S&T Bancorp (STBA) 10-Q 3 Nov 15 2015 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2015	Oct. 31, 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
Entity Registrant Name	S&T BANCORP INC
Entity Central Index Key	719,220
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		34,811,636

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands		Sep. 30, 2015	Dec. 31, 2014
ASSETS
Cash and due from banks, including interest-bearing deposits of $55,662 and $57,048 at September 30, 2015 and December 31, 2014		$ 115,347	$ 109,580
Securities available-for-sale, at fair value		660,046	640,273
Loans held for sale		13,794	2,970
Portfolio loans, net of unearned income	[1]	4,925,963	3,868,746
Allowance for loan losses		(49,907)	(47,911)
Portfolio loans, net		4,876,056	3,820,835
Bank owned life insurance		79,894	62,252
Premises and equipment, net		49,106	38,166
Federal Home Loan Bank and other restricted stock, at cost		20,352	15,135
Goodwill		291,683	175,820
Other intangible assets, net		7,000	2,631
Other assets		102,060	97,024
Total Assets		6,215,338	4,964,686
LIABILITIES
Noninterest-bearing demand		1,188,331	1,083,919
Interest-bearing demand		704,348	335,099
Money market		593,643	376,612
Savings		1,088,217	1,027,095
Certificates of deposit		1,302,870	1,086,117
Total Deposits		4,877,409	3,908,842
Securities sold under repurchase agreements		42,971	30,605
Short-term borrowings		280,000	290,000
Long-term borrowings		117,613	19,442
Junior subordinated debt securities		45,619	45,619
Other liabilities		63,923	61,789
Total Liabilities		5,427,535	4,356,297
SHAREHOLDERS' EQUITY
Common stock ($2.50 par value) Authorized—50,000,000 shares Issued—36,130,480 shares at September 30, 2015 and 31,197,365 shares at December 31, 2014 Outstanding—34,811,636 shares at September 30, 2015 and 29,796,397 shares at December 31, 2014		90,326	77,993
Additional paid-in capital		210,141	78,818
Retained earnings		533,442	504,060
Accumulated other comprehensive (loss) income		(9,736)	(13,833)
Treasury stock (1,318,844 shares at September 30, 2015 and 1,400,968 shares at December 31, 2014, at cost)		(36,370)	(38,649)
Total Shareholders’ Equity		787,803	608,389
Total Liabilities and Shareholders’ Equity		$ 6,215,338	$ 4,964,686
[1]	Includes acquired loans.

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Cash and due from banks, interest-bearing amounts	$ 55,662	$ 57,048
Common stock, par value (in dollars per share)	$ 2.50	$ 2.50
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	36,130,480	31,197,365
Common stock, shares outstanding	34,811,636	29,796,397
Treasury stock, shares	1,318,844	1,400,968

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ 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	$ 49,578	$ 37,233	$ 138,438	$ 109,496
Investment securities:
Taxable	2,522	2,313	7,298	6,480
Tax-exempt	988	964	3,006	2,872
Dividends	581	95	1,453	294
Total Interest Income	53,669	40,605	150,195	119,142
INTEREST EXPENSE
Deposits	3,275	2,480	9,333	7,466
Borrowings and junior subordinated debt securities	798	596	2,196	1,701
Total Interest Expense	4,073	3,076	11,529	9,167
NET INTEREST INCOME	49,596	37,529	138,666	109,975
Provision for loan losses	3,206	1,454	6,473	608
Net Interest Income After Provision for Loan Losses	46,390	36,075	132,193	109,367
NONINTEREST INCOME
Securities (losses) gains, net	0	0	(34)	41
Service charges on deposit accounts	3,069	2,799	8,529	7,882
Debit and credit card fees	2,996	2,909	8,732	8,135
Wealth management fees	2,814	2,756	8,667	8,548
Insurance fees	1,332	1,722	4,374	4,824
Mortgage banking	698	270	2,006	666
Other	1,572	1,475	5,674	5,022
Total Noninterest Income	12,481	11,931	37,948	35,118
NONINTEREST EXPENSE
Salaries and employee benefits	16,789	14,823	51,024	45,971
Net occupancy	2,744	2,004	8,014	6,218
Data processing	2,454	2,152	7,329	6,466
Furniture and equipment	1,653	1,308	4,461	3,856
FDIC insurance	990	607	2,493	1,817
Professional services and legal	946	950	2,270	2,488
Marketing	895	757	2,905	2,335
Other taxes	719	839	2,721	2,363
Merger related expenses	0	0	3,167	0
Other	6,639	5,000	18,515	16,005
Total Noninterest Expense	33,829	28,440	102,899	87,519
Income Before Taxes	25,042	19,566	67,242	56,966
Provision for income taxes	6,407	4,906	17,584	13,552
Net Income	$ 18,635	$ 14,660	$ 49,658	$ 43,414
Earnings per share—basic (in dollars per share)	$ 0.54	$ 0.49	$ 1.48	$ 1.46
Earnings per share—diluted (in dollars per share)	0.54	0.49	1.48	1.46
Dividends declared per share (in dollars per share)	$ 0.18	$ 0.17	$ 0.54	$ 0.5
Comprehensive Income	$ 22,420	$ 13,515	$ 53,755	$ 48,936

Consolidated Statements of Chan

Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive (Loss)/Income [Member]	Treasury Stock [Member]
Balance at Dec. 31, 2013	$ 571,306	$ 77,993	$ 78,140	$ 468,158	$ (12,694)	$ (40,291)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	43,414			43,414
Other comprehensive income (loss), net of tax	5,522				5,522
Cash dividends declared	(14,858)			(14,858)
Treasury stock issued for restricted awards	(163)			(1,805)		1,642
Recognition of restricted stock compensation expense	676		676
Balance at Sep. 30, 2014	605,897	77,993	78,816	494,909	(7,172)	(38,649)
Balance at Dec. 31, 2014	608,389	77,993	78,818	504,060	(13,833)	(38,649)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	49,658			49,658
Other comprehensive income (loss), net of tax	4,097				4,097
Cash dividends declared	(17,886)			(17,886)
Common stock issued in acquisition	142,469	12,333	130,136
Treasury stock issued for restricted awards	(111)			(2,390)		2,279
Recognition of restricted stock compensation expense	1,266		1,266
Tax benefit from stock-based compensation	53		53
Common stock issuance costs	(132)		(132)
Balance at Sep. 30, 2015	$ 787,803	$ 90,326	$ 210,141	$ 533,442	$ (9,736)	$ (36,370)

Consolidated Statements of Cha6

Consolidated Statements of Changes in Shareholders' Equity (Parenthetical) - $ / shares	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Statement of Stockholders' Equity [Abstract]
Dividends declared per share (in dollars per share)	$ 0.54	$ 0.5
Common stock issued in acquisition, shares	4,933,115
Treasury stock issued for restricted awards, net of forfeitures	87,841	80,455
Forfeitures of restricted stock, shares	5,717	21,783

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
OPERATING ACTIVITIES
Net income	$ 49,658	$ 43,414
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	6,473	608
Provision for unfunded loan commitments	687	(262)
Depreciation, amortization and accretion	(6)	3,510
Net amortization of discounts and premiums on securities	2,682	2,800
Stock-based compensation expense	1,158	594
Securities losses (gains), net	34	(41)
Tax benefit from stock-based compensation	(53)	0
Mortgage loans originated for sale	(81,966)	(28,652)
Proceeds from the sale of mortgage loans	71,872	27,894
Gain on the sale of mortgage loans, net	(730)	(232)
Net increase in interest receivable	(2,280)	(604)
Net decrease in interest payable	(637)	(423)
Net decrease in other assets	13,216	10,749
Net increase (decrease) in other liabilities	1,531	(897)
Net Cash Provided by Operating Activities	61,639	58,458
INVESTING ACTIVITIES
Purchases of securities available-for-sale	(54,465)	(149,268)
Proceeds from maturities, prepayments and calls of securities available-for-sale	36,680	46,662
Proceeds from sales of securities available-for-sale	11,119	1,418
Net purchases of Federal Home Loan Bank stock	(3,535)	(5,366)
Net increase in loans	(276,282)	(244,836)
Proceeds from sale of loans not originated for resale	2,804	5,408
Purchases of premises and equipment	(3,737)	(3,220)
Proceeds from the sale of premises and equipment	264	98
Net cash paid in excess of cash acquired from bank merger	(16,347)	0
Net Cash Used in Investing Activities	(303,499)	(349,104)
FINANCING ACTIVITIES
Net increase in core deposits	259,725	176,182
Net (decrease) increase in certificates of deposit	(12,399)	52,491
Net increase (decrease) in securities sold under repurchase agreements	12,366	(10,763)
Net (decrease) increase in short-term borrowings	(78,660)	125,000
Proceeds from long-term borrowings	100,000	0
Repayments of long-term borrowings	(1,829)	(1,768)
Repayment of junior subordinated debt	(13,500)	0
Treasury shares issued-net	(111)	(163)
Common stock issuance costs	(132)	0
Cash dividends paid to common shareholders	(17,886)	(14,858)
Tax benefit from stock-based compensation	53	0
Net Cash Provided by Financing Activities	247,627	326,121
Net increase in cash and cash equivalents	5,767	35,475
Cash and cash equivalents at beginning of period	109,580	108,356
Cash and Cash Equivalents at End of Period	115,347	143,831
Supplemental Disclosures
Loans transferred to held for sale	0	1,300
Interest paid	11,853	9,590
Income taxes paid, net of refunds	15,675	12,900
Net assets acquired from bank merger, excluding cash and cash equivalents	43,433	0
Transfers of loans to other real estate owned	$ 628	$ 430

