance for Credit Losses
Gross loans and leases receivable	0
Loss | Commercial Loans | Real estate - non-owner-occupied
Financing Receivable, Allowance for Credit Losses
Gross loans and leases receivable	$ 10

Allowance for Credit Losses a_6

Allowance for Credit Losses and Credit Quality - Schedule of Investment in Legacy Impaired Loans (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Financing Receivable, Impaired
Unpaid Principal Balance	$ 227,102		$ 227,102		$ 209,746
Recorded Investment	205,395		205,395		169,725
Related allowance	(14,015)		(14,015)		(16,342)
Average Recorded Investment	212,055	$ 197,593	207,955	$ 201,997
Interest Income Recognized	1,460	1,829	4,845	5,852
Commercial Loans
Financing Receivable, Impaired
Unpaid Principal Balance	144,093		144,093		164,209
Recorded Investment	125,065		125,065		125,706
Related allowance	(10,695)		(10,695)		(13,282)
Average Recorded Investment	130,634	157,333	131,217	162,163
Interest Income Recognized	846	1,398	3,011	4,551
Residential mortgage loans
Financing Receivable, Impaired
Unpaid Principal Balance	44,192		44,192		7,114
Recorded Investment	42,423		42,423		6,579
Related allowance	(281)		(281)		(145)
Average Recorded Investment	43,310	6,268	38,817	6,337
Interest Income Recognized	210	59	623	185
Consumer and Other Loans
Financing Receivable, Impaired
Unpaid Principal Balance	38,817		38,817		38,423
Recorded Investment	37,907		37,907		37,440
Related allowance	(3,039)		(3,039)		(2,915)
Average Recorded Investment	38,111	33,992	37,921	33,497
Interest Income Recognized	404	372	1,211	1,116
With No Related Allowance Recorded | Commercial Loans | Real estate - construction
Financing Receivable, Impaired
Unpaid Principal Balance	9,540		9,540		10,261
Recorded Investment	8,531		8,531		9,262
Average Recorded Investment	7,333	10,806	7,145	10,371
Interest Income Recognized	82	164	242	460
With No Related Allowance Recorded | Commercial Loans | Real estate - owner-occupied
Financing Receivable, Impaired
Unpaid Principal Balance	33,985		33,985		25,037
Recorded Investment	33,590		33,590		19,044
Average Recorded Investment	33,895	34,118	34,437	34,505
Interest Income Recognized	355	209	1,235	903
With No Related Allowance Recorded | Commercial Loans | Real estate - non-owner-occupied
Financing Receivable, Impaired
Unpaid Principal Balance	23,964		23,964		15,265
Recorded Investment	22,652		22,652		14,288
Average Recorded Investment	22,794	22,091	22,910	22,988
Interest Income Recognized	72	249	301	746
With No Related Allowance Recorded | Commercial Loans | Commercial and industrial
Financing Receivable, Impaired
Unpaid Principal Balance	21,813		21,813		55,554
Recorded Investment	17,771		17,771		43,886
Average Recorded Investment	20,594	43,409	20,727	40,564
Interest Income Recognized	108	523	401	1,543
With No Related Allowance Recorded | Commercial Loans | Residential mortgage
Financing Receivable, Impaired
Unpaid Principal Balance	36,182		36,182		1,244
Recorded Investment	35,089		35,089		1,221
Average Recorded Investment	35,896	1,254	31,315	1,271
Interest Income Recognized	136	9	391	36
With No Related Allowance Recorded | Consumer and Other Loans | Consumer - Home equity
Financing Receivable, Impaired
Unpaid Principal Balance	4,736		4,736		4,183
Recorded Investment	4,734		4,734		4,176
Average Recorded Investment	4,736	705	4,613	708
Interest Income Recognized	47	2	137	16
With An Allowance Recorded | Commercial Loans | Real estate - construction
Financing Receivable, Impaired
Unpaid Principal Balance	98		98		228
Recorded Investment	85		85		140
Related allowance	(1)		(1)		(11)
Average Recorded Investment	87	148	93	151
Interest Income Recognized	0	0	0	1
With An Allowance Recorded | Commercial Loans | Real estate - owner-occupied
Financing Receivable, Impaired
Unpaid Principal Balance	5,135		5,135		5,032
Recorded Investment	4,921		4,921		4,773
Related allowance	(2,529)		(2,529)		(520)
Average Recorded Investment	4,952	4,006	5,050	4,044
Interest Income Recognized	10	83	113	102
With An Allowance Recorded | Commercial Loans | Real estate - non-owner-occupied
Financing Receivable, Impaired
Unpaid Principal Balance	4,149		4,149		6,445
Recorded Investment	3,936		3,936		6,398
Related allowance	(191)		(191)		(105)
Average Recorded Investment	4,155	2,398	4,090	2,442
Interest Income Recognized	46	20	137	76
With An Allowance Recorded | Commercial Loans | Commercial and industrial
Financing Receivable, Impaired
Unpaid Principal Balance	45,409		45,409		46,387
Recorded Investment	33,579		33,579		27,915
Related allowance	(7,974)		(7,974)		(12,646)
Average Recorded Investment	36,824	40,357	36,765	47,098
Interest Income Recognized	173	150	582	720
With An Allowance Recorded | Residential mortgage loans | Residential mortgage
Financing Receivable, Impaired
Unpaid Principal Balance	8,010		8,010		5,870
Recorded Investment	7,334		7,334		5,358
Related allowance	(281)		(281)		(145)
Average Recorded Investment	7,414	5,014	7,502	5,066
Interest Income Recognized	74	50	232	149
With An Allowance Recorded | Consumer and Other Loans | Consumer - Home equity
Financing Receivable, Impaired
Unpaid Principal Balance	29,773		29,773		29,284
Recorded Investment	29,124		29,124		28,818
Related allowance	(2,577)		(2,577)		(2,427)
Average Recorded Investment	29,200	28,577	28,982	27,905
Interest Income Recognized	298	305	890	892
With An Allowance Recorded | Consumer and Other Loans | Consumer - Other
Financing Receivable, Impaired
Unpaid Principal Balance	4,308		4,308		4,956
Recorded Investment	4,049		4,049		4,446
Related allowance	(462)		(462)		$ (488)
Average Recorded Investment	4,175	4,710	4,326	4,884
Interest Income Recognized	$ 59	$ 65	$ 184	$ 208

