Hancock Whitney Corporation - 6 (HWC) 10-Q 6 Nov 15 2015 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2015	Nov. 03, 2015
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q3
Trading Symbol	HBHC
Entity Registrant Name	HANCOCK HOLDING CO
Entity Central Index Key	750,577
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		77,397,992

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
ASSETS
Cash and due from banks	$ 323,743	$ 356,455
Interest-bearing bank deposits	189,989	801,576
Federal funds sold	4,425	1,372
Securities available for sale, at fair value (amortized cost of $2,140,436 and $1,631,761)	2,168,837	1,660,165
Securities held to maturity (fair value of $2,414,682 and $2,186,340)	2,380,085	2,166,289
Loans held for sale	19,764	20,252
Loans	14,763,050	13,895,276
Less: allowance for loan losses	(139,576)	(128,762)
Loans, net	14,623,474	13,766,514
Property and equipment, net of accumulated depreciation of $203,994 and $193,527	380,809	398,384
Prepaid expenses	23,555	28,277
Other real estate, net	32,493	58,415
Accrued interest receivable	51,781	47,501
Goodwill	621,193	621,193
Other intangible assets, net	113,229	132,810
Life insurance contracts	431,524	426,617
FDIC loss share receivable	32,035	60,272
Deferred tax asset, net	66,942	74,335
Other assets	144,272	126,839
Total assets	21,608,150	20,747,266
Deposits:
Noninterest-bearing	6,075,558	5,945,208
Interest-bearing	11,364,390	10,627,623
Total deposits	17,439,948	16,572,831
Short-term borrowings	1,049,182	1,151,573
Long-term debt	497,177	374,371
Accrued interest payable	7,087	4,204
Other liabilities	161,195	171,885
Total liabilities	19,154,589	18,274,864
Stockholders' equity
Common stock - $3.33 par value per share; 350,000,000 shares authorized, 77,518,998 and 80,426,485 shares outstanding	258,138	267,820
Capital surplus	1,710,903	1,689,291
Treasury shares at cost - 9,296,513 and 7,053,028 shares	(251,082)	(158,131)
Retained earnings	781,769	723,496
Accumulated other comprehensive loss, net	(46,167)	(50,074)
Total stockholders' equity	2,453,561	2,472,402
Total liabilities and stockholders' equity	$ 21,608,150	$ 20,747,266

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Securities available for sale, amortized cost	$ 2,140,436	$ 1,631,761
Held to maturity securities, fair value	2,414,682	2,186,340
Property and equipment, accumulated depreciation	$ 203,994	$ 193,527
Common stock, par value per share	$ 3.33	$ 3.33
Common stock, shares authorized	350,000,000	350,000,000
Common stock, shares outstanding	77,518,998	80,426,485
Treasury shares, shares	9,296,513	7,053,028

Consolidated Statements of Inco

Consolidated Statements of Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Interest income:
Loans, including fees	$ 146,398	$ 150,481	$ 435,270	$ 453,066
Loans held for sale	176	197	494	544
Securities-taxable	23,631	20,824	66,095	64,601
Securities-tax exempt	839	954	2,564	2,946
Short-term investments	285	245	913	685
Total interest income	171,329	172,701	505,336	521,842
Interest expense:
Deposits	8,933	5,828	23,680	16,431
Short-term borrowings	273	238	631	2,109
Long-term debt	5,293	3,094	14,246	9,421
Total interest expense	14,499	9,160	38,557	27,961
Net interest income	156,830	163,541	466,779	493,881
Provision for loan losses	10,080	9,468	22,842	24,122
Net interest income after provision for loan losses	146,750	154,073	443,937	469,759
Noninterest income:
Service charges on deposit accounts	18,619	20,000	53,842	57,981
Trust fees	11,345	11,530	34,340	33,267
Bank card and ATM fees	11,637	11,641	34,688	33,806
Investment and annuity fees	6,149	5,506	16,037	15,555
Secondary mortgage market operations	3,413	2,313	9,695	6,036
Insurance commissions and fees	2,238	1,979	6,587	7,611
Amortization of FDIC loss share receivable	(1,564)	(2,760)	(4,034)	(9,989)
Other income	8,370	7,732	26,139	26,771
Securities transactions	4		337
Total noninterest income	60,211	57,941	177,631	171,038
Noninterest expense:
Compensation expense	71,187	69,207	206,754	204,900
Employee benefits	12,968	11,957	41,472	38,812
Personnel expense	84,155	81,164	248,226	243,712
Net occupancy expense	11,222	10,848	34,203	32,983
Equipment expense	3,598	4,619	11,623	12,958
Data processing expense	13,844	13,004	41,412	38,310
Professional services expense	7,656	7,229	31,978	22,817
Amortization of intangibles	6,027	6,570	18,493	20,352
Telecommunications and postage	3,485	3,648	10,607	11,094
Deposit insurance and regulatory fees	4,225	2,967	12,033	8,677
Other real estate expense, net	422	(104)	1,379	1,757
Other expense	16,559	19,134	53,671	60,259
Total noninterest expense	151,193	149,079	463,625	452,919
Income before income taxes	55,768	62,935	157,943	187,878
Income taxes	14,602	16,382	41,789	52,248
Net income	$ 41,166	$ 46,553	$ 116,154	$ 135,630
Earnings per common share-basic	$ 0.52	$ 0.56	$ 1.45	$ 1.62
Earnings per common share-diluted	0.52	0.56	1.45	1.62
Dividends paid per share	$ 0.24	$ 0.24	$ 0.72	$ 0.72
Weighted average shares outstanding-basic	77,928	81,721	78,452	81,965
Weighted average shares outstanding-diluted	78,075	81,942	78,609	82,204

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 41,166	$ 46,553	$ 116,154	$ 135,630
Other comprehensive income:
Net change in unrealized gain (loss)	15,131	(6,293)	2,174	9,119
Reclassification adjustment for net losses realized and included in earnings	802	98	2,208	293
Valuation adjustment for employee benefit plans	4,963	(104)	(959)	1,902
Amortization of unrealized net gain on securities transferred to held to maturity	1,023	892	2,609	2,463
Other comprehensive income (loss) before income taxes	21,919	(5,407)	6,032	13,777
Income tax expense (benefit)	8,002	(2,005)	2,125	5,091
Other comprehensive income (losses) net of income taxes	13,917	(3,402)	3,907	8,686
Comprehensive income	$ 55,083	$ 43,151	$ 120,061	$ 144,316

Consolidated Statements of Chan

Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock [Member]	Capital Surplus [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss), net [Member]	Treasury Stock [Member]
Balance at Dec. 31, 2013	$ 2,425,069	$ 273,850	$ 1,647,467	$ 628,166	$ (35,379)	$ (89,035)
Balance, Shares at Dec. 31, 2013		82,237,162
Net income	135,630			135,630
Other comprehensive income	8,686				8,686
Comprehensive income	144,316			135,630	8,686
Cash dividends declared ($0.72 per common share)	(60,290)			(60,290)
Common stock activity, long-term incentive plan	10,214	$ 749	49,119			(39,654)
Common stock activity, long-term incentive plan, shares		224,963
Purchase of common stock under stock buyback programs	(9,967)	$ (2,982)				(6,985)
Purchase of common stock under stock buyback programs, shares		(895,485)
Balance at Sep. 30, 2014	2,509,342	$ 271,617	1,696,586	703,506	(26,693)	(135,674)
Balance, Shares at Sep. 30, 2014		81,566,640
Balance at Dec. 31, 2014	2,472,402	$ 267,820	1,689,291	723,496	(50,074)	(158,131)
Balance, Shares at Dec. 31, 2014		80,426,485
Net income	116,154			116,154
Other comprehensive income	3,907				3,907
Comprehensive income	120,061			116,154	3,907
Cash dividends declared ($0.72 per common share)	(57,881)			(57,881)
Common stock activity, long-term incentive plan	9,815	$ 747	21,612			(12,544)
Common stock activity, long-term incentive plan, shares		224,399
Purchase of common stock under stock buyback programs	(90,836)	$ (10,429)				(80,407)
Purchase of common stock under stock buyback programs, shares		(3,131,886)
Balance at Sep. 30, 2015	$ 2,453,561	$ 258,138	$ 1,710,903	$ 781,769	$ (46,167)	$ (251,082)
Balance, Shares at Sep. 30, 2015		77,518,998

Consolidated Statements of Cha7

Consolidated Statements of Changes in Stockholders' Equity (Unaudited) (Parenthetical) - $ / shares	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Cash dividends declared, per common share	$ 0.72	$ 0.72
Retained Earnings [Member]
Cash dividends declared, per common share	$ 0.72	$ 0.72

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 116,154	$ 135,630
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	21,533	22,976
Provision for loan losses	22,842	24,122
Gain on other real estate owned	(521)	(34)
Deferred tax expense	11,895	24,295
Increase in cash surrender value of life insurance contracts	(7,700)	(6,960)
Loss (gain) on disposal of other assets	1,626	(1,411)
Net decrease in loans held for sale	498	7,017
Write-downs on closed branch transfers to other real estate owned		2,683
Net amortization of securities premium/discount	15,456	12,891
Amortization of intangible assets	18,493	20,352
Amortization of FDIC indemnification asset	4,034	9,989
Stock-based compensation expense	9,469	10,514
(Decrease) increase in interest payable and other liabilities	(6,753)	(9,132)
Net payments from (to) FDIC for loss share claims	14,667	(366)
Decrease in FDIC loss share receivable	6,309	7,729
(Increase) decrease in other assets	(9,339)	21,086
Other, net	4,127	6,256
Net cash provided by operating activities	222,790	287,637
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from sales of securities	9,287	1,301
Proceeds from maturities of securities available for sale	755,663	218,351
Purchases of securities available for sale	(1,286,443)	(440,187)
Proceeds from maturities of securities held to maturity	439,410	358,649
Purchases of securities held to maturity	(658,226)	(1,031)
Net decrease (increase) in interest-bearing bank deposits	611,587	(199,982)
Net increase in federal funds sold and short-term investments	(3,053)	(2,736)
Net increase in loans	(882,702)	(1,060,864)
Purchase of life insurance contracts		(30,000)
Purchases of property and equipment	(19,529)	(14,370)
Proceeds from sales of property and equipment	13,607	8,607
Proceeds from sales of other real estate	39,612	42,913
Other, net	(8,603)	4,273
Net cash used in investing activities	(989,390)	(1,115,076)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase in deposits	867,117	376,178
Net (decrease) increase in short-term borrowings	(102,391)	513,849
Repayments of long-term debt	(31,621)	(26,558)
Net proceeds from issuance of long-term debt	149,153	17,184
Dividends paid	(57,881)	(60,290)
Purchase of common stock under stock buyback program	(90,836)	(9,967)
Proceeds from exercise of stock options	347	962
Net cash provided by financing activities	733,888	811,358
NET DECREASE IN CASH AND DUE FROM BANKS	(32,712)	(16,081)
CASH AND DUE FROM BANKS, BEGINNING	356,455	348,440
CASH AND DUE FROM BANKS, ENDING	323,743	332,359
SUPPLEMENTAL INFORMATION FOR NON-CASH INVESTING AND FINANCING ACTIVITIES
Assets acquired in settlement of loans	$ 12,997	$ 23,920

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2015
Accounting Policies [Abstract]
Basis of Presentation	1. Basis of Presentation The consolidated financial statements include the accounts of Hancock Holding Company and all other entities in which it has a controlling interest (the “Company”). The financial statements include all adjustments that are, in the opinion of management, necessary to present fairly the Company’s financial condition, results of operations, changes in stockholders’ equity and cash flows for the interim periods presented. Some financial information and disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the U.S. (“GAAP”) have been condensed or omitted in this Form 10-Q pursuant to Securities and Exchange Commission rules and regulations. These financial statements should be read in conjunction with the audited consolidated financial statements and the notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2014. Financial information reported in these financial statements is not necessarily indicative of the Company’s financial condition, results of operations, or cash flows for any other interim or annual period. Use of Estimates The accounting principles the Company follows and the methods for applying these principles conform with GAAP and with those generally practiced within the banking industry. These accounting principles require management to make estimates and assumptions about future events that affect the amounts reported in the consolidated financial statements and the accompanying notes. Actual results could differ from those estimates. Critical Accounting Policies and Estimates There were no material changes or developments with respect to methodologies that the Company uses when applying what management believes are critical accounting policies and developing critical accounting estimates as disclosed in its Annual Report on Form 10-K for the year ended December 31, 2014.

Securities

Securities	9 Months Ended
	Sep. 30, 2015
Investments, Debt and Equity Securities [Abstract]
Securities	2. Securities The amortized cost and fair value of securities classified as available for sale and held to maturity follow. Securities Available for Sale (in thousands) September 30, 2015 December 31, 2014 Amortized Gross Gross Fair Value Amortized Gross Gross Fair Value US Treasury and government agency securities $ 144 $ — $ 1 $ 143 $ 300,207 $ 372 $ 71 $ 300,508 Municipal obligations 15,712 240 — 15,952 13,995 186 5 14,176 Mortgage-backed securities 1,814,818 30,021 3,470 1,841,369 1,217,293 31,094 2,823 1,245,564 Collateralized mortgage obligations 303,816 1,964 633 305,147 88,093 — 1,229 86,864 Corporate debt securities 3,500 — — 3,500 3,500 — — 3,500 Equity securities 2,446 313 33 2,726 8,673 891 11 9,553 $ 2,140,436 $ 32,538 $ 4,137 $ 2,168,837 $ 1,631,761 $ 32,543 $ 4,139 $ 1,660,165 Securities Held to Maturity (in thousands) September 30, 2015 December 31, 2014 Amortized Gross Gross Fair Value Amortized Gross Gross Fair Value US Treasury and government agency securities $ 50,000 $ 343 $ — 50,343 $ — $ — $ — $ — Municipal obligations 187,541 3,777 575 190,743 180,615 3,416 1,144 182,887 Mortgage-backed securities 992,984 27,677 — 1,020,661 899,923 23,897 162 923,658 Collateralized mortgage obligations 1,149,560 8,655 5,280 1,152,935 1,085,751 5,590 11,546 1,079,795 $ 2,380,085 $ 40,452 $ 5,855 $ 2,414,682 $ 2,166,289 $ 32,903 $ 12,852 $ 2,186,340 The following table presents the amortized cost and fair value of debt securities at September 30, 2015 by contractual maturity. Actual maturities will differ from contractual maturities because of rights to call or repay obligations with or without penalties and scheduled and unscheduled principal payments on mortgage-backed securities and collateralized mortgage obligations. (in thousands) Amortized Fair Value Debt Securities Available for Sale Due in one year or less $ 43,655 $ 43,069 Due after one year through five years 78,375 79,710 Due after five years through ten years 280,603 289,987 Due after ten years 1,735,357 1,753,345 Total available for sale debt securities $ 2,137,990 $ 2,166,111 Amortized Fair Value Debt Securities Held to Maturity Due in one year or less $ 248,854 $ 250,028 Due after one year through five years 420,607 420,768 Due after five years through ten years 107,040 107,116 Due after ten years 1,603,584 1,636,770 Total held to maturity securities $ 2,380,085 $ 2,414,682 The Company held no securities classified as trading at September 30, 2015 or December 31, 2014. The details for securities classified as available for sale with unrealized losses for the periods indicated follow. Available for Sale September 30, 2015 Losses < 12 months Losses 12 months or > Total (in thousands) Fair Value Gross Fair Value Gross Fair Value Gross US Treasury and government agency securities $ — $ — $ 88 $ 1 $ 88 $ 1 Mortgage-backed securities 482,530 1,884 115,334 1,586 597,864 3,470 Collateralized mortgage obligations 48,576 11 34,958 622 83,534 633 Equity securities 1,510 31 2 2 1,512 33 $ 532,616 $ 1,926 $ 150,382 $ 2,211 $ 682,998 $ 4,137 Available for Sale December 31, 2014 Losses < 12 months Losses 12 months or > Total (in thousands) Fair Value Gross Fair Value Gross Fair Value Gross US Treasury and government agency securities $ 99,950 $ 70 $ 121 $ 1 $ 100,071 $ 71 Municipal obligations 2,995 5 — — 2,995 5 Mortgage-backed securities 38,955 163 125,641 2,660 164,596 2,823 Collateralized mortgage obligations — — 86,864 1,229 86,864 1,229 Equity securities 5,998 10 3 1 6,001 11 $ 147,898 $ 248 $ 212,629 $ 3,891 $ 360,527 $ 4,139 The details for securities classified as held to maturity with unrealized losses for the periods indicated follow. Held to maturity September 30, 2015 Losses < 12 months Losses 12 months or > Total (in thousands) Fair Gross Fair Value Gross Fair Value Gross Municipal obligations $ 21,844 $ 65 $ 49,025 $ 510 $ 70,869 $ 575 Collateralized mortgage obligations 47,775 314 375,397 4,966 423,172 5,280 $ 69,619 $ 379 $ 424,422 $ 5,476 $ 494,041 $ 5,855 Held to maturity December 31, 2014 Losses < 12 months Losses 12 months or > Total (in thousands) Fair Value Gross Fair Value Gross Fair Value Gross Municipal obligations $ 4,316 $ 12 $ 58,105 $ 1,132 $ 62,421 $ 1,144 Mortgage-backed securities — — 95,522 162 95,522 162 Collateralized mortgage obligations 119,222 616 540,607 10,930 659,829 11,546 $ 123,538 $ 628 $ 694,234 $ 12,224 $ 817,772 $ 12,852 The unrealized losses primarily relate to changes in market rates on fixed-rate debt securities since the respective purchase dates. In all cases, the indicated impairment on these debt securities would be recovered no later than the security’s maturity date or possibly earlier if the market price for the security increases with a reduction in the yield required by the market. None of the unrealized losses relate to the marketability of the securities or the issuer’s ability to meet contractual obligations. The Company believes it has adequate liquidity and, therefore, does not plan to and, more likely than not, will not be required to sell these securities before recovery of the indicated impairment. Accordingly, the unrealized losses on these securities have been determined to be temporary. Securities with carrying values totaling $3.0 billion at September 30, 2015 and $3.2 billion at December 31, 2014 were pledged as collateral primarily to secure public deposits or securities sold under agreements to repurchase.