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2015
Accounting Policies [Abstract]
Basis of Presentation	Principles of Consolidation The interim Consolidated Financial Statements include the accounts of S&T Bancorp, Inc., or S&T, and its wholly owned subsidiaries. All significant intercompany transactions have been eliminated in consolidation. Investments of 20 percent to 50 percent of the outstanding common stock of investees are accounted for using the equity method of accounting. Basis of Presentation The accompanying unaudited interim Consolidated Financial Statements of S&T have been prepared in accordance with generally accepted accounting principles, or GAAP, in the United States for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements and should be read in conjunction with our annual report on Form 10-K for the year ended December 31, 2014 , filed with the Securities and Exchange Commission, or SEC, on February 20, 2015. In the opinion of management, the accompanying interim financial information reflects all adjustments, including normal recurring adjustments, necessary to present fairly our financial position and the results of operations for each of the interim periods presented. Results of operations for interim periods are not necessarily indicative of the results of operations that may be expected for a full year or any future period. Reclassification Certain amounts in the prior periods’ financial statements and footnotes have been reclassified to conform to the current period’s presentation. The reclassifications had no significant effect on our results of operations or financial condition. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements. Actual results could differ from those estimates. Recently Adopted Accounting Standards Updates, or ASU Repurchase-To-Maturity Transactions, Repurchase Financings, and Disclosures In June 2014, the Financial Accounting Standards Board, or FASB, issued ASU No. 2014-11, Repurchase-to-Maturity Transactions, Repurchase Financings, and Disclosures which introduces two accounting changes to the Transfers and Servicing guidance (Topic 860). Repurchase-to-maturity transactions will be accounted for as secured borrowing transactions on the balance sheet and for repurchase financing arrangements, an entity will account separately for a transfer of a financial asset executed contemporaneously with a repurchase agreement with the same counterparty. This will also generally result in secured borrowing accounting for the repurchase agreement. With respect to disclosures, a transferor is required to disclose information about transactions accounted for as a sale in which the transferor retains substantially all of the exposure to the economic return on the transferred financial assets through an agreement with the transferee. Additionally, new disclosures are required for repurchase agreements, securities lending transactions, and repurchase-to-maturity transactions that are accounted for as secured borrowings. The new disclosure for transactions accounted for as secured borrowings is required for interim periods beginning after March 15, 2015. These new disclosures are included in Note 9. Borrowings. The adoption of this ASU had no impact on our results of operations or financial position. Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity In April 2014, the FASB issued ASU No. 2014-08, Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity, which changes the criteria for determining which disposals can be presented as discontinued operations and modifies related disclosure requirements. The guidance applies to all entities that dispose of components. It will significantly change current practices for assessing discontinued operations and affect an entity’s income and earnings per share from continuing operations. An entity is required to reclassify assets and liabilities of a discontinued operation that are classified as held for sale or disposed of in the current period for all comparative periods presented. The ASU requires that an entity present in the statement of cash flows or disclose in a note either total operating and investing cash flows for discontinued operations, or depreciation, amortization, capital expenditures and significant operating and investing noncash items related to discontinued operations. Additional disclosures are required when an entity retains significant continuing involvement with a discontinued operation after its disposal, including the amount of cash flows to and from a discontinued operation. The new standard applies prospectively after the effective date of December 15, 2014, and early adoption was permitted. The adoption of this ASU had no impact on our results of operations or financial position. Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans upon Foreclosure In January 2014, the FASB issued ASU No. 2014-04, Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans upon Foreclosure. The ASU clarifies that an in substance repossession or foreclosure has occurred and a creditor is considered to have received physical possession of residential real estate property collateralizing a consumer mortgage loan, upon either the creditor obtaining legal title to the residential real estate property upon completion of a foreclosure or the borrower conveying all interest in the residential real estate property to the creditor to satisfy that loan through completion of a deed in lieu of foreclosure. Interim and annual disclosure is required of both the amount of foreclosed residential real estate property held by the creditor and the recorded investment in consumer mortgage loans collateralized by residential real estate property that are in the process of foreclosure. The new standard is effective using either the modified retrospective transition method or a prospective transition method for fiscal years and interim periods within those years, beginning after December 15, 2014, and early adoption was permitted. The adoption of this ASU had no impact on our results of operations or financial position. Accounting for Investments in Qualified Affordable Housing Projects In January 2014, the FASB issued ASU No. 2014-01, Accounting for Investments in Qualified Affordable Housing Projects. The ASU permits reporting entities to make an accounting policy election to account for investments in qualified affordable housing projects using the proportional amortization method if certain conditions are met. The proportional amortization method permits the amortization of the initial cost of the investment in proportion to the tax credits and other tax benefits received, and recognizes the net investment performance in the income statement as a component of income tax expense (benefit). The new standard is effective retrospectively for fiscal years and interim periods within those years, beginning after December 15, 2014, and early adoption was permitted. This ASU did not have a material impact on our results of operations or financial position. We did not adopt the proportional amortization method. Refer to Note 14 for additional disclosure. Recently Issued Accounting Standards Updates not yet Adopted Business Combinations – Simplifying the Accounting for Measurement Period Adjustments In September 2015, the FASB issued ASU No. 2015-16, Business Combinations – Simplifying the Accounting for Measurement Period Adjustments (Topic 805): The amendments in this ASU 2015-16 eliminate the requirement to retrospectively adjust the financial statements for measurement-period adjustments as if they were known at the acquisition date, but are recognized in the reporting period in which they are determined. Additional disclosures are required about the impact on current-period income statement line items of adjustments that would have been recognized in prior periods if that information had been revised. The measurement period is a reasonable time period after the acquisition date when the acquirer may adjust the provisional amounts recognized for a business combination if the necessary information is not available by the end of the reporting period in which the acquisition occurs. The measurement periods cannot continue for more than one year from the acquisition date. The standard is effective for annual periods and interim periods beginning after December 15, 2015. We do not expect that this ASU will have a material impact on our results of operations or financial position. Intangibles – Goodwill and Other – Internal-Use Software: Customer's Accounting for Fees Paid in a Cloud Computing Arrangement In April 2015, the FASB issued ASU No. 2015-05, Intangibles – Goodwill and Other – Internal-Use Software (Subtopic 350-40): Customer's Accounting for Fees Paid in a Cloud Computing Arrangement. The main provisions of ASU 2015-05 provide a basis for evaluating whether a cloud computing arrangement 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, then the arrangement should be accounted for as a service contract. The standard is effective for annual periods and interim periods beginning after December 15, 2015. We do not expect that this ASU will have a material impact on our results of operations or financial position. Interest – Imputation of Interest: Simplifying the Presentation of Debt Issuance Costs In April 2015, the FASB issued ASU No. 2015-03, Interest – Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs. The amendments in this ASU require 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 standard is required to be adopted by public business entities in annual periods beginning on or after December 15, 2016. We do not expect that this ASU will have a material impact on our results of operations or financial position. Consolidation: Amendments to the Consolidation Analysis In April 2015, the FASB issued ASU No. 2015-02, Consolidation (Topic 810): Amendments to the Consolidation Analysis. The amendments in this ASU affect reporting entities that are required to evaluate whether they should consolidate certain legal entities. All legal entities are subject to reevaluation under the revised consolidation model. Specifically, the amendments: 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 ASU are effective for public business entities for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2015. We are currently evaluating the impact that these amendments may have on our consolidated financial statements. We do not expect that this ASU will have a material impact on our results of operations or financial position. Income Statement – Extraordinary and Unusual Items: Simplifying Income Statement Presentation by Eliminating the Concept of Extraordinary In January 2015, the FASB issued ASU No. 2015-01, Income Statement – Extraordinary and Unusual Items (Subtopic 225-20): Simplifying Income Statement Presentation by Eliminating the Concept of Extraordinary. The amendments in this ASU eliminate from GAAP the concept of extraordinary items and eliminate the requirements for reporting entities to consider whether an underlying event or transaction is extraordinary. The presentation and disclosure guidance for items that are unusual in nature or occur infrequently will be retained and will be expanded to include items that are both unusual in nature and infrequently occurring. The standard is required to be adopted by public business entities in annual periods beginning on or after December 15, 2015. We do not expect that this ASU will have a material impact on our results of operations or financial position.

Business Combinations

Business Combinations	9 Months Ended
	Sep. 30, 2015
Business Combinations [Abstract]
Business Combinations	On March 4, 2015, we completed the acquisition of 100 percent of the voting shares of Integrity Bancshares, Inc., or Integrity, located in Camp Hill, Pennsylvania, in a tax-free reorganization transaction structured as a merger of Integrity with and into S&T, with S&T being the surviving entity. As a result of the Integrity merger, or the Merger, Integrity Bank, the wholly owned subsidiary bank of Integrity, became a separate wholly owned subsidiary bank of S&T. The merger of Integrity Bank into S&T Bank, with S&T Bank surviving the merger, and related system conversion occurred on May 8, 2015. Integrity shareholders were entitled to elect to receive for each share of Integrity common stock either $52.50 in cash or 2.0627 shares of S&T common stock subject to allocation and proration procedures in the merger agreement. The total purchase price was approximately $172.0 million which included $29.5 million of cash and 4,933,115 S&T common shares at a fair value of $28.88 per share. The fair value of $28.88 per share of S&T common stock was based on the March 4, 2015 closing price. The Merger was accounted for under the acquisition method of accounting and our consolidated financial statements include all Integrity Bank transactions from March 4, 2015, until it was merged into S&T Bank on May 8, 2015. The assets acquired and liabilities assumed were recorded at their respective fair values and represent management’s estimates based on available information. Purchase accounting guidance allows for a reasonable period of time following an acquisition for the acquirer to obtain the information necessary to complete the accounting for a business combination. This period is known as the measurement period. As of September 30, 2015, an additional $1.1 million of purchase accounting adjustments were recognized that increased goodwill. The measurement period adjustments primarily related to a $0.8 million reduction in the fair value of land recorded in the second quarter of 2015 and a $0.3 million reduction in deferred taxes recorded in the third quarter of 2015. Goodwill of $115.9 million was calculated as the excess of the consideration exchanged over the fair value of the identifiable net assets acquired. The goodwill arising from the Merger consists largely of the synergies and economies of scale expected from combining the operations of S&T and Integrity. All of the goodwill was assigned to our Community Banking segment. The goodwill recognized will not be deductible for tax purposes. The following table summarizes total consideration, assets acquired and liabilities assumed as of September 30, 2015: (dollars in thousands) Consideration Paid Cash $ 29,510 Common stock 142,469 Fair Value of Total Consideration $ 171,979 Fair Value of Assets Acquired Cash and cash equivalents $ 13,163 Securities and other investments 11,502 Loans 788,687 Bank owned life insurance 15,974 Premises and equipment 10,855 Core deposit intangible 5,713 Other assets 19,076 Total Assets Acquired 864,970 Fair Value of Liabilities Assumed Deposits 722,308 Borrowings 82,286 Other liabilities 4,259 Total Liabilities Assumed 808,853 Total Fair Value of Identifiable Net Assets 56,117 Goodwill $ 115,862 Loans acquired in the Merger were recorded at fair value with no carryover of the related allowance for loan losses. Determining the fair value of the loans involves estimating the amount and timing of principal and interest cash flows expected to be collected on the loans and discounting those cash flows at a market rate of interest. Loans acquired with evidence of credit quality deterioration were evaluated and not considered to be significant. The fair value of the loans acquired was $788.7 million net of a $14.8 million discount. The discount may be accreted to interest income over the remaining contractual life of the loans. Acquired loans included $331.6 million of commercial real estate, or CRE, $184.2 million of commercial and industrial, or C&I, $92.4 million of commercial construction, $116.9 million of residential mortgage, $25.6 million of home equity, $36.1 million of installment and other consumer and $1.9 million of consumer construction. Direct costs related to the Merger were expensed as incurred. During the nine months ended September 30, 2015, we recognized $3.2 million of merger related expenses, including $1.3 million for data processing contract termination and system conversion costs, $1.2 million in legal and professional expenses, $0.4 million in severance payments and $0.3 million in other expenses. The following table presents unaudited pro forma financial information which combines the historical consolidated statements of income of S&T and Integrity to give effect to the Merger as if it had occurred on January 1, 2014, for the periods presented. Unaudited Pro Forma Information Three Months Ended September 30, Nine Months Ended September 30, (dollars in thousands, except per share data) 2015 2014 2015 2014 Total revenue (1) $ 59,819 $ 58,875 $ 179,559 $ 174,097 Net income (2) $ 18,527 $ 18,250 $ 51,406 $ 51,651 Earnings per common share: (2) Basic $ 0.53 $ 0.53 $ 1.49 $ 1.49 Diluted $ 0.53 $ 0.53 $ 1.48 $ 1.49 (1) Total pro forma revenue is defined as net interest income plus non-interest income, excluding gains and losses on sales of investment securities available-for-sale. ( 2) Excludes merger expenses Pro forma adjustments include intangible amortization expense, net amortization or accretion of valuation amounts and income tax expense. The pro forma results are not indicative of the results of operations that would have occurred had the Merger taken place at the beginning of the periods presented nor are they intended to be indicative of results that may occur in the future.