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets - Schedule of Carrying Amount of Goodwill (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Goodwill
Balance at beginning of the period	$ 1,235,533	$ 1,188,902
Goodwill acquired and adjustments during the year	0	46,631
Balance at end of the period	1,235,533	1,235,533
Operating Segments | IBERIABANK
Goodwill
Balance at beginning of the period	1,203,810	1,160,559
Goodwill acquired and adjustments during the year	0	43,251
Balance at end of the period	1,203,810	1,203,810
Operating Segments | IMC
Goodwill
Balance at beginning of the period	23,178	23,178
Goodwill acquired and adjustments during the year	0	0
Balance at end of the period	23,178	23,178
Operating Segments | LTC
Goodwill
Balance at beginning of the period	8,545	5,165
Goodwill acquired and adjustments during the year	0	3,380
Balance at end of the period	$ 8,545	$ 8,545

Goodwill and Other Intangible_4

Goodwill and Other Intangible Assets - Schedule of Mortgage Servicing Rights at Carrying Value (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 137,774	$ 137,774
Accumulated Amortization	(78,721)	(64,608)
Net Carrying Amount	59,053	73,166
Mortgage servicing rights
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	19,517	13,612
Valuation Allowance	(195)		$ 0
Accumulated Amortization	(5,994)	(4,806)
Net Carrying Amount	$ 13,328	$ 8,806

Goodwill and Other Intangible_5

Goodwill and Other Intangible Assets - Narrative (Detail) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Title plant assets	$ 6.8	$ 6.8

Goodwill and Other Intangible_6

Goodwill and Other Intangible Assets - Schedule of Definite-Lived Intangible Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 137,774	$ 137,774
Accumulated Amortization	(78,721)	(64,608)
Net Carrying Amount	59,053	73,166
Core deposit intangible assets
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	136,183	136,183
Accumulated Amortization	(77,256)	(63,213)
Net Carrying Amount	58,927	72,970
Customer relationship intangible asset
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,385	1,385
Accumulated Amortization	(1,363)	(1,323)
Net Carrying Amount	22	62
Non-compete agreement
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	206	206
Accumulated Amortization	(102)	(72)
Net Carrying Amount	$ 104	$ 134

Derivative Instruments and Ot_3

Derivative Instruments and Other Hedging Activities - Schedule of Outstanding Derivative Instruments (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Derivative [Line Items]
Derivative Assets - Fair Value	$ 136,235	$ 27,048
Derivative Liabilities - Fair Value	10,851	22,124
Designated as Hedging Instruments
Derivative [Line Items]
Derivative Assets - Fair Value	23,339	3,469
Derivative Liabilities - Fair Value	0	0
Other Assets | Designated as Hedging Instruments | Interest rate contracts
Derivative [Line Items]
Derivative Assets - Fair Value	23,339	3,469
Other Assets | Not Designated as Hedging Instruments
Derivative [Line Items]
Derivative Assets - Fair Value	112,896	23,579
Other Assets | Not Designated as Hedging Instruments | Interest rate contracts
Derivative [Line Items]
Derivative Assets - Fair Value	104,779	16,946
Other Assets | Not Designated as Hedging Instruments | Customer swaps - upstream
Derivative [Line Items]
Derivative Assets - Fair Value	12	474
Other Assets | Not Designated as Hedging Instruments | Foreign exchange contracts
Derivative [Line Items]
Derivative Assets - Fair Value	0	18
Other Assets | Not Designated as Hedging Instruments | Forward sales contracts
Derivative [Line Items]
Derivative Assets - Fair Value	485	630
Other Assets | Not Designated as Hedging Instruments | Written and purchased options
Derivative [Line Items]
Derivative Assets - Fair Value	7,549	5,490
Other Assets | Not Designated as Hedging Instruments | Other contracts
Derivative [Line Items]
Derivative Assets - Fair Value	71	21
Other Liabilities | Designated as Hedging Instruments | Interest rate contracts
Derivative [Line Items]
Derivative Liabilities - Fair Value	0	0
Other Liabilities | Not Designated as Hedging Instruments
Derivative [Line Items]
Derivative Liabilities - Fair Value	10,851	22,124
Other Liabilities | Not Designated as Hedging Instruments | Interest rate contracts
Derivative [Line Items]
Derivative Liabilities - Fair Value	206	17,812
Other Liabilities | Not Designated as Hedging Instruments | Customer swaps - upstream
Derivative [Line Items]
Derivative Liabilities - Fair Value	6,104	191
Other Liabilities | Not Designated as Hedging Instruments | Foreign exchange contracts
Derivative [Line Items]
Derivative Liabilities - Fair Value	0	18
Other Liabilities | Not Designated as Hedging Instruments | Forward sales contracts
Derivative [Line Items]
Derivative Liabilities - Fair Value	654	750
Other Liabilities | Not Designated as Hedging Instruments | Written and purchased options
Derivative [Line Items]
Derivative Liabilities - Fair Value	3,695	3,310
Other Liabilities | Not Designated as Hedging Instruments | Other contracts
Derivative [Line Items]
Derivative Liabilities - Fair Value	$ 192	$ 43

Derivative Instruments and Ot_4

Derivative Instruments and Other Hedging Activities (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Derivative [Line Items]
Derivative Assets - Notional Amount	$ 3,759,695	$ 2,311,612
Derivative Liabilities - Notional Amount	2,994,815	1,991,559
Cash posted as variation margin for derivatives	106,500	35,800
Designated as Hedging Instruments
Derivative [Line Items]
Derivative Assets - Notional Amount	800,000	408,500
Derivative Liabilities - Notional Amount	108,500	0
Designated as Hedging Instruments | Interest rate contracts
Derivative [Line Items]
Derivative Assets - Notional Amount	800,000	408,500
Derivative Liabilities - Notional Amount	108,500	0
Not Designated as Hedging Instruments
Derivative [Line Items]
Derivative Assets - Notional Amount	2,959,695	1,903,112
Derivative Liabilities - Notional Amount	2,886,315	1,991,559
Not Designated as Hedging Instruments | Interest rate contracts
Derivative [Line Items]
Derivative Assets - Notional Amount	2,259,248	701,257
Derivative Liabilities - Notional Amount	142,425	919,653
Not Designated as Hedging Instruments | Customer swaps - upstream
Derivative [Line Items]
Derivative Assets - Notional Amount	142,425	919,653
Derivative Liabilities - Notional Amount	2,259,248	701,257
Not Designated as Hedging Instruments | Other contracts
Derivative [Line Items]
Derivative Assets - Notional Amount	74,085	50,527
Derivative Liabilities - Notional Amount	145,443	85,623
Not Designated as Hedging Instruments | Foreign exchange contracts
Derivative [Line Items]
Derivative Assets - Notional Amount	0	1,202
Derivative Liabilities - Notional Amount	0	1,202
Not Designated as Hedging Instruments | Forward sales contracts
Derivative [Line Items]
Derivative Assets - Notional Amount	144,368	1,140
Derivative Liabilities - Notional Amount	211,049	143,179
Not Designated as Hedging Instruments | Written and purchased options
Derivative [Line Items]
Derivative Assets - Notional Amount	339,569	229,333
Derivative Liabilities - Notional Amount	$ 128,150	$ 140,645