Loans and Allowance for Loan Lo

Loans and Allowance for Loan Losses	9 Months Ended
	Sep. 30, 2015
Receivables [Abstract]
Loans and Allowance for Loan Losses	3. Loans and Allowance for Loan Losses Loans, net of unearned income, consisted of the following. (in thousands) September 30, December 31, Originated loans: Commercial non-real estate $ 6,232,310 $ 5,917,728 Construction and land development 1,068,895 1,073,964 Commercial real estate 2,956,354 2,428,195 Residential mortgages 1,843,756 1,704,770 Consumer 1,976,872 1,685,542 Total originated loans $ 14,078,187 $ 12,810,199 Acquired loans: Commercial non-real estate $ 107,985 $ 120,137 Construction and land development 8,297 21,123 Commercial real estate 352,896 688,045 Residential mortgages 819 2,378 Consumer 22 985 Total acquired loans $ 470,019 $ 832,668 FDIC acquired loans: Commercial non-real estate $ 5,699 $ 6,195 Construction and land development 8,393 11,674 Commercial real estate 18,136 27,808 Residential mortgages 169,214 187,033 Consumer 13,402 19,699 Total FDIC acquired loans $ 214,844 $ 252,409 Total loans: Commercial non-real estate $ 6,345,994 $ 6,044,060 Construction and land development 1,085,585 1,106,761 Commercial real estate 3,327,386 3,144,048 Residential mortgages 2,013,789 1,894,181 Consumer 1,990,296 1,706,226 Total loans $ 14,763,050 $ 13,895,276 The following briefly describes the distinction among originated, acquired and FDIC acquired loans and certain significant accounting policies relevant to each category. Originated loans Loans reported as “originated” include both loans and leases originated for investment and acquired-performing loans where the discount (premium) has been fully accreted (amortized). Originated loans are reported at the principal balance outstanding, net of unearned income. Interest on loans and accretion of unearned income, including deferred loan fees, are computed in a manner that approximates a level yield on recorded principal. Interest on loans is recognized in income as earned. The accrual of interest on an originated loan is discontinued when, in management’s opinion, it is probable that the borrower will be unable to meet payment obligations as they become due, as well as when required by regulatory provisions. When accrual of interest is discontinued on a loan, all unpaid accrued interest is reversed and payments subsequently received are applied first to recover principal. Interest income is recognized for payments received after contractual principal has been satisfied. Loans are returned to accrual status when all the principal and interest contractually due are brought current and future payment performance is reasonably assured. Acquired loans Loans reported as “acquired” are those loans that were purchased in the 2011 Whitney Holding Corporation acquisition. These loans were recorded at estimated fair value at the acquisition date with no carryover of the related allowance for loan losses. At the time of the Whitney acquisition, the Whitney acquired loans were segregated between those considered to be performing (“acquired-performing”) and those with evidence of credit deterioration (“acquired-impaired”) based on such factors as past due status, nonaccrual status and credit risk ratings (rated substandard or worse). The acquired loans were further segregated into loan pools designed to facilitate the development of expected cash flows to be used in estimating fair value for purchase accounting. Acquired-performing loans are accounted for under ASC 310-20 and acquired-impaired loans are accounted for under ASC 310-30. Acquired-performing loans were segregated into pools based on common risk characteristics such as loan type, credit risk ratings, and contractual interest rate and repayment terms. The major loan types included commercial and industrial loans not secured by real estate, real estate construction and land development loans, commercial real estate loans, residential mortgage loans, and consumer loans, with further segregation within certain loan types as needed. Expected cash flows, both principal and interest, from each pool were estimated based on key assumptions covering such factors as prepayments, default rates, and severity of loss given a default. These assumptions were developed using both historical experience and the portfolio characteristics at acquisition as well as available market research. The fair value for each acquired-performing pool was based on the estimate of expected cash flows from the pool discounted at prevailing market rates. The difference at the acquisition date between the fair value and the contractual amounts due of an acquired-performing loan pool (the “fair value discount”) is accreted into income over the estimated life of the pool. Acquired-performing loans are placed on nonaccrual status and reported as nonperforming or past due using the same criteria applied to the originated portfolio. The acquired-impaired loans were segregated into pools by identifying loans with common credit risk profiles and were based primarily on characteristics such as loan type and market area in which originated. The major loan types included commercial and industrial loans not secured by real estate, real estate construction and land development loans, commercial real estate loans, and residential mortgage loans, with further segregation within certain loan types as needed. The acquired-impaired loans were further disaggregated by geographic region in recognition of the differences in general economic conditions affecting borrowers in certain states. The fair value estimate for each pool of acquired-impaired loans was based on the estimate of expected cash flows from the pool discounted at prevailing market rates. The excess of estimated cash flows expected to be collected from an acquired-impaired loan pool over the pool’s carrying value is referred to as the accretable yield and is recognized in interest income using an effective yield method over the expected life of the loan pool. Each pool of acquired-impaired loans is accounted for as a single asset with a single composite interest rate and an aggregate expectation of cash flows. Acquired-impaired loans in pools with an accretable yield and expected cash flows that are reasonably estimable are considered to be accruing and performing even though collection of contractual payments on loans within the pool may be in doubt, because the pool is the unit of accounting. Acquired-impaired loans are generally not subject to individual evaluation for impairment and are not reported with impaired loans or troubled debt restructurings even if they would otherwise qualify for such treatment. FDIC acquired loans and the related loss share receivable Loans reported as “FDIC acquired” are loans purchased in the 2009 acquisition of Peoples First Community Bank (“Peoples First”) that were covered by two loss share agreements between the FDIC and the Company. These loans are accounted for as acquired-impaired loans as described above in the section on acquired loans. The Company treated all loans for the Peoples First acquisition as impaired based on the significant amount of deteriorating and nonperforming loans, comprised mainly of adjustable rate mortgages and home equity loans, located in Florida. The loss share receivable is measured separately from the related covered loans as it is not contractually embedded in the loans and is not transferrable should the loans be sold. The fair value of the loss share receivable at acquisition was estimated by discounting expected reimbursements for losses from the loans covered by the loss share agreements, including appropriate consideration of possible true-up payments to the FDIC at the expiration of the agreements. The loss share receivable is reviewed and updated prospectively as loss estimates related to covered loan pools change. Increases in expected reimbursements under the loss sharing agreement will lead to an increase in the loss share receivable. A decrease in expected reimbursements is reflected first as a reversal of any previously recorded increase in the loss share receivable on the covered loan pools with the remainder reflected as an increase in the loss share receivable’s amortization rate. The loss share receivable serves to offset the impact on provision due to impairments or impairment reversals that occur as a result of changes in loss estimates on the underlying covered loan pools. The excess (or shortfall) of expected claims compared to the carrying value of the loss share receivable is accreted (amortized) into noninterest income over the shorter of the remaining life of the covered loan pool or the life of the loss share agreement. The impact on operations of an increase in the loss share receivable’s amortization rate is associated with an increase in the accretable yield on the underlying loan pool. The loss share receivable is reduced as cash is received from the FDIC related to losses incurred on covered assets. The following schedule shows activity in the loss share receivable for the nine months ended September 30, 2015 and 2014. Nine Months Ended (in thousands) September 30, September 30, Balance, January 1 $ 60,272 $ 113,834 Amortization (4,034 ) (9,989 ) Charge-offs, write-downs and other recoveries (6,733 ) (793 ) External expenses qualifying under loss share agreement 1,035 3,325 Changes due to changes in cash flow projections (1,984 ) (14,569 ) FDIC resolution of denied claims (1,854 ) (10,268 ) Net payments (from) to FDIC (14,667 ) 366 Ending balance $ 32,035 $ 81,906 The loss share agreement covering the non-single family FDIC acquired portfolio expired in December 2014. The loss share agreement covering the single family portfolio expires in December 2019. The following schedule shows activity in the allowance for loan losses by portfolio segment for the nine months ended September 30, 2015 and 2014 as well as the corresponding recorded investment in loans at the end of each period. (in thousands) Commercial non-real estate Construction Commercial Residential Consumer Total Nine Months Ended September 30, 2015 Originated loans Allowance for loan losses: Beginning balance $ 50,258 $ 5,413 $ 16,544 $ 8,051 $ 17,435 $ 97,701 Charge-offs (3,068 ) (1,483 ) (1,128 ) (1,451 ) (10,431 ) (17,561 ) Recoveries 2,589 2,006 635 578 3,418 9,226 Net provision for loan losses 13,594 (289 ) 825 283 10,119 24,532 Ending balance $ 63,373 $ 5,647 $ 16,876 $ 7,461 $ 20,541 $ 113,898 Ending balance: Individually evaluated for impairment $ 5,588 $ 21 $ 2,737 $ 96 $ 3 $ 8,445 Collectively evaluated for impairment 57,785 5,626 14,139 7,365 20,538 105,453 Loans: Ending balance: $ 6,232,310 $ 1,068,895 $ 2,956,354 $ 1,843,756 $ 1,976,872 $ 14,078,187 Individually evaluated for impairment 75,345 2,053 31,478 903 157 109,936 Collectively evaluated for impairment 6,156,965 1,066,842 2,924,876 1,842,853 1,976,715 13,968,251 Acquired loans Allowance for loan losses: Beginning balance $ — $ — $ 477 $ — $ — $ 477 Charge-offs — — — — — — Recoveries — — — — — — Net provision for loan losses — — (304 ) — — (304 ) Ending balance $ — $ — $ 173 $ — $ — $ 173 Ending balance: Individually evaluated for impairment $ — $ — $ 173 $ — $ — $ 173 Amounts related to acquired-impaired loans — — — — — — Collectively evaluated for impairment — — — — — — Loans: Ending balance: $ 107,985 $ 8,297 $ 352,896 $ 819 $ 22 $ 470,019 Individually evaluated for impairment — — 2,507 — — 2,507 Acquired-impaired loans 7,459 7,943 18,818 819 22 35,061 Collectively evaluated for impairment 100,526 354 331,571 — — 432,451 (in thousands) Commercial non-real estate Construction Commercial Residential Consumer Total Nine Months Ended September 30, 2015 FDIC acquired loans Allowance for loan losses: Beginning balance $ 911 $ 1,008 $ 4,061 $ 20,609 $ 3,995 $ 30,584 Charge-offs (1,425 ) (406 ) (2,732 ) (748 ) (140 ) (5,451 ) Recoveries 1,699 896 957 5 185 3,742 Net provision for loan losses (950 ) 235 (620 ) 1,181 (1,232 ) (1,386 ) Increase (decrease) in FDIC loss share receivable 314 (6 ) 523 (2,718 ) (97 ) (1,984 ) Ending balance $ 549 $ 1,727 $ 2,189 $ 18,329 $ 2,711 $ 25,505 Ending balance: Individually evaluated for impairment $ — $ — $ — $ — $ — $ — Amounts related to acquired-impaired loans 549 1,727 2,189 18,329 2,711 25,505 Collectively evaluated for impairment — — — — — — Loans: Ending balance: $ 5,699 $ 8,393 $ 18,136 $ 169,214 $ 13,402 $ 214,844 Individually evaluated for impairment — — — — — — Acquired-impaired loans 5,699 8,393 18,136 169,214 13,402 214,844 Collectively evaluated for impairment — — — — — — Total loans Allowance for loan losses: Beginning balance $ 51,169 $ 6,421 $ 21,082 $ 28,660 $ 21,430 $ 128,762 Charge-offs (4,493 ) (1,889 ) (3,860 ) (2,199 ) (10,571 ) (23,012 ) Recoveries 4,288 2,902 1,592 583 3,603 12,968 Net provision for loan losses 12,644 (54 ) (99 ) 1,464 8,887 22,842 Increase (decrease) in FDIC loss share receivable 314 (6 ) 523 (2,718 ) (97 ) (1,984 ) Ending balance $ 63,922 $ 7,374 $ 19,238 $ 25,790 $ 23,252 $ 139,576 Ending balance: Individually evaluated for impairment $ 5,588 $ 21 $ 2,910 $ 96 $ 3 $ 8,618 Amounts related to acquired-impaired loans 549 1,727 2,189 18,329 2,711 25,505 Collectively evaluated for impairment 57,785 5,626 14,139 7,365 20,538 105,453 Loans: Ending balance: $ 6,345,994 $ 1,085,585 $ 3,327,386 $ 2,013,789 $ 1,990,296 $ 14,763,050 Individually evaluated for impairment 75,345 2,053 33,985 903 157 112,443 Acquired-impaired loans 13,158 16,336 36,954 170,033 13,424 249,905 Collectively evaluated for impairment 6,257,491 1,067,196 3,256,447 1,842,853 1,976,715 14,400,702 Commercial non-real estate Construction Commercial Residential Consumer Total (In thousands) Nine Months Ended September 30, 2014 Originated loans Allowance for loan losses: Beginning balance $ 33,091 $ 6,180 $ 20,649 $ 6,892 $ 12,073 $ 78,885 Charge-offs (4,690 ) (2,615 ) (2,255 ) (1,793 ) (11,920 ) (23,273 ) Recoveries 2,118 1,220 1,231 501 3,722 8,792 Net provision for loan losses 3,929 2,151 (3,231 ) 3,647 10,921 17,417 Ending balance $ 34,448 $ 6,936 $ 16,394 $ 9,247 $ 14,796 $ 81,821 Ending balance: Individually evaluated for impairment $ 24 $ 250 $ 98 $ 382 $ — $ 754 Collectively evaluated for impairment 34,424 6,686 16,296 8,865 14,796 81,067 Loans: Ending balance: $ 4,806,740 $ 974,442 $ 2,245,855 $ 1,635,462 $ 1,623,069 $ 11,285,568 Individually evaluated for impairment 5,582 6,617 14,486 2,712 — 29,397 Collectively evaluated for impairment 4,801,158 967,825 2,231,369 1,632,750 1,623,069 11,256,171 Acquired loans Allowance for loan losses: Beginning balance $ 1,603 $ 10 $ 34 $ — $ — $ 1,647 Charge-offs — — — — — — Recoveries — — — — — — Net provision for loan losses 5,800 1,436 57 (4 ) 182 7,471 Ending balance $ 7,403 $ 1,446 $ 91 $ (4 ) $ 182 $ 9,118 Ending balance: Individually evaluated for impairment $ 92 $ 426 $ 46 $ — $ — $ 564 Amounts related to acquired-impaired loans — — — — — — Collectively evaluated for impairment 7,311 1,020 45 (4 ) 182 8,554 Loans: Ending balance: $ 769,226 $ 110,294 $ 813,429 $ 37,739 $ 51,488 $ 1,782,176 Individually evaluated for impairment 931 2,284 458 28 — 3,701 Acquired-impaired loans 4,064 19,200 27,392 5,038 143 55,837 Collectively evaluated for impairment 764,231 88,810 785,579 32,673 51,345 1,722,638 Commercial non-real estate Construction Commercial Residential Consumer Total (In thousands) Nine Months Ended September 30, 2014 FDIC acquired loans Allowance for loan losses: Beginning balance $ 2,323 $ 2,655 $ 10,929 $ 27,989 $ 9,198 $ 53,094 Charge-offs (176 ) (350 ) (4,480 ) (677 ) (1,192 ) (6,875 ) Recoveries 467 1,504 1,408 1 370 3,750 Net provision for loan losses (79 ) (138 ) (125 ) (257 ) (167 ) (766 ) (Decrease) increase in FDIC loss share receivable (1,507 ) (2,404 ) (2,418 ) (4,873 ) (3,368 ) (14,570 ) Ending balance $ 1,028 $ 1,267 $ 5,314 $ 22,183 $ 4,841 $ 34,633 Ending balance: Individually evaluated for impairment $ — $ — $ — $ — $ — $ — Amounts related to acquired-impaired loans 1,028 1,267 5,314 22,183 4,841 34,633 Collectively evaluated for impairment — — — — — — Loans: Ending balance: $ 11,171 $ 11,166 $ 41,550 $ 185,289 $ 31,654 $ 280,830 Individually evaluated for impairment — — — — — — Acquired-impaired loans 11,171 11,166 41,550 185,289 31,654 280,830 Collectively evaluated for impairment — — — — — — Total loans Allowance for loan losses: Beginning balance $ 37,017 $ 8,845 $ 31,612 $ 34,881 $ 21,271 $ 133,626 Charge-offs (4,866 ) (2,965 ) (6,735 ) (2,470 ) (13,112 ) (30,148 ) Recoveries 2,585 2,724 2,639 502 4,092 12,542 Net provision for loan losses 9,650 3,449 (3,299 ) 3,386 10,936 24,122 (Decrease) increase in FDIC loss share receivable (1,507 ) (2,404 ) (2,418 ) (4,873 ) (3,368 ) (14,570 ) Ending balance $ 42,879 $ 9,649 $ 21,799 $ 31,426 $ 19,819 $ 125,572 Ending balance: Individually evaluated for impairment $ 116 $ 676 $ 144 $ 382 $ — $ 1,318 Amounts related to acquired-impaired loans 1,028 1,267 5,314 22,183 4,841 34,633 Collectively evaluated for impairment 41,735 7,706 16,341 8,861 14,978 89,621 Loans: Ending balance: $ 5,587,137 $ 1,095,902 $ 3,100,834 $ 1,858,490 $ 1,706,211 $ 13,348,574 Individually evaluated for impairment 6,513 8,901 14,944 2,740 — 33,098 Acquired-impaired loans 15,235 30,366 68,942 190,327 31,797 336,667 Collectively evaluated for impairment 5,565,389 1,056,635 3,016,948 1,665,423 1,674,414 12,978,809 The following table shows the composition of nonaccrual loans by portfolio segment and class. Acquired-impaired and certain FDIC acquired loans are considered to be performing due to the application of the accretion method and are excluded from the table. FDIC acquired loans accounted for using the cost recovery method do not have an accretable yield and are included below as nonaccrual loans. Acquired-performing loans that have subsequently been placed on nonaccrual status are also included below. September 30, December 31, (in thousands) 2015 2014 Originated loans: Commercial non-real estate $ 93,448 $ 15,511 Construction and land development 5,527 6,462 Commercial real estate 36,367 22,047 Residential mortgages 21,750 21,702 Consumer 6,838 5,574 Total originated loans $ 163,930 $ 71,296 Acquired loans: Commercial non-real estate $ — $ — Construction and land development — — Commercial real estate 3,015 6,139 Residential mortgages — — Consumer — — Total acquired loans $ 3,015 $ 6,139 FDIC acquired loans: Commercial non-real estate $ — $ — Construction and land development — 1,103 Commercial real estate — 433 Residential mortgages — 392 Consumer — 174 Total FDIC acquired loans $ — $ 2,102 Total loans: Commercial non-real estate $ 93,448 $ 15,511 Construction and land development 5,527 7,565 Commercial real estate 39,382 28,619 Residential mortgages 21,750 22,094 Consumer 6,838 5,748 Total loans $ 166,945 $ 79,537 Nonaccrual loans include loans modified in troubled debt restructurings (“TDRs”) of $4.9 million and $7.0 million at September 30, 2015 and December 31, 2014, respectively. Total TDRs, both accruing and nonaccruing, were $10.7 million as of September 30, 2015 and $16.0 million at December 31, 2014. The table below details TDRs that were modified during the nine months ended September 30, 2015 and September 30, 2014 by portfolio segment. Nine Months Ended (in thousands) September 30, 2015 September 30, 2014 Troubled Debt Restructurings: Number of Pre-Modification Post-Modification Number of Pre-Modification Post-Modification Originated loans: Commercial non-real estate — $ — $ — — $ — $ — Construction and land development — — — — — — Commercial real estate 1 482 482 2 2,430 2,385 Residential mortgages 4 185 185 4 1,495 848 Consumer 1 20 20 — — — Total originated loans 6 $ 687 $ 687 6 $ 3,925 $ 3,233 Acquired loans: Commercial non-real estate — $ — $ — — $ — $ — Construction and land development — — — — — — Commercial real estate — — — — — — Residential mortgages — — — — — — Consumer — — — — — — Total acquired loans — $ — $ — — $ — $ — FDIC acquired loans: Commercial non-real estate — $ — $ — — $ — $ — Construction and land development — — — — — — Commercial real estate — — — — — — Residential mortgages — — — — — — Consumer — — — — — — Total FDIC acquired loans — $ — $ — — $ — $ — Total loans: Commercial non-real estate — $ — $ — — $ — $ — Construction and land development — — — — — — Commercial real estate 1 482 482 2 2,430 2,385 Residential mortgages 4 185 185 4 1,495 848 Consumer 1 20 20 — — — Total loans 6 $ 687 $ 687 6 $ 3,925 $ 3,233 No TDRs that subsequently defaulted within twelve months of modification were recorded in the nine months ended September 30, 2015. For the nine months ended September 30, 2014, one originated commercial non-real estate loan with a recorded investment of $0.9 million subsequently defaulted within twelve months of notification. The tables below present loans that are individually evaluated for impairment disaggregated by class at September 30, 2015 and December 31, 2014. Loans individually evaluated for impairment include TDRs and loans that are determined to be impaired and have aggregate relationship balances of $1 million or more. September 30, 2015 Recorded Investment Unpaid Balance Related Allowance Average Investment Interest Recognized (in thousands) Originated loans: With no related allowance recorded: Commercial non-real estate $ 32,963 $ 33,468 $ — $ 14,887 $ — Construction and land development 1,391 1,391 — 1,319 — Commercial real estate 12,945 14,952 — 11,018 26 Residential mortgages — — — 259 2 Consumer 95 95 — 74 — 47,394 49,906 — 27,557 28 With an allowance recorded: Commercial non-real estate 42,382 43,146 5,588 16,683 6 Construction and land development 662 2,224 21 3,443 66 Commercial real estate 18,533 18,536 2,737 12,143 70 Residential mortgages 903 1,413 96 1,578 18 Consumer 62 62 3 27 3 62,542 65,381 8,445 33,874 163 Total: Commercial non-real estate 75,345 76,614 5,588 31,570 6 Construction and land development 2,053 3,615 21 4,762 66 Commercial real estate 31,478 33,488 2,737 23,161 96 Residential mortgages 903 1,413 96 1,837 20 Consumer 157 157 3 101 3 Total originated loans $ 109,936 $ 115,287 $ 8,445 $ 61,431 $ 191 Acquired loans: With an allowance recorded: Commercial non-real estate $ — $ — $ — $ — $ — Construction and land development — — — — — Commercial real estate 2,507 2,522 173 2,580 — Residential mortgages — — — — — Consumer — — — — — 2,507 2,522 173 2,580 — Total: Commercial non-real estate — — — — — Construction and land development — — — — — Commercial real estate 2,507 2,522 173 2,580 — Residential mortgages — — — — — Consumer — — — — — Total acquired loans $ 2,507 $ 2,522 $ 173 $ 2,580 $ — September 30, 2015 Recorded Investment Unpaid Balance Related Allowance Average Investment Interest Recognized (in thousands) Total loans: With no related allowance recorded: Commercial non-real estate $ 32,963 $ 33,468 $ — $ 14,887 $ — Construction and land development 1,391 1,391 — 1,319 — Commercial real estate 12,945 14,952 — 11,018 26 Residential mortgages — — — 259 2 Consumer 95 95 — 74 — 47,394 49,906 — 27,557 28 With an allowance recorded: Commercial non-real estate 42,382 43,146 5,588 16,683 6 Construction and land development 662 2,224 21 3,443 66 Commercial real estate 21,040 21,058 2,910 14,723 70 Residential mortgages 903 1,413 96 1,578 18 Consumer 62 62 3 27 3 65,049 67,903 8,618 36,454 163 Total: Commercial non-real estate 75,345 76,614 5,588 31,570 6 Construction and land development 2,053 3,615 21 4,762 66 Commercial real estate 33,985 36,010 2,910 25,741 96 Residential mortgages 903 1,413 96 1,837 20 Consumer 157 157 3 101 3 Total loans $ 112,443 $ 117,809 $ 8,618 $ 64,011 $ 191 December 31, 2014 (in thousands) Recorded Unpaid Related Average Interest Originated loans: With no related allowance recorded: Commercial non-real estate $ 3,003 $ 3,646 $ — $ 1,209 $ 51 Construction and land development 3,345 6,486 — 3,330 142 Commercial real estate 8,467 10,575 — 8,461 331 Residential mortgages — — — 88 3 Consumer — — — — — 14,815 20,707 — 13,088 527 With an allowance recorded: Commercial non-real estate 984 984 14 5,522 99 Construction and land development 4,905 4,906 19 6,660 137 Commercial real estate 3,654 3,654 11 7,500 109 Residential mortgages 2,656 3,311 330 2,204 50 Consumer 6 6 3 1 — 12,205 12,861 377 21,887 395 Total: Commercial non-real estate 3,987 4,630 14 6,732 150 Construction and land development 8,250 11,392 19 9,990 279 Commercial real estate 12,121 14,229 11 15,961 439 Residential mortgages 2,656 3,311 330 2,292 53 Consumer 6 6 3 1 — Total originated loans $ 27,020 $ 33,568 $ 377 $ 34,976 $ 921 Acquired loans: With no related allowance recorded: Commercial non-real estate $ — $ — $ — $ 357 $ — Construction and land development — — — 121 — Commercial real estate — — — 311 — Residential mortgages — — — 88 — Consumer — — — — — — — — 877 — With an allowance recorded: Commercial non-real estate — — — 1,059 122 Construction and land development — — — 1,037 56 Commercial real estate 2,691 2,720 477 1,357 75 Residential mortgages — — — — — Consumer — — — — — 2,691 2,720 477 3,453 253 Total: Commercial non-real estate — — — 1,416 122 Construction and land development — — — 1,158 56 Commercial real estate 2,691 2,720 477 1,668 75 Residential mortgages — — — 88 — Consumer — — — — — Total acquired loans $ 2,691 $ 2,720 $ 477 $ 4,330 $ 253 December 31, 2014 (in thousands) Recorded Unpaid Related Average Interest Total loans: With no related allowance recorded: Commercial non-real estate $ 3,003 $ 3,646 $ — $ 1,566 $ 51 Construction and land development 3,345 6,486 — 3,451 142 Commercial real estate 8,467 10,575 — 8,772 331 Residential mortgages — — — 176 3 Consumer — — — — — 14,815 20,707 — 13,965 527 With an allowance recorded: Commercial non-real estate 984 984 14 6,581 221 Construction and land development 4,905 4,906 19 7,697 193 Commercial real estate 6,345 6,374 488 8,857 184 Residential mortgages 2,656 3,311 330 2,204 50 Consumer 6 6 3 1 — 14,896 15,581 854 25,340 648 Total: Commercial non-real estate 3,987 4,630 14 8,147 272 Construction and land development 8,250 11,392 19 11,148 335 Commercial real estate 14,812 16,949 488 17,629 515 Residential mortgages 2,656 3,311 330 2,380 53 Consumer 6 6 3 1 — Total loans $ 29,711 $ 36,288 $ 854 $ 39,305 $ 1,175 The tables below present the age analysis of past due loans at September 30, 2015 and December 31, 2014. FDIC acquired and acquired-impaired loans accounted for in pools with an accretable yield are considered to be current. September 30, 2015 30-59 days 60-89 days Greater than past due Total past due Current Total Loans Recorded (in thousands) Originated loans: Commercial non-real estate $ 19,298 $ 3,271 $ 6,805 $ 29,374 $ 6,202,936 $ 6,232,310 $ 878 Construction and land development 2,489 602 4,471 7,562 1,061,333 1,068,895 1,700 Commercial real estate 5,823 3,572 16,289 25,684 2,930,670 2,956,354 1,773 Residential mortgages 25,525 4,619 9,669 39,813 1,803,943 1,843,756 46 Consumer 13,037 5,490 5,271 23,798 1,953,074 1,976,872 1,350 Total $ 66,172 $ 17,554 $ 42,505 $ 126,231 $ 13,951,956 $ 14,078,187 $ 5,747 Acquired loans: Commercial non-real estate $ — $ — $ — $ — $ 107,985 $ 107,985 $ — Construction and land development — — — — 8,297 8,297 — Commercial real estate 744 428 445 1,617 351,279 352,896 129 Residential mortgages — — — — 819 819 — Consumer — — — — 22 22 — Total $ 744 $ 428 $ 445 $ 1,617 $ 468,402 $ 470,019 $ 129 FDIC acquired loans: Commercial non-real estate $ — $ — $ — $ — $ 5,699 $ 5,699 $ — Construction and land development — — — — 8,393 8,393 — Commercial real estate — — — — 18,136 18,136 — Residential mortgages — — — — 169,214 169,214 — Consumer — — — — 13,402 13,402 — Total $ — $ — $ — $ — $ 214,844 $ 214,844 $ — Total loans: Commercial non-real estate $ 19,298 $ 3,271 $ 6,805 $ 29,374 $ 6,316,620 $ 6,345,994 $ 878 Construction and land development 2,489 602 4,471 7,562 1,078,023 1,085,585 1,700 Commercial real estate 6,567 4,000 16,734 27,301 3,300,085 3,327,386 1,902 Residential mortgages 25,525 4,619 9,669 39,813 1,973,976 2,013,789 46 Consumer 13,037 5,490 5,271 23,798 1,966,498 1,990,296 1,350 Total $ 66,916 $ 17,982 $ 42,950 $ 127,848 $ 14,635,202 $ 14,763,050 $ 5,876 December 31, 2014 30-59 days 60-89 days Greater than Total past due Current Total Loans Recorded (in thousands) Originated loans: Commercial non-real estate $ 4,380 $ 1,742 $ 8,560 $ 14,682 $ 5,903,046 $ 5,917,728 $ 630 Construction and land development 6,620 1,532 4,453 12,605 1,061,359 1,073,964 142 Commercial real estate 6,527 2,964 13,234 22,725 2,405,470 2,428,195 696 Residential mortgages 14,730 3,261 11,208 29,199 1,675,571 1,704,770 1,199 Consumer 8,422 2,450 4,365 15,237 1,670,305 1,685,542 1,897 Total $ 40,679 $ 11,949 $ 41,820 $ 94,448 $ 12,715,751 $ 12,810,199 $ 4,564 Acquired loans: Commercial non-real estate $ — $ — $ — $ — $ 120,137 $ 120,137 $ — Construction and land development 111 — — 111 21,012 21,123 — Commercial real estate 3,861 282 1,591 5,734 682,311 688,045 261 Residential mortgages — — — — 2,378 2,378 — Consumer — — — — 985 985 — Total $ 3,972 $ 282 $ 1,591 $ 5,845 $ 826,823 $ 832,668 $ 261 FDIC acquired loans: Commercial non-real estate $ — $ — $ — $ — $ 6,195 $ 6,195 $ — Construction and land development — — 1,103 1,103 10,571 11,674 — Commercial real estate — — 433 433 27,375 27,808 — Residential mortgages — 272 — 272 186,761 187,033 — Consumer 1 — 34 35 19,664 19,699 — Total $ 1 $ 272 $ 1,570 $ 1,843 $ 250,566 $ 252,409 $ — Total loans: Commercial non-real estate $ 4,380 $ 1,742 $ 8,560 $ 14,682 $ 6,029,378 $ 6,044,060 $ 630 Construction and land development 6,731 1,532 5,556 13,819 1,092,942 1,106,761 142 Commercial real estate 10,388 3,246 15,258 28,892 3,115,156 3,144,048 957 Residential mortgages 14,730 3,533 11,208 29,471 1,864,710 1,894,181 1,199 Consumer 8,423 2,450 4,399 15,272 1,690,954 1,706,226 1,897 Total $ 44,652 $ 12,503 $ 44,981 $ 102,136 $ 13,793,140 $ 13,895,276 $ 4,825 The following tables present the credit quality indicators of the Company’s various classes of loans at September 30, 2015 and December 31, 2014. Commercial Non-Real Estate Credit Exposure Credit Risk Profile by Internally Assigned Grade (in thousands) September 30, 2015 December 31, 2014 Originated Acquired FDIC acquired Total Originated Acquired FDIC acquired Total Grade: Pass $ 5,531,569 $ 100,836 $ 2,201 $ 5,634,606 $ 5,577,827 $ 111,847 $ 2,027 $ 5,691,701 Pass-Watch 134,860 76 883 135,819 174,742 715 1,120 176,577 Special Mention 225,228 328 — 225,556 52,962 350 — 53,312 Substandard 340,618 6,745 2,615 349,978 112,153 7,225 3,017 122,395 Doubtful 35 — — 35 44 — 31 75 Total $ 6,232,310 $ 107,985 $ 5,699 $ 6,345,994 $ 5,917,728 $ 120,137 $ 6,195 $ 6,044,060 Construction Credit Exposure Credit Risk Profile by Internally Assigned Grade (in thousands) September 30, 2015 December 31, 2014 Originated Acquired FDIC acquired Total Originated Acquired FDIC acquired Total Grade: Pass $ 1,020,611 $ 1,354 $ 2,238 $ 1,024,203 $ 1,012,128 $ 14,377 $ 2,468 $ 1,028,973 Pass-Watch 3,038 2,324 947 6,309 21,516 432 532 22,480 Special Mention 11,612 — 286 11,898 7,097 129 319 7,545 Substandard 33,634 4,619 4,922 43,175 33,223 6,185 8,355 47,763 Total $ 1,068,895 $ 8,297 $ 8,393 $ 1,085,585 $ 1,073,964 $ 21,123 $ 11,674 $ 1,106,761 Commercial Real Estate Credit Exposure Credit Risk Profile by Internally Assigned Grade (in thousands) September 30, 2015 December 31, 2014 Originated Acquired FDIC acquired Total Originated Acquired FDIC acquired Total Grade: Pass $ 2,769,860 $ 328,821 $ 3,298 $ 3,101,979 $ 2,241,391 $ 641,966 $ 4,139 $ 2,887,496 Pass-Watch 41,344 5,247 2,585 49,176 61,589 11,142 4,547 77,278 Special Mention 42,674 5,373 1,433 49,480 21,543 8,113 1,319 30,975 Substandard 102,459 13,455 10,820 126,734 103,651 26,824 17,803 148,278 Doubtful 17 — — 17 21 — — 21 Total $ 2,956,354 $ 352,896 $ 18,136 $ 3,327,386 $ 2,428,195 $ 688,045 $ 27,808 $ 3,144,048 Residential Mortgage Credit Exposure Credit Risk Profile Based on Payment Activity and Accrual Status (in thousands) September 30, 2015 December 31, 2014 Originated Acquired FDIC acquired Total Originated Acquired FDIC acquired Total Performing $ 1,821,959 $ 819 $ 169,214 $ 1,991,992 $ 1,681,868 $ 2,378 $ 186,641 $ 1,870,887 Nonperforming 21,797 — — 21,797 22,902 — 392 23,294 Total $ 1,843,756 $ 819 $ 169,214 $ 2,013,789 $ 1,704,770 $ 2,378 $ 187,033 $ 1,894,181 Consumer Credit Exposure Credit Risk Profile Based on Payment Activity and Accrual Status (in thousands) September 30, 2015 December 31, 2014 Originated Acquired FDIC acquired Total Originated Acquired FDIC acquired Total Performing $ 1,968,684 $ 22 $ 13,402 $ 1,982,108 $ 1,678,069 $ 985 $ 19,525 $ 1,698,579 Nonperforming 8,188 — — 8,188 7,473 — 174 7,647 Total $ 1,976,872 $ 22 $ 13,402 $ 1,990,296 $ 1,685,542 $

Securities Sold under Agreement

Securities Sold under Agreements to Repurchase	9 Months Ended
	Sep. 30, 2015
Brokers and Dealers [Abstract]
Securities Sold under Agreements to Repurchase	4. Securities Sold under Agreements to Repurchase Included in short term borrowings at September 30, 2015 was $439.0 million of customer securities sold under agreements to repurchase (“repurchase agreements”) that mature daily and were secured by agency securities. The Company borrows funds on a secured basis by selling securities under agreements to repurchase, mainly in connection with treasury-management services offered to its deposit customers. As the Company maintains effective control over assets sold under agreements to repurchase, the securities continue to be carried on the consolidated statements of financial condition. Because the Company acts as borrower transferring assets to the counterparty, and the agreements mature daily, the Company’s risk is very limited.

Long-Term Debt

Long-Term Debt	9 Months Ended
	Sep. 30, 2015
Debt Disclosure [Abstract]
Long-Term Debt	5. Long-Term Debt Long-term debt consisted of the following. ( in thousands) September 30, December 31, Subordinated notes payable, maturing June 2045 $ 150,000 $ — Subordinated notes payable, maturing April 2017 98,011 98,011 Term note payable, maturing December 2015 123,200 149,600 Other long-term debt 125,966 126,760 Total long-term debt $ 497,177 $ 374,371 On March 9, 2015, the Company completed the issuance of subordinated notes payable with an aggregate principal amount of $150 million. The notes mature on June 15, 2045 and accrue interest at a rate of 5.95% per annum. Quarterly interest payments began in June. Subject to prior approval by the Federal Reserve, the Company may redeem the notes in whole or in part on any interest payment date on or after June 15, 2020. This debt qualifies as Tier 2 capital in the calculation of certain regulatory capital ratios. The 5.875% fixed-rate subordinated notes maturing April 2017 were issued by Whitney National Bank and later assumed by Hancock in the Whitney acquisition. As of September 30, 2015, 20% of the balance of these notes qualifies as capital in the calculation of certain regulatory capital ratios. The notes will no longer qualify as capital as of April 1, 2016. On December 21, 2012, the Company entered into a three-year term loan agreement that provides for a $220 million term loan facility, all of which was borrowed on the closing date. The agreement also provides for up to $50 million in additional borrowings under the loan facility, subject to obtaining additional commitments from existing or new lenders and satisfaction of certain other conditions. Amounts borrowed under the loan facility bear interest at a variable rate based on LIBOR plus 1.875% per annum. The loan agreement requires quarterly principal payments of $8.8 million, and outstanding borrowings may be prepaid in whole or in part at any time prior to the December 21, 2015 maturity date without premium or penalty. The Company and the Bank must comply with certain financial covenants in the term loan agreement and are subject to other restrictions customary in financings of this nature, none of which are expected to adversely impact their operations. The financial covenants cover, among other things, the maintenance of minimum levels for regulatory capital ratios, consolidated net worth, consolidated return on assets, and holding company liquidity and dividend capacity, and specify a maximum ratio of consolidated nonperforming assets to consolidated total loans and other real estate, calculated without FDIC acquired assets. The Company was in compliance with all covenants as of September 30, 2015 and December 31, 2014. Substantially all of the other long-term debt consists of borrowings associated with tax credit fund activities. Although these borrowings have indicated maturities through 2053, they are expected to be paid off at the end of the seven-year compliance period for the related tax credit investments.