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2015
Earnings Per Share [Abstract]
Earnings Per Share	The following table reconciles the components of basic earnings per share with that of diluted earnings per share for the periods presented: Three Months Ended September 30, Nine Months Ended September 30, (in thousands, except shares and per share data) 2015 2014 2015 2014 Numerator for Earnings per Share—Basic: Net income $ 18,635 $ 14,660 $ 49,658 $ 43,414 Less: Income allocated to participating shares 81 51 204 115 Net Income Allocated to Shareholders $ 18,554 $ 14,609 $ 49,454 $ 43,299 Numerator for Earnings per Share—Diluted: Net income 18,635 14,660 $ 49,658 $ 43,414 Net Income Available to Shareholders $ 18,635 $ 14,660 $ 49,658 $ 43,414 Denominators for Earnings per Share: Weighted Average Shares Outstanding—Basic 34,660,007 29,693,417 33,527,549 29,679,623 Add: Potentially dilutive shares 32,985 21,195 33,980 25,732 Denominator for Treasury Stock Method—Diluted 34,692,992 29,714,612 33,561,529 29,705,355 Weighted Average Shares Outstanding—Basic 34,660,007 29,693,417 33,527,549 29,679,623 Add: Average participating shares outstanding 151,972 102,980 138,441 78,835 Denominator for Two-Class Method—Diluted 34,811,979 29,796,397 33,665,990 29,758,458 Earnings per share—basic $ 0.54 $ 0.49 $ 1.48 $ 1.46 Earnings per share—diluted $ 0.54 $ 0.49 $ 1.48 $ 1.46 Warrants considered anti-dilutive excluded from potentially dilutive shares - exercise price $31.53 per share, expires January 2019 517,012 517,012 517,012 517,012 Stock options considered anti-dilutive excluded from potentially dilutive shares 155,500 427,362 155,500 428,233 Restricted stock considered anti-dilutive excluded from potentially dilutive shares 118,987 81,785 104,461 53,103

Fair Value Measurement

Fair Value Measurement	9 Months Ended
	Sep. 30, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurements	We use fair value measurements when recording and disclosing certain financial assets and liabilities. Securities available-for-sale, trading assets and derivatives are recorded at fair value on a recurring basis. Additionally, from time to time, we may be required to record other assets at fair value on a nonrecurring basis, such as loans held for sale, impaired loans, other real estate owned, or OREO, mortgage servicing rights, or MSRs, and certain other assets. Fair value is the price that would be received to sell an asset or paid to transfer a liability in the principal or most advantageous market in an orderly transaction between market participants at the measurement date. An orderly transaction is a transaction that assumes exposure to the market for a period prior to the measurement date to allow for marketing activities that are usual and customary for transactions involving such assets or liabilities; it is not a forced transaction. In determining fair value, we use various valuation approaches, including market, income and cost approaches. The fair value standard establishes a hierarchy for inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that observable inputs be used when available. Observable inputs are inputs that market participants would use in pricing an asset or liability, which is developed, based on market data we have obtained from independent sources. Unobservable inputs reflect our estimate of assumptions that market participants would use in pricing an asset or liability, which are developed based on the best information available in the circumstances. The fair value hierarchy gives the highest priority to unadjusted quoted market prices in active markets for identical assets or liabilities (Level 1 measurement) and the lowest priority to unobservable inputs (Level 3 measurement). The fair value hierarchy is broken down into three levels based on the reliability of inputs as follows: Level 1: valuation is based upon unadjusted quoted market prices for identical instruments traded in active markets. Level 2: valuation is based upon quoted market prices for similar instruments traded in active markets, quoted market prices for identical or similar instruments traded in markets that are not active and model-based valuation techniques for which all significant assumptions are observable in the market or can be corroborated by market data. Level 3: valuation is derived from other valuation methodologies, including discounted cash flow models and similar techniques that use significant assumptions not observable in the market. These unobservable assumptions reflect estimates of assumptions that market participants would use in determining fair value. A financial instrument’s level within the fair value hierarchy is based on the lowest level of input that is significant to the fair value measurement. Our policy is to recognize transfers between any of the fair value hierarchy levels at the end of the reporting period in which the transfer occurred. The following are descriptions of the valuation methodologies that we use for financial instruments recorded at fair value on either a recurring or nonrecurring basis. Recurring Basis Securities Available-for-Sale Securities available-for-sale include both debt and marketable equity securities. We obtain fair values for debt securities from a third-party pricing service which utilizes several sources for valuing fixed-income securities. We validate prices received from our pricing service through comparison to a secondary pricing service and broker quotes. We review the methodologies of the pricing service which provides us with a sufficient understanding of the valuation models, assumptions, inputs and pricing to reasonably measure the fair value of our debt securities. The market valuation sources for debt securities include observable inputs rather than significant unobservable inputs and are classified as Level 2. The service provider utilizes pricing models that vary by asset class and include available trade, bid and other market information. Generally, the methodologies include broker quotes, proprietary models and vast descriptive terms and conditions databases, as well as extensive quality control programs. Marketable equity securities that have an active, quotable market are classified as Level 1. Marketable equity securities that are quotable, but are thinly traded or inactive, are classified as Level 2. Marketable equity securities that are not readily traded and do not have a quotable market are classified as Level 3. Trading Assets We use quoted market prices to determine the fair value of our trading assets. Our trading assets are held in a Rabbi Trust under a deferred compensation plan and are invested in readily quoted mutual funds. Accordingly, these assets are classified as Level 1. Derivative Financial Instruments We use derivative instruments including interest rate swaps for commercial loans with our customers, interest rate lock commitments and the sale of mortgage loans in the secondary market. We calculate the fair value for derivatives using widely accepted valuation techniques, including discounted cash flow analysis on the expected cash flows of each derivative. Each valuation considers the contractual terms of the derivative, including the period to maturity, and uses observable market based inputs, such as interest rate curves and implied volatilities. Accordingly, derivatives are classified as Level 2. We incorporate credit valuation adjustments into the valuation models to appropriately reflect both our own nonperformance risk and the respective counterparties' nonperformance risk in calculating fair value measurements. In adjusting the fair value of our derivative contracts for the effect of nonperformance risk, we have considered the impact of netting any applicable credit enhancements and collateral postings. Nonrecurring Basis Loans Held for Sale Loans held for sale consist of 1-4 family residential loans originated for sale in the secondary market and, from time to time, certain loans transferred from the loan portfolio to loans held for sale, all of which are carried at the lower of cost or fair value. The fair value of 1-4 family residential loans is based on the principal or most advantageous market currently offered for similar loans using observable market data. The fair value of the loans transferred from the loan portfolio is based on the amounts offered for these loans in currently pending sales transactions. Loans held for sale carried at fair value are classified as Level 3. Impaired Loans Impaired loans are carried at the lower of carrying value or fair value. Fair value is determined as the recorded investment balance less any specific reserve. We establish a specific reserve based on the following three impairment methods: 1) the present value of expected future cash flows discounted at the loan’s original effective interest rate, 2) the loan’s observable market price or 3) the fair value of the collateral less estimated selling costs when the loan is collateral dependent and we expect to liquidate the collateral. However, if repayment is expected to come from the operation of the collateral, rather than liquidation, then we do not consider estimated selling costs in determining the fair value of the collateral. Collateral values are generally based upon appraisals by approved, independent state certified appraisers. Appraisals may be discounted based on our historical knowledge, changes in market conditions from the time of appraisal or our knowledge of the borrower and the borrower’s business. Impaired loans carried at fair value are classified as Level 3. OREO and Other Repossessed Assets OREO and other repossessed assets obtained in partial or total satisfaction of a loan are recorded at the lower of recorded investment in the loan or fair value less cost to sell. Subsequent to foreclosure, these assets are carried at the lower of the amount recorded at acquisition date or fair value less cost to sell. Accordingly, it may be necessary to record nonrecurring fair value adjustments. Fair value, when recorded, is generally based upon appraisals by approved, independent state certified appraisers. Like impaired loans, appraisals on OREO may be discounted based on our historical knowledge, changes in market conditions from the time of appraisal or other information available to us. OREO and other repossessed assets carried at fair value are classified as Level 3. Mortgage Servicing Rights The fair value of MSRs is determined by calculating the present value of estimated future net servicing cash flows, considering expected mortgage loan prepayment rates, discount rates, servicing costs and other economic factors, which are determined based on current market conditions. The expected rate of mortgage loan prepayments is the most significant factor driving the value of MSRs. MSRs are considered impaired if the carrying value exceeds fair value. The valuation model includes significant unobservable inputs; therefore, MSRs are classified as Level 3. Financial Instruments In addition to financial instruments recorded at fair value in our financial statements, fair value accounting guidance requires disclosure of the fair value of all of an entity’s assets and liabilities that are considered financial instruments. The majority of our assets and liabilities are considered financial instruments. Many of these instruments lack an available trading market as characterized by a willing buyer and willing seller engaged in an exchange transaction. Also, it is our general practice and intent to hold our financial instruments to maturity and to not engage in trading or sales activities with respect to such financial instruments. For fair value disclosure purposes, we substantially utilize the fair value measurement criteria as required and explained above. In cases where quoted fair values are not available, we use present value methods to determine the fair value of our financial instruments. Cash and Cash Equivalents The carrying amounts reported in the Consolidated Balance Sheets for cash and due from banks, including interest-bearing deposits, approximate fair value. Loans The fair value of variable rate performing loans that may reprice frequently at short-term market rates is based on carrying values adjusted for credit risk. The fair value of variable rate performing loans that reprice at intervals of one year or longer, such as adjustable rate mortgage products, is estimated using discounted cash flow analyses that utilize interest rates currently being offered for similar loans and adjusted for credit risk. The fair value of fixed rate performing loans is estimated using a discounted cash flow analysis that utilizes interest rates currently being offered for similar loans and adjusted for credit risk. The fair value of impaired nonperforming loans is based on their carrying values less any specific reserve. The carrying amount of accrued interest approximates fair value. Bank Owned Life Insurance Fair value approximates net cash surrender value of bank owned life insurance. Federal Home Loan Bank, or FHLB, and Other Restricted Stock It is not practical to determine the fair value of our FHLB and other restricted stock due to the restrictions placed on the transferability of these stocks; therefore, it is presented at carrying value. Deposits The fair values disclosed for deposits without defined maturities (e.g., noninterest and interest-bearing demand, money market and savings accounts) are by definition equal to the amounts payable on demand. The carrying amounts for variable rate, fixed-term time deposits approximate their fair values. Estimated fair values for fixed rate and other time deposits are based on discounted cash flow analysis using interest rates currently offered for time deposits with similar terms. The carrying amount of accrued interest approximates fair value. Short-Term Borrowings The carrying amounts of securities sold under repurchase agreements and other short-term borrowings approximate their fair values. Long-Term Borrowings The fair values disclosed for fixed rate long-term borrowings are determined by discounting their contractual cash flows using current interest rates for long-term borrowings of similar remaining maturities. The carrying amounts of variable rate long-term borrowings approximate their fair values. Junior Subordinated Debt Securities The variable rate junior subordinated debt securities reprice quarterly; therefore, the fair values approximate the carrying values. Loan Commitments and Standby Letters of Credit Off-balance sheet financial instruments consist of commitments to extend credit and letters of credit. Except for interest rate lock commitments, estimates of the fair value of these off-balance sheet items are not made because of the short-term nature of these arrangements and the credit standing of the counterparties. Other Estimates of fair value are not made for items that are not defined as financial instruments, including such items as our core deposit intangibles and the value of our trust operations. The following tables present our assets and liabilities that are measured at fair value on a recurring basis by fair value hierarchy level at September 30, 2015 and December 31, 2014 . Due to limited trading volume, we transferred marketable equity securities with a fair value of $0.2 million from Level 1 to Level 2 during the nine month period ended September 30, 2015. There were no other transfers between Level 1 and Level 2 for items measured at fair value on a recurring basis during the periods presented. September 30, 2015 (dollars in thousands) Level 1 Level 2 Level 3 Total ASSETS Securities available-for-sale: U.S. Treasury securities $ — $ 15,062 $ — $ 15,062 Obligations of U.S. government corporations and agencies — 271,332 — 271,332 Collateralized mortgage obligations of U.S. government corporations and agencies — 135,216 — 135,216 Residential mortgage-backed securities of U.S. government corporations and agencies — 42,065 — 42,065 Commercial mortgage-backed securities of U.S. government corporations and agencies — 50,223 — 50,223 Obligations of states and political subdivisions — 137,335 — 137,335 Marketable equity securities — 8,813 — 8,813 Total securities available-for-sale — 660,046 — 660,046 Trading securities held in a Rabbi Trust 3,690 — — 3,690 Total securities 3,690 660,046 — 663,736 Derivative financial assets: Interest rate swaps — 14,232 — 14,232 Interest rate lock commitments — 574 — 574 Total Assets $ 3,690 $ 674,852 $ — $ 678,542 LIABILITIES Derivative financial liabilities: Interest rate swaps $ — $ 14,184 $ — $ 14,184 Forward sale contracts — 126 — 126 Total Liabilities $ — $ 14,310 $ — $ 14,310 December 31, 2014 (dollars in thousands) Level 1 Level 2 Level 3 Total ASSETS Securities available-for-sale: U.S. Treasury securities $ — $ 14,880 $ — $ 14,880 Obligations of U.S. government corporations and agencies — 269,285 — 269,285 Collateralized mortgage obligations of U.S. government corporations and agencies — 118,006 — 118,006 Residential mortgage-backed securities of U.S. government corporations and agencies — 46,668 — 46,668 Commercial mortgage-backed securities of U.S. government corporations and agencies — 39,673 — 39,673 Obligations of states and political subdivisions — 142,702 — 142,702 Marketable equity securities 178 8,881 — 9,059 Total securities available-for-sale 178 640,095 — 640,273 Trading securities held in a Rabbi Trust 3,456 — — 3,456 Total securities 3,634 640,095 — 643,729 Derivative financial assets: Interest rate swaps — 12,981 — 12,981 Interest rate lock commitments — 235 — 235 Total Assets $ 3,634 $ 653,311 $ — $ 656,945 LIABILITIES Derivative financial liabilities: Interest rate swaps $ — $ 12,953 $ — $ 12,953 Forward sale contracts — 57 — 57 Total Liabilities $ — $ 13,010 $ — $ 13,010 We classify financial instruments as Level 3 when valuation models are used because significant inputs are not observable in the market. We had no assets or liabilities measured at fair value on a recurring basis for which we have utilized Level 3 inputs to determine the fair value at either September 30, 2015 or December 31, 2014 . We may be required to measure certain assets and liabilities on a nonrecurring basis. Nonrecurring assets are recorded at the lower of cost or fair value in our financial statements. The following table presents our assets that were measured at fair value on a nonrecurring basis by the fair value hierarchy level at September 30, 2015 and December 31, 2014 . There were no liabilities measured at fair value on a nonrecurring basis during these periods. September 30, 2015 December 31, 2014 (dollars in thousands) Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total ASSETS (1) Loans held for sale $ — $ — $ 216 $ 216 $ — $ — $ — $ — Impaired loans — — 8,870 8,870 — — 12,916 12,916 Other real estate owned — — 439 439 — — 117 117 Mortgage servicing rights — — 1,827 1,827 — — 2,934 2,934 Total Assets $ — $ — $ 11,352 $ 11,352 $ — $ — $ 15,967 $ 15,967 (1) This table presents only the nonrecurring items that are recorded at fair value in our financial statements. The carrying values and fair values of our financial instruments at September 30, 2015 and December 31, 2014 are presented in the following tables: Carrying Value (1) Fair Value Measurements at September 30, 2015 (dollars in thousands) Total Level 1 Level 2 Level 3 ASSETS Cash and due from banks, including interest-bearing deposits $ 115,347 $ 115,347 $ 115,347 $ — $ — Securities available-for-sale 660,046 660,046 — 660,046 — Loans held for sale 13,794 14,134 — — 14,134 Portfolio loans, net of unearned income 4,925,963 4,902,661 — — 4,902,661 Bank owned life insurance 79,894 79,894 — 79,894 — FHLB and other restricted stock 20,352 20,352 — — 20,352 Trading securities held in a Rabbi Trust 3,690 3,690 3,690 — — Mortgage servicing rights 3,083 3,170 — — 3,170 Interest rate swaps 14,232 14,232 — 14,232 — Interest rate lock commitments 574 574 — 574 — LIABILITIES Deposits $ 4,877,409 $ 4,883,132 $ — $ — $ 4,883,132 Securities sold under repurchase agreements 42,971 42,971 — — 42,971 Short-term borrowings 280,000 280,000 — — 280,000 Long-term borrowings 117,613 118,646 — — 118,646 Junior subordinated debt securities 45,619 45,619 — — 45,619 Interest rate swaps 14,184 14,184 — 14,184 — Forward sale contracts 126 126 — 126 — (1) As reported in the Consolidated Balance Sheets Carrying Value (1) Fair Value Measurements at December 31, 2014 (dollars in thousands) Total Level 1 Level 2 Level 3 ASSETS Cash and due from banks, including interest-bearing deposits $ 109,580 $ 109,580 $ 109,580 $ — $ — Securities available-for-sale 640,273 640,273 178 640,095 — Loans held for sale 2,970 2,991 — — 2,991 Portfolio loans, net of unearned income 3,868,746 3,827,634 — — 3,827,634 Bank owned life insurance 62,252 62,252 — 62,252 — FHLB and other restricted stock 15,135 15,135 — — 15,135 Trading securities held in a Rabbi Trust 3,456 3,456 3,456 — — Mortgage servicing rights 2,817 2,934 — — 2,934 Interest rate swaps 12,981 12,981 — 12,981 — Interest rate lock commitments 235 235 — 235 — LIABILITIES Deposits $ 3,908,842 $ 3,910,342 $ — $ — $ 3,910,342 Securities sold under repurchase agreements 30,605 30,605 — — 30,605 Short-term borrowings 290,000 290,000 — — 290,000 Long-term borrowings 19,442 20,462 — — 20,462 Junior subordinated debt securities 45,619 45,619 — — 45,619 Interest rate swaps 12,953 12,953 — 12,953 — Forward sale contracts 57 57 — 57 — (1) As reported in the Consolidated Balance Sheets