Derivative Instruments and Ot_5

Derivative Instruments and Other Hedging Activities - Reconciliation of Gross Amounts in Consolidated Balance Sheets (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Derivative assets
Gross derivative assets	$ 131,710	$ 24,174
Gross amounts not offset in the Balance Sheet, derivatives	(6,119)	(619)
Gross amounts not offset in the Balance Sheet, collateral	0	0
Net derivative assets	125,591	23,555
Derivative liabilities
Gross derivative liabilities	9,891	21,288
Gross amounts not offset in the Balance Sheet, derivatives	(6,119)	(619)
Gross amounts not offset in the Balance Sheet, collateral	0	0
Net derivative liabilities	3,772	20,669
Written and purchased options
Derivative assets
Gross derivative assets	3,581	3,285
Gross amounts not offset in the Balance Sheet, derivatives	0	0
Gross amounts not offset in the Balance Sheet, collateral	0	0
Net derivative assets	3,581	3,285
Derivative liabilities
Gross derivative liabilities	3,581	3,285
Gross amounts not offset in the Balance Sheet, derivatives	0	0
Gross amounts not offset in the Balance Sheet, collateral	0	0
Net derivative liabilities	3,581	3,285
Designated as Hedging Instruments | Interest rate contracts
Derivative assets
Gross derivative assets	23,338	3,469
Gross amounts not offset in the Balance Sheet, derivatives	0	0
Gross amounts not offset in the Balance Sheet, collateral	0	0
Net derivative assets	23,338	3,469
Not Designated as Hedging Instruments | Interest rate contracts
Derivative assets
Gross derivative assets	104,791	17,420
Gross amounts not offset in the Balance Sheet, derivatives	(6,119)	(619)
Gross amounts not offset in the Balance Sheet, collateral	0	0
Net derivative assets	98,672	16,801
Derivative liabilities
Gross derivative liabilities	6,310	18,003
Gross amounts not offset in the Balance Sheet, derivatives	(6,119)	(619)
Gross amounts not offset in the Balance Sheet, collateral	0	0
Net derivative liabilities	$ 191	$ 17,384

Derivative Instruments and Ot_6

Derivative Instruments and Other Hedging Activities - Effect of Hedging Instruments on Consolidated Financial Statements (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Designated as Hedging Instruments | Cash Flow Hedging | Interest rate contracts | Interest expense
Derivative Instruments and Hedging Activities Disclosures
Amount of gain (loss) recognized	$ (162)	$ (22)	$ (467)	$ (178)
Derivative, included component, gain (loss) recognized in earnings	102	(22)	212	(178)
Amount of gain (loss) recognized in income on derivatives (amount excluded from effectiveness testing)	(264)	0	(679)	0
Derivative instruments, gain (loss) recognized in income, ineffective portion and amount excluded from effectiveness testing, net	0	0	0	0
Derivative instruments, gain (loss) recognized in income, ineffective portion and amount excluded from effectiveness testing, included component net	0	0	0	0
Derivative instruments, gain (loss) recognized in income, ineffective portion and amount excluded from effectiveness testing, excluding component, net	0	0	0	0
Not Designated as Hedging Instruments
Derivative Instruments and Hedging Activities Disclosures
Amount of gain (loss) recognized	390	2,850	4,266	10,142
Not Designated as Hedging Instruments | Interest rate contracts | Commission income
Derivative Instruments and Hedging Activities Disclosures
Amount of gain (loss) recognized	4,067	2,586	10,761	5,093
Not Designated as Hedging Instruments | Foreign exchange contracts | Commission income
Derivative Instruments and Hedging Activities Disclosures
Amount of gain (loss) recognized	8	7	14	17
Not Designated as Hedging Instruments | Forward sales contracts | Mortgage income
Derivative Instruments and Hedging Activities Disclosures
Amount of gain (loss) recognized	(1,765)	948	(8,085)	4,563
Not Designated as Hedging Instruments | Written and purchased options | Mortgage income
Derivative Instruments and Hedging Activities Disclosures
Amount of gain (loss) recognized	(1,848)	(692)	1,675	473
Not Designated as Hedging Instruments | Other contracts | Commission income
Derivative Instruments and Hedging Activities Disclosures
Amount of gain (loss) recognized	(72)	1	(99)	(4)
OCI | Designated as Hedging Instruments | Cash Flow Hedging | Interest rate contracts
Derivative Instruments and Hedging Activities Disclosures
Amount of gain (loss) recognized	(264)	818	1,992	4,762
Derivative, included component, gain (loss) recognized in earnings	312	818	3,196	4,762
Amount of gain (loss) recognized in income on derivatives (amount excluded from effectiveness testing)	$ (576)	$ 0	$ (1,204)	$ 0

Leases - Additional Information

Leases - Additional Information (Details) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2019USD ($)	Sep. 30, 2019USD ($)
Lessor, Lease, Description [Line Items]
Lease expense	$ 6.9	$ 20.5
Amounts included in measurement of lease liabilities	6.7	21.1
Amount to obtain ROU assets	18.1	$ 31.3
Term of options to extend leases		12 months
Term for option to terminate leases		1 year
Interest income for sales-type and direct finance leases	$ 3.1	$ 7.4
Minimum
Lessor, Lease, Description [Line Items]
Term of contract on operating lease	1 year	1 year
Renewal term of operating lease	1 year	1 year
Remaining lease terms on sales type and direct finance leases		3 years
Maximum
Lessor, Lease, Description [Line Items]
Term of contract on operating lease	44 years	44 years
Renewal term of operating lease	5 years	5 years
Remaining lease terms on sales type and direct finance leases		20 years