Fair Value

Fair Value	9 Months Ended
	Sep. 30, 2015
Fair Value Disclosures [Abstract]
Fair Value	6. Fair Value The Financial Accounting Standards Board (“FASB”) defines fair value as the exchange price that would be received to sell an asset or paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The FASB’s guidance also established a fair value hierarchy that prioritizes the inputs to these valuation techniques used to measure fair value, giving preference to quoted prices in active markets for identical assets or liabilities (“level 1”) and the lowest priority to unobservable inputs such as a reporting entity’s own data (“level 3”). Level 2 inputs include quoted prices for similar assets or liabilities in active markets, quoted prices for identical assets or liabilities in markets that are not active, observable inputs other than quoted prices, such as interest rates and yield curves, and inputs that are derived principally from or corroborated by observable market data by correlation or other means. Fair Value of Assets and Liabilities Measured on a Recurring Basis The following tables present for each of the fair value hierarchy levels the Company’s assets and liabilities that are measured at fair value on a recurring basis in the consolidated balance sheets. September 30, 2015 (in thousands) Level 1 Level 2 Total Assets Available for sale debt securities: U.S. Treasury and government agency securities $ — $ 143 $ 143 Municipal obligations — 15,952 15,952 Corporate debt securities — 3,500 3,500 Mortgage-backed securities — 1,841,369 1,841,369 Collateralized mortgage obligations — 305,147 305,147 Equity securities 2,726 — 2,726 Total available for sale securities 2,726 2,166,111 2,168,837 Derivative assets (1) — 31,399 31,399 Total recurring fair value measurements – assets $ 2,726 $ 2,197,510 $ 2,200,236 Liabilities Derivative liabilities (1) $ — $ 30,908 $ 30,908 Total recurring fair value measurements – liabilities $ — $ 30,908 $ 30,908 (1) For further disaggregation of derivative assets and liabilities, see Note 7 – Derivatives. December 31, 2014 (in thousands) Level 1 Level 2 Total Assets Available for sale debt securities: U.S. Treasury and government agency securities $ — $ 300,508 $ 300,508 Municipal obligations — 14,176 14,176 Corporate debt securities — 3,500 3,500 Mortgage-backed securities — 1,245,564 1,245,564 Collateralized mortgage obligations — 86,864 86,864 Equity securities 9,553 — 9,553 Total available for sale securities 9,553 1,650,612 1,660,165 Derivative assets (1) — 19,432 19,432 Total recurring fair value measurements – assets $ 9,553 $ 1,670,044 $ 1,679,597 Liabilities Derivative liabilities (1) $ — $ 20,860 $ 20,860 Total recurring fair value measurements – liabilities $ — $ 20,860 $ 20,860 (1) For further disaggregation of derivative assets and liabilities, see Note 7 – Derivatives. Securities classified as level 1 within the valuation hierarchy include U.S. Treasury securities and certain other debt and equity securities. Level 2 classified securities include obligations of U.S. Government agencies and U.S. Government-sponsored agencies, residential mortgage-backed securities and collateralized mortgage obligations that are issued or guaranteed by U.S. government agencies, and state and municipal bonds. The level 2 fair value measurements for investment securities are obtained quarterly from a third-party pricing service that uses industry-standard pricing models. Substantially all of the model inputs are observable in the marketplace or can be supported by observable data. The Company invests only in securities of investment grade quality with a targeted duration, for the overall portfolio, generally between two and five. Company policies generally limit investments to agency securities and municipal securities determined to be investment grade according to an internally generated score which generally includes a rating of not less than “Baa” or its equivalent by a nationally recognized statistical rating agency. There were no transfers between valuation hierarchy levels during the periods shown. The fair value of derivative financial instruments, which are predominantly customer interest rate swaps, is obtained from a third-party pricing service that uses an industry-standard discounted cash flow model that relies on inputs, LIBOR swap curves and Overnight Index swap rate curves, observable in the marketplace. To comply with the accounting guidance, credit valuation adjustments are incorporated in the fair values to appropriately reflect nonperformance risk for both the Company and the counterparties. Although the Company has determined that the majority of the inputs used to value the derivative instruments fall within level 2 of the fair value hierarchy, the credit value adjustments utilize level 3 inputs, such as estimates of current credit spreads. The Company has determined that the impact of the credit valuation adjustments is not significant to the overall valuation of these derivatives. As a result, the Company has classified its derivative valuations in their entirety in level 2 of the fair value hierarchy. The Company’s policy is to measure counterparty credit risk quarterly for all derivative instruments, including those subject to master netting arrangements consistent with how market participants would price the net risk exposure at the measurement date. The Company also has certain derivative instruments associated with the Bank’s mortgage-banking activities. These derivative instruments include interest rate lock commitments on prospective residential mortgage loans and forward commitments to sell these loans to investors on a best efforts delivery basis. The fair value of these derivative instruments is measured using observable market prices for similar instruments and is classified as a level 2 measurement. Fair Value of Assets Measured on a Nonrecurring Basis Certain assets and liabilities are measured at fair value on a nonrecurring basis. Collateral-dependent impaired loans are level 2 assets measured at the fair value of the underlying collateral based on independent third-party appraisals that take into consideration market-based information such as recent sales activity for similar assets in the property’s market. Other real estate owned, including both foreclosed property and surplus banking property, are level 3 assets that are adjusted to fair value, less estimated selling costs, upon transfer to other real estate owned. Subsequently, other real estate owned is carried at the lower of carrying value or fair value less estimated selling costs. Fair values are determined by sales agreement or third-party appraisals as discounted for estimated selling costs, information from comparable sales, and marketability of the property. The fair value information presented below is not as of the period-end, rather it was as of the date the fair value adjustment was recorded during the twelve months ended for each of the dates presented below, and excludes nonrecurring fair value measurements of assets no longer on the balance sheet. The following tables present the Company’s financial assets that are measured at fair value on a nonrecurring basis for each of the fair value hierarchy levels. September 30, 2015 (in thousands) Level 1 Level 2 Level 3 Total Collateral-dependent impaired loans $ — $ 98,019 $ — $ 98,019 Other real estate owned — — 21,778 21,778 Total nonrecurring fair value measurements $ — $ 98,019 $ 21,778 $ 119,797 December 31, 2014 (in thousands) Level 1 Level 2 Level 3 Total Collateral-dependent impaired loans $ — $ 30,204 $ — $ 30,204 Other real estate owned — — 29,715 29,715 Total nonrecurring fair value measurements $ — $ 30,204 $ 29,715 $ 59,919 Accounting guidance from the FASB requires the disclosure of estimated fair value information about certain on- and off-balance sheet financial instruments, including those financial instruments that are not measured and reported at fair value on a recurring basis. The significant methods and assumptions used by the Company to estimate the fair value of financial instruments are discussed below. Cash, Short-Term short-term Securities Loans, Net Loans Held for Sale Deposits Securities Sold under Agreements to Repurchase, Federal Funds Purchased, and Federal Home Loan Bank (“FHLB”) Borrowings Long-Term Debt Derivative Financial Instruments The following tables present the estimated fair values of the Company’s financial instruments by fair value hierarchy levels and the corresponding carrying amount at September 30, 2015 and December 31, 2014. September 30, 2015 (in thousands) Level 1 Level 2 Level 3 Total Fair Value Carrying Amount Financial assets: Cash, interest-bearing bank deposits, and federal funds sold $ 518,157 $ — $ — $ 518,157 $ 518,157 Available for sale securities 2,726 2,166,111 — 2,168,837 2,168,837 Held to maturity securities — 2,414,682 — 2,414,682 2,380,085 Loans, net — 98,019 14,558,423 14,656,442 14,623,474 Loans held for sale — 19,764 — 19,764 19,764 Derivative financial instruments — 31,399 — 31,399 31,399 Financial liabilities: Deposits $ — $ — $ 17,423,721 $ 17,423,721 $ 17,439,948 Federal funds purchased 10,200 — — 10,200 10,200 Securities sold under agreements to repurchase 438,982 — — 438,982 438,982 FHLB borrowings 600,000 — — 600,000 600,000 Long-term debt — 504,475 — 504,475 497,177 Derivative financial instruments — 30,908 — 30,908 30,908 December 31, 2014 (in thousands) Level 1 Level 2 Level 3 Total Fair Value Carrying Amount Financial assets: Cash, interest-bearing bank deposits, and federal funds sold $ 1,159,403 $ — $ — $ 1,159,403 $ 1,159,403 Available for sale securities 9,553 1,650,612 — 1,660,165 1,660,165 Held to maturity securities — 2,186,340 — 2,186,340 2,166,289 Loans, net — 30,204 13,672,427 13,702,631 13,766,514 Loans held for sale — 20,252 — 20,252 20,252 Derivative financial instruments — 19,432 — 19,432 19,432 Financial liabilities: Deposits $ — $ — $ 16,398,878 $ 16,398,878 $ 16,572,831 Federal funds purchased 12,000 — — 12,000 12,000 Securities sold under agreements to repurchase 624,573 — — 624,573 624,573 FHLB borrowings 515,000 — — 515,000 515,000 Long-term debt — 346,379 — 346,379 374,371 Derivative financial instruments — 20,860 — 20,860 20,860

Derivatives

Derivatives	9 Months Ended
	Sep. 30, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives	7. Derivatives Risk Management Objective of Using Derivatives The Company enters into derivative financial instruments to manage risks related to differences in the amount, timing, and duration of the Company’s known or expected cash receipts and its known or expected cash payments, currently related to its variable rate borrowing. The Bank has also entered into interest rate derivative agreements as a service to certain qualifying customers. The Bank manages a matched book with respect to these customer derivatives in order to minimize their net risk exposure resulting from such agreements. The Bank also enters into risk participation agreements under which they may either sell or buy credit risk associated with a customer’s performance under certain interest rate derivative contracts related to loans in which participation interests have been sold to or purchased from other banks. Fair Values of Derivative Instruments on the Balance Sheet The table below presents the notional amounts and fair values of the Company’s derivative financial instruments as well as their classification on the consolidated balance sheets as of September 30, 2015 and December 31, 2014. Fair Values (1) Notional Amounts Assets Liabilities (in thousands) Type of September 30, December 31, September 30, December 31, September 30, December 31, Derivatives designated as hedging instruments: Interest rate swaps Cash Flow $ 500,000 $ 300,000 $ 1,419 $ — $ — $ 592 $ 500,000 $ 300,000 $ 1,419 $ — $ — $ 592 Derivatives not designated as hedging instruments: Interest rate swaps (2) N/A $ 728,674 $ 747,754 $ 26,621 $ 17,806 $ 27,362 $ 18,419 Risk participation agreements N/A 87,184 80,438 107 125 206 208 Forward commitments to sell residential mortgage loans N/A 38,817 52,238 100 80 329 250 Interest rate-lock commitments on residential mortgage loans N/A 22,127 33,068 161 111 45 44 Foreign exchange forward contracts N/A 62,221 89,432 2,991 1,310 2,966 1,347 $ 939,023 $ 1,002,930 $ 29,980 $ 19,432 $ 30,908 $ 20,268 (1) Derivative assets and liabilities are reported with other assets or other liabilities, respectively, in the consolidated balance sheets. (2) The notional amount represents both the customer accommodation agreements and offsetting agreements with unrelated financial institutions. Cash Flow Hedges of Interest Rate Risk The Company is party to two interest rate swap agreements – one with a notional amount of $300 million and the second with a notional amount of $200 million. For both agreements, the Company receives interest at a fixed rate and pays at a variable rate. The derivative instruments represented by these swap agreements were designated as and qualify as cash flow hedges of the Company’s forecasted variable cash flows for a pool of variable rate loans. The $300 million swap agreement expires in January, 2017 and the $200 million swap agreement expires in June, 2017. During the terms of the swap agreements, the effective portion of changes in the fair value of the derivative instruments are recorded in accumulated other comprehensive income (“AOCI”) and subsequently reclassified into earnings in the periods that the hedged forecasted variable-rate interest payments affects earnings. The impact on AOCI was insignificant for the three-month and nine-month periods ended September 30, 2015. There was no ineffective portion of the change in fair value of the derivative recognized directly in earnings. Derivatives Not Designated as Hedges Customer interest rate derivative program The Bank enters into interest rate derivative agreements, primarily rate swaps, with commercial banking customers to facilitate their risk management strategies. The Bank enters into offsetting agreements with unrelated financial institutions, thereby mitigating its net risk exposure resulting from such transactions. Because the interest rate derivatives associated with this program do not meet hedge accounting requirements, changes in the fair value of both the customer derivatives and the offsetting derivatives are recognized directly in earnings. Risk participation agreements The Bank also enters into risk participation agreements under which it may either assume or sell credit risk associated with a borrower’s performance under certain interest rate derivative contracts. In those instances where the Bank has assumed credit risk, it is not a direct counterparty to the derivative contract with the borrower and has entered into the risk participation agreement because it is a party to the related loan agreement with the borrower. In those instances in which the Bank has sold credit risk, it is the sole counterparty to the derivative contract with the borrower and has entered into the risk participation agreement because other banks participate in the related loan agreement. The Bank manages their credit risk under risk participation agreements by monitoring the creditworthiness of the borrower, based on its normal credit review process. Mortgage banking derivatives The Bank also enters into certain derivative agreements as part of its mortgage banking activities. These agreements include interest rate lock commitments on prospective residential mortgage loans and forward commitments to sell these loans to investors on a best efforts delivery basis. Customer foreign exchange forward contract derivatives The Bank enters into foreign exchange forward derivative agreements, primarily forward currency contracts, with commercial banking customers to facilitate its risk management strategies. The Bank manages its risk exposure from such transactions by entering into offsetting agreements with unrelated financial institutions. Because the foreign exchange forward contract derivatives associated with this program do not meet hedge accounting requirements, changes in the fair value of both the customer derivatives and the offsetting derivatives are recognized directly in earnings. Effect of Derivative Instruments on the Income Statement The effect of the Company’s derivative financial instruments on the income statement was immaterial for the three-month and nine-month periods ended September 30, 2015 and 2014. Credit risk-related Contingent Features Certain of the Bank’s derivative instruments contain provisions allowing the financial institution counterparty to terminate the contracts in certain circumstances, such as the downgrade of the Bank’s credit ratings below specified levels, a default by the Bank on its indebtedness, or the failure of the Bank to maintain specified minimum regulatory capital ratios or its regulatory status as a well-capitalized institution. These derivative agreements also contain provisions regarding the posting of collateral by each party. As of September 30, 2015, the aggregate fair value of derivative instruments with credit risk-related contingent features that were in a net liability position was $12.8 million, for which the Bank had posted collateral of $28.9 million. Offsetting Assets and Liabilities Offsetting information in regards to derivative assets and liabilities subject to master netting agreements at September 30, 2015 and December 31, 2014 is presented in the following tables. Gross Gross Net Amounts the Statement Gross Amounts Not Offset in the (in thousands) Financial Cash Net As of September 30, 2015 Derivative Assets $ 26,728 $ — $ 26,728 $ 118 $ — $ 26,610 Total $ 26,728 $ — $ 26,728 $ 118 $ — $ 26,610 Derivative Liabilities $ 27,568 $ — $ 27,568 $ 118 $ 28,796 $ (1,346 ) Total $ 27,568 $ — $ 27,568 $ 118 $ 28,796 $ (1,346 ) Gross Gross Statement Net Amounts Gross Amounts Not Offset in the Description Financial Cash Net As of December 31, 2014 Derivative Assets $ 17,931 $ — $ 17,931 $ 936 $ — $ 16,995 Total $ 17,931 $ — $ 17,931 $ 936 $ — $ 16,995 Derivative Liabilities $ 18,627 $ — $ 18,627 $ 936 $ 17,343 $ 348 Total $ 18,627 $ — $ 18,627 $ 936 $ 17,343 $ 348

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2015
Equity [Abstract]
Stockholders' Equity	8. Stockholders’ Equity Stock Repurchase Program On August 28, 2015, the Company’s board of directors approved a stock repurchase plan that authorizes the repurchase of up to 5%, or approximately 3.9 million shares of its outstanding common stock. The approved plan allows the Company to repurchase its common shares either in the open market in compliance with Rule 10b-18 promulgated under the Securities Exchange Act of 1934, as amended, or in privately negotiated transactions with non-affiliated sellers or as otherwise determined by the Company from time to time until September 30, 2016. Under this plan, the Company has repurchased 568,279 shares of its common stock at an average price of $27.39 per share during the nine months ended September 30, 2015. In March 2015, the Company completed the prior stock repurchase program that had been approved by the Company’s board of directors on July 16, 2014 which authorized the repurchase of up to 5%, or approximately 4.1 million shares, of its outstanding common stock. Under this plan, the Company repurchased a total of 4.1 million shares of its common stock at an average price of $30.02 per share. Accumulated Other Comprehensive Income (Loss) AOCI is reported as a component of stockholders’ equity. AOCI can include, among other items, unrealized holding gains and losses on securities available for sale (“AFS”), gains and losses associated with pension or other post retirement benefits that are not recognized immediately as a component of net periodic benefit cost, and gains and losses on derivative instruments that are designated as, and qualify as, cash flow hedges. Net unrealized gains/losses on AFS securities reclassified as securities held to maturity (“HTM”) also continue to be reported as a component of AOCI and will be amortized over the estimated remaining life of the securities as an adjustment to interest income. The components of AOCI are reported net of related tax effects. The components of AOCI and changes in those components are presented in the following table. (in thousands) Available HTM Securities Employee Loss on Total Balance, December 31, 2013 $ 8,263 $ (21,189 ) $ (22,453 ) $ — $ (35,379 ) Other comprehensive income before income taxes: Net change in unrealized gain 9,119 — — — 9,119 Reclassification of net losses realized and included in earnings — — 293 — 293 Valuation adjustment for employee benefit plans — — 1,902 — 1,902 Amortization of unrealized net loss on securities transferred to HTM — 2,463 — — 2,463 Income tax expense 3,309 879 903 — 5,091 Balance, September 30, 2014 $ 14,073 $ (19,605 ) $ (21,161 ) $ — $ (26,693 ) Balance, December 31, 2014 $ 18,001 $ (19,074 ) $ (48,626 ) $ (375 ) $ (50,074 ) Other comprehensive income before income taxes: Net change in unrealized gain 163 — — 2,011 2,174 Reclassification of net (gain) losses realized and included in earnings (165 ) — 2,373 — 2,208 Valuation adjustment for employee benefit plans — — (959 ) (959 ) Amortization of unrealized net loss on securities transferred to HTM — 2,609 — — 2,609 Income tax (benefit) expense (73 ) 953 513 732 2,125 Balance, September 30, 2015 $ 18,072 $ (17,418 ) $ (47,725 ) $ 904 $ (46,167 ) The following table shows the line items in the consolidated income statements affected by amounts reclassified from accumulated other comprehensive income. Nine Months Ended September 30, Affected line item on the income statement Amount reclassified from AOCI (a) (in thousands) 2015 2014 Gain on sale of AFS securities $ 165 $ — Securities gains (losses) Tax effect (58 ) — Income taxes Net of tax 107 — Net income Amortization of unrealized net loss on securities transferred to HTM $ (2,609 ) $ (2,463 ) Interest income Tax effect 953 879 Income taxes Net of tax (1,656 ) (1,584 ) Net income Amortization of defined benefit pension and post-retirement items (2,373 ) (293 ) Employee benefits expense (b) Tax effect 831 103 Income taxes Net of tax (1,542 ) (190 ) Net income Total reclassifications, net of tax $ (3,091 ) $ (1,774 ) Net income (a) Amounts in parenthesis indicate reduction in net income. (b) These accumulated other comprehensive income components are included in the computation of net periodic pension and post-retirement cost that is reported with employee benefits expense (see Note 11 for additional details).

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2015
Earnings Per Share [Abstract]
Earnings Per Share	9. Earnings Per Share Hancock calculates earnings per share using the two-class method. The two-class method allocates net income to each class of common stock and participating security according to common dividends declared and participation rights in undistributed earnings. Participating securities consist of unvested stock-based payment awards that contain nonforfeitable rights to dividends or dividend equivalents. A summary of the information used in the computation of earnings per common share follows. Three Months Ended Nine Months Ended (in thousands, except per share data) 2015 2014 2015 2014 Numerator: Net income to common shareholders $ 41,166 $ 46,553 $ 116,154 $ 135,630 Net income allocated to participating securities – basic and diluted 840 883 2,541 2,783 Net income allocated to common shareholders – basic and diluted $ 40,326 $ 45,670 $ 113,613 $ 132,847 Denominator: Weighted-average common shares – basic 77,928 81,721 78,452 81,965 Dilutive potential common shares 147 221 157 239 Weighted-average common shares – diluted 78,075 81,942 78,609 82,204 Earnings per common share: Basic $ 0.52 $ 0.56 $ 1.45 $ 1.62 Diluted $ 0.52 $ 0.56 $ 1.45 $ 1.62 Potential common shares consist of employee and director stock options. These potential common shares do not enter into the calculation of diluted earnings per share if the impact would be anti-dilutive, i.e., increase earnings per share or reduce a loss per share. Weighted-average anti-dilutive potential common shares totaled 761,113 and 815,765, respectively, for the three and nine months ended September 30, 2015 and 569,404 and 639,486, respectively, for the three and nine months ended September 30, 2014.

Share-Based Payment Arrangement

Share-Based Payment Arrangements	9 Months Ended
	Sep. 30, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-Based Payment Arrangements	10. Share-Based Payment Arrangements Hancock maintains incentive compensation plans that provide for awards of share-based compensation to employees and directors. These plans have been approved by the Company’s shareholders. Detailed descriptions of these plans were included in Note 12 to the consolidated financial statements in the Company’s Annual Report on Form 10-K for the year ended December 31, 2014. A summary of option activity for the nine months ended September 30, 2015 is presented below. Options Number of Weighted Weighted Aggregate Outstanding at January 1, 2015 933,750 $ 37.03 Exercised (11,577 ) 29.94 Cancelled/Forfeited (56,987 ) 35.89 Expired (111,424 ) 34.79 Outstanding at September 30, 2015 753,762 $ 37.55 3.9 $ — Exercisable at September 30, 2015 635,712 $ 38.90 3.5 $ — The total intrinsic value of options exercised was $0.2 million for both the nine months ended September 30, 2015 and 2014. The restricted and performance shares in the table below are subject to service requirements. A summary of the status of the Company’s nonvested restricted and performance shares as of September 30, 2015 and changes during the nine months ended September 30, 2015, is presented in the following table. Number of Weighted Nonvested at January 1, 2015 2,040,299 $ 32.27 Granted 106,833 27.40 Vested (239,761 ) 31.93 Forfeited (143,884 ) 32.64 Nonvested at September 30, 2015 1,763,487 $ 31.99 As of September 30, 2015, there were $32.2 million of total unrecognized compensation expense related to nonvested restricted and performance shares expected to vest. This compensation is expected to be recognized in expense over a weighted average period of 3.1 years. The total fair value of shares which vested during the nine months ended September 30, 2015 and 2014 was $7.6 million and $10.0 million, respectively. During the nine months ended September 30, 2015, the Company granted 59,312 performance shares with a grant date fair value of $25.77 per share to key members of executive and senior management. The number of 2015 performance shares that ultimately vest at the end of the three-year required service period, if any, will be based on the relative rank of Hancock’s three-year total shareholder return (“TSR”) among the TSRs of a peer group of fifty regional banks. The maximum number of performance shares that could vest is 200% of the target award. The fair value of the performance awards at the grant date was determined using a Monte Carlo simulation method. Compensation expense for these performance shares is recognized on a straight-line basis over the service period.

Retirement Plans

Retirement Plans	9 Months Ended
	Sep. 30, 2015
Compensation and Retirement Disclosure [Abstract]
Retirement Plans	11. Retirement Plans The Company has a qualified defined benefit pension plan covering all eligible employees. Eligibility is based on minimum age-related and service-related requirements as well as job classification. Accrued benefits under a nonqualified plan covering certain legacy Whitney employees were frozen as of December 31, 2012 and no future benefits will be accrued under this plan. The Company also sponsors defined benefit postretirement plans for both legacy Hancock and legacy Whitney employees that provide health care and life insurance benefits. Benefits under the Hancock plan are not available to employees hired on or after January 1, 2000. Benefits under the Whitney plan are restricted to retirees who were already receiving benefits at the time of plan amendments in 2007 or active participants who were eligible to receive benefits as of December 31, 2007. The following tables show the components of net periodic benefits cost included in expense for the plans for the periods indicated. (in thousands) Pension benefits Other Post- 2015 2014 2015 2014 Three Months Ended September 30, Service cost $ 3,383 $ 3,230 $ 23 $ 31 Interest cost 4,672 4,812 174 285 Expected return on plan assets (8,207 ) (8,056 ) — — Amortization of net loss 842 7 (40 ) 91 Net periodic benefit cost $ 690 $ (7 ) $ 157 $ 407 Nine Months Ended September 30, Service cost $ 10,128 $ 9,690 $ 95 $ 94 Interest cost 13,963 14,438 717 855 Expected return on plan assets (24,626 ) (24,167 ) — — Amortization of net loss 2,328 20 45 273 Net periodic benefit cost $ 1,793 $ (19 ) $ 857 $ 1,222 Hancock contributed $10 million to the pension plan during the first quarter of 2015. While no further contribution is required in 2015 to meet minimum funding requirements, the Company may consider making an additional contribution during the fourth quarter based on the performance of plan assets and the updated estimated plan liability. The Company also provides a defined contribution 401(k) retirement benefit plan. Under the plan, the Company matches 100% of the first 1% of compensation saved by a participant, and 50% of the next 5% of compensation saved.

Other Noninterest Income

Other Noninterest Income	9 Months Ended
	Sep. 30, 2015
Equity [Abstract]
Other Noninterest Income	12. Other Noninterest Income Components of other noninterest income are as follows. Three Months Ended Nine Months Ended (in thousands) 2015 2014 2015 2014 Income from bank-owned life insurance $ 2,451 $ 2,377 $ 7,788 $ 7,048 Credit related fees 2,718 2,822 7,786 8,388 Income from derivatives 74 191 1,486 1,431 Net gain (loss) on sale of assets 418 (56 ) 363 1,409 Safety deposit box income 441 448 1,356 1,404 Other miscellaneous 2,268 1,950 7,360 7,091 Total other noninterest income $ 8,370 $ 7,732 $ 26,139 $ 26,771

Other Noninterest Expense

Other Noninterest Expense	9 Months Ended
	Sep. 30, 2015
Text Block [Abstract]
Other Noninterest Expense	13. Other Noninterest Expense Components of other noninterest expense are as follows. Three Months Ended Nine Months Ended (in thousands) 2015 2014 2015 2014 Advertising $ 2,856 $ 2,457 $ 7,154 $ 6,395 Ad valorem and franchise taxes 2,868 3,098 8,319 8,397 Printing and supplies 1,193 1,189 3,568 3,467 Insurance expense 794 944 2,644 3,002 Travel expense 1,419 1,009 3,946 2,966 Entertainment and contributions 1,634 1,396 5,009 4,337 Tax credit investment amortization 2,161 2,220 6,352 6,590 Other miscellaneous 3,634 6,821 16,679 25,105 Total other noninterest expense $ 16,559 $ 19,134 $ 53,671 $ 60,259 There were no nonoperating expenses included in other miscellaneous expense in the table above in the third quarter of 2015 compared to $1.1 million in the third quarter of 2014. For the first nine months of 2015 and 2014, other miscellaneous expense included nonoperating expenses totaling $2.7 million and $8.4 million, respectively. In 2015, these nonoperating expenses primarily include the net impact from branch sales and closings and the resolution of FDIC denied claims. Other nonoperating expenses in 2014 included expenses related to the FDIC settlement, sale of certain insurance business lines, branch closures and fees related to the early termination of reverse purchase obligations.