Securities Available-for-Sale

Securities Available-for-Sale	9 Months Ended
	Sep. 30, 2015
Investments, Debt and Equity Securities [Abstract]
Securities Available-for-Sale	The following tables present the amortized cost and fair value of available-for-sale securities as of the dates presented: September 30, 2015 December 31, 2014 (dollars in thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value U.S. Treasury securities $ 14,903 $ 159 $ — $ 15,062 $ 14,873 $ 7 $ — $ 14,880 Obligations of U.S. government corporations and agencies 267,328 4,032 (28 ) 271,332 268,029 2,334 (1,078 ) 269,285 Collateralized mortgage obligations of U.S. government corporations and agencies 132,691 2,536 (11 ) 135,216 116,897 1,257 (148 ) 118,006 Residential mortgage-backed securities of U.S. government corporations and agencies 40,678 1,467 (80 ) 42,065 45,274 1,548 (154 ) 46,668 Commercial mortgage-backed securities of U.S. government corporations and agencies 49,596 669 (42 ) 50,223 39,834 232 (393 ) 39,673 Obligations of states and political subdivisions 132,139 5,249 (53 ) 137,335 136,977 5,789 (64 ) 142,702 Debt Securities 637,335 14,112 (214 ) 651,233 621,884 11,167 (1,837 ) 631,214 Marketable equity securities 7,579 1,234 — 8,813 7,579 1,480 — 9,059 Total $ 644,914 $ 15,346 $ (214 ) $ 660,046 $ 629,463 $ 12,647 $ (1,837 ) $ 640,273 Realized gains and losses on the sale of securities are determined using the specific-identification method. The following table shows the composition of gross and net realized gains and losses for the periods presented: Three Months Ended September 30, Nine Months Ended September 30, (dollars in thousands) 2015 2014 2015 2014 Gross realized gains $ — $ — $ — $ 41 Gross realized losses — — (34 ) — Net Realized Gains $ — $ — $ (34 ) $ 41 The following tables present the fair value and the age of gross unrealized losses by investment category as of the dates presented: September 30, 2015 Less Than 12 Months 12 Months or More Total (dollars in thousands) Number of Securities Fair Value Unrealized Number of Securities Fair Value Unrealized Number of Securities Fair Value Unrealized Obligations of U.S. government corporations and agencies — $ — $ — 2 $ 14,720 $ (28 ) 2 $ 14,720 $ (28 ) Collateralized mortgage obligations of U.S. government corporations and agencies 1 10,694 (11 ) — — — 1 10,694 (11 ) Residential mortgage-backed securities of U.S. government corporations and agencies 1 8,377 (80 ) — — — 1 8,377 (80 ) Commercial mortgage-backed securities of U.S. government corporations and agencies — — — 1 9,709 (42 ) 1 9,709 (42 ) Obligations of states and political subdivisions 2 10,666 (53 ) — — — 2 10,666 (53 ) Total Temporarily Impaired Securities 4 $ 29,737 $ (144 ) 3 $ 24,429 $ (70 ) 7 $ 54,166 $ (214 ) December 31, 2014 Less Than 12 Months 12 Months or More Total (dollars in thousands) Number of Securities Fair Value Unrealized Losses Number of Securities Fair Value Unrealized Losses Number of Securities Fair Value Unrealized Losses Obligations of U.S. government corporations and agencies 4 $ 39,745 $ (207 ) 8 $ 63,149 $ (871 ) 12 $ 102,894 $ (1,078 ) Collateralized mortgage obligations of U.S. government corporations and agencies 1 9,323 (148 ) — — — 1 9,323 (148 ) Residential mortgage-backed securities of U.S. government corporations and agencies — — — 1 8,982 (154 ) 1 8,982 (154 ) Commercial mortgage-backed securities of U.S. government corporations and agencies 1 9,998 (25 ) 2 20,640 (368 ) 3 30,638 (393 ) Obligations of states and political subdivisions 1 263 (1 ) 2 10,756 (63 ) 3 11,019 (64 ) Total Temporarily Impaired Securities 7 $ 59,329 $ (381 ) 13 $ 103,527 $ (1,456 ) 20 $ 162,856 $ (1,837 ) We do not believe any individual unrealized loss as of September 30, 2015 represents an other than temporary impairment. As of September 30, 2015 , the unrealized losses on 7 debt securities were attributable to changes in interest rates and not related to the credit quality of these securities. All debt securities are determined to be investment grade and are paying principal and interest according to the contractual terms of the security. There were no unrealized losses on marketable equity securities as of September 30, 2015 . We do not intend to sell and it is not more likely than not that we will be required to sell any of the securities, referenced in the table above, in an unrealized loss position before recovery of their amortized cost. The following table displays net unrealized gains and losses, net of tax on securities available for sale included in accumulated other comprehensive (loss)/income for the periods presented: September 30, 2015 December 31, 2014 (dollars in thousands) Gross Unrealized Gains Gross Unrealized Losses Net Unrealized Gains/ (Losses) Gross Unrealized Gains Gross Unrealized Losses Net Unrealized Gains/ (Losses) Total unrealized gains/(losses) on securities available-for-sale $ 15,346 $ (214 ) $ 15,132 $ 12,647 $ (1,837 ) $ 10,810 Income tax expense/(benefit) 5,371 (75 ) 5,296 4,426 (643 ) 3,783 Net unrealized gains/(losses), net of tax included in accumulated other comprehensive income/(loss) $ 9,975 $ (139 ) $ 9,836 $ 8,221 $ (1,194 ) $ 7,027 The amortized cost and fair value of securities available-for-sale at September 30, 2015 by contractual maturity are included in the table below. Actual maturities may differ from contractual maturities because issuers may have the right to call or prepay obligations with or without call or prepayment penalties. September 30, 2015 (dollars in thousands) Amortized Cost Fair Value Obligations of the U.S. Treasury, U.S. government corporations and agencies, and obligations of states and political subdivisions Due in one year or less $ 37,404 $ 37,767 Due after one year through five years 224,669 228,005 Due after five years through ten years 65,260 67,613 Due after ten years 87,037 90,344 414,370 423,729 Collateralized mortgage obligations of U.S. government corporations and agencies 132,691 135,216 Residential mortgage-backed securities of U.S. government corporations and agencies 40,678 42,065 Commercial mortgage-backed securities of U.S. government corporations and agencies 49,596 50,223 Debt Securities 637,335 651,233 Marketable equity securities 7,579 8,813 Total $ 644,914 $ 660,046 At September 30, 2015 and December 31, 2014 , securities with carrying values of $296.1 million and $289.1 million were pledged for various regulatory and legal requirements.