Leases - Right-of-use Assets an

Leases - Right-of-use Assets and Lease Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019
Leases [Abstract]
Right-of-use assets	$ 112,156	$ 94,200
Lease liabilities	$ 131,800	$ 118,900
Weighted average remaining lease term	7 years 11 months 12 days
Weighted average discount rate	3.14%

Leases - Maturities of Operatin

Leases - Maturities of Operating Leases (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019
Leases [Abstract]
2019	$ 6,732
2020	25,895
2021	23,847
2022	21,414
2023	16,659
2024 and thereafter	55,296
Total operating lease payments	149,843
Less: Imputed interest	18,043
Lease liabilities	$ 131,800	$ 118,900

Leases - Components of Net Inve

Leases - Components of Net Investment in Leases (Details) $ in Thousands	Sep. 30, 2019USD ($)
Leases [Abstract]
Lease payment receivable	$ 363,224
Unguaranteed residual assets	34,991
Total net investment in leases	$ 398,215

Leases - Direct Finance and Sal

Leases - Direct Finance and Sales Type Leases (Details) $ in Thousands	Sep. 30, 2019USD ($)
Leases [Abstract]
2019	$ 21,480
2020	82,993
2021	68,163
2022	62,809
2023	48,670
2024 and thereafter	90,277
Total future minimum lease payments	374,392
Less: Imputed interest	11,168
Lease receivables	$ 363,224

Shareholders' Equity, Capital_3

Shareholders' Equity, Capital Ratios and Other Regulatory Matters - Shareholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	Aug. 01, 2024	Apr. 04, 2019	May 09, 2016	Aug. 05, 2015	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Class of Stock [Line Items]
Preferred stock, shares issued					23,750		23,750		13,750
Preferred stock, par value (in usd per share)					$ 1		$ 1		$ 1
Liquidation preference (per share)					$ 10,000		$ 10,000		$ 10,000
Liquidation preference value			$ 237,500
Carrying Amount					$ 228,485		$ 228,485		$ 132,097
Common stock repurchases					$ 40,016	$ 30,376	$ 204,740	$ 61,046
Shares authorized to be repurchased					1,165,000		1,165,000
Series B Preferred Stock
Class of Stock [Line Items]
Ownership per share				6.625%
Liquidation preference value				$ 80,000
Carrying Amount					$ 76,812		$ 76,812		76,812
Series C Preferred Stock
Class of Stock [Line Items]
Ownership per share			6.60%
Liquidation preference value			$ 57,500
Carrying Amount					55,285		55,285		55,285
Series D Preferred Stock
Class of Stock [Line Items]
Ownership per share		6.10%
Preferred stock, par value (in usd per share)		$ 1
Liquidation preference (per share)		$ 10,000
Liquidation preference value		$ 100,000
Carrying Amount					$ 96,388		$ 96,388		$ 0
Series D Depositary Shares
Class of Stock [Line Items]
Preferred stock, shares issued		4,000,000
Liquidation preference (per share)		$ 25
Common Stock
Class of Stock [Line Items]
Common stock repurchases (in shares)					552,230	363,210	2,700,000	763,210
Common stock repurchases					$ 552	$ 363	$ 2,700	$ 763
2018 Share Repurchase Plan | Common Stock
Class of Stock [Line Items]
Number of shares authorized to be repurchased									2,765,000
Common stock repurchases (in shares)					117,230
2019 Share Repurchase Program | Common Stock
Class of Stock [Line Items]
Number of shares authorized to be repurchased					1,600,000		1,600,000
Percentage of outstanding common shares					3.00%
2016 and 2018 Share Repurchase Program
Class of Stock [Line Items]
Common stock repurchases					$ 40,000	$ 30,400	$ 204,700
Average cost of common stock shares repurchased (in usd per share)					$ 72.46	$ 83.63	$ 75.83	$ 79.99
2016 and 2018 Share Repurchase Program | Common Stock
Class of Stock [Line Items]
Common stock repurchases (in shares)					552,230	363,210	2,700,000	763,210
Common stock repurchases								$ 61,000
Forecast | Series D Preferred Stock
Class of Stock [Line Items]
Variable dividend rate after August 1, 2024	3.859%

Shareholders' Equity, Capital_4

Shareholders' Equity, Capital Ratios and Other Regulatory Matters - Actual Capital Amounts and Ratios (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Total Risk-Based Capital
Capital Conversion Buffer	4.34%
Consolidated
Tier 1 Leverage
Minimum amount	$ 1,208,894	$ 1,168,343
Minimum ratio	4.00%	4.00%
Actual amount	$ 2,955,775	$ 2,812,863
Actual ratio	9.78%	9.63%
Common Equity Tier 1 (CET1)
Minimum amount	$ 1,179,356	$ 1,125,405
Minimum ratio	4.50%	4.50%
Actual amount	$ 2,727,290	$ 2,680,766
Actual Ratio	10.41%	10.72%
Tier 1 Risk-Based Capital
Minimum amount	$ 1,572,475	$ 1,500,540
Minimum ratio	6.00%	6.00%
Actual amount	$ 2,955,775	$ 2,812,863
Actual ratio	11.28%	11.25%
Total Risk-Based Capital
Minimum amount	$ 2,096,633	$ 2,000,720
Minimum ratio	8.00%	8.00%
Actual amount	$ 3,234,654	$ 3,084,764
Actual ratio	12.34%	12.33%
IBERIABANK
Tier 1 Leverage
Minimum amount	$ 1,206,257	$ 1,165,537
Minimum ratio	4.00%	4.00%
Well capitalized amount	$ 1,507,821	$ 1,456,921
Well capitalized ratio	5.00%	5.00%
Actual amount	$ 2,861,883	$ 2,733,099
Actual ratio	9.49%	9.38%
Common Equity Tier 1 (CET1)
Minimum amount	$ 1,175,984	$ 1,122,712
Minimum ratio	4.50%	4.50%
Well capitalized amount	$ 1,698,643	$ 1,621,695
Well capitalized ratio	6.50%	6.50%
Actual amount	$ 2,861,883	$ 2,733,099
Actual Ratio	10.95%	10.95%
Tier 1 Risk-Based Capital
Minimum amount	$ 1,567,978	$ 1,496,949
Minimum ratio	6.00%	6.00%
Well capitalized amount	$ 2,090,638	$ 1,995,932
Well capitalized ratio	8.00%	8.00%
Actual amount	$ 2,861,883	$ 2,733,099
Actual ratio	10.95%	10.95%
Total Risk-Based Capital
Minimum amount	$ 2,090,638	$ 1,995,932
Minimum ratio	8.00%	8.00%
Well capitalized amount	$ 2,613,297	$ 2,494,915
Well capitalized ratio	10.00%	10.00%
Actual amount	$ 3,024,262	$ 2,888,500
Actual ratio	11.57%	11.58%
Capital Conversion Buffer	3.57%