New Accounting Pronouncements

New Accounting Pronouncements	9 Months Ended
	Sep. 30, 2015
Accounting Changes and Error Corrections [Abstract]
New Accounting Pronouncements	14. New Accounting Pronouncements In September 2015, the FASB issued an Accounting Standards Update (“ASU”) that eliminates the requirement to restate prior period financial statements for measurement period adjustments. The new guidance requires that the cumulative impact of a measurement period adjustment (including the impact on prior periods) be recognized in the reporting period in which the adjustment is identified. The new standard should be applied prospectively to measurement period adjustments that occur after the effective date. The amendments in this update are effective for public business entities for fiscal years beginning after December 15, 2015, and interim periods within those fiscal years. The adoption of this guidance is not expected to have a material impact on the Company’s financial condition or results of operations. In May 2015, the FASB issued an ASU to remove the requirement to categorize within the fair value hierarchy all investments for which fair value is measured using the net asset value per share practical expedient and remove the requirement to make certain disclosures for all investments that are eligible to be measured at fair value using the net asset value per share practical expedient. The amendments in this update are effective for public business entities for fiscal years beginning after December 15, 2015, and interim periods within those fiscal years. The adoption of this guidance is not expected to have a material impact on the Company’s financial condition or results of operations. In April 2015, the FASB issued an ASU to provide guidance to customers about how to account for a cloud computing arrangement depending on whether or not it includes a software license. If a cloud computing arrangement includes a software license, then the customer should account for the software license element of the arrangement consistent with the acquisition of other software licenses. If a cloud computing arrangement does not include a software license, the customer should account for the arrangement as a service contract. The guidance will not change GAAP for a customer’s accounting for service contracts. For public business entities, the amendments will be effective for annual periods, including interim periods within those annual periods, beginning after December 15, 2015. Early adoption is permitted for all entities. The adoption of this guidance is not expected to have a material impact on the Company’s financial condition or results of operations. In April 2015, the FASB issued an ASU to simplify presentation of debt issuance costs by requiring that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. The guidance in this ASU does not address presentation or subsequent measurement of debt issuance costs related to line-of-credit arrangements. Therefore, the FASB issued an ASU in August 2015 to clarify the SEC staff position that they would not object to an entity deferring and presenting debt issuance costs as an asset and subsequently amortizing the deferred debt issuance costs ratably over the term of the line-of-credit arrangement, regardless of whether there are any outstanding borrowings on the line-of-credit arrangement. The amendments in this update are effective for public business entities for fiscal years beginning after December 15, 2015. Early adoption of the amendments in this update is permitted for financial statements that have not been previously issued. The adoption of this guidance is not expected to have a material impact on the Company’s financial condition or results of operations. In February 2015, the FASB issued an ASU to change the analysis that a reporting entity must perform to determine whether it should consolidate certain types of legal entities. The amendments in this ASU (1) modify the evaluation of whether limited partnerships and similar legal entities are variable interest entities (VIEs) or voting interest entities; (2) eliminate the presumption that a general partner should consolidate a limited partnership; (3) affect the consolidation analysis of reporting entities that are involved with VIEs, particularly those that have fee arrangements and related party relationships; and (4) provide a scope exception from consolidation guidance for reporting entities with interests in legal entities that are required to comply with or operate in accordance with requirements that are similar to those in Rule 2a-7 of the Investment Company Act of 1940 for registered money market funds. The amendments in this update are effective for public business entities for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2015. Early adoption is permitted, including adoption in an interim period. The adoption of this guidance is not expected to have a material impact on the Company’s financial condition or results of operations. In January 2015, the FASB issued an ASU to address the elimination of the concept of extraordinary items. The standard is the first in the FASB’s simplification initiative that is aimed at reducing the cost and complexity of financial reporting while improving or maintaining the usefulness of information reported to investors. The amendments in this update are effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2015. Early adoption is permitted but adoption must occur at the beginning of the year. The Company adopted this guidance in January 2015 and it did not have a material impact on the Company’s financial condition or results of operations. In August 2014, the FASB issued an ASU to address the diversity in practice regarding the classification and measurement of foreclosed loans which were part of a government-sponsored loan guarantee program. The ASU outlines certain criteria that, if met, the loan (residential or commercial) should be derecognized and a separate other receivable should be recorded upon foreclosure at the amount of the loan balance (principal and interest) expected to be recovered from the guarantor. This ASU was effective for annual reporting periods beginning after December 15, 2014, including interim periods within that reporting period. The Company adopted this guidance in January 2015 and it did not have a material impact on the Company’s financial condition or results of operations. In June 2014, the FASB issued an ASU regarding repurchase-to-maturity transactions, repurchase financings, and disclosures. Under the new standard, repurchase-to-maturity transactions will be reported as secured borrowings, and transferors will no longer apply the current “linked” accounting model to repurchase agreements executed contemporaneously with the initial transfer of the underlying financial asset with the same counterparty. Public business entities are generally required to apply the accounting changes and comply with the enhanced disclosure requirements for periods beginning after December 15, 2014 and interim periods beginning after March 15, 2015. A public business entity may not early adopt the standard’s provisions. The Company adopted the accounting guidance in January 2015 and it did not have a material impact on the Company’s financial condition or results of operations. The new disclosure requirements are included in Note 4 – Securities Sold under Agreements to Repurchase. In May 2014, the FASB issued an ASU regarding revenue from contracts with customers affecting any entity that enters into contracts with customers to transfer goods or services or enters into contracts for the transfer of nonfinancial assets unless those contracts are within the scope of other standards. The core principle of this standard is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The standard will be effective for the Company for annual reporting periods beginning after December 15, 2017. The Company is currently assessing this pronouncement and adoption of this guidance is not expected to have a material impact on the Company’s financial condition or results of operations. In January 2014, the FASB issued an ASU on reclassification of residential real estate collateralized consumer mortgage loans upon foreclosure. The new ASU clarifies when an in substance repossession or foreclosure occurs – that is, when a creditor should be considered to have received physical possession of residential real estate property collateralizing a consumer mortgage loan such that the loan receivable should be derecognized and the real estate property recognized. The new ASU requires a creditor to reclassify a collateralized consumer mortgage loan to real estate property upon obtaining legal title to the real estate collateral, or the borrower voluntarily conveying all interest in the real estate property to the lender to satisfy the loan through a deed in lieu of foreclosure or similar legal agreement. The ASU is effective for interim and annual reporting periods beginning after December 15, 2014. The Company adopted this guidance in January 2015 and it did not have a material impact on the Company’s financial condition or results of operations. The new disclosure requirements are included at the end of Note 3 – Loans and Allowance for Loan Losses. In January 2014, the FASB issued an ASU in order to provide guidance on accounting for investments in flow-through limited liability entities that manage or invest in affordable housing projects that qualify for low-income housing tax credit (“LIHTC”). Through the Company’s investments in these entities, the Company receives tax credits and/or tax deductions from operating losses, which are allowable on the Company’s filed income tax returns over the life of the project beginning with the first year the tax credits are earned. The Company adopted this guidance in January 2015 and it did not have a material impact on the Company’s financial condition or results of operations.

Basis of Presentation (Policies

Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2015
Accounting Policies [Abstract]
Basis of Presentation	1. Basis of Presentation The consolidated financial statements include the accounts of Hancock Holding Company and all other entities in which it has a controlling interest (the “Company”). The financial statements include all adjustments that are, in the opinion of management, necessary to present fairly the Company’s financial condition, results of operations, changes in stockholders’ equity and cash flows for the interim periods presented. Some financial information and disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the U.S. (“GAAP”) have been condensed or omitted in this Form 10-Q pursuant to Securities and Exchange Commission rules and regulations. These financial statements should be read in conjunction with the audited consolidated financial statements and the notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2014. Financial information reported in these financial statements is not necessarily indicative of the Company’s financial condition, results of operations, or cash flows for any other interim or annual period.
Use of Estimates	Use of Estimates The accounting principles the Company follows and the methods for applying these principles conform with GAAP and with those generally practiced within the banking industry. These accounting principles require management to make estimates and assumptions about future events that affect the amounts reported in the consolidated financial statements and the accompanying notes. Actual results could differ from those estimates.

Securities (Tables)

Securities (Tables)	9 Months Ended
	Sep. 30, 2015
Amortized Cost and Fair Value of Available for Sale Securities	The amortized cost and fair value of securities classified as available for sale and held to maturity follow. Securities Available for Sale (in thousands) September 30, 2015 December 31, 2014 Amortized Gross Gross Fair Value Amortized Gross Gross Fair Value US Treasury and government agency securities $ 144 $ — $ 1 $ 143 $ 300,207 $ 372 $ 71 $ 300,508 Municipal obligations 15,712 240 — 15,952 13,995 186 5 14,176 Mortgage-backed securities 1,814,818 30,021 3,470 1,841,369 1,217,293 31,094 2,823 1,245,564 Collateralized mortgage obligations 303,816 1,964 633 305,147 88,093 — 1,229 86,864 Corporate debt securities 3,500 — — 3,500 3,500 — — 3,500 Equity securities 2,446 313 33 2,726 8,673 891 11 9,553 $ 2,140,436 $ 32,538 $ 4,137 $ 2,168,837 $ 1,631,761 $ 32,543 $ 4,139 $ 1,660,165
Amortized Cost and Fair Value of Held to Maturity Securities	Securities Held to Maturity (in thousands) September 30, 2015 December 31, 2014 Amortized Gross Gross Fair Value Amortized Gross Gross Fair Value US Treasury and government agency securities $ 50,000 $ 343 $ — 50,343 $ — $ — $ — $ — Municipal obligations 187,541 3,777 575 190,743 180,615 3,416 1,144 182,887 Mortgage-backed securities 992,984 27,677 — 1,020,661 899,923 23,897 162 923,658 Collateralized mortgage obligations 1,149,560 8,655 5,280 1,152,935 1,085,751 5,590 11,546 1,079,795 $ 2,380,085 $ 40,452 $ 5,855 $ 2,414,682 $ 2,166,289 $ 32,903 $ 12,852 $ 2,186,340
Available for Sale Securities Unrealized Losses	The details for securities classified as available for sale with unrealized losses for the periods indicated follow. Available for Sale September 30, 2015 Losses < 12 months Losses 12 months or > Total (in thousands) Fair Value Gross Fair Value Gross Fair Value Gross US Treasury and government agency securities $ — $ — $ 88 $ 1 $ 88 $ 1 Mortgage-backed securities 482,530 1,884 115,334 1,586 597,864 3,470 Collateralized mortgage obligations 48,576 11 34,958 622 83,534 633 Equity securities 1,510 31 2 2 1,512 33 $ 532,616 $ 1,926 $ 150,382 $ 2,211 $ 682,998 $ 4,137 Available for Sale December 31, 2014 Losses < 12 months Losses 12 months or > Total (in thousands) Fair Value Gross Fair Value Gross Fair Value Gross US Treasury and government agency securities $ 99,950 $ 70 $ 121 $ 1 $ 100,071 $ 71 Municipal obligations 2,995 5 — — 2,995 5 Mortgage-backed securities 38,955 163 125,641 2,660 164,596 2,823 Collateralized mortgage obligations — — 86,864 1,229 86,864 1,229 Equity securities 5,998 10 3 1 6,001 11 $ 147,898 $ 248 $ 212,629 $ 3,891 $ 360,527 $ 4,139
Held to Maturity with Unrealized Losses	The details for securities classified as held to maturity with unrealized losses for the periods indicated follow. Held to maturity September 30, 2015 Losses < 12 months Losses 12 months or > Total (in thousands) Fair Gross Fair Value Gross Fair Value Gross Municipal obligations $ 21,844 $ 65 $ 49,025 $ 510 $ 70,869 $ 575 Collateralized mortgage obligations 47,775 314 375,397 4,966 423,172 5,280 $ 69,619 $ 379 $ 424,422 $ 5,476 $ 494,041 $ 5,855 Held to maturity December 31, 2014 Losses < 12 months Losses 12 months or > Total (in thousands) Fair Value Gross Fair Value Gross Fair Value Gross Municipal obligations $ 4,316 $ 12 $ 58,105 $ 1,132 $ 62,421 $ 1,144 Mortgage-backed securities — — 95,522 162 95,522 162 Collateralized mortgage obligations 119,222 616 540,607 10,930 659,829 11,546 $ 123,538 $ 628 $ 694,234 $ 12,224 $ 817,772 $ 12,852
Available for Sale Securities [Member]
Amortized Cost and Fair Value of Available for Sale Securities by Final Contractual Maturity	The following table presents the amortized cost and fair value of debt securities at September 30, 2015 by contractual maturity. Actual maturities will differ from contractual maturities because of rights to call or repay obligations with or without penalties and scheduled and unscheduled principal payments on mortgage-backed securities and collateralized mortgage obligations. (in thousands) Amortized Fair Value Debt Securities Available for Sale Due in one year or less $ 43,655 $ 43,069 Due after one year through five years 78,375 79,710 Due after five years through ten years 280,603 289,987 Due after ten years 1,735,357 1,753,345 Total available for sale debt securities $ 2,137,990 $ 2,166,111
Held-to-maturity Securities [Member]
Amortized Cost and Fair Value of Available for Sale Securities by Final Contractual Maturity	Amortized Fair Value Debt Securities Held to Maturity Due in one year or less $ 248,854 $ 250,028 Due after one year through five years 420,607 420,768 Due after five years through ten years 107,040 107,116 Due after ten years 1,603,584 1,636,770 Total held to maturity securities $ 2,380,085 $ 2,414,682

Loans and Allowance for Loan 25

Loans and Allowance for Loan Losses (Tables)	9 Months Ended
	Sep. 30, 2015
Loans, Net of Unearned Income	Loans, net of unearned income, consisted of the following. (in thousands) September 30, December 31, Originated loans: Commercial non-real estate $ 6,232,310 $ 5,917,728 Construction and land development 1,068,895 1,073,964 Commercial real estate 2,956,354 2,428,195 Residential mortgages 1,843,756 1,704,770 Consumer 1,976,872 1,685,542 Total originated loans $ 14,078,187 $ 12,810,199 Acquired loans: Commercial non-real estate $ 107,985 $ 120,137 Construction and land development 8,297 21,123 Commercial real estate 352,896 688,045 Residential mortgages 819 2,378 Consumer 22 985 Total acquired loans $ 470,019 $ 832,668 FDIC acquired loans: Commercial non-real estate $ 5,699 $ 6,195 Construction and land development 8,393 11,674 Commercial real estate 18,136 27,808 Residential mortgages 169,214 187,033 Consumer 13,402 19,699 Total FDIC acquired loans $ 214,844 $ 252,409 Total loans: Commercial non-real estate $ 6,345,994 $ 6,044,060 Construction and land development 1,085,585 1,106,761 Commercial real estate 3,327,386 3,144,048 Residential mortgages 2,013,789 1,894,181 Consumer 1,990,296 1,706,226 Total loans $ 14,763,050 $ 13,895,276
Schedule of Activity in Loss Share Receivable	The following schedule shows activity in the loss share receivable for the nine months ended September 30, 2015 and 2014. Nine Months Ended (in thousands) September 30, September 30, Balance, January 1 $ 60,272 $ 113,834 Amortization (4,034 ) (9,989 ) Charge-offs, write-downs and other recoveries (6,733 ) (793 ) External expenses qualifying under loss share agreement 1,035 3,325 Changes due to changes in cash flow projections (1,984 ) (14,569 ) FDIC resolution of denied claims (1,854 ) (10,268 ) Net payments (from) to FDIC (14,667 ) 366 Ending balance $ 32,035 $ 81,906
Allowance for Loan Losses by Portfolio Segment and Related Recorded Investment in Loans	The following schedule shows activity in the allowance for loan losses by portfolio segment for the nine months ended September 30, 2015 and 2014 as well as the corresponding recorded investment in loans at the end of each period. (in thousands) Commercial non-real estate Construction Commercial Residential Consumer Total Nine Months Ended September 30, 2015 Originated loans Allowance for loan losses: Beginning balance $ 50,258 $ 5,413 $ 16,544 $ 8,051 $ 17,435 $ 97,701 Charge-offs (3,068 ) (1,483 ) (1,128 ) (1,451 ) (10,431 ) (17,561 ) Recoveries 2,589 2,006 635 578 3,418 9,226 Net provision for loan losses 13,594 (289 ) 825 283 10,119 24,532 Ending balance $ 63,373 $ 5,647 $ 16,876 $ 7,461 $ 20,541 $ 113,898 Ending balance: Individually evaluated for impairment $ 5,588 $ 21 $ 2,737 $ 96 $ 3 $ 8,445 Collectively evaluated for impairment 57,785 5,626 14,139 7,365 20,538 105,453 Loans: Ending balance: $ 6,232,310 $ 1,068,895 $ 2,956,354 $ 1,843,756 $ 1,976,872 $ 14,078,187 Individually evaluated for impairment 75,345 2,053 31,478 903 157 109,936 Collectively evaluated for impairment 6,156,965 1,066,842 2,924,876 1,842,853 1,976,715 13,968,251 Acquired loans Allowance for loan losses: Beginning balance $ — $ — $ 477 $ — $ — $ 477 Charge-offs — — — — — — Recoveries — — — — — — Net provision for loan losses — — (304 ) — — (304 ) Ending balance $ — $ — $ 173 $ — $ — $ 173 Ending balance: Individually evaluated for impairment $ — $ — $ 173 $ — $ — $ 173 Amounts related to acquired-impaired loans — — — — — — Collectively evaluated for impairment — — — — — — Loans: Ending balance: $ 107,985 $ 8,297 $ 352,896 $ 819 $ 22 $ 470,019 Individually evaluated for impairment — — 2,507 — — 2,507 Acquired-impaired loans 7,459 7,943 18,818 819 22 35,061 Collectively evaluated for impairment 100,526 354 331,571 — — 432,451 (in thousands) Commercial non-real estate Construction Commercial Residential Consumer Total Nine Months Ended September 30, 2015 FDIC acquired loans Allowance for loan losses: Beginning balance $ 911 $ 1,008 $ 4,061 $ 20,609 $ 3,995 $ 30,584 Charge-offs (1,425 ) (406 ) (2,732 ) (748 ) (140 ) (5,451 ) Recoveries 1,699 896 957 5 185 3,742 Net provision for loan losses (950 ) 235 (620 ) 1,181 (1,232 ) (1,386 ) Increase (decrease) in FDIC loss share receivable 314 (6 ) 523 (2,718 ) (97 ) (1,984 ) Ending balance $ 549 $ 1,727 $ 2,189 $ 18,329 $ 2,711 $ 25,505 Ending balance: Individually evaluated for impairment $ — $ — $ — $ — $ — $ — Amounts related to acquired-impaired loans 549 1,727 2,189 18,329 2,711 25,505 Collectively evaluated for impairment — — — — — — Loans: Ending balance: $ 5,699 $ 8,393 $ 18,136 $ 169,214 $ 13,402 $ 214,844 Individually evaluated for impairment — — — — — — Acquired-impaired loans 5,699 8,393 18,136 169,214 13,402 214,844 Collectively evaluated for impairment — — — — — — Total loans Allowance for loan losses: Beginning balance $ 51,169 $ 6,421 $ 21,082 $ 28,660 $ 21,430 $ 128,762 Charge-offs (4,493 ) (1,889 ) (3,860 ) (2,199 ) (10,571 ) (23,012 ) Recoveries 4,288 2,902 1,592 583 3,603 12,968 Net provision for loan losses 12,644 (54 ) (99 ) 1,464 8,887 22,842 Increase (decrease) in FDIC loss share receivable 314 (6 ) 523 (2,718 ) (97 ) (1,984 ) Ending balance $ 63,922 $ 7,374 $ 19,238 $ 25,790 $ 23,252 $ 139,576 Ending balance: Individually evaluated for impairment $ 5,588 $ 21 $ 2,910 $ 96 $ 3 $ 8,618 Amounts related to acquired-impaired loans 549 1,727 2,189 18,329 2,711 25,505 Collectively evaluated for impairment 57,785 5,626 14,139 7,365 20,538 105,453 Loans: Ending balance: $ 6,345,994 $ 1,085,585 $ 3,327,386 $ 2,013,789 $ 1,990,296 $ 14,763,050 Individually evaluated for impairment 75,345 2,053 33,985 903 157 112,443 Acquired-impaired loans 13,158 16,336 36,954 170,033 13,424 249,905 Collectively evaluated for impairment 6,257,491 1,067,196 3,256,447 1,842,853 1,976,715 14,400,702 Commercial non-real estate Construction Commercial Residential Consumer Total (In thousands) Nine Months Ended September 30, 2014 Originated loans Allowance for loan losses: Beginning balance $ 33,091 $ 6,180 $ 20,649 $ 6,892 $ 12,073 $ 78,885 Charge-offs (4,690 ) (2,615 ) (2,255 ) (1,793 ) (11,920 ) (23,273 ) Recoveries 2,118 1,220 1,231 501 3,722 8,792 Net provision for loan losses 3,929 2,151 (3,231 ) 3,647 10,921 17,417 Ending balance $ 34,448 $ 6,936 $ 16,394 $ 9,247 $ 14,796 $ 81,821 Ending balance: Individually evaluated for impairment $ 24 $ 250 $ 98 $ 382 $ — $ 754 Collectively evaluated for impairment 34,424 6,686 16,296 8,865 14,796 81,067 Loans: Ending balance: $ 4,806,740 $ 974,442 $ 2,245,855 $ 1,635,462 $ 1,623,069 $ 11,285,568 Individually evaluated for impairment 5,582 6,617 14,486 2,712 — 29,397 Collectively evaluated for impairment 4,801,158 967,825 2,231,369 1,632,750 1,623,069 11,256,171 Acquired loans Allowance for loan losses: Beginning balance $ 1,603 $ 10 $ 34 $ — $ — $ 1,647 Charge-offs — — — — — — Recoveries — — — — — — Net provision for loan losses 5,800 1,436 57 (4 ) 182 7,471 Ending balance $ 7,403 $ 1,446 $ 91 $ (4 ) $ 182 $ 9,118 Ending balance: Individually evaluated for impairment $ 92 $ 426 $ 46 $ — $ — $ 564 Amounts related to acquired-impaired loans — — — — — — Collectively evaluated for impairment 7,311 1,020 45 (4 ) 182 8,554 Loans: Ending balance: $ 769,226 $ 110,294 $ 813,429 $ 37,739 $ 51,488 $ 1,782,176 Individually evaluated for impairment 931 2,284 458 28 — 3,701 Acquired-impaired loans 4,064 19,200 27,392 5,038 143 55,837 Collectively evaluated for impairment 764,231 88,810 785,579 32,673 51,345 1,722,638 Commercial non-real estate Construction Commercial Residential Consumer Total (In thousands) Nine Months Ended September 30, 2014 FDIC acquired loans Allowance for loan losses: Beginning balance $ 2,323 $ 2,655 $ 10,929 $ 27,989 $ 9,198 $ 53,094 Charge-offs (176 ) (350 ) (4,480 ) (677 ) (1,192 ) (6,875 ) Recoveries 467 1,504 1,408 1 370 3,750 Net provision for loan losses (79 ) (138 ) (125 ) (257 ) (167 ) (766 ) (Decrease) increase in FDIC loss share receivable (1,507 ) (2,404 ) (2,418 ) (4,873 ) (3,368 ) (14,570 ) Ending balance $ 1,028 $ 1,267 $ 5,314 $ 22,183 $ 4,841 $ 34,633 Ending balance: Individually evaluated for impairment $ — $ — $ — $ — $ — $ — Amounts related to acquired-impaired loans 1,028 1,267 5,314 22,183 4,841 34,633 Collectively evaluated for impairment — — — — — — Loans: Ending balance: $ 11,171 $ 11,166 $ 41,550 $ 185,289 $ 31,654 $ 280,830 Individually evaluated for impairment — — — — — — Acquired-impaired loans 11,171 11,166 41,550 185,289 31,654 280,830 Collectively evaluated for impairment — — — — — — Total loans Allowance for loan losses: Beginning balance $ 37,017 $ 8,845 $ 31,612 $ 34,881 $ 21,271 $ 133,626 Charge-offs (4,866 ) (2,965 ) (6,735 ) (2,470 ) (13,112 ) (30,148 ) Recoveries 2,585 2,724 2,639 502 4,092 12,542 Net provision for loan losses 9,650 3,449 (3,299 ) 3,386 10,936 24,122 (Decrease) increase in FDIC loss share receivable (1,507 ) (2,404 ) (2,418 ) (4,873 ) (3,368 ) (14,570 ) Ending balance $ 42,879 $ 9,649 $ 21,799 $ 31,426 $ 19,819 $ 125,572 Ending balance: Individually evaluated for impairment $ 116 $ 676 $ 144 $ 382 $ — $ 1,318 Amounts related to acquired-impaired loans 1,028 1,267 5,314 22,183 4,841 34,633 Collectively evaluated for impairment 41,735 7,706 16,341 8,861 14,978 89,621 Loans: Ending balance: $ 5,587,137 $ 1,095,902 $ 3,100,834 $ 1,858,490 $ 1,706,211 $ 13,348,574 Individually evaluated for impairment 6,513 8,901 14,944 2,740 — 33,098 Acquired-impaired loans 15,235 30,366 68,942 190,327 31,797 336,667 Collectively evaluated for impairment 5,565,389 1,056,635 3,016,948 1,665,423 1,674,414 12,978,809
Summary of Composition of Non-Accrual Loans by Portfolio Segment	The following table shows the composition of nonaccrual loans by portfolio segment and class. Acquired-impaired and certain FDIC acquired loans are considered to be performing due to the application of the accretion method and are excluded from the table. FDIC acquired loans accounted for using the cost recovery method do not have an accretable yield and are included below as nonaccrual loans. Acquired-performing loans that have subsequently been placed on nonaccrual status are also included below. September 30, December 31, (in thousands) 2015 2014 Originated loans: Commercial non-real estate $ 93,448 $ 15,511 Construction and land development 5,527 6,462 Commercial real estate 36,367 22,047 Residential mortgages 21,750 21,702 Consumer 6,838 5,574 Total originated loans $ 163,930 $ 71,296 Acquired loans: Commercial non-real estate $ — $ — Construction and land development — — Commercial real estate 3,015 6,139 Residential mortgages — — Consumer — — Total acquired loans $ 3,015 $ 6,139 FDIC acquired loans: Commercial non-real estate $ — $ — Construction and land development — 1,103 Commercial real estate — 433 Residential mortgages — 392 Consumer — 174 Total FDIC acquired loans $ — $ 2,102 Total loans: Commercial non-real estate $ 93,448 $ 15,511 Construction and land development 5,527 7,565 Commercial real estate 39,382 28,619 Residential mortgages 21,750 22,094 Consumer 6,838 5,748 Total loans $ 166,945 $ 79,537
Schedule of Troubled Debt Restructurings Occurred During Period by Portfolio Segment	The table below details TDRs that were modified during the nine months ended September 30, 2015 and September 30, 2014 by portfolio segment. Nine Months Ended (in thousands) September 30, 2015 September 30, 2014 Troubled Debt Restructurings: Number of Pre-Modification Post-Modification Number of Pre-Modification Post-Modification Originated loans: Commercial non-real estate — $ — $ — — $ — $ — Construction and land development — — — — — — Commercial real estate 1 482 482 2 2,430 2,385 Residential mortgages 4 185 185 4 1,495 848 Consumer 1 20 20 — — — Total originated loans 6 $ 687 $ 687 6 $ 3,925 $ 3,233 Acquired loans: Commercial non-real estate — $ — $ — — $ — $ — Construction and land development — — — — — — Commercial real estate — — — — — — Residential mortgages — — — — — — Consumer — — — — — — Total acquired loans — $ — $ — — $ — $ — FDIC acquired loans: Commercial non-real estate — $ — $ — — $ — $ — Construction and land development — — — — — — Commercial real estate — — — — — — Residential mortgages — — — — — — Consumer — — — — — — Total FDIC acquired loans — $ — $ — — $ — $ — Total loans: Commercial non-real estate — $ — $ — — $ — $ — Construction and land development — — — — — — Commercial real estate 1 482 482 2 2,430 2,385 Residential mortgages 4 185 185 4 1,495 848 Consumer 1 20 20 — — — Total loans 6 $ 687 $ 687 6 $ 3,925 $ 3,233
Summary of Impaired Loans Disaggregated by Class	The tables below present loans that are individually evaluated for impairment disaggregated by class at September 30, 2015 and December 31, 2014. Loans individually evaluated for impairment include TDRs and loans that are determined to be impaired and have aggregate relationship balances of $1 million or more. September 30, 2015 Recorded Investment Unpaid Balance Related Allowance Average Investment Interest Recognized (in thousands) Originated loans: With no related allowance recorded: Commercial non-real estate $ 32,963 $ 33,468 $ — $ 14,887 $ — Construction and land development 1,391 1,391 — 1,319 — Commercial real estate 12,945 14,952 — 11,018 26 Residential mortgages — — — 259 2 Consumer 95 95 — 74 — 47,394 49,906 — 27,557 28 With an allowance recorded: Commercial non-real estate 42,382 43,146 5,588 16,683 6 Construction and land development 662 2,224 21 3,443 66 Commercial real estate 18,533 18,536 2,737 12,143 70 Residential mortgages 903 1,413 96 1,578 18 Consumer 62 62 3 27 3 62,542 65,381 8,445 33,874 163 Total: Commercial non-real estate 75,345 76,614 5,588 31,570 6 Construction and land development 2,053 3,615 21 4,762 66 Commercial real estate 31,478 33,488 2,737 23,161 96 Residential mortgages 903 1,413 96 1,837 20 Consumer 157 157 3 101 3 Total originated loans $ 109,936 $ 115,287 $ 8,445 $ 61,431 $ 191 Acquired loans: With an allowance recorded: Commercial non-real estate $ — $ — $ — $ — $ — Construction and land development — — — — — Commercial real estate 2,507 2,522 173 2,580 — Residential mortgages — — — — — Consumer — — — — — 2,507 2,522 173 2,580 — Total: Commercial non-real estate — — — — — Construction and land development — — — — — Commercial real estate 2,507 2,522 173 2,580 — Residential mortgages — — — — — Consumer — — — — — Total acquired loans $ 2,507 $ 2,522 $ 173 $ 2,580 $ — September 30, 2015 Recorded Investment Unpaid Balance Related Allowance Average Investment Interest Recognized (in thousands) Total loans: With no related allowance recorded: Commercial non-real estate $ 32,963 $ 33,468 $ — $ 14,887 $ — Construction and land development 1,391 1,391 — 1,319 — Commercial real estate 12,945 14,952 — 11,018 26 Residential mortgages — — — 259 2 Consumer 95 95 — 74 — 47,394 49,906 — 27,557 28 With an allowance recorded: Commercial non-real estate 42,382 43,146 5,588 16,683 6 Construction and land development 662 2,224 21 3,443 66 Commercial real estate 21,040 21,058 2,910 14,723 70 Residential mortgages 903 1,413 96 1,578 18 Consumer 62 62 3 27 3 65,049 67,903 8,618 36,454 163 Total: Commercial non-real estate 75,345 76,614 5,588 31,570 6 Construction and land development 2,053 3,615 21 4,762 66 Commercial real estate 33,985 36,010 2,910 25,741 96 Residential mortgages 903 1,413 96 1,837 20 Consumer 157 157 3 101 3 Total loans $ 112,443 $ 117,809 $ 8,618 $ 64,011 $ 191 December 31, 2014 (in thousands) Recorded Unpaid Related Average Interest Originated loans: With no related allowance recorded: Commercial non-real estate $ 3,003 $ 3,646 $ — $ 1,209 $ 51 Construction and land development 3,345 6,486 — 3,330 142 Commercial real estate 8,467 10,575 — 8,461 331 Residential mortgages — — — 88 3 Consumer — — — — — 14,815 20,707 — 13,088 527 With an allowance recorded: Commercial non-real estate 984 984 14 5,522 99 Construction and land development 4,905 4,906 19 6,660 137 Commercial real estate 3,654 3,654 11 7,500 109 Residential mortgages 2,656 3,311 330 2,204 50 Consumer 6 6 3 1 — 12,205 12,861 377 21,887 395 Total: Commercial non-real estate 3,987 4,630 14 6,732 150 Construction and land development 8,250 11,392 19 9,990 279 Commercial real estate 12,121 14,229 11 15,961 439 Residential mortgages 2,656 3,311 330 2,292 53 Consumer 6 6 3 1 — Total originated loans $ 27,020 $ 33,568 $ 377 $ 34,976 $ 921 Acquired loans: With no related allowance recorded: Commercial non-real estate $ — $ — $ — $ 357 $ — Construction and land development — — — 121 — Commercial real estate — — — 311 — Residential mortgages — — — 88 — Consumer — — — — — — — — 877 — With an allowance recorded: Commercial non-real estate — — — 1,059 122 Construction and land development — — — 1,037 56 Commercial real estate 2,691 2,720 477 1,357 75 Residential mortgages — — — — — Consumer — — — — — 2,691 2,720 477 3,453 253 Total: Commercial non-real estate — — — 1,416 122 Construction and land development — — — 1,158 56 Commercial real estate 2,691 2,720 477 1,668 75 Residential mortgages — — — 88 — Consumer — — — — — Total acquired loans $ 2,691 $ 2,720 $ 477 $ 4,330 $ 253 December 31, 2014 (in thousands) Recorded Unpaid Related Average Interest Total loans: With no related allowance recorded: Commercial non-real estate $ 3,003 $ 3,646 $ — $ 1,566 $ 51 Construction and land development 3,345 6,486 — 3,451 142 Commercial real estate 8,467 10,575 — 8,772 331 Residential mortgages — — — 176 3 Consumer — — — — — 14,815 20,707 — 13,965 527 With an allowance recorded: Commercial non-real estate 984 984 14 6,581 221 Construction and land development 4,905 4,906 19 7,697 193 Commercial real estate 6,345 6,374 488 8,857 184 Residential mortgages 2,656 3,311 330 2,204 50 Consumer 6 6 3 1 — 14,896 15,581 854 25,340 648 Total: Commercial non-real estate 3,987 4,630 14 8,147 272 Construction and land development 8,250 11,392 19 11,148 335 Commercial real estate 14,812 16,949 488 17,629 515 Residential mortgages 2,656 3,311 330 2,380 53 Consumer 6 6 3 1 — Total loans $ 29,711 $ 36,288 $ 854 $ 39,305 $ 1,175
Summary of Age Analysis of Past Due Loans	The tables below present the age analysis of past due loans at September 30, 2015 and December 31, 2014. September 30, 2015 30-59 days 60-89 days Greater than past due Total past due Current Total Loans Recorded (in thousands) Originated loans: Commercial non-real estate $ 19,298 $ 3,271 $ 6,805 $ 29,374 $ 6,202,936 $ 6,232,310 $ 878 Construction and land development 2,489 602 4,471 7,562 1,061,333 1,068,895 1,700 Commercial real estate 5,823 3,572 16,289 25,684 2,930,670 2,956,354 1,773 Residential mortgages 25,525 4,619 9,669 39,813 1,803,943 1,843,756 46 Consumer 13,037 5,490 5,271 23,798 1,953,074 1,976,872 1,350 Total $ 66,172 $ 17,554 $ 42,505 $ 126,231 $ 13,951,956 $ 14,078,187 $ 5,747 Acquired loans: Commercial non-real estate $ — $ — $ — $ — $ 107,985 $ 107,985 $ — Construction and land development — — — — 8,297 8,297 — Commercial real estate 744 428 445 1,617 351,279 352,896 129 Residential mortgages — — — — 819 819 — Consumer — — — — 22 22 — Total $ 744 $ 428 $ 445 $ 1,617 $ 468,402 $ 470,019 $ 129 FDIC acquired loans: Commercial non-real estate $ — $ — $ — $ — $ 5,699 $ 5,699 $ — Construction and land development — — — — 8,393 8,393 — Commercial real estate — — — — 18,136 18,136 — Residential mortgages — — — — 169,214 169,214 — Consumer — — — — 13,402 13,402 — Total $ — $ — $ — $ — $ 214,844 $ 214,844 $ — Total loans: Commercial non-real estate $ 19,298 $ 3,271 $ 6,805 $ 29,374 $ 6,316,620 $ 6,345,994 $ 878 Construction and land development 2,489 602 4,471 7,562 1,078,023 1,085,585 1,700 Commercial real estate 6,567 4,000 16,734 27,301 3,300,085 3,327,386 1,902 Residential mortgages 25,525 4,619 9,669 39,813 1,973,976 2,013,789 46 Consumer 13,037 5,490 5,271 23,798 1,966,498 1,990,296 1,350 Total $ 66,916 $ 17,982 $ 42,950 $ 127,848 $ 14,635,202 $ 14,763,050 $ 5,876 December 31, 2014 30-59 days 60-89 days Greater than Total past due Current Total Loans Recorded (in thousands) Originated loans: Commercial non-real estate $ 4,380 $ 1,742 $ 8,560 $ 14,682 $ 5,903,046 $ 5,917,728 $ 630 Construction and land development 6,620 1,532 4,453 12,605 1,061,359 1,073,964 142 Commercial real estate 6,527 2,964 13,234 22,725 2,405,470 2,428,195 696 Residential mortgages 14,730 3,261 11,208 29,199 1,675,571 1,704,770 1,199 Consumer 8,422 2,450 4,365 15,237 1,670,305 1,685,542 1,897 Total $ 40,679 $ 11,949 $ 41,820 $ 94,448 $ 12,715,751 $ 12,810,199 $ 4,564 Acquired loans: Commercial non-real estate $ — $ — $ — $ — $ 120,137 $ 120,137 $ — Construction and land development 111 — — 111 21,012 21,123 — Commercial real estate 3,861 282 1,591 5,734 682,311 688,045 261 Residential mortgages — — — — 2,378 2,378 — Consumer — — — — 985 985 — Total $ 3,972 $ 282 $ 1,591 $ 5,845 $ 826,823 $ 832,668 $ 261 FDIC acquired loans: Commercial non-real estate $ — $ — $ — $ — $ 6,195 $ 6,195 $ — Construction and land development — — 1,103 1,103 10,571 11,674 — Commercial real estate — — 433 433 27,375 27,808 — Residential mortgages — 272 — 272 186,761 187,033 — Consumer 1 — 34 35 19,664 19,699 — Total $ 1 $ 272 $ 1,570 $ 1,843 $ 250,566 $ 252,409 $ — Total loans: Commercial non-real estate $ 4,380 $ 1,742 $ 8,560 $ 14,682 $ 6,029,378 $ 6,044,060 $ 630 Construction and land development 6,731 1,532 5,556 13,819 1,092,942 1,106,761 142 Commercial real estate 10,388 3,246 15,258 28,892 3,115,156 3,144,048 957 Residential mortgages 14,730 3,533 11,208 29,471 1,864,710 1,894,181 1,199 Consumer 8,423 2,450 4,399 15,272 1,690,954 1,706,226 1,897 Total $ 44,652 $ 12,503 $ 44,981 $ 102,136 $ 13,793,140 $ 13,895,276 $ 4,825
Changes in Carrying Amount of Acquired Loans and Accretable Yield for Loans Receivable	Changes in the carrying amount of acquired-impaired loans and accretable yield are presented in the following table for the nine months ended September 30, 2015 and the year ended December 31, 2014. (in thousands) September 30, 2015 December 31, 2014 FDIC acquired Acquired FDIC acquired Acquired Carrying Accretable Carrying Accretable Carrying Accretable Carrying Accretable Balance at beginning of period $ 252,409 $ 112,788 $ 61,276 $ 74,668 $ 358,666 $ 122,715 $ 68,075 $ 131,370 Payments received, net (47,732 ) (395 ) (38,243 ) (14,256 ) (125,388 ) (1,071 ) (50,178 ) (32,855 ) Accretion 10,167 (10,167 ) 12,028 (12,028 ) 19,131 (19,131 ) 43,379 (43,379 ) Decrease in expected cash flows based on actual cash flows and changes in cash flow assumptions — (1,385 ) — (627 ) — (1,137 ) — (203 ) Net transfers from nonaccretable difference to accretable yield — (2,485 ) — (466 ) — 11,412 — 19,735 Balance at end of period $ 214,844 $ 98,356 $ 35,061 $ 47,291 $ 252,409 $ 112,788 $ 61,276 $ 74,668
Commercial Non-Real Estate [Member]
Schedule of Credit Quality Indicators of Various Classes of Loans - Credit Risk Profile by Internally Assigned Grade	The following tables present the credit quality indicators of the Company’s various classes of loans at September 30, 2015 and December 31, 2014. Commercial Non-Real Estate Credit Exposure Credit Risk Profile by Internally Assigned Grade (in thousands) September 30, 2015 December 31, 2014 Originated Acquired FDIC acquired Total Originated Acquired FDIC acquired Total Grade: Pass $ 5,531,569 $ 100,836 $ 2,201 $ 5,634,606 $ 5,577,827 $ 111,847 $ 2,027 $ 5,691,701 Pass-Watch 134,860 76 883 135,819 174,742 715 1,120 176,577 Special Mention 225,228 328 — 225,556 52,962 350 — 53,312 Substandard 340,618 6,745 2,615 349,978 112,153 7,225 3,017 122,395 Doubtful 35 — — 35 44 — 31 75 Total $ 6,232,310 $ 107,985 $ 5,699 $ 6,345,994 $ 5,917,728 $ 120,137 $ 6,195 $ 6,044,060
Construction and Land Development [Member]
Schedule of Credit Quality Indicators of Various Classes of Loans - Credit Risk Profile by Internally Assigned Grade	Construction Credit Exposure Credit Risk Profile by Internally Assigned Grade (in thousands) September 30, 2015 December 31, 2014 Originated Acquired FDIC acquired Total Originated Acquired FDIC acquired Total Grade: Pass $ 1,020,611 $ 1,354 $ 2,238 $ 1,024,203 $ 1,012,128 $ 14,377 $ 2,468 $ 1,028,973 Pass-Watch 3,038 2,324 947 6,309 21,516 432 532 22,480 Special Mention 11,612 — 286 11,898 7,097 129 319 7,545 Substandard 33,634 4,619 4,922 43,175 33,223 6,185 8,355 47,763 Total $ 1,068,895 $ 8,297 $ 8,393 $ 1,085,585 $ 1,073,964 $ 21,123 $ 11,674 $ 1,106,761
Commercial Real Estate [Member]
Schedule of Credit Quality Indicators of Various Classes of Loans - Credit Risk Profile by Internally Assigned Grade	Commercial Real Estate Credit Exposure Credit Risk Profile by Internally Assigned Grade (in thousands) September 30, 2015 December 31, 2014 Originated Acquired FDIC acquired Total Originated Acquired FDIC acquired Total Grade: Pass $ 2,769,860 $ 328,821 $ 3,298 $ 3,101,979 $ 2,241,391 $ 641,966 $ 4,139 $ 2,887,496 Pass-Watch 41,344 5,247 2,585 49,176 61,589 11,142 4,547 77,278 Special Mention 42,674 5,373 1,433 49,480 21,543 8,113 1,319 30,975 Substandard 102,459 13,455 10,820 126,734 103,651 26,824 17,803 148,278 Doubtful 17 — — 17 21 — — 21 Total $ 2,956,354 $ 352,896 $ 18,136 $ 3,327,386 $ 2,428,195 $ 688,045 $ 27,808 $ 3,144,048
Residential Mortgages [Member]
Schedule of Credit Quality Indicators of Various Classes of Loans - Credit Risk Profile Based on Payment Activity and Accrual Status	Residential Mortgage Credit Exposure Credit Risk Profile Based on Payment Activity and Accrual Status (in thousands) September 30, 2015 December 31, 2014 Originated Acquired FDIC acquired Total Originated Acquired FDIC acquired Total Performing $ 1,821,959 $ 819 $ 169,214 $ 1,991,992 $ 1,681,868 $ 2,378 $ 186,641 $ 1,870,887 Nonperforming 21,797 — — 21,797 22,902 — 392 23,294 Total $ 1,843,756 $ 819 $ 169,214 $ 2,013,789 $ 1,704,770 $ 2,378 $ 187,033 $ 1,894,181
Consumer [Member]
Schedule of Credit Quality Indicators of Various Classes of Loans - Credit Risk Profile Based on Payment Activity and Accrual Status	Residential Mortgage Credit Exposure Credit Risk Profile Based on Payment Activity and Accrual Status (in thousands) September 30, 2015 December 31, 2014 Originated Acquired FDIC acquired Total Originated Acquired FDIC acquired Total Performing $ 1,821,959 $ 819 $ 169,214 $ 1,991,992 $ 1,681,868 $ 2,378 $ 186,641 $ 1,870,887 Nonperforming 21,797 — — 21,797 22,902 — 392 23,294 Total $ 1,843,756 $ 819 $ 169,214 $ 2,013,789 $ 1,704,770 $ 2,378 $ 187,033 $ 1,894,181 Consumer Credit Exposure Credit Risk Profile Based on Payment Activity and Accrual Status (in thousands) September 30, 2015 December 31, 2014 Originated Acquired FDIC acquired Total Originated Acquired FDIC acquired Total Performing $ 1,968,684 $ 22 $ 13,402 $ 1,982,108 $ 1,678,069 $ 985 $ 19,525 $ 1,698,579 Nonperforming 8,188 — — 8,188 7,473 — 174 7,647 Total $ 1,976,872 $ 22 $ 13,402 $ 1,990,296 $ 1,685,542 $ 985 $ 19,699 $ 1,706,226