Loans and Loans Held for Sale

Loans and Loans Held for Sale	9 Months Ended
	Sep. 30, 2015
Receivables [Abstract]
Loans and Loans Held for Sale	Loans are presented net of unearned income of $2.7 million and $2.1 million at September 30, 2015 and December 31, 2014 and net of a discount related to purchase accounting fair value adjustments of $12.0 million and $2.0 million at September 30, 2015 and December 31, 2014. The following table indicates the composition of the loans as of the dates presented: (dollars in thousands) September 30, 2015 December 31, 2014 Commercial Commercial real estate $ 2,111,585 $ 1,682,236 Commercial and industrial 1,237,915 994,138 Commercial construction 384,328 216,148 Total Commercial Loans 3,733,828 2,892,522 Consumer Residential mortgage 625,251 489,586 Home equity 467,698 418,563 Installment and other consumer 91,122 65,567 Consumer construction 8,064 2,508 Total Consumer Loans 1,192,135 976,224 Total Portfolio Loans 4,925,963 3,868,746 Loans held for sale 13,794 2,970 Total Loans $ 4,939,757 $ 3,871,716 We attempt to limit our exposure to credit risk by diversifying our loan portfolio by segment, geography, collateral and industry and actively managing concentrations. When concentrations exist in certain segments, we mitigate this risk by monitoring the relevant economic indicators and internal risk rating trends and through stress testing of the loans in these segments. Total commercial loans represented 76 percent of total portfolio loans at September 30, 2015 and 75 percent of total portfolio loans at December 31, 2014 . Within our commercial portfolio, the CRE and commercial construction portfolios combined comprised $2.5 billion or 67 percent of total commercial loans and 51 percent of total portfolio loans at September 30, 2015 and 66 percent of total commercial loans and 49 percent of total portfolio loans at December 31, 2014 . Of the $2.5 billion of CRE and commercial construction loans, $424.0 million were added as a result of the Merger. Further segmentation of the CRE and commercial construction portfolios by industry and collateral type reveal no concentration in excess of 7.0 percent of total loans at September 30, 2015 and December 31, 2014 . Our market area includes Pennsylvania and the contiguous states of Ohio, West Virginia, New York and Maryland. The majority of our commercial and consumer loans are made to businesses and individuals in this market area resulting in a geographic concentration. We believe our knowledge and familiarity with customers and conditions locally outweighs this geographic concentration risk. The conditions of the local and regional economies are monitored closely through publicly available data as well as information supplied by our customers. Management believes underwriting guidelines, active monitoring of economic conditions and ongoing review by credit administration mitigates the concentration risk present in the loan portfolio. Our CRE and commercial construction portfolios had out-of-market exposure of 6.4 percent of the combined portfolio and 3.3 percent of total loans at September 30, 2015 and 8.0 percent of the combined portfolio and 3.9 percent of total loans at December 31, 2014 . Troubled debt restructurings, or TDRs, are loans where we, for economic or legal reasons related to a borrower’s financial difficulties, grant a concession to the borrower that we would not otherwise grant. We strive to identify borrowers in financial difficulty early and work with them to modify the terms before their loan reaches nonaccrual status. These modified terms generally include extensions of maturity dates at a stated interest rate lower than the current market rate for a new loan with similar risk characteristics, reductions in contractual interest rates or principal deferment. While unusual, there may be instances of principal forgiveness. These modifications are generally for longer term periods that would not be considered insignificant. Additionally, we classify loans where the debt obligation has been discharged through a Chapter 7 Bankruptcy and not reaffirmed as TDRs. We individually evaluate all substandard commercial loans that have experienced a forbearance or change in terms agreement, as well as all substandard consumer and residential mortgage loans that entered into an agreement to modify their existing loan to determine if they should be designated as TDRs. All TDRs are considered to be impaired loans and will be reported as impaired loans for the remaining life of the loan, unless the restructuring agreement specifies an interest rate equal to or greater than the rate that would be accepted at the time of the restructuring for a new loan with comparable risk and it is fully expected that the remaining principal and interest will be collected according to the restructured agreement. Further, all impaired loans are reported as nonaccrual loans unless the loan is a TDR that has met the requirements to be returned to accruing status. TDRs can be returned to accruing status if the ultimate collectability of all contractual amounts due, according to the restructured agreement, is not in doubt and there is a period of a minimum of six months of satisfactory payment performance by the borrower either immediately before or after the restructuring. The following table summarizes the restructured loans as of the dates presented: September 30, 2015 December 31, 2014 (dollars in thousands) Performing TDRs Nonperforming TDRs Total TDRs Performing TDRs Nonperforming TDRs Total TDRs Commercial real estate $ 8,062 $ 3,552 $ 11,614 $ 16,939 $ 2,180 $ 19,119 Commercial and industrial 6,360 1,839 8,199 8,074 356 8,430 Commercial construction 5,627 1,610 7,237 5,736 1,869 7,605 Residential mortgage 2,609 591 3,200 2,839 459 3,298 Home equity 3,363 412 3,775 3,342 562 3,904 Installment and other consumer 28 88 116 53 10 63 Total $ 26,049 $ 8,092 $ 34,141 $ 36,983 $ 5,436 $ 42,419 There were three TDRs that returned to accruing status totaling $0.2 million during the three months ended September 30, 2015 and nine TDRs that returned to accruing status totaling $0.5 million for the nine months ended September 30, 2015 . There were five TDRs for $0.5 million returned to accruing status during the three months ended September 30, 2014 and ten TDRs for $2.0 million were returned to accruing status during the nine months ended September 30, 2014. The following tables present the restructured loans during the periods presented: Three Months Ended September 30, 2015 Three Months Ended September 30, 2014 (dollars in thousands) Number of Loans Pre-Modification Outstanding Recorded Investment ( 1) Post-Modification Outstanding Recorded Investment (1) Total Difference in Recorded Investment Number of Loans Pre-Modification Outstanding Recorded Investment (1) Post-Modification Outstanding Recorded Investment (1) Total Difference in Recorded Investment Commercial real estate Principal deferral — $ — $ — $ — 1 $ 487 $ 475 $ (12 ) Chapter 7 bankruptcy (2) — — — — 1 83 83 — Maturity date extension 1 264 260 (4 ) — — — — Commercial and industrial Principal deferral — — — — 2 381 366 (15 ) Commercial Construction Maturity date extension 2 813 812 (1 ) — — — — Residential mortgage Chapter 7 bankruptcy (2) 2 74 74 — 2 135 134 (1 ) Maturity date extension 1 180 180 — — — — — Home equity Chapter 7 bankruptcy (2) 5 115 110 (5 ) 2 14 14 — Maturity date extension and interest rate reduction 2 138 138 — 2 96 96 — Installment and other consumer Chapter 7 bankruptcy (2) 1 9 4 $ (5 ) 2 14 11 $ (3 ) Total by Concession Type Principal deferral — — — — 3 868 841 (27 ) Maturity date extension and interest rate reduction 2 138 138 — 2 96 96 — Chapter 7 bankruptcy (2) 8 198 188 (10 ) 7 246 242 (4 ) Maturity date extension 4 1,257 1,252 (5 ) — — — — Total 14 $ 1,593 $ 1,578 $ (15 ) 12 $ 1,210 $ 1,179 $ (31 ) (1) Excludes loans that were fully paid off or fully charged-off by period end. The pre-modification balance represents the balance outstanding prior to modification. The post-modification balance represents the outstanding balance at period end. (2) Chapter 7 bankruptcy loans where the debt has been legally discharged through the bankruptcy court and not reaffirmed. Nine Months Ended September 30, 2015 Nine Months Ended September 30, 2014 (dollars in thousands) Number of Pre-Modification (1) Post-Modification (1) Total Difference Number of Pre-Modification ( 1) Post-Modification (1) Total Difference Commercial real estate Principal deferral 2 $ 2,851 $ 1,841 $ (1,010 ) 2 $ 616 $ 602 $ (14 ) Chapter 7 bankruptcy (2) — — — — 1 83 83 — Maturity date extension 1 264 260 (4 ) — — — — Commercial and industrial Principal forgiveness 1 400 273 (127 ) — — — — Principal deferral 6 661 363 (298 ) 2 381 366 (15 ) Chapter 7 bankruptcy (2) 1 3 — (3 ) 1 287 286 (1 ) Maturity date extension 1 780 720 (60 ) — — — — Commercial Construction Principal deferral 1 104 — (104 ) — — — — Maturity date extension 2 813 812 (1 ) 1 1,019 1,019 — Residential mortgage Chapter 7 bankruptcy (2) 2 74 74 — 7 464 461 (3 ) Maturity date extension 1 180 180 — — — — — Maturity date extension and interest rate reduction 2 225 229 4 — — — — Home equity Chapter 7 bankruptcy (2) 17 428 389 (39 ) 12 283 265 (18 ) Maturity date extension and interest rate reduction 2 138 138 — 2 96 96 — Maturity date extension 1 71 70 (1 ) — — — — Installment and other consumer Chapter 7 bankruptcy (2) 1 9 4 $ (5 ) 3 23 20 $ (3 ) Total by Concession Type Principal forgiveness 1 $ 400 $ 273 $ (127 ) — $ — $ — $ — Principal deferral 9 3,616 2,204 (1,412 ) 4 997 968 (29 ) Chapter 7 bankruptcy (2) 21 514 467 (47 ) 24 1,140 1,115 (25 ) Maturity date extension and interest rate reduction 4 363 367 4 2 96 96 — Maturity date extension 6 2,108 2,042 (66 ) 1 1,019 1,019 — Total 41 7,001 5,353 $ (1,648 ) 31 $ 3,252 $ 3,198 $ (54 ) (1) Excludes loans that were fully paid off or fully charged-off by period end. The pre-modification balance represents the balance outstanding prior to modification. The post-modification balance represents the outstanding balance at period end. (2) Chapter 7 bankruptcy loans where the debt has been legally discharged through the bankruptcy court and not reaffirmed. For the three months ended September 30, 2015 , we modified two C&I loans totaling $1.1 million , 11 commercial construction loans totaling $7.1 million , three CRE loans totaling $4.3 million , one home equity loan totaling $0.1 million and one residential real estate loan totaling $0.1 million that were not considered to be TDRs. For the nine months ended September 30, 2015 we modified eight C&I loans totaling $6.8 million , 13 commercial construction loans totaling $8.4 million , six CRE loans totaling $5.3 million , three home equity loans totaling $0.3 million and one residential real estate loan totaling $0.1 million that were not considered to be TDRs. The modifications primarily represented instances where we were adequately compensated through additional collateral or a higher interest rate or there was an insignificant delay in payment of three months or less. As of September 30, 2015 we have no commitments to lend additional funds on any TDRs. Defaulted TDRs are defined as loans having a payment default of 90 days or more after the restructuring takes place. The following tables present a summary of TDRs which defaulted during the periods presented that had been restructured within the last 12 months prior to defaulting: Defaulted TDRs Three Months Ended Three Months Ended (dollars in thousands) Number of Defaults Recorded Investment Number of Defaults Recorded Investment Commercial real estate — $ — — $ — Commercial and Industrial — — — — Commercial construction — — — — Residential mortgage — — — — Home equity — $ — — $ — Installment and other consumer — — — — Consumer construction — — — — Total — $ — — $ — Defaulted TDRs Nine Months Ended Nine Months Ended (dollars in thousands) Number of Defaults Recorded Investment Number of Defaults Recorded Investment Commercial real estate — $ — — $ — Commercial and Industrial — — — — Commercial construction — — — — Residential mortgage 1 $ 183 1 $ 72 Home equity 3 124 — — Installment and other consumer — — — — Consumer construction — — — — Total 4 $ 307 1 $ 72 The following table is a summary of nonperforming assets as of the dates presented: Nonperforming Assets (dollars in thousands) September 30, 2015 December 31, 2014 Nonperforming Assets Nonaccrual loans $ 15,716 $ 7,021 Nonaccrual TDRs 8,092 5,436 Total nonaccrual loans 23,808 12,457 OREO 472 166 Total Nonperforming Assets $ 24,280 $ 12,623