Earnings Per Share - Schedule o

Earnings Per Share - Schedule of Calculation of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Common Share - Basic:
Net income	$ 99,850	$ 101,465	$ 301,579	$ 240,210
Less: Preferred stock dividends	3,599	3,599	8,146	8,146
Less: Dividends and undistributed earnings allocated to unvested restricted shares	874	908	2,806	2,341
Earnings allocated to common shareholders - basic	$ 95,377	$ 96,958	$ 290,627	$ 229,723
Weighted average common shares outstanding	51,984	55,571	53,160	55,047
Earnings per common share - basic (in usd per share)	$ 1.83	$ 1.74	$ 5.47	$ 4.17
Earnings Per Common Share - Diluted:
Earnings allocated to common shareholders - basic	$ 95,377	$ 96,958	$ 290,627	$ 229,723
Adjustment for undistributed earnings allocated to unvested restricted shares	(17)	(25)	(37)	(49)
Earnings allocated to common shareholders - diluted	$ 95,360	$ 96,933	$ 290,590	$ 229,674
Weighted average common shares outstanding	51,984	55,571	53,160	55,047
Dilutive potential common shares	308	374	333	360
Weighted average common shares outstanding - diluted	52,292	55,945	53,493	55,407
Earnings per common share - diluted (in usd per share)	$ 1.82	$ 1.73	$ 5.43	$ 4.14

Earnings Per Share - Narrative

Earnings Per Share - Narrative (Detail) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share
Weighted average number of shares held by Recognition and Retention Plan excluded from the calculation for basic shares outstanding	491,977	542,796	525,652	581,397
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive securities excluded from the computation of earnings per share	152,991	60,931	152,991	147,834

Share-Based Compensation - Narr

Share-Based Compensation - Narrative (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Future awards shares under approved incentive compensation plans	3,450,647
Share-based compensation maximum option term (in years)	10 years
Stock Option Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unearned share-based compensation associated with awards	$ 2.4
Unrecognized compensation cost related to stock options expected to be recognized over a weighted-average period	2 years 8 months 12 days
Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unearned share-based compensation associated with awards	$ 24.3	$ 30.9
Unrecognized compensation cost related to stock options expected to be recognized over a weighted-average period	1 year 3 months 18 days
Restricted Share Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	3 years
Phantom Stock Awards | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	5 years

Share-Based Compensation - Acti

Share-Based Compensation - Activity Related to Stock Options (Detail) - Stock Option Awards - $ / shares	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Number of shares
Balance at beginning of the period (in shares)	714,420,000	686,366,000
Granted (in shares)	127,090,000	97,620,000
Exercised (in shares)	(50,375,000)	(41,697,000)
Forfeited or expired (in shares)	(12,227,000)	(27,328,000)
Balance at end of the period (in shares)	778,908,000	714,961,000
Exercisable at period end (in shares)	533,784,000	500,349,000
Weighted Average Exercise Price
Balance at beginning of the period (in usd per share)	$ 61.41	$ 58.24
Granted (in usd per share)	70.34	82.02
Exercised (in usd per share)	52.99	53.12
Forfeited or expired (in usd per share)	72.79	68.19
Balance at end of the period (in usd per share)	63.23	61.41
Exercisable at period end (in usd per share)	$ 58.60	$ 56.70

Share-Based Compensation - Esti

Share-Based Compensation - Estimate Fair Value of Stock Option Awards with Weighted-Average Assumptions (Detail) - Stock Option Awards - $ / shares	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividends	2.30%	1.80%
Expected volatility	24.50%	24.30%
Risk-free interest rate	2.50%	2.70%
Expected term (in years)	5 years 8 months 12 days	5 years 9 months 18 days
Weighted-average grant-date fair value	$ 14.44	$ 18.48

Share-Based Compensation - Comp

Share-Based Compensation - Compensation Expense Included in Non-Interest Expense and Related Income Tax Benefits (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Stock Option Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	$ 373	$ 321	$ 1,058	$ 952
Income tax benefit	28	23	78	70
Restricted Stock And Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	5,088	4,843	16,242	14,192
Income tax benefit	1,068	1,017	3,411	2,980
Phantom Stock and Performance Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	$ 2,257	$ 2,375	$ 7,902	$ 7,388

Share-Based Compensation - Unve

Share-Based Compensation - Unvested Restricted Stock Award Activity (Detail) - Restricted Stock And Restricted Stock Units - shares	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Balance at beginning of the period (in shares)	700,628,000	738,187,000
Granted (in shares)	217,078,000	229,181,000
Forfeited (in shares)	(18,955,000)	(70,981,000)
Vested (in shares)	(248,047,000)	(192,217,000)
Balance at end of the period (in shares)	650,704,000	704,170,000

Share-Based Compensation - Sche

Share-Based Compensation - Schedule of Share and Dividend Equivalent Share Award Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Value of share equivalents
Market price of Company's stock (in usd per share)	$ 75.54	$ 81.35
Phantom Stock and Performance Stock Units
Number of share equivalents
Balance at beginning of the period (in shares)	353,407,000	393,844,000
Granted (in shares)	183,879,000	151,908,000
Forfeited share equivalents (in shares)	(30,283,000)	(59,550,000)
Vested share equivalents (in shares)	(107,592,000)	(130,497,000)
Balance at end of the period (in shares)	399,411,000	355,705,000
Value of share equivalents
Balance at beginning of the period (in shares)	$ 22,717	$ 30,523
Granted (in shares)	13,890	12,358
Forfeited share equivalents (in shares)	2,288	4,844
Vested share equivalents (in shares)	8,116	10,871
Balance at end of the period (in shares)	$ 30,171	$ 28,937