Long-Term Debt (Tables)

Long-Term Debt (Tables)	9 Months Ended
	Sep. 30, 2015
Debt Disclosure [Abstract]
Long-Term Debt	Long-term debt consisted of the following. ( in thousands) September 30, December 31, Subordinated notes payable, maturing June 2045 $ 150,000 $ — Subordinated notes payable, maturing April 2017 98,011 98,011 Term note payable, maturing December 2015 123,200 149,600 Other long-term debt 125,966 126,760 Total long-term debt $ 497,177 $ 374,371

Fair Value (Tables)

Fair Value (Tables)	9 Months Ended
	Sep. 30, 2015
Fair Value Disclosures [Abstract]
Schedule of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis	The following tables present for each of the fair value hierarchy levels the Company’s assets and liabilities that are measured at fair value on a recurring basis in the consolidated balance sheets. September 30, 2015 (in thousands) Level 1 Level 2 Total Assets Available for sale debt securities: U.S. Treasury and government agency securities $ — $ 143 $ 143 Municipal obligations — 15,952 15,952 Corporate debt securities — 3,500 3,500 Mortgage-backed securities — 1,841,369 1,841,369 Collateralized mortgage obligations — 305,147 305,147 Equity securities 2,726 — 2,726 Total available for sale securities 2,726 2,166,111 2,168,837 Derivative assets (1) — 31,399 31,399 Total recurring fair value measurements – assets $ 2,726 $ 2,197,510 $ 2,200,236 Liabilities Derivative liabilities (1) $ — $ 30,908 $ 30,908 Total recurring fair value measurements – liabilities $ — $ 30,908 $ 30,908 (1) For further disaggregation of derivative assets and liabilities, see Note 7 – Derivatives. December 31, 2014 (in thousands) Level 1 Level 2 Total Assets Available for sale debt securities: U.S. Treasury and government agency securities $ — $ 300,508 $ 300,508 Municipal obligations — 14,176 14,176 Corporate debt securities — 3,500 3,500 Mortgage-backed securities — 1,245,564 1,245,564 Collateralized mortgage obligations — 86,864 86,864 Equity securities 9,553 — 9,553 Total available for sale securities 9,553 1,650,612 1,660,165 Derivative assets (1) — 19,432 19,432 Total recurring fair value measurements – assets $ 9,553 $ 1,670,044 $ 1,679,597 Liabilities Derivative liabilities (1) $ — $ 20,860 $ 20,860 Total recurring fair value measurements – liabilities $ — $ 20,860 $ 20,860 (1) For further disaggregation of derivative assets and liabilities, see Note 7 – Derivatives.
Schedule of Financial Assets Measured at Fair Value on Nonrecurring Basis	The following tables present the Company’s financial assets that are measured at fair value on a nonrecurring basis for each of the fair value hierarchy levels. September 30, 2015 (in thousands) Level 1 Level 2 Level 3 Total Collateral-dependent impaired loans $ — $ 98,019 $ — $ 98,019 Other real estate owned — — 21,778 21,778 Total nonrecurring fair value measurements $ — $ 98,019 $ 21,778 $ 119,797 December 31, 2014 (in thousands) Level 1 Level 2 Level 3 Total Collateral-dependent impaired loans $ — $ 30,204 $ — $ 30,204 Other real estate owned — — 29,715 29,715 Total nonrecurring fair value measurements $ — $ 30,204 $ 29,715 $ 59,919
Schedule of Estimated Fair Values of Financial Instruments	The following tables present the estimated fair values of the Company’s financial instruments by fair value hierarchy levels and the corresponding carrying amount at September 30, 2015 and December 31, 2014. September 30, 2015 (in thousands) Level 1 Level 2 Level 3 Total Fair Value Carrying Amount Financial assets: Cash, interest-bearing bank deposits, and federal funds sold $ 518,157 $ — $ — $ 518,157 $ 518,157 Available for sale securities 2,726 2,166,111 — 2,168,837 2,168,837 Held to maturity securities — 2,414,682 — 2,414,682 2,380,085 Loans, net — 98,019 14,558,423 14,656,442 14,623,474 Loans held for sale — 19,764 — 19,764 19,764 Derivative financial instruments — 31,399 — 31,399 31,399 Financial liabilities: Deposits $ — $ — $ 17,423,721 $ 17,423,721 $ 17,439,948 Federal funds purchased 10,200 — — 10,200 10,200 Securities sold under agreements to repurchase 438,982 — — 438,982 438,982 FHLB borrowings 600,000 — — 600,000 600,000 Long-term debt — 504,475 — 504,475 497,177 Derivative financial instruments — 30,908 — 30,908 30,908 December 31, 2014 (in thousands) Level 1 Level 2 Level 3 Total Fair Value Carrying Amount Financial assets: Cash, interest-bearing bank deposits, and federal funds sold $ 1,159,403 $ — $ — $ 1,159,403 $ 1,159,403 Available for sale securities 9,553 1,650,612 — 1,660,165 1,660,165 Held to maturity securities — 2,186,340 — 2,186,340 2,166,289 Loans, net — 30,204 13,672,427 13,702,631 13,766,514 Loans held for sale — 20,252 — 20,252 20,252 Derivative financial instruments — 19,432 — 19,432 19,432 Financial liabilities: Deposits $ — $ — $ 16,398,878 $ 16,398,878 $ 16,572,831 Federal funds purchased 12,000 — — 12,000 12,000 Securities sold under agreements to repurchase 624,573 — — 624,573 624,573 FHLB borrowings 515,000 — — 515,000 515,000 Long-term debt — 346,379 — 346,379 374,371 Derivative financial instruments — 20,860 — 20,860 20,860

Derivatives (Tables)

Derivatives (Tables)	9 Months Ended
	Sep. 30, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Fair Values of Derivative Instruments on Balance Sheet	The table below presents the notional amounts and fair values of the Company’s derivative financial instruments as well as their classification on the consolidated balance sheets as of September 30, 2015 and December 31, 2014. Fair Values (1) Notional Amounts Assets Liabilities (in thousands) Type of September 30, December 31, September 30, December 31, September 30, December 31, Derivatives designated as hedging instruments: Interest rate swaps Cash Flow $ 500,000 $ 300,000 $ 1,419 $ — $ — $ 592 $ 500,000 $ 300,000 $ 1,419 $ — $ — $ 592 Derivatives not designated as hedging instruments: Interest rate swaps (2) N/A $ 728,674 $ 747,754 $ 26,621 $ 17,806 $ 27,362 $ 18,419 Risk participation agreements N/A 87,184 80,438 107 125 206 208 Forward commitments to sell residential mortgage loans N/A 38,817 52,238 100 80 329 250 Interest rate-lock commitments on residential mortgage loans N/A 22,127 33,068 161 111 45 44 Foreign exchange forward contracts N/A 62,221 89,432 2,991 1,310 2,966 1,347 $ 939,023 $ 1,002,930 $ 29,980 $ 19,432 $ 30,908 $ 20,268 (1) Derivative assets and liabilities are reported with other assets or other liabilities, respectively, in the consolidated balance sheets. (2) The notional amount represents both the customer accommodation agreements and offsetting agreements with unrelated financial institutions.
Offsetting Derivative Assets and Liabilities	Offsetting information in regards to derivative assets and liabilities subject to master netting agreements at September 30, 2015 and December 31, 2014 is presented in the following tables. Gross Gross Net Amounts the Statement Gross Amounts Not Offset in the (in thousands) Financial Cash Net As of September 30, 2015 Derivative Assets $ 26,728 $ — $ 26,728 $ 118 $ — $ 26,610 Total $ 26,728 $ — $ 26,728 $ 118 $ — $ 26,610 Derivative Liabilities $ 27,568 $ — $ 27,568 $ 118 $ 28,796 $ (1,346 ) Total $ 27,568 $ — $ 27,568 $ 118 $ 28,796 $ (1,346 ) Gross Gross Statement Net Amounts Gross Amounts Not Offset in the Description Financial Cash Net As of December 31, 2014 Derivative Assets $ 17,931 $ — $ 17,931 $ 936 $ — $ 16,995 Total $ 17,931 $ — $ 17,931 $ 936 $ — $ 16,995 Derivative Liabilities $ 18,627 $ — $ 18,627 $ 936 $ 17,343 $ 348 Total $ 18,627 $ — $ 18,627 $ 936 $ 17,343 $ 348

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2015
Equity [Abstract]
Components of Accumulated Other Comprehensive Income (Loss)	The components of AOCI and changes in those components are presented in the following table. (in thousands) Available HTM Securities Employee Loss on Total Balance, December 31, 2013 $ 8,263 $ (21,189 ) $ (22,453 ) $ — $ (35,379 ) Other comprehensive income before income taxes: Net change in unrealized gain 9,119 — — — 9,119 Reclassification of net losses realized and included in earnings — — 293 — 293 Valuation adjustment for employee benefit plans — — 1,902 — 1,902 Amortization of unrealized net loss on securities transferred to HTM — 2,463 — — 2,463 Income tax expense 3,309 879 903 — 5,091 Balance, September 30, 2014 $ 14,073 $ (19,605 ) $ (21,161 ) $ — $ (26,693 ) Balance, December 31, 2014 $ 18,001 $ (19,074 ) $ (48,626 ) $ (375 ) $ (50,074 ) Other comprehensive income before income taxes: Net change in unrealized gain 163 — — 2,011 2,174 Reclassification of net (gain) losses realized and included in earnings (165 ) — 2,373 — 2,208 Valuation adjustment for employee benefit plans — — (959 ) (959 ) Amortization of unrealized net loss on securities transferred to HTM — 2,609 — — 2,609 Income tax (benefit) expense (73 ) 953 513 732 2,125 Balance, September 30, 2015 $ 18,072 $ (17,418 ) $ (47,725 ) $ 904 $ (46,167 )
Summary of Line Items in Consolidated Income Statements Affected by Amounts Reclassified from Accumulated Other Comprehensive Income	The following table shows the line items in the consolidated income statements affected by amounts reclassified from accumulated other comprehensive income. Nine Months Ended September 30, Affected line item on the income statement Amount reclassified from AOCI (a) (in thousands) 2015 2014 Gain on sale of AFS securities $ 165 $ — Securities gains (losses) Tax effect (58 ) — Income taxes Net of tax 107 — Net income Amortization of unrealized net loss on securities transferred to HTM $ (2,609 ) $ (2,463 ) Interest income Tax effect 953 879 Income taxes Net of tax (1,656 ) (1,584 ) Net income Amortization of defined benefit pension and post-retirement items (2,373 ) (293 ) Employee benefits expense (b) Tax effect 831 103 Income taxes Net of tax (1,542 ) (190 ) Net income Total reclassifications, net of tax $ (3,091 ) $ (1,774 ) Net income (a) Amounts in parenthesis indicate reduction in net income. (b) These accumulated other comprehensive income components are included in the computation of net periodic pension and post-retirement cost that is reported with employee benefits expense (see Note 11 for additional details).

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2015
Earnings Per Share [Abstract]
Computation of Earnings Per Common Share	A summary of the information used in the computation of earnings per common share follows. Three Months Ended Nine Months Ended (in thousands, except per share data) 2015 2014 2015 2014 Numerator: Net income to common shareholders $ 41,166 $ 46,553 $ 116,154 $ 135,630 Net income allocated to participating securities – basic and diluted 840 883 2,541 2,783 Net income allocated to common shareholders – basic and diluted $ 40,326 $ 45,670 $ 113,613 $ 132,847 Denominator: Weighted-average common shares – basic 77,928 81,721 78,452 81,965 Dilutive potential common shares 147 221 157 239 Weighted-average common shares – diluted 78,075 81,942 78,609 82,204 Earnings per common share: Basic $ 0.52 $ 0.56 $ 1.45 $ 1.62 Diluted $ 0.52 $ 0.56 $ 1.45 $ 1.62

Share-Based Payment Arrangeme31

Share-Based Payment Arrangements (Tables)	9 Months Ended
	Sep. 30, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Option Activity Under Stock Option Plans	A summary of option activity for the nine months ended September 30, 2015 is presented below. Options Number of Weighted Weighted Aggregate Outstanding at January 1, 2015 933,750 $ 37.03 Exercised (11,577 ) 29.94 Cancelled/Forfeited (56,987 ) 35.89 Expired (111,424 ) 34.79 Outstanding at September 30, 2015 753,762 $ 37.55 3.9 $ — Exercisable at September 30, 2015 635,712 $ 38.90 3.5 $ —
Schedule of Nonvested Restricted and Performance Shares	A summary of the status of the Company’s nonvested restricted and performance shares as of September 30, 2015 and changes during the nine months ended September 30, 2015, is presented in the following table. Number of Weighted Nonvested at January 1, 2015 2,040,299 $ 32.27 Granted 106,833 27.40 Vested (239,761 ) 31.93 Forfeited (143,884 ) 32.64 Nonvested at September 30, 2015 1,763,487 $ 31.99

Retirement Plans (Tables)

Retirement Plans (Tables)	9 Months Ended
	Sep. 30, 2015
Compensation and Retirement Disclosure [Abstract]
Components of Net Periodic Benefits Cost	The following tables show the components of net periodic benefits cost included in expense for the plans for the periods indicated. (in thousands) Pension benefits Other Post- 2015 2014 2015 2014 Three Months Ended September 30, Service cost $ 3,383 $ 3,230 $ 23 $ 31 Interest cost 4,672 4,812 174 285 Expected return on plan assets (8,207 ) (8,056 ) — — Amortization of net loss 842 7 (40 ) 91 Net periodic benefit cost $ 690 $ (7 ) $ 157 $ 407 Nine Months Ended September 30, Service cost $ 10,128 $ 9,690 $ 95 $ 94 Interest cost 13,963 14,438 717 855 Expected return on plan assets (24,626 ) (24,167 ) — — Amortization of net loss 2,328 20 45 273 Net periodic benefit cost $ 1,793 $ (19 ) $ 857 $ 1,222

Other Noninterest Income (Table

Other Noninterest Income (Tables)	9 Months Ended
	Sep. 30, 2015
Equity [Abstract]
Components of Other Noninterest Income	Components of other noninterest expense are as follows. Three Months Ended Nine Months Ended (in thousands) 2015 2014 2015 2014 Advertising $ 2,856 $ 2,457 $ 7,154 $ 6,395 Ad valorem and franchise taxes 2,868 3,098 8,319 8,397 Printing and supplies 1,193 1,189 3,568 3,467 Insurance expense 794 944 2,644 3,002 Travel expense 1,419 1,009 3,946 2,966 Entertainment and contributions 1,634 1,396 5,009 4,337 Tax credit investment amortization 2,161 2,220 6,352 6,590 Other miscellaneous 3,634 6,821 16,679 25,105 Total other noninterest expense $ 16,559 $ 19,134 $ 53,671 $ 60,259

Other Noninterest Expense (Tabl

Other Noninterest Expense (Tables)	9 Months Ended
	Sep. 30, 2015
Text Block [Abstract]
Components of Other Noninterest Expense	Components of other noninterest expense are as follows. Three Months Ended Nine Months Ended (in thousands) 2015 2014 2015 2014 Advertising $ 2,856 $ 2,457 $ 7,154 $ 6,395 Ad valorem and franchise taxes 2,868 3,098 8,319 8,397 Printing and supplies 1,193 1,189 3,568 3,467 Insurance expense 794 944 2,644 3,002 Travel expense 1,419 1,009 3,946 2,966 Entertainment and contributions 1,634 1,396 5,009 4,337 Tax credit investment amortization 2,161 2,220 6,352 6,590 Other miscellaneous 3,634 6,821 16,679 25,105 Total other noninterest expense $ 16,559 $ 19,134 $ 53,671 $ 60,259