Allowance for Loan Losses

Allowance for Loan Losses	9 Months Ended
	Sep. 30, 2015
Receivables [Abstract]
Allowance for Loan Losses	We maintain an allowance for loan losses, or ALL, at a level determined to be adequate to absorb estimated probable credit losses inherent in the loan portfolio as of the balance sheet date. We develop and document a systematic ALL methodology based on the following portfolio segments: 1) CRE, 2) C&I, 3) Commercial Construction, 4) Consumer Real Estate and 5) Other Consumer. The following are key risks within each portfolio segment: CRE —Loans secured by commercial purpose real estate, including both owner occupied properties and investment properties, for various purposes such as hotels, strip malls and apartments. Operations of the individual projects as well as global cash flows of the debtors are the primary sources of repayment for these loans. The condition of the local economy is an important indicator of risk, but there are also more specific risks depending on the collateral type as well as the business prospects of the lessee, if the project is not owner occupied. C&I —Loans made to operating companies or manufacturers for the purpose of production, operating capacity, accounts receivable, inventory or equipment financing. Cash flow from the operations of the company is the primary source of repayment for these loans. The condition of the local economy is an important indicator of risk, but there are also more specific risks depending on the industry of the company. Collateral for these types of loans often do not have sufficient value in a distressed or liquidation scenario to satisfy the outstanding debt. Commercial Construction —Loans made to finance construction of buildings or other structures, as well as to finance the acquisition and development of raw land for various purposes. While the risk of these loans is generally confined to the construction period, if there are problems, the project may not be complete, and as such, may not provide sufficient cash flow on its own to service the debt or have sufficient value in a liquidation to cover the outstanding principal. The condition of the local economy is an important indicator of risk, but there are also more specific risks depending on the type of project and the experience and resources of the developer. Consumer Real Estate —Loans secured by first and second liens such as home equity loans, home equity lines of credit and 1-4 family residences, including purchase money mortgages. The primary source of repayment for these loans is the income and assets of the borrower. The condition of the local economy, in particular the unemployment rate, is an important indicator of risk for this segment. The state of the local housing market can also have a significant impact on this segment because low demand and/or declining home values can limit the ability of borrowers to sell a property and satisfy the debt. Other Consumer —Loans made to individuals that may be secured by assets other than 1-4 family residences, as well as unsecured loans. This segment includes auto loans, unsecured loans and lines and credit cards. The primary source of repayment for these loans is the income and assets of the borrower. The condition of the local economy, in particular the unemployment rate, is an important indicator of risk for this segment. The value of the collateral, if there is any, is less likely to be a source of repayment due to less certain collateral values. We further assess risk within each portfolio segment by pooling loans with similar risk characteristics. For the commercial loan classes, the most important indicator of risk is the internally assigned risk rating, including pass, special mention and substandard. Consumer loans are pooled by type of collateral, lien position and loan to value, or LTV, ratio for Consumer Real Estate loans. Historical loss rates are applied to these loan pools to determine the reserve for loans collectively evaluated for impairment. The ALL methodology for groups of loans collectively evaluated for impairment is comprised of both a quantitative and qualitative analysis. A key assumption in the quantitative component of the reserve is the loss emergence period, or LEP. The LEP is an estimate of the average amount of time from the point at which a loss is incurred on a loan to the point at which the loss is confirmed. In general, the LEP will be shorter in an economic slowdown or recession and longer during times of economic stability or growth, as customers are better able to delay loss confirmation after a potential loss event has occurred. Another key assumption is the look-back period, or LBP, which represents the historical data period utilized to calculate loss rates. Management monitors various credit quality indicators for both the commercial and consumer loan portfolios, including delinquency, nonperforming status and changes in risk ratings on a monthly basis. The following tables present the age analysis of past due loans segregated by class of loans as of September 30, 2015 and December 31, 2014 : September 30, 2015 (dollars in thousands) Current 30-59 Days Past Due 60-89 Days Past Due 90 Days Past Due (1) Nonaccrual Total Past Due Total Loans Commercial real estate $ 2,092,139 $ 8,987 $ 1,567 $ 973 $ 7,919 $ 19,446 $ 2,111,585 Commercial and industrial 1,228,571 2,183 1,791 — 5,370 9,344 1,237,915 Commercial construction 374,001 3,955 1,364 — 5,008 10,327 384,328 Residential mortgage 614,609 3,563 3,281 556 3,242 10,642 625,251 Home equity 463,145 2,144 262 — 2,147 4,553 467,698 Installment and other consumer 90,624 344 32 — 122 498 91,122 Consumer construction 8,064 — — — — — 8,064 Loans held for sale 13,794 — — — — — 13,794 Totals $ 4,884,947 $ 21,176 $ 8,297 $ 1,529 $ 23,808 $ 54,810 $ 4,939,757 (1) Represents acquired loans that were recorded at fair value at the acquisition date. December 31, 2014 (dollars in thousands) Current 30-59 Days Past Due 60-89 Days Past Due 90 Days Past Due Nonaccrual Total Past Due Total Loans Commercial real estate $ 1,674,930 $ 2,548 $ 323 $ — $ 4,435 $ 7,306 $ 1,682,236 Commercial and industrial 991,136 1,227 153 — 1,622 3,002 994,138 Commercial construction 214,174 — — — 1,974 1,974 216,148 Residential mortgage 485,465 565 1,220 — 2,336 4,121 489,586 Home equity 414,303 1,756 445 — 2,059 4,260 418,563 Installment and other consumer 65,111 352 73 — 31 456 65,567 Consumer construction 2,508 — — — — — 2,508 Loans held for sale 2,970 — — — — — 2,970 Totals $ 3,850,597 $ 6,448 $ 2,214 $ — $ 12,457 $ 21,119 $ 3,871,716 We continually monitor the commercial loan portfolio through an internal risk rating system. Loan risk ratings are assigned based upon the creditworthiness of the borrower and are reviewed on an ongoing basis according to our internal policies. Loans within the pass rating generally have a lower risk of loss than loans risk rated as special mention or substandard. Our risk ratings are consistent with regulatory guidance and are as follows: Pass —The loan is currently performing and is of high quality. Special Mention —A special mention loan has potential weaknesses that warrant management’s close attention. If left uncorrected, these potential weaknesses may result in deterioration of the repayment prospects or in the strength of our credit position at some future date. Economic and market conditions, beyond the borrower’s control, may in the future necessitate this classification. Substandard —A substandard loan is not adequately protected by the net worth and/or paying capacity of the borrower or by the collateral pledged, if any. Substandard loans have a well-defined weakness or weaknesses that jeopardize the liquidation of the debt. These loans are characterized by the distinct possibility that we will sustain some loss if the deficiencies are not corrected. The following tables present the recorded investment in commercial loan classes by internally assigned risk ratings as of the dates presented: September 30, 2015 (dollars in thousands) Commercial Real Estate % of Total Commercial and Industrial % of Total Commercial Construction % of Total Total % of Total Pass $ 2,036,905 96.5 % $ 1,169,828 94.5 % $ 344,513 89.6 % $ 3,551,246 95.1 % Special mention 32,371 1.5 % 45,750 3.7 % 18,771 4.9 % 96,892 2.6 % Substandard 42,309 2.0 % 22,337 1.8 % 21,044 5.5 % 85,690 2.3 % Total $ 2,111,585 100 % $ 1,237,915 100.0 % $ 384,328 100.0 % $ 3,733,828 100.0 % December 31, 2014 (dollars in thousands) Commercial Real Estate % of Total Commercial and Industrial % of Total Commercial Construction % of Total Total % of Total Pass $ 1,635,132 97.2 % $ 948,663 95.4 % $ 196,520 90.9 % $ 2,780,315 96.1 % Special mention 23,597 1.4 % 30,357 3.1 % 12,014 5.6 % 65,968 2.3 % Substandard 23,507 1.4 % 15,118 1.5 % 7,614 3.5 % 46,239 1.6 % Total $ 1,682,236 100.0 % $ 994,138 100.0 % $ 216,148 100.0 % $ 2,892,522 100.0 % We monitor the delinquent status of the consumer portfolio on a monthly basis. Loans are considered nonperforming when interest and principal are 90 days or more past due or management has determined that a material deterioration in the borrower’s financial condition exists. The risk of loss is generally highest for nonperforming loans. The following tables present the recorded investment in consumer loan classes by performing and nonperforming status as of the dates presented: September 30, 2015 (dollars in thousands) Residential Mortgage % of Total Home Equity % of Total Installment and other consumer % of Total Consumer Construction % of Total Total % of Total Performing $ 622,009 99.5 % $ 465,551 99.5 % $ 91,000 99.9 % $ 8,064 100.0 % $ 1,186,624 99.5 % Nonperforming 3,242 0.5 % 2,147 0.5 % 122 0.1 % — — % 5,511 0.5 % Total $ 625,251 100.0 % $ 467,698 100.0 % $ 91,122 100.0 % $ 8,064 100.0 % $ 1,192,135 100.0 % December 31, 2014 (dollars in thousands) Residential Mortgage % of Total Home Equity % of Total Installment and other consumer % of Total Consumer Construction % of Total Total % of Total Performing $ 487,250 99.5 % $ 416,504 99.5 % $ 65,536 99.9 % $ 2,508 100.0 % $ 971,798 99.5 % Nonperforming 2,336 0.5 % 2,059 0.5 % 31 0.1 % — — % 4,426 0.5 % Total $ 489,586 100.0 % $ 418,563 100.0 % $ 65,567 100.0 % $ 2,508 100.0 % $ 976,224 100.0 % We individually evaluate all substandard and nonaccrual commercial loans greater than $0.5 million for impairment. Loans are considered to be impaired when based upon current information and events it is probable that we will be unable to collect all principal and interest payments due according to the original contractual terms of the loan agreement. All TDRs will be reported as an impaired loan for the remaining life of the loan, unless the restructuring agreement specifies an interest rate equal to or greater than the rate that would be accepted at the time of the restructuring for a new loan with comparable risk and it is expected that the remaining principal and interest will be fully collected according to the restructured agreement. For all TDRs, regardless of size, as well as all other impaired loans, we conduct further analysis to determine the probable loss and assign a specific reserve to the loan if deemed appropriate. The following tables summarize investments in loans considered to be impaired and the related information on those impaired loans as of the dates presented: September 30, 2015 December 31, 2014 (dollars in thousands) Recorded Investment Unpaid Principal Balance Related Allowance Recorded Investment Unpaid Principal Balance Related Allowance Without a related allowance recorded: Commercial real estate $ 14,080 $ 14,576 $ — $ 19,890 $ 25,262 $ — Commercial and industrial 8,746 10,918 — 9,218 9,449 — Commercial construction 9,315 12,977 — 7,605 11,293 — Consumer real estate 6,852 7,401 — 7,159 7,733 — Other consumer 119 191 — 42 48 — Total without a Related Allowance Recorded 39,112 46,063 — 43,914 53,785 — With a related allowance recorded: Commercial real estate — — — — — — Commercial and industrial 1,969 1,969 1,224 — — — Commercial construction — — — — — — Consumer real estate 118 118 34 43 43 43 Other consumer 2 2 2 20 20 11 Total with a Related Allowance Recorded 2,089 2,089 1,260 63 63 54 Total: Commercial real estate 14,080 14,576 — 19,890 25,262 — Commercial and industrial 10,715 12,887 1,224 9,218 9,449 — Commercial construction 9,315 12,977 — 7,605 11,293 — Consumer real estate 6,970 7,519 34 7,202 7,776 43 Other consumer 121 193 2 62 68 11 Total $ 41,201 $ 48,152 $ 1,260 $ 43,977 $ 53,848 $ 54 The following tables summarize investments in loans considered to be impaired and related information on those impaired loans for the periods presented: Three Months Ended September 30, 2015 September 30, 2014 (dollars in thousands) Average Recorded Investment Interest Income Recognized Average Recorded Investment Interest Income Recognized Without a related allowance recorded: Commercial real estate $ 14,101 $ 352 $ 21,110 $ 159 Commercial and industrial 8,993 44 9,702 63 Commercial construction 11,034 67 8,160 58 Consumer real estate 6,829 92 7,034 100 Other consumer 183 — 115 1 Total without a Related Allowance Recorded 41,140 555 46,121 381 With a related allowance recorded: Commercial real estate — — — — Commercial and industrial 1,977 7 — — Commercial construction — — — — Consumer real estate 119 2 47 1 Other consumer 2 — 23 — Total with a Related Allowance Recorded 2,098 9 70 1 Total: Commercial real estate 14,101 352 21,110 159 Commercial and industrial 10,970 51 9,702 63 Commercial construction 11,034 67 8,160 58 Consumer real estate 6,948 94 7,081 101 Other consumer 185 — 138 1 Total $ 43,238 $ 564 $ 46,191 $ 382 Nine Months Ended September 30, 2015 September 30, 2014 (dollars in thousands) Average Recorded Investment Interest Income Recognized Average Recorded Investment Interest Income Recognized Without a related allowance recorded: Commercial real estate $ 14,994 $ 731 $ 21,593 $ 512 Commercial and industrial 9,742 131 9,477 177 Commercial construction 8,920 200 8,254 172 Consumer real estate 6,856 279 7,181 306 Other consumer 119 1 122 3 Total without a Related Allowance Recorded 40,631 1,342 46,627 1,170 With a related allowance recorded: Commercial real estate $ — $ — $ — $ — Commercial and industrial 1,980 42 — — Commercial construction — — — — Consumer real estate 121 5 49 2 Other consumer 2 — 24 2 Total with a Related Allowance Recorded 2,103 47 73 4 Total: Commercial real estate 14,994 731 21,593 512 Commercial and industrial 11,722 173 9,477 177 Commercial construction 8,920 200 8,254 172 Consumer real estate 6,977 284 7,230 308 Other consumer 121 1 146 5 Total $ 42,734 $ 1,389 $ 46,700 $ 1,174 The following tables detail activity in the ALL for the periods presented: Three Months Ended September 30, 2015 (dollars in thousands) Commercial Real Estate Commercial and Industrial Commercial Construction Consumer Real Estate Other Consumer Total Loans Balance at beginning of period $ 19,018 $ 13,308 $ 7,671 $ 7,027 $ 1,790 $ 48,814 Charge-offs (2,361 ) (1,121 ) (1,247 ) (445 ) (467 ) (5,641 ) Recoveries 2,896 272 129 132 99 3,528 Net (Charge-offs)/ Recoveries 535 (849 ) (1,118 ) (313 ) (368 ) (2,113 ) Provision for loan losses (2,575 ) 12 4,983 302 484 3,206 Balance at End of Period $ 16,978 $ 12,471 $ 11,536 $ 7,016 $ 1,906 $ 49,907 Three Months Ended September 30, 2014 (dollars in thousands) Commercial Real Estate Commercial and Industrial Commercial Construction Consumer Real Estate Other Consumer Total Loans Balance at beginning of period $ 20,733 $ 13,004 $ 4,759 $ 6,705 $ 1,379 $ 46,580 Charge-offs — (37 ) (234 ) (436 ) (295 ) (1,002 ) Recoveries (154 ) 315 — 48 75 284 Net (Charge-offs)/ Recoveries (154 ) 278 (234 ) (388 ) (220 ) (718 ) Provision for loan losses (602 ) 616 653 446 341 1,454 Balance at End of Period $ 19,977 $ 13,898 $ 5,178 $ 6,763 $ 1,500 $ 47,316 Nine Months Ended September 30, 2015 (dollars in thousands) Commercial Real Estate Commercial and Industrial Commercial Construction Consumer Real Estate Other Consumer Total Loans Balance at beginning of period $ 20,164 $ 13,668 $ 6,093 $ 6,333 $ 1,653 $ 47,911 Charge-offs (2,738 ) (2,819 ) (1,247 ) (997 ) (1,046 ) (8,847 ) Recoveries 3,072 475 132 379 312 4,370 Net (Charge-offs)/Recoveries 334 (2,344 ) (1,115 ) (618 ) (734 ) (4,477 ) Provision for loan losses (3,520 ) 1,147 6,558 1,301 987 6,473 Balance at End of Period $ 16,978 $ 12,471 $ 11,536 $ 7,016 $ 1,906 $ 49,907 Nine Months Ended September 30, 2014 (dollars in thousands) Commercial Real Estate Commercial and Industrial Commercial Construction Consumer Real Estate Other Consumer Total Loans Balance at beginning of period $ 18,921 $ 14,433 $ 5,374 $ 6,362 $ 1,165 $ 46,255 Charge-offs (2,002 ) (1,070 ) (693 ) (983 ) (740 ) (5,488 ) Recoveries 1,681 3,564 140 272 284 5,941 Net (Charge-offs)/Recoveries (321 ) 2,494 (553 ) (711 ) (456 ) 453 Provision for loan losses 1,377 (3,029 ) 357 1,112 791 608 Balance at End of Period $ 19,977 $ 13,898 $ 5,178 $ 6,763 $ 1,500 $ 47,316 The following tables present the ALL and recorded investments in loans by category as of the periods presented: September 30, 2015 Allowance for Loan Losses Portfolio Loans (dollars in thousands) Individually Evaluated for Impairment Collectively Evaluated for Impairment Total Individually Evaluated for Impairment Collectively Evaluated for Impairment Total (1) Commercial real estate $ — $ 16,978 $ 16,978 $ 14,080 $ 2,097,505 $ 2,111,585 Commercial and industrial 1,224 11,247 12,471 10,715 1,227,200 1,237,915 Commercial construction — 11,536 11,536 9,315 375,013 384,328 Consumer real estate 34 6,982 7,016 6,970 1,094,043 1,101,013 Other consumer 2 1,904 1,906 121 91,001 91,122 Total $ 1,260 $ 48,647 $ 49,907 $ 41,201 $ 4,884,762 $ 4,925,963 (1) Includes acquired loans. December 31, 2014 Allowance for Loan Losses Portfolio Loans (dollars in thousands) Individually Evaluated for Impairment Collectively Evaluated for Impairment Total Individually Evaluated for Impairment Collectively Evaluated for Impairment Total (1) Commercial real estate $ — $ 20,164 $ 20,164 $ 19,890 $ 1,662,346 $ 1,682,236 Commercial and industrial — 13,668 13,668 9,218 984,920 994,138 Commercial construction — 6,093 6,093 7,605 208,543 216,148 Consumer real estate 43 6,290 6,333 7,202 903,455 910,657 Other consumer 11 1,642 1,653 62 65,505 65,567 Total $ 54 $ 47,857 $ 47,911 $ 43,977 $ 3,824,769 $ 3,868,746 (1) Includes acquired loans. Acquired loans are recorded at fair value with no carryover of the ALL. Credit deterioration on acquired loans incurred subsequent to the acquisition date was recognized in the ALL through the provision.