Fair Value Measurements - Finan

Fair Value Measurements - Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Assets
Securities available for sale, at fair value	$ 4,238,082,000	$ 4,783,579,000
Mortgage loans held for sale	255,276,000	107,734,000
Mortgage loans held for investment, at fair value option	4,138,000	3,143,000
Derivative instruments	131,710,000	24,174,000
Liabilities
Derivative instruments	9,891,000	21,288,000
Fair value assets transferred from Level 1 to Level 2	0
Level 1
Assets
Securities available for sale, at fair value	0	0
Mortgage loans held for investment, at fair value option	0	0
Level 2
Assets
Securities available for sale, at fair value	4,238,082,000	4,783,579,000
Mortgage loans held for investment, at fair value option	0	0
Level 3
Assets
Securities available for sale, at fair value	0	0
Mortgage loans held for investment, at fair value option	4,138,000	3,143,000
Recurring
Assets
Securities available for sale, at fair value	4,238,082,000	4,783,579,000
Mortgage loans held for sale	255,276,000	107,734,000
Mortgage loans held for investment, at fair value option	4,138,000	3,143,000
Derivative instruments	136,235,000	27,048,000
Total	4,633,731,000	4,921,504,000
Liabilities
Derivative instruments	10,851,000	22,124,000
Total	10,851,000	22,124,000
Recurring | Level 1
Assets
Securities available for sale, at fair value	0	0
Mortgage loans held for sale	0	0
Mortgage loans held for investment, at fair value option	0	0
Derivative instruments	0	0
Total	0	0
Liabilities
Derivative instruments	0	0
Total	0	0
Recurring | Level 2
Assets
Securities available for sale, at fair value	4,238,082,000	4,783,579,000
Mortgage loans held for sale	255,276,000	107,734,000
Mortgage loans held for investment, at fair value option	0	0
Derivative instruments	136,235,000	27,048,000
Total	4,629,593,000	4,918,361,000
Liabilities
Derivative instruments	10,851,000	22,124,000
Total	10,851,000	22,124,000
Recurring | Level 3
Assets
Securities available for sale, at fair value	0	0
Mortgage loans held for sale	0	0
Mortgage loans held for investment, at fair value option	4,138,000	3,143,000
Derivative instruments	0	0
Total	4,138,000	3,143,000
Liabilities
Derivative instruments	0	0
Total	$ 0	$ 0

Fair Value Measurements - Fin_2

Fair Value Measurements - Financial Assets and Liabilities Measured at Fair Value on Nonrecurring Basis (Detail) - Nonrecurring - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Assets
Impaired loans	$ 79,442	$ 65,914
OREO, net	4,008	6,433
Total	83,450	72,347
Level 1
Assets
Impaired loans	0	0
OREO, net	0	0
Total	0	0
Level 2
Assets
Impaired loans	0	0
OREO, net	0	0
Total	0	0
Level 3
Assets
Impaired loans	79,442	65,914
OREO, net	4,008	6,433
Total	$ 83,450	$ 72,347

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Difference Between the Aggregate Fair Value and the Aggregate Unpaid Principal Balance for Mortgage Loans Held for Sale and Mortgage Loans Held for Investment (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Mortgage loans held for sale, at fair value
Aggregate Fair Value	$ 255,276	$ 107,734
Aggregate Unpaid Principal	248,256	104,345
Aggregate Fair Value Less Unpaid Principal	7,020	3,389
Mortgage loans held for investment, at fair value
Aggregate Fair Value	4,138	3,143
Aggregate Unpaid Principal	4,306	3,595
Aggregate Fair Value Less Unpaid Principal	$ (168)	$ (452)

Fair Value Measurements - Amoun

Fair Value Measurements - Amount of Net Gains (Losses) from Fair Value Changes (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Mortgage loans held for sale, at fair value	$ 100	$ (1,041)	$ 3,631	$ (2,513)
Mortgage loans held for investment, at fair value	$ (14)	$ (296)	$ 73	$ (1,217)

Fair Value of Financial Instr_3

Fair Value of Financial Instruments - Estimated Fair Values and Carrying Amounts of Financial Instruments (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
Financial Assets
Securities available for sale, at fair value	$ 4,238,082	$ 4,783,579
Mortgage loans held for sale, at fair value	255,276	107,734
Mortgage loans held for investment, at fair value option	4,138	3,143
Derivative instruments	136,235	27,048
Cash and cash equivalents	930,933	690,453
Securities held to maturity	185,007	207,446
Financial Liabilities
Derivative instruments	10,851	22,124
Deposits	24,977,285	23,763,431	$ 23,193,446
Short-term borrowings	498,049	1,482,882
Long-term debt	1,394,202	1,166,151
Level 1
Financial Assets
Securities available for sale, at fair value	0	0
Mortgage loans held for sale, at fair value	0	0
Mortgage loans held for investment, at fair value option	0	0
Derivative instruments	0	0
Cash and cash equivalents	930,933	690,453
Securities held to maturity	0	0
Loans and leases, carried at amortized cost, net of unearned income and allowance for loan and lease losses	0	0
Financial Liabilities
Derivative instruments	0	0
Deposits	0	0
Short-term borrowings	223,049	315,882
Long-term debt	0	0
Level 2
Financial Assets
Securities available for sale, at fair value	4,238,082	4,783,579
Mortgage loans held for sale, at fair value	255,276	107,734
Mortgage loans held for investment, at fair value option	0	0
Derivative instruments	136,235	27,048
Cash and cash equivalents	0	0
Securities held to maturity	192,586	204,277
Loans and leases, carried at amortized cost, net of unearned income and allowance for loan and lease losses	0	0
Financial Liabilities
Derivative instruments	10,851	22,124
Deposits	24,985,510	23,752,139
Short-term borrowings	275,000	1,167,000
Long-term debt	0	0
Level 3
Financial Assets
Securities available for sale, at fair value	0	0
Mortgage loans held for sale, at fair value	0	0
Mortgage loans held for investment, at fair value option	4,138	3,143
Derivative instruments	0	0
Cash and cash equivalents	0	0
Securities held to maturity	0	0
Loans and leases, carried at amortized cost, net of unearned income and allowance for loan and lease losses	23,290,286	22,088,236
Financial Liabilities
Derivative instruments	0	0
Deposits	0	0
Short-term borrowings	0	0
Long-term debt	1,391,857	1,154,062
Carrying Amount
Financial Assets
Securities available for sale, at fair value	4,238,082	4,783,579
Mortgage loans held for sale, at fair value	255,276	107,734
Mortgage loans held for investment, at fair value option	4,138	3,143
Derivative instruments	136,235	27,048
Cash and cash equivalents	930,933	690,453
Securities held to maturity	185,007	207,446
Loans and leases, carried at amortized cost, net of unearned income and allowance for loan and lease losses	23,526,164	22,376,101
Financial Liabilities
Derivative instruments	10,851	22,124
Deposits	24,977,285	23,763,431
Short-term borrowings	498,049	1,482,882
Long-term debt	1,394,202	1,166,151
Fair Value
Financial Assets
Securities available for sale, at fair value	4,238,082	4,783,579
Mortgage loans held for sale, at fair value	255,276	107,734
Mortgage loans held for investment, at fair value option	4,138	3,143
Derivative instruments	136,235	27,048
Cash and cash equivalents	930,933	690,453
Securities held to maturity	192,586	204,277
Loans and leases, carried at amortized cost, net of unearned income and allowance for loan and lease losses	23,290,286	22,088,236
Financial Liabilities
Derivative instruments	10,851	22,124
Deposits	24,985,510	23,752,139
Short-term borrowings	498,049	1,482,882
Long-term debt	$ 1,391,857	$ 1,154,062