Securities - Amortized Cost and

Securities - Amortized Cost and Fair Value of Available for Sale Securities (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, amortized cost	$ 2,140,436	$ 1,631,761
Securities available for sale, Gross Unrealized Gains	32,538	32,543
Securities available for sale, Gross Unrealized Losses	4,137	4,139
Securities Available for Sale, Fair Value	2,168,837	1,660,165
U.S. Treasury and Government Agency Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, amortized cost	144	300,207
Securities available for sale, Gross Unrealized Gains		372
Securities available for sale, Gross Unrealized Losses	1	71
Securities Available for Sale, Fair Value	143	300,508
Municipal Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, amortized cost	15,712	13,995
Securities available for sale, Gross Unrealized Gains	240	186
Securities available for sale, Gross Unrealized Losses		5
Securities Available for Sale, Fair Value	15,952	14,176
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, amortized cost	3,500	3,500
Securities Available for Sale, Fair Value	3,500	3,500
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, amortized cost	2,446	8,673
Securities available for sale, Gross Unrealized Gains	313	891
Securities available for sale, Gross Unrealized Losses	33	11
Securities Available for Sale, Fair Value	2,726	9,553
Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, amortized cost	1,814,818	1,217,293
Securities available for sale, Gross Unrealized Gains	30,021	31,094
Securities available for sale, Gross Unrealized Losses	3,470	2,823
Securities Available for Sale, Fair Value	1,841,369	1,245,564
Collateralized Mortgage Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, amortized cost	303,816	88,093
Securities available for sale, Gross Unrealized Gains	1,964
Securities available for sale, Gross Unrealized Losses	633	1,229
Securities Available for Sale, Fair Value	$ 305,147	$ 86,864

Securities - Amortized Cost a36

Securities - Amortized Cost and Fair Value of Held to Maturity Securities (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Schedule of Held-to-maturity Securities [Line Items]
Securities Held to Maturity, Amortized Cost	$ 2,380,085	$ 2,166,289
Securities Held to Maturity, Gross Unrealized Gains	40,452	32,903
Securities Held to Maturity, Gross Unrealized Losses	5,855	12,852
Securities Held to Maturity, Fair Value	2,414,682	2,186,340
U.S. Treasury and Government Agency Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Securities Held to Maturity, Amortized Cost	50,000
Securities Held to Maturity, Gross Unrealized Gains	343
Securities Held to Maturity, Fair Value	50,343
Municipal Obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Securities Held to Maturity, Amortized Cost	187,541	180,615
Securities Held to Maturity, Gross Unrealized Gains	3,777	3,416
Securities Held to Maturity, Gross Unrealized Losses	575	1,144
Securities Held to Maturity, Fair Value	190,743	182,887
Mortgage-Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Securities Held to Maturity, Amortized Cost	992,984	899,923
Securities Held to Maturity, Gross Unrealized Gains	27,677	23,897
Securities Held to Maturity, Gross Unrealized Losses		162
Securities Held to Maturity, Fair Value	1,020,661	923,658
Collateralized Mortgage Obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Securities Held to Maturity, Amortized Cost	1,149,560	1,085,751
Securities Held to Maturity, Gross Unrealized Gains	8,655	5,590
Securities Held to Maturity, Gross Unrealized Losses	5,280	11,546
Securities Held to Maturity, Fair Value	$ 1,152,935	$ 1,079,795

Securities - Amortized Cost a37

Securities - Amortized Cost and Fair Value of Available for Sale Securities by Final Contractual Maturity (Detail) $ in Thousands	Sep. 30, 2015USD ($)
Amortized Cost And Estimated Fair Value Of Debt Securities By Contractual Maturity [Abstract]
Securities Available for Sale, Due in one year or less, Amortized Cost	$ 43,655
Securities Available for Sale, Due after one year through five years, Amortized Cost	78,375
Securities Available for Sale, Due after five years through ten years, Amortized Cost	280,603
Securities Available for Sale, Due after ten years, Amortized Cost	1,735,357
Total available for sale securities, Amortized Cost	2,137,990
Securities Available for Sale, Due in one year or less, Fair Value	43,069
Securities Available for Sale, Due after one year through five years, Fair Value	79,710
Securities Available for Sale, Due after five years through ten years, Fair Value	289,987
Securities Available for Sale, Due after ten years, Fair Value	1,753,345
Available for sale debt securities	$ 2,166,111

Securities - Amortized Cost a38

Securities - Amortized Cost and Fair Value of Held to Maturity Securities by Final Contractual Maturity (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Amortized Cost And Estimated Fair Value Of Debt Securities By Contractual Maturity [Abstract]
Securities Held to Maturity, Due in one year or less, Amortized Cost	$ 248,854
Securities Held to Maturity, Due after one year through five years, Amortized Cost	420,607
Securities Held to Maturity, Due after five years through ten years, Amortized Cost	107,040
Securities Held to Maturity, Due after ten years, Amortized Cost	1,603,584
Securities Held to Maturity, Amortized Cost	2,380,085	$ 2,166,289
Securities Held to Maturity, Due in one year or less, Fair Value	250,028
Securities Held to Maturity, Due after one year through five years, Fair Value	420,768
Securities Held to Maturity, Due after five years through ten years, Fair Value	107,116
Securities Held to Maturity, Due after ten years, Fair Value	1,636,770
Total Held to Maturity Securities, Fair Value	$ 2,414,682	$ 2,186,340

Securities - Available for Sale

Securities - Available for Sale Securities Unrealized Losses (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Unrealized Loss And Fair Value Available For Sale Securities [Line Items]
Available for sale securities, Losses less than 12 months, Fair Value	$ 532,616	$ 147,898
Available for sale securities, Losses Less than 12 months, Gross Unrealized Losses	1,926	248
Available for sale securities, Losses 12 months or longer, Fair value	150,382	212,629
Available for sale securities, Losses 12 months or longer, Gross Unrealized Losses	2,211	3,891
Available for sale securities, Total, Fair value	682,998	360,527
Available for sale securities, Total, Gross Unrealized Losses	4,137	4,139
Equity Securities [Member]
Unrealized Loss And Fair Value Available For Sale Securities [Line Items]
Available for sale securities, Losses less than 12 months, Fair Value	1,510	5,998
Available for sale securities, Losses Less than 12 months, Gross Unrealized Losses	31	10
Available for sale securities, Losses 12 months or longer, Fair value	2	3
Available for sale securities, Losses 12 months or longer, Gross Unrealized Losses	2	1
Available for sale securities, Total, Fair value	1,512	6,001
Available for sale securities, Total, Gross Unrealized Losses	33	11
U.S. Treasury and Government Agency Securities [Member]
Unrealized Loss And Fair Value Available For Sale Securities [Line Items]
Available for sale securities, Losses less than 12 months, Fair Value		99,950
Available for sale securities, Losses Less than 12 months, Gross Unrealized Losses		70
Available for sale securities, Losses 12 months or longer, Fair value	88	121
Available for sale securities, Losses 12 months or longer, Gross Unrealized Losses	1	1
Available for sale securities, Total, Fair value	88	100,071
Available for sale securities, Total, Gross Unrealized Losses	1	71
Municipal Obligations [Member]
Unrealized Loss And Fair Value Available For Sale Securities [Line Items]
Available for sale securities, Losses less than 12 months, Fair Value		2,995
Available for sale securities, Losses Less than 12 months, Gross Unrealized Losses		5
Available for sale securities, Total, Fair value		2,995
Available for sale securities, Total, Gross Unrealized Losses		5
Mortgage-Backed Securities [Member]
Unrealized Loss And Fair Value Available For Sale Securities [Line Items]
Available for sale securities, Losses less than 12 months, Fair Value	482,530	38,955
Available for sale securities, Losses Less than 12 months, Gross Unrealized Losses	1,884	163
Available for sale securities, Losses 12 months or longer, Fair value	115,334	125,641
Available for sale securities, Losses 12 months or longer, Gross Unrealized Losses	1,586	2,660
Available for sale securities, Total, Fair value	597,864	164,596
Available for sale securities, Total, Gross Unrealized Losses	3,470	2,823
Collateralized Mortgage Obligations [Member]
Unrealized Loss And Fair Value Available For Sale Securities [Line Items]
Available for sale securities, Losses less than 12 months, Fair Value	48,576
Available for sale securities, Losses Less than 12 months, Gross Unrealized Losses	11
Available for sale securities, Losses 12 months or longer, Fair value	34,958	86,864
Available for sale securities, Losses 12 months or longer, Gross Unrealized Losses	622	1,229
Available for sale securities, Total, Fair value	83,534	86,864
Available for sale securities, Total, Gross Unrealized Losses	$ 633	$ 1,229

Securities - Held to Maturity w

Securities - Held to Maturity with Unrealized Losses (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Schedule of Held-to-maturity Securities [Line Items]
Held to maturity securities, Losses less than 12 months, Fair Value	$ 69,619	$ 123,538
Held to maturity securities, Losses Less than 12 months, Gross Unrealized Losses	379	628
Held to maturity securities, Losses 12 months or longer, Fair value	424,422	694,234
Held to maturity securities, Losses 12 months or longer, Gross Unrealized Losses	5,476	12,224
Held to maturity securities, Total, Fair value	494,041	817,772
Held to maturity securities, Total, Gross Unrealized Losses	5,855	12,852
Mortgage-Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held to maturity securities, Losses 12 months or longer, Fair value		95,522
Held to maturity securities, Losses 12 months or longer, Gross Unrealized Losses		162
Held to maturity securities, Total, Fair value		95,522
Held to maturity securities, Total, Gross Unrealized Losses		162
Collateralized Mortgage Obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held to maturity securities, Losses less than 12 months, Fair Value	47,775	119,222
Held to maturity securities, Losses Less than 12 months, Gross Unrealized Losses	314	616
Held to maturity securities, Losses 12 months or longer, Fair value	375,397	540,607
Held to maturity securities, Losses 12 months or longer, Gross Unrealized Losses	4,966	10,930
Held to maturity securities, Total, Fair value	423,172	659,829
Held to maturity securities, Total, Gross Unrealized Losses	5,280	11,546
Municipal Obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held to maturity securities, Losses less than 12 months, Fair Value	21,844	4,316
Held to maturity securities, Losses Less than 12 months, Gross Unrealized Losses	65	12
Held to maturity securities, Losses 12 months or longer, Fair value	49,025	58,105
Held to maturity securities, Losses 12 months or longer, Gross Unrealized Losses	510	1,132
Held to maturity securities, Total, Fair value	70,869	62,421
Held to maturity securities, Total, Gross Unrealized Losses	$ 575	$ 1,144

Securities - Additional Informa

Securities - Additional Information (Detail) - USD ($) $ in Billions	Sep. 30, 2015	Dec. 31, 2014
Amortized Cost and Fair Value Debt Securities [Abstract]
Securities pledged to secure public deposits and securities sold under agreements to repurchase	$ 3	$ 3.2

Loans and Allowance for Loan 42

Loans and Allowance for Loan Losses - Loans, Net of Unearned Income (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Loans Receivable [Line Items]
Total FDIC acquired loans	$ 214,844	$ 252,409
Total loans	14,763,050	13,895,276
Commercial Non-Real Estate [Member]
Loans Receivable [Line Items]
Total FDIC acquired loans	5,699	6,195
Total loans	6,345,994	6,044,060
Construction and Land Development [Member]
Loans Receivable [Line Items]
Total FDIC acquired loans	8,393	11,674
Total loans	1,085,585	1,106,761
Commercial Real Estate [Member]
Loans Receivable [Line Items]
Total FDIC acquired loans	18,136	27,808
Total loans	3,327,386	3,144,048
Residential Mortgages [Member]
Loans Receivable [Line Items]
Total FDIC acquired loans	169,214	187,033
Total loans	2,013,789	1,894,181
Consumer [Member]
Loans Receivable [Line Items]
Total FDIC acquired loans	13,402	19,699
Total loans	1,990,296	1,706,226
Originated Loans [Member]
Loans Receivable [Line Items]
Total loans	14,078,187	12,810,199
Originated Loans [Member] | Commercial Non-Real Estate [Member]
Loans Receivable [Line Items]
Total Commercial non-real estate	6,232,310	5,917,728
Originated Loans [Member] | Construction and Land Development [Member]
Loans Receivable [Line Items]
Total Construction and land development	1,068,895	1,073,964
Originated Loans [Member] | Commercial Real Estate [Member]
Loans Receivable [Line Items]
Total Commercial real estate	2,956,354	2,428,195
Originated Loans [Member] | Residential Mortgages [Member]
Loans Receivable [Line Items]
Total Residential mortgages	1,843,756	1,704,770
Originated Loans [Member] | Consumer [Member]
Loans Receivable [Line Items]
Total Consumer	1,976,872	1,685,542
Acquired Loans [Member]
Loans Receivable [Line Items]
Total loans	470,019	832,668
Acquired Loans [Member] | Commercial Non-Real Estate [Member]
Loans Receivable [Line Items]
Total Commercial non-real estate	107,985	120,137
Acquired Loans [Member] | Construction and Land Development [Member]
Loans Receivable [Line Items]
Total Construction and land development	8,297	21,123
Acquired Loans [Member] | Commercial Real Estate [Member]
Loans Receivable [Line Items]
Total Commercial real estate	352,896	688,045
Acquired Loans [Member] | Residential Mortgages [Member]
Loans Receivable [Line Items]
Total Residential mortgages	819	2,378
Acquired Loans [Member] | Consumer [Member]
Loans Receivable [Line Items]
Total Consumer	$ 22	$ 985

Loans and Allowance for Loan 43

Loans and Allowance for Loan Losses - Schedule of Activity in Loss Share Receivable (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Receivables [Abstract]
Beginning balance			$ 60,272	$ 113,834
Amortization	$ (1,564)	$ (2,760)	(4,034)	(9,989)
Charge-offs, write-downs and other recoveries			(6,733)	(793)
External expenses qualifying under loss share agreement			1,035	3,325
Changes due to changes in cash flow projections			(1,984)	(14,569)
FDIC resolution of denied claims			(1,854)	(10,268)
Net payments (from) to FDIC			(14,667)	366
Ending balance	$ 32,035	$ 81,906	$ 32,035	$ 81,906

Loans and Allowance for Loan 44

Loans and Allowance for Loan Losses - Allowance for Loan Losses by Portfolio Segment and Related Recorded Investment in Loans (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases receivable, Allowance, Beginning Balance	$ 128,762
Ending balance: FDIC acquired loans	214,844		$ 252,409
Ending balance: Loans	14,763,050		13,895,276
Increase (decrease) in FDIC loss share receivable	(1,984)	$ (14,569)
Loans and Leases receivable, Allowance, Ending Balance	139,576
Allowance for Loan Losses [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases receivable, Allowance, Beginning Balance	128,762	133,626
Charge-offs	(23,012)	(30,148)
Recoveries	12,968	12,542
Net provision for loan losses	22,842	24,122
Increase (decrease) in FDIC loss share receivable	(1,984)	(14,570)
Loans and Leases receivable, Allowance, Ending Balance	139,576	125,572
Ending balance: Individually evaluated for impairment	8,618	1,318
Ending balance: Collectively evaluated for impairment	105,453	89,621
Allowance for Loan Losses [Member] | Acquired-Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Amounts related to acquired-impaired loans	25,505	34,633
Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Loans	14,763,050	13,348,574
Ending balance: Individually evaluated for impairment	112,443	33,098
Ending balance: Collectively evaluated for impairment	14,400,702	12,978,809
Loans [Member] | Acquired-Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Acquired-impaired loans	249,905	336,667
Commercial Non-Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: FDIC acquired loans	5,699		6,195
Ending balance: Loans	6,345,994		6,044,060
Commercial Non-Real Estate [Member] | Allowance for Loan Losses [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases receivable, Allowance, Beginning Balance	51,169	37,017
Charge-offs	(4,493)	(4,866)
Recoveries	4,288	2,585
Net provision for loan losses	12,644	9,650
Increase (decrease) in FDIC loss share receivable	314	(1,507)
Loans and Leases receivable, Allowance, Ending Balance	63,922	42,879
Ending balance: Individually evaluated for impairment	5,588	116
Ending balance: Collectively evaluated for impairment	57,785	41,735
Commercial Non-Real Estate [Member] | Allowance for Loan Losses [Member] | Acquired-Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Amounts related to acquired-impaired loans	549	1,028
Commercial Non-Real Estate [Member] | Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Loans	6,345,994	5,587,137
Ending balance: Individually evaluated for impairment	75,345	6,513
Ending balance: Collectively evaluated for impairment	6,257,491	5,565,389
Commercial Non-Real Estate [Member] | Loans [Member] | Acquired-Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Acquired-impaired loans	13,158	15,235
Construction and Land Development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: FDIC acquired loans	8,393		11,674
Ending balance: Loans	1,085,585		1,106,761
Construction and Land Development [Member] | Allowance for Loan Losses [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases receivable, Allowance, Beginning Balance	6,421	8,845
Charge-offs	(1,889)	(2,965)
Recoveries	2,902	2,724
Net provision for loan losses	(54)	3,449
Increase (decrease) in FDIC loss share receivable	(6)	(2,404)
Loans and Leases receivable, Allowance, Ending Balance	7,374	9,649
Ending balance: Individually evaluated for impairment	21	676
Ending balance: Collectively evaluated for impairment	5,626	7,706
Construction and Land Development [Member] | Allowance for Loan Losses [Member] | Acquired-Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Amounts related to acquired-impaired loans	1,727	1,267
Construction and Land Development [Member] | Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Loans	1,085,585	1,095,902
Ending balance: Individually evaluated for impairment	2,053	8,901
Ending balance: Collectively evaluated for impairment	1,067,196	1,056,635
Construction and Land Development [Member] | Loans [Member] | Acquired-Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Acquired-impaired loans	16,336	30,366
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: FDIC acquired loans	18,136		27,808
Ending balance: Loans	3,327,386		3,144,048
Commercial Real Estate [Member] | Allowance for Loan Losses [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases receivable, Allowance, Beginning Balance	21,082	31,612
Charge-offs	(3,860)	(6,735)
Recoveries	1,592	2,639
Net provision for loan losses	(99)	(3,299)
Increase (decrease) in FDIC loss share receivable	523	(2,418)
Loans and Leases receivable, Allowance, Ending Balance	19,238	21,799
Ending balance: Individually evaluated for impairment	2,910	144
Ending balance: Collectively evaluated for impairment	14,139	16,341
Commercial Real Estate [Member] | Allowance for Loan Losses [Member] | Acquired-Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Amounts related to acquired-impaired loans	2,189	5,314
Commercial Real Estate [Member] | Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Loans	3,327,386	3,100,834
Ending balance: Individually evaluated for impairment	33,985	14,944
Ending balance: Collectively evaluated for impairment	3,256,447	3,016,948
Commercial Real Estate [Member] | Loans [Member] | Acquired-Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Acquired-impaired loans	36,954	68,942
Residential Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: FDIC acquired loans	169,214		187,033
Ending balance: Loans	2,013,789		1,894,181
Residential Mortgages [Member] | Allowance for Loan Losses [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases receivable, Allowance, Beginning Balance	28,660	34,881
Charge-offs	(2,199)	(2,470)
Recoveries	583	502
Net provision for loan losses	1,464	3,386
Increase (decrease) in FDIC loss share receivable	(2,718)	(4,873)
Loans and Leases receivable, Allowance, Ending Balance	25,790	31,426
Ending balance: Individually evaluated for impairment	96	382
Ending balance: Collectively evaluated for impairment	7,365	8,861
Residential Mortgages [Member] | Allowance for Loan Losses [Member] | Acquired-Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Amounts related to acquired-impaired loans	18,329	22,183
Residential Mortgages [Member] | Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Loans	2,013,789	1,858,490
Ending balance: Individually evaluated for impairment	903	2,740
Ending balance: Collectively evaluated for impairment	1,842,853	1,665,423
Residential Mortgages [Member] | Loans [Member] | Acquired-Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Acquired-impaired loans	170,033	190,327
Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: FDIC acquired loans	13,402		19,699
Ending balance: Loans	1,990,296		1,706,226
Consumer [Member] | Allowance for Loan Losses [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases receivable, Allowance, Beginning Balance	21,430	21,271
Charge-offs	(10,571)	(13,112)
Recoveries	3,603	4,092
Net provision for loan losses	8,887	10,936
Increase (decrease) in FDIC loss share receivable	(97)	(3,368)
Loans and Leases receivable, Allowance, Ending Balance	23,252	19,819
Ending balance: Individually evaluated for impairment	3
Ending balance: Collectively evaluated for impairment	20,538	14,978
Consumer [Member] | Allowance for Loan Losses [Member] | Acquired-Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Amounts related to acquired-impaired loans	2,711	4,841
Consumer [Member] | Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Loans	1,990,296	1,706,211
Ending balance: Individually evaluated for impairment	157
Ending balance: Collectively evaluated for impairment	1,976,715	1,674,414
Consumer [Member] | Loans [Member] | Acquired-Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Acquired-impaired loans	13,424	31,797
Originated Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Loans	14,078,187		12,810,199
Originated Loans [Member] | Allowance for Loan Losses [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses, Beginning Balance	97,701	78,885
Charge-offs	(17,561)	(23,273)
Recoveries	9,226	8,792
Net provision for loan losses	24,532	17,417
Allowance for loan losses, Ending Balance	113,898	81,821
Ending balance: Individually evaluated for impairment	8,445	754
Ending balance: Collectively evaluated for impairment	105,453	81,067
Originated Loans [Member] | Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Loans	14,078,187	11,285,568
Ending balance: Individually evaluated for impairment	109,936	29,397
Ending balance: Collectively evaluated for impairment	13,968,251	11,256,171
Originated Loans [Member] | Commercial Non-Real Estate [Member] | Allowance for Loan Losses [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses, Beginning Balance	50,258	33,091
Charge-offs	(3,068)	(4,690)
Recoveries	2,589	2,118
Net provision for loan losses	13,594	3,929
Allowance for loan losses, Ending Balance	63,373	34,448
Ending balance: Individually evaluated for impairment	5,588	24
Ending balance: Collectively evaluated for impairment	57,785	34,424
Originated Loans [Member] | Commercial Non-Real Estate [Member] | Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Loans	6,232,310	4,806,740
Ending balance: Individually evaluated for impairment	75,345	5,582
Ending balance: Collectively evaluated for impairment	6,156,965	4,801,158
Originated Loans [Member] | Construction and Land Development [Member] | Allowance for Loan Losses [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses, Beginning Balance	5,413	6,180
Charge-offs	(1,483)	(2,615)
Recoveries	2,006	1,220
Net provision for loan losses	(289)	2,151
Allowance for loan losses, Ending Balance	5,647	6,936
Ending balance: Individually evaluated for impairment	21	250
Ending balance: Collectively evaluated for impairment	5,626	6,686
Originated Loans [Member] | Construction and Land Development [Member] | Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Loans	1,068,895	974,442
Ending balance: Individually evaluated for impairment	2,053	6,617
Ending balance: Collectively evaluated for impairment	1,066,842	967,825
Originated Loans [Member] | Commercial Real Estate [Member] | Allowance for Loan Losses [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses, Beginning Balance	16,544	20,649
Charge-offs	(1,128)	(2,255)
Recoveries	635	1,231
Net provision for loan losses	825	(3,231)
Allowance for loan losses, Ending Balance	16,876	16,394
Ending balance: Individually evaluated for impairment	2,737	98
Ending balance: Collectively evaluated for impairment	14,139	16,296
Originated Loans [Member] | Commercial Real Estate [Member] | Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Loans	2,956,354	2,245,855
Ending balance: Individually evaluated for impairment	31,478	14,486
Ending balance: Collectively evaluated for impairment	2,924,876	2,231,369
Originated Loans [Member] | Residential Mortgages [Member] | Allowance for Loan Losses [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses, Beginning Balance	8,051	6,892
Charge-offs	(1,451)	(1,793)
Recoveries	578	501
Net provision for loan losses	283	3,647
Allowance for loan losses, Ending Balance	7,461	9,247
Ending balance: Individually evaluated for impairment	96	382
Ending balance: Collectively evaluated for impairment	7,365	8,865
Originated Loans [Member] | Residential Mortgages [Member] | Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Loans	1,843,756	1,635,462
Ending balance: Individually evaluated for impairment	903	2,712
Ending balance: Collectively evaluated for impairment	1,842,853	1,632,750
Originated Loans [Member] | Consumer [Member] | Allowance for Loan Losses [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses, Beginning Balance	17,435	12,073
Charge-offs	(10,431)	(11,920)
Recoveries	3,418	3,722
Net provision for loan losses	10,119	10,921
Allowance for loan losses, Ending Balance	20,541	14,796
Ending balance: Individually evaluated for impairment	3
Ending balance: Collectively evaluated for impairment	20,538	14,796
Originated Loans [Member] | Consumer [Member] | Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Loans	1,976,872	1,623,069
Ending balance: Individually evaluated for impairment	157
Ending balance: Collectively evaluated for impairment	1,976,715	1,623,069
Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Loans	470,019		$ 832,668
Acquired Loans [Member] | Allowance for Loan Losses [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses, Beginning Balance	477	1,647
Net provision for loan losses	(304)	7,471
Allowance for loan losses, Ending Balance	173	9,118
Ending balance: Individually evaluated for impairment	173	564
Ending balance: Collectively evaluated for impairment		8,554
Acquired Loans [Member] | Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Loans	470,019	1,782,176
Ending balance: Individually evaluated for impairment	2,507	3,701
Ending balance: Collectively evaluated for impairment	432,451	1,722,638
Acquired Loans [Member] | Loans [Member] | Acquired-Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Acquired-impaired loans	35,061	55,837
Acquired Loans [Member] | Commercial Non-Real Estate [Member] | Allowance for Loan Losses [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses, Beginning Balance		1,603
Net provision for loan losses		5,800
Allowance for loan losses, Ending Balance		7,403
Ending balance: Individually evaluated for impairment		92
Ending balance: Collectively evaluated for impairment		7,311
Acquired Loans [Member] | Commercial Non-Real Estate [Member] | Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Loans	107,985	769,226
Ending balance: Individually evaluated for impairment		931
Ending balance: Collectively evaluated for impairment	100,526	764,231
Acquired Loans [Member] | Commercial Non-Real Estate [Member] | Loans [Member] | Acquired-Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Acquired-impaired loans	7,459	4,064
Acquired Loans [Member] | Construction and Land Development [Member] | Allowance for Loan Losses [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses, Beginning Balance		10
Net provision for loan losses		1,436
Allowance for loan losses, Ending Balance		1,446
Ending balance: Individually evaluated for impairment		426
Ending balance: Collectively evaluated for impairment		1,020
Acquired Loans [Member] | Construction and Land Development [Member] | Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Loans	8,297	110,294
Ending balance: Individually evaluated for impairment		2,284
Ending balance: Collectively evaluated for impairment	354	88,810
Acquired Loans [Member] | Construction and Land Development [Member] | Loans [Member] | Acquired-Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Acquired-impaired loans	7,943	19,200
Acquired Loans [Member] | Commercial Real Estate [Member] | Allowance for Loan Losses [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses, Beginning Balance	477	34
Net provision for loan losses	(304)	57
Allowance for loan losses, Ending Balance	173	91
Ending balance: Individually evaluated for impairment	173	46
Ending balance: Collectively evaluated for impairment		45
Acquired Loans [Member] | Commercial Real Estate [Member] | Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Loans	352,896	813,429
Ending balance: Individually evaluated for impairment	2,507	458
Ending balance: Collectively evaluated for impairment	331,571	785,579
Acquired Loans [Member] | Commercial Real Estate [Member] | Loans [Member] | Acquired-Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Acquired-impaired loans	18,818	27,392
Acquired Loans [Member] | Residential Mortgages [Member] | Allowance for Loan Losses [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net provision for loan losses		(4)
Allowance for loan losses, Ending Balance		(4)
Ending balance: Collectively evaluated for impairment		(4)
Acquired Loans [Member] | Residential Mortgages [Member] | Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Loans	819	37,739
Ending balance: Individually evaluated for impairment		28
Ending balance: Collectively evaluated for impairment		32,673
Acquired Loans [Member] | Residential Mortgages [Member] | Loans [Member] | Acquired-Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Acquired-impaired loans	819	5,038
Acquired Loans [Member] | Consumer [Member] | Allowance for Loan Losses [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net provision for loan losses		182
Allowance for loan losses, Ending Balance		182
Ending balance: Collectively evaluated for impairment		182
Acquired Loans [Member] | Consumer [Member] | Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Loans	22	51,488
Ending balance: Collectively evaluated for impairment		51,345
Acquired Loans [Member] | Consumer [Member] | Loans [Member] | Acquired-Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Acquired-impaired loans	22	143
FDIC Acquired Loans [Member] | Allowance for Loan Losses [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases receivable, Allowance, Beginning Balance	30,584	53,094
Charge-offs	(5,451)	(6,875)
Recoveries	3,742	3,750
Net provision for loan losses	(1,386)	(766)
Increase (decrease) in FDIC loss share receivable	(1,984)	(14,570)
Loans and Leases receivable, Allowance, Ending Balance	25,505	34,633
FDIC Acquired Loans [Member] | Allowance for Loan Losses [Member] | Acquired-Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Amounts related to acquired-impaired loans	25,505	34,633
FDIC Acquired Loans [Member] | Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: FDIC acquired loans	214,844	280,830
FDIC Acquired Loans [Member] | Loans [Member] | Acquired-Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Acquired-impaired loans	214,844	280,830
FDIC Acquired Loans [Member] | Commercial Non-Real Estate [Member] | Allowance for Loan Losses [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases receivable, Allowance, Beginning Balance	911	2,323
Charge-offs	(1,425)	(176)
Recoveries	1,699	467
Net provision for loan losses	(950)	(79)
Increase (decrease) in FDIC loss share receivable	314	(1,507)
Loans and Leases receivable, Allowance, Ending Balance	549	1,028
FDIC Acquired Loans [Member] | Commercial Non-Real Estate [Member] | Allowance for Loan Losses [Member] | Acquired-Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Amounts related to acquired-impaired loans	549	1,028
FDIC Acquired Loans [Member] | Commercial Non-Real Estate [Member] | Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: FDIC acquired loans	5,699	11,171
FDIC Acquired Loans [Member] | Commercial Non-Real Estate [Member] | Loans [Member] | Acquired-Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Acquired-impaired loans	5,699	11,171
FDIC Acquired Loans [Member] | Construction and Land Development [Member] | Allowance for Loan Losses [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases receivable, Allowance, Beginning Balance	1,008	2,655
Charge-offs	(406)	(350)
Recoveries	896	1,504
Net provision for loan losses	235	(138)
Increase (decrease) in FDIC loss share receivable	(6)	(2,404)
Loans and Leases receivable, Allowance, Ending Balance	1,727	1,267
FDIC Acquired Loans [Member] | Construction and Land Development [Member] | Allowance for Loan Losses [Member] | Acquired-Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Amounts related to acquired-impaired loans	1,727	1,267
FDIC Acquired Loans [Member] | Construction and Land Development [Member] | Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: FDIC acquired loans	8,393	11,166
FDIC Acquired Loans [Member] | Construction and Land Development [Member] | Loans [Member] | Acquired-Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Acquired-impaired loans	8,393	11,166
FDIC Acquired Loans [Member] | Commercial Real Estate [Member] | Allowance for Loan Losses [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases receivable, Allowance, Beginning Balance	4,061	10,929
Charge-offs	(2,732)	(4,480)
Recoveries	957	1,408
Net provision for loan losses	(620)	(125)
Increase (decrease) in FDIC loss share receivable	523	(2,418)
Loans and Leases receivable, Allowance, Ending Balance	2,189	5,314
FDIC Acquired Loans [Member] | Commercial Real Estate [Member] | Allowance for Loan Losses [Member] | Acquired-Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Amounts related to acquired-impaired loans	2,189	5,314
FDIC Acquired Loans [Member] | Commercial Real Estate [Member] | Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: FDIC acquired loans	18,136	41,550
FDIC Acquired Loans [Member] | Commercial Real Estate [Member] | Loans [Member] | Acquired-Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Acquired-impaired loans	18,136	41,550
FDIC Acquired Loans [Member] | Residential Mortgages [Member] | Allowance for Loan Losses [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases receivable, Allowance, Beginning Balance	20,609	27,989
Charge-offs	(748)	(677)
Recoveries	5	1
Net provision for loan losses	1,181	(257)
Increase (decrease) in FDIC loss share receivable	(2,718)	(4,873)
Loans and Leases receivable, Allowance, Ending Balance	18,329	22,183
FDIC Acquired Loans [Member] | Residential Mortgages [Member] | Allowance for Loan Losses [Member] | Acquired-Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Amounts related to acquired-impaired loans	18,329	22,183
FDIC Acquired Loans [Member] | Residential Mortgages [Member] | Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: FDIC acquired loans	169,214	185,289
FDIC Acquired Loans [Member] | Residential Mortgages [Member] | Loans [Member] | Acquired-Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Acquired-impaired loans	169,214	185,289
FDIC Acquired Loans [Member] | Consumer [Member] | Allowance for Loan Losses [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases receivable, Allowance, Beginning Balance	3,995	9,198
Charge-offs	(140)	(1,192)
Recoveries	185	370
Net provision for loan losses	(1,232)	(167)
Increase (decrease) in FDIC loss share receivable	(97)	(3,368)
Loans and Leases receivable, Allowance, Ending Balance	2,711	4,841
FDIC Acquired Loans [Member] | Consumer [Member] | Allowance for Loan Losses [Member] | Acquired-Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Amounts related to acquired-impaired loans	2,711	4,841
FDIC Acquired Loans [Member] | Consumer [Member] | Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: FDIC acquired loans	13,402	31,654
FDIC Acquired Loans [Member] | Consumer [Member] | Loans [Member] | Acquired-Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance: Acquired-impaired loans	$ 13,402	$ 31,654