Derivative Instruments and Hedg

Derivative Instruments and Hedging Activities	9 Months Ended
	Sep. 30, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments and Hedging Activities	Interest Rate Swaps In accordance with applicable accounting guidance for derivatives and hedging, all derivatives are recognized as either assets or liabilities on the balance sheet at fair value. Interest rate swaps are contracts in which a series of interest rate flows (fixed and variable) are exchanged over a prescribed period. The notional amounts on which the interest payments are based are not exchanged. These derivative positions relate to transactions in which we enter into an interest rate swap with a commercial customer while at the same time entering into an offsetting interest rate swap with another financial institution. In connection with each transaction, we agree to pay interest to the customer on a notional amount at a variable interest rate and receive interest from the customer on the same notional amount at a fixed rate. At the same time, we agree to pay another financial institution the same fixed interest rate on the same notional amount and receive the same variable interest rate on the same notional amount. The transaction allows our customer to effectively convert a variable rate loan to a fixed rate loan with us receiving a variable rate. These agreements could have floors or caps on the contracted interest rates. Pursuant to our agreements with various financial institutions, we may receive collateral or may be required to post collateral based upon mark-to-market positions. Beyond unsecured threshold levels, collateral in the form of cash or securities may be made available to counterparties of interest rate swap transactions. Based upon our current positions and related future collateral requirements relating to them, we believe any effect on our cash flow or liquidity position to be immaterial. Derivatives contain an element of credit risk, including the possibility that we will incur a loss because a counterparty, which may be a financial institution or a customer, fails to meet its contractual obligations. All derivative contracts with financial institutions may be executed only with counterparties approved by our Asset and Liability Committee and derivatives with customers may only be executed with customers within credit exposure limits approved by our Senior Loan Committee. Interest rate swaps are considered derivatives, but are not accounted for using hedge accounting. As such, changes in the estimated fair value of the derivatives are recorded in current earnings and included in other noninterest income in the Consolidated Statements of Comprehensive Income. Interest Rate Lock Commitments and Forward Sale Contracts In the normal course of business, we sell originated mortgage loans into the secondary mortgage loan market. We also offer interest rate lock commitments to potential borrowers. The commitments are generally for 60 days and guarantee a specified interest rate for a loan if underwriting standards are met, but the commitment does not obligate the potential borrower to close on the loan. Accordingly, some commitments expire prior to becoming loans. We may encounter pricing risks if interest rates increase significantly before the loan can be closed and sold. We may utilize forward sale contracts in order to mitigate this pricing risk. Whenever a customer desires these products, a mortgage originator quotes a secondary market rate guaranteed for that day by the investor. The rate lock is executed between the mortgagee and us and in turn a forward sale contract may be executed between us and the investor. Both the interest rate lock commitment and the corresponding forward sale contract for each customer are considered derivatives, but are not accounted for using hedge accounting. As such, changes in the estimated fair value of the derivatives during the commitment period are recorded in current earnings and included in mortgage banking in the Consolidated Statements of Comprehensive Income. The following table indicates the amounts representing the value of derivative assets and derivative liabilities as of the dates presented: Derivatives (included in Other Assets) Derivatives (included in Other Liabilities) (dollars in thousands) September 30, 2015 December 31, 2014 September 30, 2015 December 31, 2014 Derivatives not Designated as Hedging Instruments: Interest Rate Swap Contracts- Commercial Loans Fair value $ 14,232 $ 12,981 $ 14,184 $ 12,953 Notional amount 239,277 245,152 239,277 245,152 Collateral posted — — 12,548 12,059 Interest Rate Lock Commitments- Mortgage Loans Fair value 574 235 — — Notional amount 16,969 8,822 — — Forward Sale Contracts- Mortgage Loans Fair value — — 126 57 Notional amount $ — $ — $ 14,320 $ 7,789 Presenting offsetting derivatives that are subject to legally enforceable netting arrangements with the same party is permitted. For example, we may have a derivative asset as well as a derivative liability with the same counterparty to a swap transaction and are permitted to offset the asset position and the liability position resulting in a net presentation. The following table indicates the gross amounts of commercial loan swap derivative assets and derivative liabilities, the amounts offset and the carrying values in the Consolidated Balance Sheets as of the dates presented: Derivatives (included in Other Assets) Derivatives (included in Other Liabilities) (dollars in thousands) September 30, 2015 December 31, 2014 September 30, 2015 December 31, 2014 Derivatives not Designated as Hedging Instruments: Gross amounts recognized $ 14,232 $ 13,203 $ 14,184 $ 13,175 Gross amounts offset — (222 ) — (222 ) Net amounts presented in the Consolidated Balance Sheets 14,232 12,981 14,184 12,953 Gross amounts not offset (1) — — (12,548 ) (12,059 ) Net Amount $ 14,232 $ 12,981 $ 1,636 $ 894 (1) Amounts represent posted collateral. The following table indicates the gain or loss recognized in income on derivatives for the periods presented: Three Months Ended September 30, Nine Months Ended September 30, (dollars in thousands) 2015 2014 2015 2014 Derivatives not Designated as Hedging Instruments Interest rate swap contracts—commercial loans $ 29 $ (10 ) $ 20 $ (29 ) Interest rate lock commitments—mortgage loans 208 (105 ) 339 102 Forward sale contracts—mortgage loans (143 ) 49 (69 ) (43 ) Total Derivatives Gain (Loss) $ 94 $ (66 ) $ 290 $ 30