Business Segments (Detail)

Business Segments (Detail) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)Segment	Sep. 30, 2018USD ($)	Dec. 31, 2018USD ($)
Segment Reporting Information
Number of business segments | Segment			3
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Interest and dividend income	$ 333,178	$ 317,067	$ 995,229	$ 891,433
Interest expense	83,845	57,842	240,073	143,206
Net interest income	249,333	259,225	755,156	748,227
Other Income and Expenses [Abstract]
Provision for/(reversal of) loan losses	8,986	11,384	33,504	27,290
Other non-interest income (expense)	39,072	34,078	107,993	97,395
Allocated expenses (income)	0	0	0	0
Non-interest expense	172,662	169,062	501,033	553,910
Income before income tax expense	131,359	131,866	395,627	318,620
Income tax expense	31,509	30,401	94,048	78,410
Net income	99,850	101,465	301,579	240,210
Total loans, leases, and loans held for sale, net of unearned income	23,931,813	22,386,882	23,931,813	22,386,882
Total assets	31,734,598	30,118,387	31,734,598	30,118,387	$ 30,833,015
Deposits	24,977,285	23,193,446	24,977,285	23,193,446	$ 23,763,431
Average assets	31,554,291	30,046,231	31,222,511	29,323,445
Title revenue
Other Income and Expenses [Abstract]
Non-interest income	7,170	6,280	19,290	18,153
Mortgage income
Other Income and Expenses [Abstract]
Non-interest income	17,432	12,729	47,725	36,045
Operating Segments | IBERIABANK
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Interest and dividend income	330,896	315,467	989,595	886,629
Interest expense	83,845	57,842	240,073	143,206
Net interest income	247,051	257,625	749,522	743,423
Other Income and Expenses [Abstract]
Provision for/(reversal of) loan losses	8,974	11,386	33,539	27,316
Other non-interest income (expense)	35,881	33,594	104,840	96,981
Allocated expenses (income)	(4,068)	(3,691)	(10,515)	(9,043)
Non-interest expense	152,988	154,000	447,882	505,423
Income before income tax expense	125,038	129,524	383,456	316,708
Income tax expense	29,938	29,765	91,047	78,516
Net income	95,100	99,759	292,409	238,192
Total loans, leases, and loans held for sale, net of unearned income	23,650,057	22,302,679	23,650,057	22,302,679
Total assets	31,386,350	29,974,065	31,386,350	29,974,065
Deposits	24,946,708	23,179,549	24,946,708	23,179,549
Average assets	31,256,216	29,863,742	30,981,906	29,136,369
Operating Segments | IMC
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Interest and dividend income	2,282	1,599	5,633	4,802
Interest expense	0	0	0	0
Net interest income	2,282	1,599	5,633	4,802
Other Income and Expenses [Abstract]
Provision for/(reversal of) loan losses	12	(2)	(35)	(26)
Other non-interest income (expense)	3,194	(16)	3,172	(83)
Allocated expenses (income)	2,991	2,680	7,741	6,714
Non-interest expense	14,676	10,223	38,807	34,105
Income before income tax expense	5,229	1,411	10,017	(29)
Income tax expense	1,282	386	2,425	(7)
Net income	3,947	1,025	7,592	(22)
Total loans, leases, and loans held for sale, net of unearned income	281,756	84,203	281,756	84,203
Total assets	320,994	119,322	320,994	119,322
Deposits	30,577	13,897	30,577	13,897
Average assets	271,817	158,464	215,306	164,039
Operating Segments | LTC
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Interest and dividend income	0	1	1	2
Interest expense	0	0	0	0
Net interest income	0	1	1	2
Other Income and Expenses [Abstract]
Provision for/(reversal of) loan losses	0	0	0	0
Other non-interest income (expense)	(3)	500	(19)	497
Allocated expenses (income)	1,077	1,011	2,774	2,329
Non-interest expense	4,998	4,839	14,344	14,382
Income before income tax expense	1,092	931	2,154	1,941
Income tax expense	289	250	576	(99)
Net income	803	681	1,578	2,040
Total loans, leases, and loans held for sale, net of unearned income	0	0	0	0
Total assets	27,254	25,000	27,254	25,000
Deposits	0	0	0	0
Average assets	26,258	24,025	25,299	23,037
Operating Segments | Title revenue | IBERIABANK
Other Income and Expenses [Abstract]
Non-interest income	0	0	0	0
Operating Segments | Title revenue | IMC
Other Income and Expenses [Abstract]
Non-interest income	0	0	0	0
Operating Segments | Title revenue | LTC
Other Income and Expenses [Abstract]
Non-interest income	7,170	6,280	19,290	18,153
Operating Segments | Mortgage income | IBERIABANK
Other Income and Expenses [Abstract]
Non-interest income	0	0	0	0
Operating Segments | Mortgage income | IMC
Other Income and Expenses [Abstract]
Non-interest income	17,432	12,729	47,725	36,045
Operating Segments | Mortgage income | LTC
Other Income and Expenses [Abstract]
Non-interest income	$ 0	$ 0	$ 0	$ 0