Loans and Allowance for Loan 45

Loans and Allowance for Loan Losses - Summary of Composition of Non-Accrual Loans by Portfolio Segment (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Nonaccrual Loans By Portfolio [Line Items]
Nonaccrual loans	$ 166,945	$ 79,537
Commercial Non-Real Estate [Member]
Nonaccrual Loans By Portfolio [Line Items]
Nonaccrual loans	93,448	15,511
Construction and Land Development [Member]
Nonaccrual Loans By Portfolio [Line Items]
Nonaccrual loans	5,527	7,565
Commercial Real Estate [Member]
Nonaccrual Loans By Portfolio [Line Items]
Nonaccrual loans	39,382	28,619
Residential Mortgages [Member]
Nonaccrual Loans By Portfolio [Line Items]
Nonaccrual loans	21,750	22,094
Consumer [Member]
Nonaccrual Loans By Portfolio [Line Items]
Nonaccrual loans	6,838	5,748
Originated Loans [Member]
Nonaccrual Loans By Portfolio [Line Items]
Nonaccrual loans	163,930	71,296
Originated Loans [Member] | Commercial Non-Real Estate [Member]
Nonaccrual Loans By Portfolio [Line Items]
Nonaccrual loans	93,448	15,511
Originated Loans [Member] | Construction and Land Development [Member]
Nonaccrual Loans By Portfolio [Line Items]
Nonaccrual loans	5,527	6,462
Originated Loans [Member] | Commercial Real Estate [Member]
Nonaccrual Loans By Portfolio [Line Items]
Nonaccrual loans	36,367	22,047
Originated Loans [Member] | Residential Mortgages [Member]
Nonaccrual Loans By Portfolio [Line Items]
Nonaccrual loans	21,750	21,702
Originated Loans [Member] | Consumer [Member]
Nonaccrual Loans By Portfolio [Line Items]
Nonaccrual loans	6,838	5,574
Acquired Loans [Member]
Nonaccrual Loans By Portfolio [Line Items]
Nonaccrual loans	3,015	6,139
Acquired Loans [Member] | Commercial Real Estate [Member]
Nonaccrual Loans By Portfolio [Line Items]
Nonaccrual loans	$ 3,015	6,139
FDIC Acquired Loans [Member]
Nonaccrual Loans By Portfolio [Line Items]
Nonaccrual loans		2,102
FDIC Acquired Loans [Member] | Construction and Land Development [Member]
Nonaccrual Loans By Portfolio [Line Items]
Nonaccrual loans		1,103
FDIC Acquired Loans [Member] | Commercial Real Estate [Member]
Nonaccrual Loans By Portfolio [Line Items]
Nonaccrual loans		433
FDIC Acquired Loans [Member] | Residential Mortgages [Member]
Nonaccrual Loans By Portfolio [Line Items]
Nonaccrual loans		392
FDIC Acquired Loans [Member] | Consumer [Member]
Nonaccrual Loans By Portfolio [Line Items]
Nonaccrual loans		$ 174

Loans and Allowance for Loan 46

Loans and Allowance for Loan Losses - Additional Information (Detail)	9 Months Ended		12 Months Ended
	Sep. 30, 2015USD ($)Contract	Sep. 30, 2014USD ($)Contract	Dec. 31, 2014USD ($)
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Nonaccrual loans	$ 166,945,000		$ 79,537,000
Troubled debt restructuring both accruing and nonaccruing	$ 10,700,000		16,000,000
Number of TDRs subsequently defaulted | Contract	0
Minimum bank portfolio loan need to be reviewed	$ 1,000,000
Real estate acquired through foreclosure	32,493,000		58,415,000
Commercial Non-Real Estate [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Nonaccrual loans	93,448,000		15,511,000
Consumer [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Nonaccrual loans	6,838,000		5,748,000
Mortgage loan in process of foreclosure	9,000,000		13,700,000
Real estate acquired through foreclosure	$ 7,900,000		12,700,000
Performing [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Period for which payments of principal and interest are past due	Less than 90 days
Troubled Debt Restructurings [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Nonaccrual loans	$ 4,900,000		7,000,000
Originated Loans [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Nonaccrual loans	163,930,000		71,296,000
Originated Loans [Member] | Commercial Non-Real Estate [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Nonaccrual loans	93,448,000		15,511,000
Number of TDRs subsequently defaulted | Contract		1
Recorded investment		$ 900,000
Originated Loans [Member] | Consumer [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Nonaccrual loans	6,838,000		5,574,000
FDIC Acquired Loans [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Nonaccrual loans			2,102,000
FDIC Acquired Loans [Member] | Consumer [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Nonaccrual loans			174,000
Mortgage loan in process of foreclosure	5,400,000		8,100,000
Real estate acquired through foreclosure	$ 2,300,000		$ 8,200,000

Loans and Allowance for Loan 47

Loans and Allowance for Loan Losses - Schedule of Troubled Debt Restructurings Occurred During Period by Portfolio Segment (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2015USD ($)Contract	Sep. 30, 2014USD ($)Contract
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts | Contract	6	6
Pre-Modification Outstanding Recorded Investment	$ 687	$ 3,925
Post-Modification Outstanding Recorded Investment	$ 687	$ 3,233
Commercial Real Estate [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts | Contract	1	2
Pre-Modification Outstanding Recorded Investment	$ 482	$ 2,430
Post-Modification Outstanding Recorded Investment	$ 482	$ 2,385
Residential Mortgages [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts | Contract	4	4
Pre-Modification Outstanding Recorded Investment	$ 185	$ 1,495
Post-Modification Outstanding Recorded Investment	$ 185	$ 848
Consumer [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts | Contract	1
Pre-Modification Outstanding Recorded Investment	$ 20
Post-Modification Outstanding Recorded Investment	$ 20
Originated Loans [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts | Contract	6	6
Pre-Modification Outstanding Recorded Investment	$ 687	$ 3,925
Post-Modification Outstanding Recorded Investment	$ 687	$ 3,233
Originated Loans [Member] | Commercial Real Estate [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts | Contract	1	2
Pre-Modification Outstanding Recorded Investment	$ 482	$ 2,430
Post-Modification Outstanding Recorded Investment	$ 482	$ 2,385
Originated Loans [Member] | Residential Mortgages [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts | Contract	4	4
Pre-Modification Outstanding Recorded Investment	$ 185	$ 1,495
Post-Modification Outstanding Recorded Investment	$ 185	$ 848
Originated Loans [Member] | Consumer [Member]
Troubled Debt Restructuring, Debtor, Current Period [Line Items]
Number of Contracts | Contract	1
Pre-Modification Outstanding Recorded Investment	$ 20
Post-Modification Outstanding Recorded Investment	$ 20

Loans and Allowance for Loan 48

Loans and Allowance for Loan Losses - Summary of Impaired Loans Disaggregated by Class (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded	$ 47,394	$ 14,815
Recorded Investment, With a related allowance recorded	65,049	14,896
Recorded Investment, Total	112,443	29,711
Interest Income Recognized, With no related allowance recorded	28	527
Unpaid Principal Balance, With no related allowance recorded	49,906	20,707
Interest Income Recognized, With a related allowance recorded	163	648
Unpaid Principal Balance, With a related allowance recorded	67,903	15,581
Interest Income Recognized, Total	191	1,175
Unpaid Principal Balance, Total	117,809	36,288
Related Allowance, With no related allowance recorded	0	0
Related Allowance, With a related allowance recorded	8,618	854
Related Allowance, Total	8,618	854
Average Recorded Investment, With no related allowance recorded	27,557	13,965
Average Recorded Investment, With a related allowance recorded	36,454	25,340
Average Recorded Investment, Total	64,011	39,305
Commercial Non-Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded	32,963	3,003
Recorded Investment, With a related allowance recorded	42,382	984
Recorded Investment, Total	75,345	3,987
Interest Income Recognized, With no related allowance recorded		51
Unpaid Principal Balance, With no related allowance recorded	33,468	3,646
Interest Income Recognized, With a related allowance recorded	6	221
Unpaid Principal Balance, With a related allowance recorded	43,146	984
Interest Income Recognized, Total	6	272
Unpaid Principal Balance, Total	76,614	4,630
Related Allowance, With no related allowance recorded	0	0
Related Allowance, With a related allowance recorded	5,588	14
Related Allowance, Total	5,588	14
Average Recorded Investment, With no related allowance recorded	14,887	1,566
Average Recorded Investment, With a related allowance recorded	16,683	6,581
Average Recorded Investment, Total	31,570	8,147
Construction and Land Development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded	1,391	3,345
Recorded Investment, With a related allowance recorded	662	4,905
Recorded Investment, Total	2,053	8,250
Interest Income Recognized, With no related allowance recorded		142
Unpaid Principal Balance, With no related allowance recorded	1,391	6,486
Interest Income Recognized, With a related allowance recorded	66	193
Unpaid Principal Balance, With a related allowance recorded	2,224	4,906
Interest Income Recognized, Total	66	335
Unpaid Principal Balance, Total	3,615	11,392
Related Allowance, With no related allowance recorded	0	0
Related Allowance, With a related allowance recorded	21	19
Related Allowance, Total	21	19
Average Recorded Investment, With no related allowance recorded	1,319	3,451
Average Recorded Investment, With a related allowance recorded	3,443	7,697
Average Recorded Investment, Total	4,762	11,148
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded	12,945	8,467
Recorded Investment, With a related allowance recorded	21,040	6,345
Recorded Investment, Total	33,985	14,812
Interest Income Recognized, With no related allowance recorded	26	331
Unpaid Principal Balance, With no related allowance recorded	14,952	10,575
Interest Income Recognized, With a related allowance recorded	70	184
Unpaid Principal Balance, With a related allowance recorded	21,058	6,374
Interest Income Recognized, Total	96	515
Unpaid Principal Balance, Total	36,010	16,949
Related Allowance, With no related allowance recorded	0	0
Related Allowance, With a related allowance recorded	2,910	488
Related Allowance, Total	2,910	488
Average Recorded Investment, With no related allowance recorded	11,018	8,772
Average Recorded Investment, With a related allowance recorded	14,723	8,857
Average Recorded Investment, Total	25,741	17,629
Residential Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With a related allowance recorded	903	2,656
Recorded Investment, Total	903	2,656
Interest Income Recognized, With no related allowance recorded	2	3
Interest Income Recognized, With a related allowance recorded	18	50
Unpaid Principal Balance, With a related allowance recorded	1,413	3,311
Interest Income Recognized, Total	20	53
Unpaid Principal Balance, Total	1,413	3,311
Related Allowance, With no related allowance recorded	0	0
Related Allowance, With a related allowance recorded	96	330
Related Allowance, Total	96	330
Average Recorded Investment, With no related allowance recorded	259	176
Average Recorded Investment, With a related allowance recorded	1,578	2,204
Average Recorded Investment, Total	1,837	2,380
Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded	95
Recorded Investment, With a related allowance recorded	62	6
Recorded Investment, Total	157	6
Unpaid Principal Balance, With no related allowance recorded	95
Interest Income Recognized, With a related allowance recorded	3
Unpaid Principal Balance, With a related allowance recorded	62	6
Interest Income Recognized, Total	3
Unpaid Principal Balance, Total	157	6
Related Allowance, With no related allowance recorded	0	0
Related Allowance, With a related allowance recorded	3	3
Related Allowance, Total	3	3
Average Recorded Investment, With no related allowance recorded	74
Average Recorded Investment, With a related allowance recorded	27	1
Average Recorded Investment, Total	101	1
Originated Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded	47,394	14,815
Recorded Investment, With a related allowance recorded	62,542	12,205
Recorded Investment, Total	109,936	27,020
Interest Income Recognized, With no related allowance recorded	28	527
Unpaid Principal Balance, With no related allowance recorded	49,906	20,707
Interest Income Recognized, With a related allowance recorded	163	395
Unpaid Principal Balance, With a related allowance recorded	65,381	12,861
Interest Income Recognized, Total	191	921
Unpaid Principal Balance, Total	115,287	33,568
Related Allowance, With no related allowance recorded	0	0
Related Allowance, With a related allowance recorded	8,445	377
Related Allowance, Total	8,445	377
Average Recorded Investment, With no related allowance recorded	27,557	13,088
Average Recorded Investment, With a related allowance recorded	33,874	21,887
Average Recorded Investment, Total	61,431	34,976
Originated Loans [Member] | Commercial Non-Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded	32,963	3,003
Recorded Investment, With a related allowance recorded	42,382	984
Recorded Investment, Total	75,345	3,987
Interest Income Recognized, With no related allowance recorded		51
Unpaid Principal Balance, With no related allowance recorded	33,468	3,646
Interest Income Recognized, With a related allowance recorded	6	99
Unpaid Principal Balance, With a related allowance recorded	43,146	984
Interest Income Recognized, Total	6	150
Unpaid Principal Balance, Total	76,614	4,630
Related Allowance, With no related allowance recorded	0	0
Related Allowance, With a related allowance recorded	5,588	14
Related Allowance, Total	5,588	14
Average Recorded Investment, With no related allowance recorded	14,887	1,209
Average Recorded Investment, With a related allowance recorded	16,683	5,522
Average Recorded Investment, Total	31,570	6,732
Originated Loans [Member] | Construction and Land Development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded	1,391	3,345
Recorded Investment, With a related allowance recorded	662	4,905
Recorded Investment, Total	2,053	8,250
Interest Income Recognized, With no related allowance recorded		142
Unpaid Principal Balance, With no related allowance recorded	1,391	6,486
Interest Income Recognized, With a related allowance recorded	66	137
Unpaid Principal Balance, With a related allowance recorded	2,224	4,906
Interest Income Recognized, Total	66	279
Unpaid Principal Balance, Total	3,615	11,392
Related Allowance, With no related allowance recorded	0	0
Related Allowance, With a related allowance recorded	21	19
Related Allowance, Total	21	19
Average Recorded Investment, With no related allowance recorded	1,319	3,330
Average Recorded Investment, With a related allowance recorded	3,443	6,660
Average Recorded Investment, Total	4,762	9,990
Originated Loans [Member] | Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded	12,945	8,467
Recorded Investment, With a related allowance recorded	18,533	3,654
Recorded Investment, Total	31,478	12,121
Interest Income Recognized, With no related allowance recorded	26	331
Unpaid Principal Balance, With no related allowance recorded	14,952	10,575
Interest Income Recognized, With a related allowance recorded	70	109
Unpaid Principal Balance, With a related allowance recorded	18,536	3,654
Interest Income Recognized, Total	96	439
Unpaid Principal Balance, Total	33,488	14,229
Related Allowance, With no related allowance recorded	0	0
Related Allowance, With a related allowance recorded	2,737	11
Related Allowance, Total	2,737	11
Average Recorded Investment, With no related allowance recorded	11,018	8,461
Average Recorded Investment, With a related allowance recorded	12,143	7,500
Average Recorded Investment, Total	23,161	15,961
Originated Loans [Member] | Residential Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With a related allowance recorded	903	2,656
Recorded Investment, Total	903	2,656
Interest Income Recognized, With no related allowance recorded	2	3
Interest Income Recognized, With a related allowance recorded	18	50
Unpaid Principal Balance, With a related allowance recorded	1,413	3,311
Interest Income Recognized, Total	20	53
Unpaid Principal Balance, Total	1,413	3,311
Related Allowance, With no related allowance recorded	0	0
Related Allowance, With a related allowance recorded	96	330
Related Allowance, Total	96	330
Average Recorded Investment, With no related allowance recorded	259	88
Average Recorded Investment, With a related allowance recorded	1,578	2,204
Average Recorded Investment, Total	1,837	2,292
Originated Loans [Member] | Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With no related allowance recorded	95
Recorded Investment, With a related allowance recorded	62	6
Recorded Investment, Total	157	6
Unpaid Principal Balance, With no related allowance recorded	95
Interest Income Recognized, With a related allowance recorded	3
Unpaid Principal Balance, With a related allowance recorded	62	6
Interest Income Recognized, Total	3
Unpaid Principal Balance, Total	157	6
Related Allowance, With no related allowance recorded	0	0
Related Allowance, With a related allowance recorded	3	3
Related Allowance, Total	3	3
Average Recorded Investment, With no related allowance recorded	74
Average Recorded Investment, With a related allowance recorded	27	1
Average Recorded Investment, Total	101	1
Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With a related allowance recorded	2,507	2,691
Recorded Investment, Total	2,507	2,691
Interest Income Recognized, With a related allowance recorded		253
Unpaid Principal Balance, With a related allowance recorded	2,522	2,720
Interest Income Recognized, Total		253
Unpaid Principal Balance, Total	2,522	2,720
Related Allowance, With no related allowance recorded		0
Related Allowance, With a related allowance recorded	173	477
Related Allowance, Total	173	477
Average Recorded Investment, With no related allowance recorded		877
Average Recorded Investment, With a related allowance recorded	2,580	3,453
Average Recorded Investment, Total	2,580	4,330
Acquired Loans [Member] | Commercial Non-Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest Income Recognized, With a related allowance recorded		122
Interest Income Recognized, Total		122
Related Allowance, With no related allowance recorded		0
Average Recorded Investment, With no related allowance recorded		357
Average Recorded Investment, With a related allowance recorded		1,059
Average Recorded Investment, Total		1,416
Acquired Loans [Member] | Construction and Land Development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest Income Recognized, With a related allowance recorded		56
Interest Income Recognized, Total		56
Related Allowance, With no related allowance recorded		0
Average Recorded Investment, With no related allowance recorded		121
Average Recorded Investment, With a related allowance recorded		1,037
Average Recorded Investment, Total		1,158
Acquired Loans [Member] | Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded Investment, With a related allowance recorded	2,507	2,691
Recorded Investment, Total	2,507	2,691
Interest Income Recognized, With a related allowance recorded		75
Unpaid Principal Balance, With a related allowance recorded	2,522	2,720
Interest Income Recognized, Total		75
Unpaid Principal Balance, Total	2,522	2,720
Related Allowance, With no related allowance recorded		0
Related Allowance, With a related allowance recorded	173	477
Related Allowance, Total	173	477
Average Recorded Investment, With no related allowance recorded		311
Average Recorded Investment, With a related allowance recorded	2,580	1,357
Average Recorded Investment, Total	$ 2,580	1,668
Acquired Loans [Member] | Residential Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Related Allowance, With no related allowance recorded		0
Average Recorded Investment, With no related allowance recorded		88
Average Recorded Investment, Total		88
Acquired Loans [Member] | Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Related Allowance, With no related allowance recorded		$ 0

Loans and Allowance for Loan 49

Loans and Allowance for Loan Losses - Summary of Age Analysis of Past Due Loans (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total FDIC acquired loans	$ 214,844	$ 252,409
Total loans	14,763,050	13,895,276
Total past due	127,848
Current	14,635,202
Recorded investment > 90 days and accruing	5,876
30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	66,916
60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	17,982
Greater Than 90 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	42,950
Commercial Non-Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total FDIC acquired loans	5,699	6,195
Total loans	6,345,994	6,044,060
Total past due	29,374
Current	6,316,620
Recorded investment > 90 days and accruing	878
Commercial Non-Real Estate [Member] | 30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	19,298
Commercial Non-Real Estate [Member] | 60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	3,271
Commercial Non-Real Estate [Member] | Greater Than 90 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	6,805
Construction and Land Development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total FDIC acquired loans	8,393	11,674
Total loans	1,085,585	1,106,761
Total past due	7,562
Current	1,078,023
Recorded investment > 90 days and accruing	1,700
Construction and Land Development [Member] | 30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	2,489
Construction and Land Development [Member] | 60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	602
Construction and Land Development [Member] | Greater Than 90 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	4,471
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total FDIC acquired loans	18,136	27,808
Total loans	3,327,386	3,144,048
Total past due	27,301
Current	3,300,085
Recorded investment > 90 days and accruing	1,902
Commercial Real Estate [Member] | 30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	6,567
Commercial Real Estate [Member] | 60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	4,000
Commercial Real Estate [Member] | Greater Than 90 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	16,734
Residential Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total FDIC acquired loans	169,214	187,033
Total loans	2,013,789	1,894,181
Total past due	39,813
Current	1,973,976
Recorded investment > 90 days and accruing	46
Residential Mortgages [Member] | 30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	25,525
Residential Mortgages [Member] | 60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	4,619
Residential Mortgages [Member] | Greater Than 90 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	9,669
Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total FDIC acquired loans	13,402	19,699
Total loans	1,990,296	1,706,226
Total past due	23,798
Current	1,966,498
Recorded investment > 90 days and accruing	1,350
Consumer [Member] | 30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	13,037
Consumer [Member] | 60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	5,490
Consumer [Member] | Greater Than 90 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	5,271
Originated Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	14,078,187	12,810,199
Total past due	126,231
Current	13,951,956
Recorded investment > 90 days and accruing	5,747
Originated Loans [Member] | 30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	66,172
Originated Loans [Member] | 60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	17,554
Originated Loans [Member] | Greater Than 90 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	42,505
Originated Loans [Member] | Commercial Non-Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Commercial non-real estate	6,232,310	5,917,728
Total past due	29,374
Current	6,202,936
Recorded investment > 90 days and accruing	878
Originated Loans [Member] | Commercial Non-Real Estate [Member] | 30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	19,298
Originated Loans [Member] | Commercial Non-Real Estate [Member] | 60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	3,271
Originated Loans [Member] | Commercial Non-Real Estate [Member] | Greater Than 90 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	6,805
Originated Loans [Member] | Construction and Land Development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Construction and land development	1,068,895	1,073,964
Total past due	7,562
Current	1,061,333
Recorded investment > 90 days and accruing	1,700
Originated Loans [Member] | Construction and Land Development [Member] | 30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	2,489
Originated Loans [Member] | Construction and Land Development [Member] | 60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	602
Originated Loans [Member] | Construction and Land Development [Member] | Greater Than 90 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	4,471
Originated Loans [Member] | Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Commercial real estate	2,956,354	2,428,195
Total past due	25,684
Current	2,930,670
Recorded investment > 90 days and accruing	1,773
Originated Loans [Member] | Commercial Real Estate [Member] | 30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	5,823
Originated Loans [Member] | Commercial Real Estate [Member] | 60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	3,572
Originated Loans [Member] | Commercial Real Estate [Member] | Greater Than 90 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	16,289
Originated Loans [Member] | Residential Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Residential mortgages	1,843,756	1,704,770
Total past due	39,813
Current	1,803,943
Recorded investment > 90 days and accruing	46
Originated Loans [Member] | Residential Mortgages [Member] | 30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	25,525
Originated Loans [Member] | Residential Mortgages [Member] | 60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	4,619
Originated Loans [Member] | Residential Mortgages [Member] | Greater Than 90 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	9,669
Originated Loans [Member] | Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Consumer	1,976,872	1,685,542
Total past due	23,798
Current	1,953,074
Recorded investment > 90 days and accruing	1,350
Originated Loans [Member] | Consumer [Member] | 30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	13,037
Originated Loans [Member] | Consumer [Member] | 60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	5,490
Originated Loans [Member] | Consumer [Member] | Greater Than 90 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	5,271
Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	470,019	832,668
Total past due	1,617
Current	468,402
Recorded investment > 90 days and accruing	129
Acquired Loans [Member] | 30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	744
Acquired Loans [Member] | 60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	428
Acquired Loans [Member] | Greater Than 90 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	445
Acquired Loans [Member] | Commercial Non-Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Commercial non-real estate	107,985	120,137
Current	107,985
Acquired Loans [Member] | Construction and Land Development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Construction and land development	8,297	21,123
Current	8,297
Acquired Loans [Member] | Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Commercial real estate	352,896	688,045
Total past due	1,617
Current	351,279
Recorded investment > 90 days and accruing	129
Acquired Loans [Member] | Commercial Real Estate [Member] | 30-59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	744
Acquired Loans [Member] | Commercial Real Estate [Member] | 60-89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	428
Acquired Loans [Member] | Commercial Real Estate [Member] | Greater Than 90 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due	445
Acquired Loans [Member] | Residential Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Residential mortgages	819	2,378
Current	819
Acquired Loans [Member] | Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Consumer	22	$ 985
Current	22
FDIC Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	214,844
FDIC Acquired Loans [Member] | Commercial Non-Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	5,699
FDIC Acquired Loans [Member] | Construction and Land Development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	8,393
FDIC Acquired Loans [Member] | Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	18,136
FDIC Acquired Loans [Member] | Residential Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	169,214
FDIC Acquired Loans [Member] | Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	$ 13,402