Business Segments - Schedule of

Business Segments - Schedule of Segment Reporting Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Segment Reporting Information
Interest and dividend income	$ 333,178	$ 317,067	$ 995,229	$ 891,433
Interest expense	83,845	57,842	240,073	143,206
Net interest income	249,333	259,225	755,156	748,227
Provision for/(reversal of) loan losses	8,986	11,384	33,504	27,290
Other non-interest income (expense)	39,072	34,078	107,993	97,395
Allocated expenses (income)	0	0	0	0
Non-interest expense	172,662	169,062	501,033	553,910
Income before income tax expense	131,359	131,866	395,627	318,620
Income tax expense	31,509	30,401	94,048	78,410
Net income	99,850	101,465	301,579	240,210
Total loans, leases, and loans held for sale, net of unearned income	23,931,813	22,386,882	23,931,813	22,386,882
Total assets	31,734,598	30,118,387	31,734,598	30,118,387	$ 30,833,015
Total deposits	24,977,285	23,193,446	24,977,285	23,193,446	$ 23,763,431
Average assets	31,554,291	30,046,231	31,222,511	29,323,445
Operating Segments | IBERIABANK
Segment Reporting Information
Interest and dividend income	330,896	315,467	989,595	886,629
Interest expense	83,845	57,842	240,073	143,206
Net interest income	247,051	257,625	749,522	743,423
Provision for/(reversal of) loan losses	8,974	11,386	33,539	27,316
Other non-interest income (expense)	35,881	33,594	104,840	96,981
Allocated expenses (income)	(4,068)	(3,691)	(10,515)	(9,043)
Non-interest expense	152,988	154,000	447,882	505,423
Income before income tax expense	125,038	129,524	383,456	316,708
Income tax expense	29,938	29,765	91,047	78,516
Net income	95,100	99,759	292,409	238,192
Total loans, leases, and loans held for sale, net of unearned income	23,650,057	22,302,679	23,650,057	22,302,679
Total assets	31,386,350	29,974,065	31,386,350	29,974,065
Total deposits	24,946,708	23,179,549	24,946,708	23,179,549
Average assets	31,256,216	29,863,742	30,981,906	29,136,369
Operating Segments | IMC
Segment Reporting Information
Interest and dividend income	2,282	1,599	5,633	4,802
Interest expense	0	0	0	0
Net interest income	2,282	1,599	5,633	4,802
Provision for/(reversal of) loan losses	12	(2)	(35)	(26)
Other non-interest income (expense)	3,194	(16)	3,172	(83)
Allocated expenses (income)	2,991	2,680	7,741	6,714
Non-interest expense	14,676	10,223	38,807	34,105
Income before income tax expense	5,229	1,411	10,017	(29)
Income tax expense	1,282	386	2,425	(7)
Net income	3,947	1,025	7,592	(22)
Total loans, leases, and loans held for sale, net of unearned income	281,756	84,203	281,756	84,203
Total assets	320,994	119,322	320,994	119,322
Total deposits	30,577	13,897	30,577	13,897
Average assets	271,817	158,464	215,306	164,039
Operating Segments | LTC
Segment Reporting Information
Interest and dividend income	0	1	1	2
Interest expense	0	0	0	0
Net interest income	0	1	1	2
Provision for/(reversal of) loan losses	0	0	0	0
Other non-interest income (expense)	(3)	500	(19)	497
Allocated expenses (income)	1,077	1,011	2,774	2,329
Non-interest expense	4,998	4,839	14,344	14,382
Income before income tax expense	1,092	931	2,154	1,941
Income tax expense	289	250	576	(99)
Net income	803	681	1,578	2,040
Total loans, leases, and loans held for sale, net of unearned income	0	0	0	0
Total assets	27,254	25,000	27,254	25,000
Total deposits	0	0	0	0
Average assets	26,258	24,025	25,299	23,037
Mortgage income
Segment Reporting Information
Non-interest income	17,432	12,729	47,725	36,045
Mortgage income | Operating Segments | IBERIABANK
Segment Reporting Information
Non-interest income	0	0	0	0
Mortgage income | Operating Segments | IMC
Segment Reporting Information
Non-interest income	17,432	12,729	47,725	36,045
Mortgage income | Operating Segments | LTC
Segment Reporting Information
Non-interest income	0	0	0	0
Title revenue
Segment Reporting Information
Non-interest income	7,170	6,280	19,290	18,153
Title revenue | Operating Segments | IBERIABANK
Segment Reporting Information
Non-interest income	0	0	0	0
Title revenue | Operating Segments | IMC
Segment Reporting Information
Non-interest income	0	0	0	0
Title revenue | Operating Segments | LTC
Segment Reporting Information
Non-interest income	$ 7,170	$ 6,280	$ 19,290	$ 18,153

Commitments and Contingencies_2

Commitments and Contingencies (Detail) - USD ($) $ in Millions	Dec. 11, 2017	Sep. 30, 2019	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Fair value of guarantees under commercial and standby letters of credit		$ 2.2	$ 2.4
Settled Litigation
Loss Contingencies [Line Items]
Settlement amount	$ 11.7
Pending Litigation
Loss Contingencies [Line Items]
Damages sought		$ 11.7

Commitments and Contingencies -

Commitments and Contingencies - Summary of Financial Instruments Outstanding (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments to extend credit	$ 883,615	$ 642,162
Unfunded commitments under lines of credit	7,252,052	6,883,963
Commercial and standby letters of credit	215,664	240,436
Reserve for unfunded lending commitments	$ 16,144	$ 14,830	$ 14,721	$ 13,208

Subsequent Events (Details)

Subsequent Events (Details)	3 Months Ended
	Jun. 30, 2020$ / shares
Forecast | Subsequent Event
Subsequent Event [Line Items]
Number of shares exchanged per Company share	$ 4.584

Uncategorized Items - ibkc10-q9

Label	Element	Value
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ (345,000)	[1]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets	us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleCumulativeEffectOfChangeOnEquityOrNetAssets1	1,847,000	[2]
Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	(345,000)	[1]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets	us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleCumulativeEffectOfChangeOnEquityOrNetAssets1	$ 1,847,000	[2]
[1]	Cumulative-effect adjustment to beginning retained earnings for fair value adjustments related to the reclassification of certain equity investments in accordance with ASU 2016-01, adopted as of January 1, 2018.
[2]	Cumulative-effect adjustment to beginning retained earnings related to the recognition of pre-existing lease liabilities and previously deferred gains on sale-leaseback transactions in accordance with ASU 2016-02, adopted as of January 1, 2019.