Loans and Allowance for Loan 50

Loans and Allowance for Loan Losses - Schedule of Credit Quality Indicators of Various Classes of Loans - Credit Risk Profile by Internally Assigned Grade (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Construction Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	$ 1,085,585	$ 1,106,761
Commercial Non Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	6,345,994	6,044,060
Commercial Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	3,327,386	3,144,048
Originated Loans [Member] | Construction Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	1,068,895	1,073,964
Originated Loans [Member] | Commercial Non Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	6,232,310	5,917,728
Originated Loans [Member] | Commercial Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	2,956,354	2,428,195
Acquired Loans [Member] | Construction Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	8,297	21,123
Acquired Loans [Member] | Commercial Non Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	107,985	120,137
Acquired Loans [Member] | Commercial Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	352,896	688,045
FDIC Acquired Loans [Member] | Construction Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	8,393	11,674
FDIC Acquired Loans [Member] | Commercial Non Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	5,699	6,195
FDIC Acquired Loans [Member] | Commercial Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	18,136	27,808
Pass [Member] | Construction Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	1,024,203	1,028,973
Pass [Member] | Commercial Non Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	5,634,606	5,691,701
Pass [Member] | Commercial Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	3,101,979	2,887,496
Pass [Member] | Originated Loans [Member] | Construction Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	1,020,611	1,012,128
Pass [Member] | Originated Loans [Member] | Commercial Non Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	5,531,569	5,577,827
Pass [Member] | Originated Loans [Member] | Commercial Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	2,769,860	2,241,391
Pass [Member] | Acquired Loans [Member] | Construction Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	1,354	14,377
Pass [Member] | Acquired Loans [Member] | Commercial Non Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	100,836	111,847
Pass [Member] | Acquired Loans [Member] | Commercial Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	328,821	641,966
Pass [Member] | FDIC Acquired Loans [Member] | Construction Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	2,238	2,468
Pass [Member] | FDIC Acquired Loans [Member] | Commercial Non Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	2,201	2,027
Pass [Member] | FDIC Acquired Loans [Member] | Commercial Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	3,298	4,139
Pass-Watch [Member] | Construction Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	6,309	22,480
Pass-Watch [Member] | Commercial Non Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	135,819	176,577
Pass-Watch [Member] | Commercial Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	49,176	77,278
Pass-Watch [Member] | Originated Loans [Member] | Construction Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	3,038	21,516
Pass-Watch [Member] | Originated Loans [Member] | Commercial Non Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	134,860	174,742
Pass-Watch [Member] | Originated Loans [Member] | Commercial Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	41,344	61,589
Pass-Watch [Member] | Acquired Loans [Member] | Construction Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	2,324	432
Pass-Watch [Member] | Acquired Loans [Member] | Commercial Non Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	76	715
Pass-Watch [Member] | Acquired Loans [Member] | Commercial Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	5,247	11,142
Pass-Watch [Member] | FDIC Acquired Loans [Member] | Construction Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	947	532
Pass-Watch [Member] | FDIC Acquired Loans [Member] | Commercial Non Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	883	1,120
Pass-Watch [Member] | FDIC Acquired Loans [Member] | Commercial Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	2,585	4,547
Special Mention [Member] | Construction Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	11,898	7,545
Special Mention [Member] | Commercial Non Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	225,556	53,312
Special Mention [Member] | Commercial Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	49,480	30,975
Special Mention [Member] | Originated Loans [Member] | Construction Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	11,612	7,097
Special Mention [Member] | Originated Loans [Member] | Commercial Non Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	225,228	52,962
Special Mention [Member] | Originated Loans [Member] | Commercial Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	42,674	21,543
Special Mention [Member] | Acquired Loans [Member] | Construction Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade		129
Special Mention [Member] | Acquired Loans [Member] | Commercial Non Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	328	350
Special Mention [Member] | Acquired Loans [Member] | Commercial Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	5,373	8,113
Special Mention [Member] | FDIC Acquired Loans [Member] | Construction Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	286	319
Special Mention [Member] | FDIC Acquired Loans [Member] | Commercial Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	1,433	1,319
Substandard [Member] | Construction Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	43,175	47,763
Substandard [Member] | Commercial Non Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	349,978	122,395
Substandard [Member] | Commercial Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	126,734	148,278
Substandard [Member] | Originated Loans [Member] | Construction Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	33,634	33,223
Substandard [Member] | Originated Loans [Member] | Commercial Non Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	340,618	112,153
Substandard [Member] | Originated Loans [Member] | Commercial Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	102,459	103,651
Substandard [Member] | Acquired Loans [Member] | Construction Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	4,619	6,185
Substandard [Member] | Acquired Loans [Member] | Commercial Non Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	6,745	7,225
Substandard [Member] | Acquired Loans [Member] | Commercial Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	13,455	26,824
Substandard [Member] | FDIC Acquired Loans [Member] | Construction Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	4,922	8,355
Substandard [Member] | FDIC Acquired Loans [Member] | Commercial Non Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	2,615	3,017
Substandard [Member] | FDIC Acquired Loans [Member] | Commercial Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	10,820	17,803
Doubtful [Member] | Commercial Non Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	35	75
Doubtful [Member] | Commercial Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	17	21
Doubtful [Member] | Originated Loans [Member] | Commercial Non Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	35	44
Doubtful [Member] | Originated Loans [Member] | Commercial Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade	$ 17	21
Doubtful [Member] | FDIC Acquired Loans [Member] | Commercial Non Real Estate Credit Exposure [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile by internally assigned grade		$ 31

Loans and Allowance for Loan 51

Loans and Allowance for Loan Losses - Schedule of Credit Quality Indicators of Various Classes of Loans - Credit Risk Profile Based on Payment Activity and Accrual Status (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Residential Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity and accrual status	$ 2,013,789	$ 1,894,181
Residential Mortgages [Member] | Performing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity and accrual status	1,991,992	1,870,887
Residential Mortgages [Member] | Nonperforming [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity and accrual status	21,797	23,294
Residential Mortgages [Member] | Originated Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity and accrual status	1,843,756	1,704,770
Residential Mortgages [Member] | Originated Loans [Member] | Performing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity and accrual status	1,821,959	1,681,868
Residential Mortgages [Member] | Originated Loans [Member] | Nonperforming [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity and accrual status	21,797	22,902
Residential Mortgages [Member] | Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity and accrual status	819	2,378
Residential Mortgages [Member] | Acquired Loans [Member] | Performing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity and accrual status	819	2,378
Residential Mortgages [Member] | FDIC Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity and accrual status	169,214	187,033
Residential Mortgages [Member] | FDIC Acquired Loans [Member] | Performing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity and accrual status	169,214	186,641
Residential Mortgages [Member] | FDIC Acquired Loans [Member] | Nonperforming [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity and accrual status		392
Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity and accrual status	1,990,296	1,706,226
Consumer [Member] | Performing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity and accrual status	1,982,108	1,698,579
Consumer [Member] | Nonperforming [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity and accrual status	8,188	7,647
Consumer [Member] | Originated Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity and accrual status	1,976,872	1,685,542
Consumer [Member] | Originated Loans [Member] | Performing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity and accrual status	1,968,684	1,678,069
Consumer [Member] | Originated Loans [Member] | Nonperforming [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity and accrual status	8,188	7,473
Consumer [Member] | Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity and accrual status	22	985
Consumer [Member] | Acquired Loans [Member] | Performing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity and accrual status	22	985
Consumer [Member] | FDIC Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity and accrual status	13,402	19,699
Consumer [Member] | FDIC Acquired Loans [Member] | Performing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity and accrual status	$ 13,402	19,525
Consumer [Member] | FDIC Acquired Loans [Member] | Nonperforming [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Credit risk profile based on payment activity and accrual status		$ 174

Loans and Allowance for Loan 52

Loans and Allowance for Loan Losses - Changes in Carrying Amount of Acquired Loans and Accretable Yield for Loans Receivable (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
FDIC Acquired Loans [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount of Loans, Balance at beginning of period	$ 252,409	$ 358,666
Carrying Amount of Loans, Payments received, net	(47,732)	(125,388)
Carrying Amount of Loans, Accretion	10,167	19,131
Carrying Amount of Loans, Balance at end of period	214,844	252,409
Accretable Yield, Balance at beginning of period	112,788	122,715
Accretable Yield, Payments received, net	(395)	(1,071)
Accretable Yield, Accretion	(10,167)	(19,131)
Accretable Yield, Decrease in expected cash flows based on actual cash flows and changes in cash flow assumptions	(1,385)	(1,137)
Net transfers from nonaccretable difference to accretable yield	(2,485)	11,412
Accretable Yield, Balance at end of period	98,356	112,788
Acquired Loans [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount of Loans, Balance at beginning of period	61,276	68,075
Carrying Amount of Loans, Payments received, net	(38,243)	(50,178)
Carrying Amount of Loans, Accretion	12,028	43,379
Carrying Amount of Loans, Balance at end of period	35,061	61,276
Accretable Yield, Balance at beginning of period	74,668	131,370
Accretable Yield, Payments received, net	(14,256)	(32,855)
Accretable Yield, Accretion	(12,028)	(43,379)
Accretable Yield, Decrease in expected cash flows based on actual cash flows and changes in cash flow assumptions	(627)	(203)
Net transfers from nonaccretable difference to accretable yield	(466)	19,735
Accretable Yield, Balance at end of period	$ 47,291	$ 74,668

Securities Sold under Agreeme53

Securities Sold under Agreements to Repurchase - Additional Information (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Banking and Thrift [Abstract]
Securities sold under agreements to repurchase	$ 438,982	$ 624,573

Long-Term Debt - Long-Term Debt

Long-Term Debt - Long-Term Debt (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Mar. 09, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Other long-term debt	$ 125,966		$ 126,760
Total long-term debt	497,177		374,371
Term Note Payable Maturing December 2015 [Member]
Debt Instrument [Line Items]
Term note payable	123,200		149,600
Subordinated Debt [Member] | Subordinated Notes Payable Maturing June 2045 [Member]
Debt Instrument [Line Items]
Subordinated notes payable	150,000	$ 150,000
Subordinated Debt [Member] | Subordinated Notes Payable Maturing April 2017 [Member]
Debt Instrument [Line Items]
Subordinated notes payable	$ 98,011		$ 98,011

Long-Term Debt - Long-Term De55

Long-Term Debt - Long-Term Debt (Parenthetical) (Detail) - Subordinated Debt [Member]	9 Months Ended
	Sep. 30, 2015
Subordinated Notes Payable Maturing June 2045 [Member]
Debt Instrument [Line Items]
Subordinated notes payable maturity date	Jun. 15, 2045
Subordinated Notes Payable Maturing April 2017 [Member]
Debt Instrument [Line Items]
Subordinated notes payable maturity date	Apr. 1, 2017

Long-Term Debt - Additional Inf

Long-Term Debt - Additional Information (Detail) - USD ($) $ in Thousands	Mar. 09, 2015	Dec. 21, 2012	Sep. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Other long term debt maturity date, ending period			2,053
Expected compliance period			7 years
Subordinated Debt [Member]
Debt Instrument [Line Items]
Subordinated notes interest rate			5.875%
Qualified percentage of subordinated notes in regulatory capital			20.00%
Subordinated Notes Payable Maturing June 2045 [Member] | Subordinated Debt [Member]
Debt Instrument [Line Items]
Sale of aggregate principal amount of subordinated notes	$ 150,000		$ 150,000
Subordinated notes payable maturity date			Jun. 15, 2045
Subordinated notes interest rate	5.95%
Subordinated Notes Payable Maturing April 2017 [Member] | Subordinated Debt [Member]
Debt Instrument [Line Items]
Sale of aggregate principal amount of subordinated notes			$ 98,011	$ 98,011
Subordinated notes payable maturity date			Apr. 1, 2017
Three Year Term Loan [Member]
Debt Instrument [Line Items]
Term note payable		$ 220,000
Term loan agreement period		3 years
Additional borrowings		$ 50,000
Reference rate for loan variable rate			LIBOR
Percentage points added to reference rate		1.875%
Debt instrument term loan facility maturity date			Dec. 21, 2015
Principal payment of term loan		$ 8,800

Fair Value - Schedule of Financ

Fair Value - Schedule of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale debt securities	$ 2,166,111
Available for sale equity securities	2,726	$ 9,553
Available for sale securities	2,168,837	1,660,165
Derivative assets	31,399	19,432
Total recurring fair value measurements - assets	2,200,236	1,679,597
Derivative liabilities	30,908	20,860
Total recurring fair value measurements - liabilities	30,908	20,860
Municipal Obligations [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale debt securities	15,952	14,176
Available for sale securities	15,952	14,176
U.S. Treasury and Government Agency Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale debt securities	143	300,508
Corporate Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale debt securities	3,500	3,500
Mortgage-Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale debt securities	1,841,369	1,245,564
Collateralized Mortgage Obligations [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale debt securities	305,147	86,864
Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale equity securities	2,726	9,553
Available for sale securities	2,726	9,553
Total recurring fair value measurements - assets	2,726	9,553
Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale securities	2,166,111	1,650,612
Derivative assets	31,399	19,432
Total recurring fair value measurements - assets	2,197,510	1,670,044
Derivative liabilities	30,908	20,860
Total recurring fair value measurements - liabilities	30,908	20,860
Level 2 [Member] | Municipal Obligations [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale debt securities	15,952	14,176
Level 2 [Member] | U.S. Treasury and Government Agency Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale debt securities	143	300,508
Level 2 [Member] | Corporate Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale debt securities	3,500	3,500
Level 2 [Member] | Mortgage-Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale debt securities	1,841,369	1,245,564
Level 2 [Member] | Collateralized Mortgage Obligations [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale debt securities	$ 305,147	$ 86,864

Fair Value - Additional Informa

Fair Value - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2015
Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Period of Investment	2 years
Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Period of Investment	5 years

Fair Value - Schedule of Fina59

Fair Value - Schedule of Financial Assets Measured at Fair Value on Nonrecurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Collateral-dependent impaired loans	$ 98,019	$ 30,204
Other real estate owned	21,778	29,715
Total nonrecurring fair value measurements	119,797	59,919
Level 2 [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Collateral-dependent impaired loans	98,019	30,204
Total nonrecurring fair value measurements	98,019	30,204
Level 3 [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Other real estate owned	21,778	29,715
Total nonrecurring fair value measurements	$ 21,778	$ 29,715

Fair Value - Schedule of Estima

Fair Value - Schedule of Estimated Fair Values of Financial Instruments (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Available for sale securities	$ 2,168,837	$ 1,660,165
Held to maturity securities	2,380,085	2,166,289
Loans, net	14,623,474	13,766,514
Loans held for sale	19,764	20,252
Derivative financial instruments	31,399	19,432
Deposits	17,439,948	16,572,831
Securities sold under agreements to repurchase	438,982	624,573
Long-term debt	497,177	374,371
Derivative financial instruments	30,908	20,860
Level 1 [Member]
Cash, interest-bearing bank deposits, and federal funds sold	518,157	1,159,403
Available for sale securities	2,726	9,553
Federal funds purchased	10,200	12,000
Securities sold under agreements to repurchase	438,982	624,573
FHLB borrowings	600,000	515,000
Level 2 [Member]
Available for sale securities	2,166,111	1,650,612
Held to maturity securities	2,414,682	2,186,340
Loans, net	98,019	30,204
Loans held for sale	19,764	20,252
Derivative financial instruments	31,399	19,432
Long-term debt	504,475	346,379
Derivative financial instruments	30,908	20,860
Level 3 [Member]
Loans, net	14,558,423	13,672,427
Deposits	17,423,721	16,398,878
Total Fair Value [Member]
Cash, interest-bearing bank deposits, and federal funds sold	518,157	1,159,403
Available for sale securities	2,168,837	1,660,165
Held to maturity securities	2,414,682	2,186,340
Loans, net	14,656,442	13,702,631
Loans held for sale	19,764	20,252
Derivative financial instruments	31,399	19,432
Deposits	17,423,721	16,398,878
Federal funds purchased	10,200	12,000
Securities sold under agreements to repurchase	438,982	624,573
FHLB borrowings	600,000	515,000
Long-term debt	504,475	346,379
Derivative financial instruments	30,908	20,860
Carrying Amount [Member]
Cash, interest-bearing bank deposits, and federal funds sold	518,157	1,159,403
Available for sale securities	2,168,837	1,660,165
Held to maturity securities	2,380,085	2,166,289
Loans, net	14,623,474	13,766,514
Loans held for sale	19,764	20,252
Derivative financial instruments	31,399	19,432
Deposits	17,439,948	16,572,831
Federal funds purchased	10,200	12,000
Securities sold under agreements to repurchase	438,982	624,573
FHLB borrowings	600,000	515,000
Long-term debt	497,177	374,371
Derivative financial instruments	$ 30,908	$ 20,860

Derivatives - Fair Values of De

Derivatives - Fair Values of Derivative Instruments on Balance Sheet (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Derivative Fair Value Of Asset	$ 31,399	$ 19,432
Derivative Fair Value Of Liability	30,908	20,860
Derivatives Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	500,000	300,000
Derivative Fair Value Of Asset	1,419
Derivative Fair Value Of Liability		592
Derivatives Designated as Hedging Instruments [Member] | Interest Rate Swaps [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	500,000	300,000
Derivative Fair Value Of Asset	1,419
Derivative Fair Value Of Liability		592
Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	939,023	1,002,930
Derivative Fair Value Of Asset	29,980	19,432
Derivative Fair Value Of Liability	30,908	20,268
Derivatives Not Designated as Hedging Instruments [Member] | Interest Rate Swaps [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	728,674	747,754
Derivative Fair Value Of Asset	26,621	17,806
Derivative Fair Value Of Liability	27,362	18,419
Derivatives Not Designated as Hedging Instruments [Member] | Risk Participation Agreements [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	87,184	80,438
Derivative Fair Value Of Asset	107	125
Derivative Fair Value Of Liability	206	208
Derivatives Not Designated as Hedging Instruments [Member] | Forward Commitments to Sell Residential Mortgage Loans [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	38,817	52,238
Derivative Fair Value Of Asset	100	80
Derivative Fair Value Of Liability	329	250
Derivatives Not Designated as Hedging Instruments [Member] | Interest Rate-Lock Commitments on Residential Mortgage Loans [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	22,127	33,068
Derivative Fair Value Of Asset	161	111
Derivative Fair Value Of Liability	45	44
Derivatives Not Designated as Hedging Instruments [Member] | Foreign Exchange Forward Contracts [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	62,221	89,432
Derivative Fair Value Of Asset	2,991	1,310
Derivative Fair Value Of Liability	$ 2,966	$ 1,347

Derivatives - Additional Inform

Derivatives - Additional Information (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2015USD ($)Agreement
Derivative [Line Items]
Termination value of derivatives in a net liability position	$ 12.8
Collateral obligations for derivative counterparties	$ 28.9
Interest Rate Swaps [Member]
Derivative [Line Items]
Number of interest rate swap agreements | Agreement	2
Interest Rate Swaps [Member] | $300 Million Swap Agreement [Member]
Derivative [Line Items]
Notional amount of derivatives	$ 300
Variable rate term loan agreement maturity	January 2,017
Interest Rate Swaps [Member] | $200 Million Swap Agreement [Member]
Derivative [Line Items]
Notional amount of derivatives	$ 200
Variable rate term loan agreement maturity	June 2,017

Derivatives - Offsetting Deriva

Derivatives - Offsetting Derivative Assets and Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gross Amounts Recognized, Derivative Assets	$ 26,728	$ 17,931
Gross Amounts Offset in the Statement of Financial Position, Derivative Assets	0	0
Net Amounts Presented in the Statement of Financial Position, Derivative Assets	26,728	17,931
Gross Amounts Not Offset in the Statement of Financial Position - Financial Instruments, Derivative Assets	118	936
Gross Amounts Not offset in the Statement of Financial Position -Cash Collateral, Derivative Assets	0	0
Net Amount, Derivative Assets	26,610	16,995
Gross Amounts Recognized, Derivative Liabilities	27,568	18,627
Gross Amounts Offset in the Statement of Financial Position, Derivative Liabilities	0	0
Net Amounts Presented in the Statement of Financial Position, Derivative Liabilities	27,568	18,627
Gross Amounts Not Offset in the Statement of Financial Position - Financial Instruments, Derivative Liabilities	118	936
Gross Amounts Not offset in the Statement of Financial Position -Cash Collateral, Derivative Liabilities	28,796	17,343
Net Amount, Derivative Liabilities	$ (1,346)	$ 348

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - $ / shares	Aug. 28, 2015	Jul. 16, 2014	Sep. 30, 2015
Stockholders' Equity Note [Abstract]
Shares authorized for repurchase	5.00%	5.00%
Number of shares authorized for repurchase	3,900,000	4,100,000
Repurchased common stock shares		4,100,000	568,279
Shares repurchased, price per share		$ 30.02	$ 27.39

Stockholders' Equity - Componen

Stockholders' Equity - Components of Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), Beginning balance			$ (50,074)	$ (35,379)
Net change in unrealized gain	$ 15,131	$ (6,293)	2,174	9,119
Reclassification of net (gain) losses realized and included in earnings			2,208	293
Valuation adjustment for employee benefit plans	4,963	(104)	(959)	1,902
Amortization of unrealized net loss on securities transferred to HTM	1,023	892	2,609	2,463
Income tax (benefit) expense	8,002	(2,005)	2,125	5,091
Accumulated other comprehensive income (loss), Ending balance	(46,167)	(26,693)	(46,167)	(26,693)
Available for Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), Beginning balance			18,001	8,263
Net change in unrealized gain			163	9,119
Reclassification of net (gain) losses realized and included in earnings			(165)
Income tax (benefit) expense			(73)	3,309
Accumulated other comprehensive income (loss), Ending balance	18,072	14,073	18,072	14,073
Held to Maturity Securities Transferred from AFS [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), Beginning balance			(19,074)	(21,189)
Amortization of unrealized net loss on securities transferred to HTM			2,609	2,463
Income tax (benefit) expense			953	879
Accumulated other comprehensive income (loss), Ending balance	(17,418)	(19,605)	(17,418)	(19,605)
Employee Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), Beginning balance			(48,626)	(22,453)
Reclassification of net (gain) losses realized and included in earnings			2,373	293
Valuation adjustment for employee benefit plans			(959)	1,902
Income tax (benefit) expense			513	903
Accumulated other comprehensive income (loss), Ending balance	(47,725)	$ (21,161)	(47,725)	$ (21,161)
Gains and Losses on Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), Beginning balance			(375)
Net change in unrealized gain			2,011
Income tax (benefit) expense			732
Accumulated other comprehensive income (loss), Ending balance	$ 904		$ 904

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Line Items in Consolidated Income Statements Affected by Amounts Reclassified from Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Tax effect	$ (14,602)	$ (16,382)	$ (41,789)	$ (52,248)
Net income	$ 41,166	$ 46,553	116,154	135,630
Amount Reclassified from Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income			(3,091)	(1,774)
Amount Reclassified from Accumulated Other Comprehensive Income [Member] | Available for Sale Securities [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Gain on sale of AFS securities			165
Tax effect			(58)
Net income			107
Amount Reclassified from Accumulated Other Comprehensive Income [Member] | Unrealized Gains and Losses on Securities Available for Sale Transferred to Held to Maturity [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of unrealized net loss on securities transferred to HTM			(2,609)	(2,463)
Tax effect			953	879
Net income			(1,656)	(1,584)
Amount Reclassified from Accumulated Other Comprehensive Income [Member] | Employee Benefit Plans [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of defined benefit pension and post-retirement items			(2,373)	(293)
Tax effect			831	103
Net income			$ (1,542)	$ (190)

Earnings Per Share - Computatio

Earnings Per Share - Computation of Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Numerator:
Net income to common shareholders	$ 41,166	$ 46,553	$ 116,154	$ 135,630
Net income allocated to participating securities - basic and diluted	840	883	2,541	2,783
Net income allocated to common shareholders - basic and diluted	$ 40,326	$ 45,670	$ 113,613	$ 132,847
Denominator:
Weighted-average common shares - basic	77,928	81,721	78,452	81,965
Dilutive potential common shares	147	221	157	239
Weighted-average common shares - diluted	78,075	81,942	78,609	82,204
Earnings per common share:
Basic	$ 0.52	$ 0.56	$ 1.45	$ 1.62
Diluted	$ 0.52	$ 0.56	$ 1.45	$ 1.62

Earnings Per Share - Additional

Earnings Per Share - Additional Information (Detail) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share [Abstract]
Weighted-average anti-dilutive potential common shares	761,113	569,404	815,765	639,486

Share-Based Payment Arrangeme69

Share-Based Payment Arrangements - Schedule of Option Activity Under Stock Option Plans (Detail) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2015USD ($)$ / sharesshares
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Number of Shares, Outstanding at Beginning | shares	933,750
Number of Shares, Exercised | shares	(11,577)
Number of Shares, Cancelled/Forfeited | shares	(56,987)
Number of Shares, Expired | shares	(111,424)
Number of Shares, Outstanding at Ending | shares	753,762
Number of Shares, Exercisable at Ending | shares	635,712
Weighted- Average Exercise Price, Outstanding at Beginning	$ 37.03
Weighted- Average Exercise Price, Exercised	29.94
Weighted- Average Exercise Price, Cancelled/Forfeited	35.89
Weighted- Average Exercise Price, Expired	34.79
Weighted- Average Exercise Price, Outstanding at Ending	37.55
Weighted- Average Exercise Price, Exercisable at Ending	$ 38.90
Weighted-Average Remaining Contractual Term, Outstanding at Ending Balance (in years)	3 years 10 months 24 days
Weighted-Average Remaining Contractual Term, Exercisable at Ending Balance (in years)	3 years 6 months
Aggregate Intrinsic Value, Outstanding at Ending | $	$ 0
Aggregate Intrinsic Value, Exercisable at Ending | $	$ 0

Share-Based Payment Arrangeme70

Share-Based Payment Arrangements - Additional Information (Detail) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2015USD ($)Bank$ / sharesshares	Sep. 30, 2014USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Intrinsic value of options exercised	$ 0.2	$ 0.2
Unrecognized compensation cost	$ 32.2
Weighted-average period in years	3 years 1 month 6 days
Total fair value of shares vested	$ 7.6	$ 10
Shareholder return period	3 years
Number of peer group of regional banks | Bank	50
Performance Share Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted to key members of executives and senior management | shares	59,312
Weighted average fair value of shares granted | $ / shares	$ 25.77
Percentage of maximum number of shares earned of target award	200.00%

Share-Based Payment Arrangeme71

Share-Based Payment Arrangements - Schedule of Nonvested Restricted and Performance Shares (Detail) - Restricted Stock and Performance Shares [Member]	9 Months Ended
	Sep. 30, 2015$ / sharesshares
Nonvested Share Activity [Line Items]
Number of Shares, Nonvested at Beginning | shares	2,040,299
Number of Shares, Granted | shares	106,833
Number of Shares, Vested | shares	(239,761)
Number of Shares, Forfeited | shares	(143,884)
Number of Shares, Nonvested at Ending | shares	1,763,487
Weighted-Average Grant-Date Fair Value, Nonvested at Beginning	$ 32.27
Weighted-Average Grant-Date Fair Value, Granted	27.40
Weighted-Average Grant-Date Fair Value, Vested	31.93
Weighted-Average Grant-Date Fair Value, Cancelled/Forfeited	32.64
Weighted-Average Grant-Date Fair Value, Nonvested at Ending	$ 31.99

Retirement Plans - Components o

Retirement Plans - Components of Net Periodic Benefits Cost (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Pension Benefits [Member]
Defined Benefit Plan Net Periodic Benefit Cost [Line Items]
Service cost	$ 3,383	$ 3,230	$ 10,128	$ 9,690
Interest cost	4,672	4,812	13,963	14,438
Expected return on plan assets	(8,207)	(8,056)	(24,626)	(24,167)
Amortization of net loss	842	7	2,328	20
Net periodic benefit cost	690	(7)	1,793	(19)
Other Post-retirement Benefits [Member]
Defined Benefit Plan Net Periodic Benefit Cost [Line Items]
Service cost	23	31	95	94
Interest cost	174	285	717	855
Amortization of net loss	(40)	91	45	273
Net periodic benefit cost	$ 157	$ 407	$ 857	$ 1,222

Retirement Plans - Additional I

Retirement Plans - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Mar. 31, 2015	Sep. 30, 2015
Compensation and Retirement Disclosure [Abstract]
Contributed to pension plan	$ 10
Percentage of compensation saved by participant for which employer contributes hundred percent		100.00%
Employer matching contribution for first one percent of compensation saved		1.00%
Percentage of compensation saved by participant for which employer contributes fifty percent		50.00%
Employer matching contribution for next five percent of compensation saved		5.00%

Other Noninterest Income - Comp

Other Noninterest Income - Components of Other Noninterest Income (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Noninterest Income [Abstract]
Income from bank-owned life insurance	$ 2,451	$ 2,377	$ 7,788	$ 7,048
Credit related fees	2,718	2,822	7,786	8,388
Income from derivatives	74	191	1,486	1,431
Net gain (loss) on sale of assets	418	(56)	363	1,409
Safety deposit box income	441	448	1,356	1,404
Other miscellaneous	2,268	1,950	7,360	7,091
Total other noninterest income	$ 8,370	$ 7,732	$ 26,139	$ 26,771

Other Noninterest Expense - Com

Other Noninterest Expense - Components of Other Noninterest Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Noninterest Expense [Abstract]
Advertising	$ 2,856	$ 2,457	$ 7,154	$ 6,395
Ad valorem and franchise taxes	2,868	3,098	8,319	8,397
Printing and supplies	1,193	1,189	3,568	3,467
Insurance expense	794	944	2,644	3,002
Travel expense	1,419	1,009	3,946	2,966
Entertainment and contributions	1,634	1,396	5,009	4,337
Tax credit investment amortization	2,161	2,220	6,352	6,590
Other miscellaneous	3,634	6,821	16,679	25,105
Total other noninterest expense	$ 16,559	$ 19,134	$ 53,671	$ 60,259

Other Noninterest Expense - Add

Other Noninterest Expense - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Nonoperating expense [Line Items]
Other miscellaneous expenses	$ 3,634	$ 6,821	$ 16,679	$ 25,105
Other Miscellaneous Expense [Member]
Nonoperating expense [Line Items]
Other miscellaneous expenses	$ 0	$ 1,100	$ 2,700	$ 8,400