Borrowings

Borrowings	9 Months Ended
	Sep. 30, 2015
Debt Disclosure [Abstract]
Borrowings	Short-term borrowings are for terms under one year and were comprised of retail repurchase agreements, or REPOs, and FHLB advances. FHLB advances are for various terms and are secured by a blanket lien on residential mortgages and other real estate secured loans. All REPOs are overnight short-term investments and are not insured by the Federal Deposit Insurance Corporation. Securities pledged as collateral under these REPO financing arrangements cannot be sold or repledged by the secured party and are therefore accounted for as a secured borrowing. Mortgage backed securities with a total carrying value of $46.2 million at September 30, 2015 and $35.6 million at December 31, 2014 were pledged as collateral for these secured transactions. The pledged securities are held in safekeeping at the Federal Reserve. Due to the overnight short-term nature of REPOs, potential risk due to a decline in the value of the pledged collateral is low. Collateral pledging requirements with REPOs are monitored daily. Long-term borrowings are for original terms greater than or equal to one year and were comprised of FHLB advances, a capital lease and junior subordinated debt securities. Long-term FHLB advances are secured by the same loans as short-term FHLB advances. We had total long-term borrowings outstanding of $14.4 million at a fixed rate and $148.9 million at a variable rate at September 30, 2015 , excluding our capital lease of $0.2 million . On March 5, 2015, we paid off $8.5 million and on June 18, 2015, we paid off the remaining $5.0 million of the $13.5 million junior subordinated debt assumed in the Merger. Information pertaining to borrowings is summarized in the table below as of the dates presented: September 30, 2015 December 31, 2014 (dollars in thousands) Balance Weighted Average Rate Balance Weighted Average Rate Short-term borrowings Securities sold under repurchase agreements $ 42,971 0.01 % $ 30,605 0.01 % Short-term borrowings 280,000 0.37 % 290,000 0.31 % Total short-term borrowings 322,971 0.32 % 320,605 0.27 % Long-term borrowings Other long-term borrowings 117,613 0.76 % 19,442 3.00 % Junior subordinated debt securities 45,619 2.80 % 45,619 2.70 % Total long-term borrowings 163,232 1.33 % 65,061 2.79 % Total Borrowings $ 486,203 0.66 % $ 385,666 0.70 % We had total borrowings at September 30, 2015 and December 31, 2014 at the FHLB of Pittsburgh of $397.5 million and $309.3 million . The $397.5 million at September 30, 2015 consisted of $280.0 million in short-term borrowings and $117.6 million in long-term borrowings. Our maximum borrowing capacity with the FHLB of Pittsburgh was $1.9 billion at September 30, 2015 . Our remaining borrowing availability is $1.4 billion . We utilized $0.5 billion of our borrowing capacity at September 30, 2015 consisting of $397.5 million for borrowings and $152.8 million for letters of credit to collateralize public funds.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments In the normal course of business, we offer off-balance sheet credit arrangements to enable our customers to meet their financing objectives. These instruments involve, to varying degrees, elements of credit and interest rate risk in excess of the amount recognized in the financial statements. Our exposure to credit loss, in the event a customer does not satisfy the terms of the agreement, equals the contractual amount of the obligation less the value of any collateral. We apply the same credit policies in making commitments and standby letters of credit that are used for the underwriting of loans to customers. Commitments generally have fixed expiration dates, annual renewals or other termination clauses and may require payment of a fee. Because many of the commitments are expected to expire without being drawn upon, the total commitment amounts do not necessarily represent future cash requirements. Our allowance for unfunded commitments totaled $3.0 million at September 30, 2015 and $2.3 million at December 31, 2014 . The allowance for unfunded commitments is included in other liabilities in the Consolidated Balance Sheets. The allowance for unfunded commitments is determined using a similar methodology as our ALL. The reserve is calculated by applying historical loss rates and qualitative adjustments to our unfunded commitments. Estimates of the fair value of these off-balance sheet items were not made because of the short-term nature of these arrangements and the credit standing of the counterparties. The following table sets forth the commitments and letters of credit as of the dates presented: (dollars in thousands) September 30, 2015 December 31, 2014 Commitments to extend credit $ 1,538,397 $ 1,158,628 Standby letters of credit 96,612 73,584 Total $ 1,635,009 $ 1,232,212 Litigation In the normal course of business, we are subject to various legal and administrative proceedings and claims. While any type of litigation contains a level of uncertainty, we believe that the outcome of such proceedings or claims pending will not have a material adverse effect on our consolidated financial position or results of operations.

Other Comprehensive Income

Other Comprehensive Income	9 Months Ended
	Sep. 30, 2015
Equity [Abstract]
Other Comprehensive Income	The following table presents the tax effects of the components of other comprehensive income (loss) for the periods presented: Three Months Ended September 30, 2015 Three Months Ended September 30, 2014 (dollars in thousands) Pre-Tax Amount Tax (Expense) Benefit Net of Tax Amount Pre-Tax Amount Tax (Expense) Benefit Net of Tax Amount Change in net unrealized gains/(losses) on securities available-for-sale $ 5,177 $ (1,812 ) $ 3,365 $ (2,032 ) $ 712 $ (1,320 ) Reclassification adjustment for net (gains)/losses on securities available-for-sale included in net income (1) — — — — — — Adjustment to funded status of employee benefit plans 647 (227 ) 420 269 (94 ) 175 Other Comprehensive Income/(Loss) $ 5,824 $ (2,039 ) $ 3,785 $ (1,763 ) $ 618 $ (1,145 ) (1) Reclassification adjustments are comprised of realized security gains or losses. The realized gains or losses have been reclassified out of accumulated other comprehensive income/(loss) and have affected certain lines in the Consolidated Statements of Comprehensive Income as follows; the pre-tax amount is included in securities gains/losses-net, the tax expense amount is included in the provision for income taxes and the net of tax amount is included in net income. Nine Months Ended September 30, 2015 Nine Months Ended September 30, 2014 (dollars in thousands) Pre-Tax Amount Tax (Expense) Benefit Net of Tax Amount Pre-Tax Amount Tax (Expense) Benefit Net of Tax Amount Change in net unrealized gains/(losses) on securities available-for-sale $ 4,288 $ (1,501 ) $ 2,787 $ 7,844 $ (2,746 ) $ 5,098 Reclassification adjustment for net (gains)/losses on securities available-for-sale included in net income (1) 34 (12 ) 22 (41 ) 15 (26 ) Adjustment to funded status of employee benefit plans 1,839 (551 ) 1,288 692 (242 ) 450 Other Comprehensive Income $ 6,161 $ (2,064 ) $ 4,097 $ 8,495 $ (2,973 ) $ 5,522 (1) Reclassification adjustments are comprised of realized security gains or losses. The realized gains or losses have been reclassified out of accumulated other comprehensive income and have affected certain lines in the consolidated statement of comprehensive income as follows; the pre-tax amount is included in securities gains/losses-net, the tax expense amount is included in the provision for income taxes and the net of tax amount is included in net income.

Employee Benefits

Employee Benefits	9 Months Ended
	Sep. 30, 2015
Compensation and Retirement Disclosure [Abstract]
Employee Benefits	We maintain a defined benefit pension plan, or Plan, covering all employees hired prior to January 1, 2008. The benefits are based on years of service and the employee’s compensation for the highest five consecutive years in the last ten years . Contributions are intended to provide for benefits attributed to employee service to date and for those benefits expected to be earned in the future. At this time, we are not required to make a cash contribution to the Plan in 2015. The expected long-term rate of return on plan assets is 8.00 percent . Effective January 1, 2015, the Plan was amended to provide unmarried participants with the ability to name a beneficiary to receive a lump sum death benefit equal to 80.00 percent of the participant’s accrued benefit payable at normal retirement age, in the event the participant dies while employed by S&T. The following table summarizes the components of net periodic pension cost for the periods presented: Three Months Ended September 30, Nine Months Ended September 30, (dollars in thousands) 2015 2014 2015 2014 Components of Net Periodic Pension Cost Service cost—benefits earned during the period $ 606 $ 516 $ 1,951 $ 1,778 Interest cost on projected benefit obligation 1,120 1,141 3,319 3,353 Expected return on plan assets (1,772 ) (1,710 ) (5,385 ) (5,180 ) Amortization of prior service (credit) cost (34 ) (34 ) (104 ) (104 ) Recognized net actuarial loss 586 287 1,521 705 Net Periodic Pension Expense $ 506 $ 200 $ 1,302 $ 552

Segments

Segments	9 Months Ended
	Sep. 30, 2015
Segment Reporting [Abstract]
Segments	We operate three reportable operating segments: Community Banking, Insurance and Wealth Management. • Our Community Banking segment offers services which include accepting time and demand deposits, originating commercial and consumer loans and providing letters of credit and credit card services. • Our Insurance segment includes a full-service insurance agency offering commercial property and casualty insurance, group life and health coverage, employee benefit solutions and personal insurance lines. • Our Wealth Management segment offers brokerage services, services as executor and trustee under wills and deeds, guardian and custodian of employee benefits and other trust and brokerage services, as well as a registered investment advisor that manages institutional accounts. The following table represents total assets by reportable operating segment as of the dates presented: (dollars in thousands) September 30, 2015 December 31, 2014 Community Banking $ 6,203,446 $ 4,954,728 Insurance 8,255 7,468 Wealth Management 3,637 2,490 Total Assets $ 6,215,338 $ 4,964,686 The following tables provide financial information for our three operating segments for the three and nine month periods ended September 30, 2015 and 2014 . The financial results of the business segments include allocations for shared services based on an internal analysis that supports line of business and branch performance measurement. Shared services include expenses such as employee benefits, occupancy expense, computer support and other corporate overhead. Even with these allocations, the financial results are not necessarily indicative of the business segments’ financial condition and results of operations as if they existed as independent entities. The information provided under the caption “Eliminations” represents operations not considered to be reportable segments and/or general operating expenses and eliminations and adjustments, which are necessary for purposes of reconciling to the Consolidated Financial Statements. Three Months Ended September 30, 2015 (dollars in thousands) Community Banking Insurance Wealth Management Eliminations Consolidated Interest income $ 53,625 $ 1 $ 108 $ (65 ) $ 53,669 Interest expense 4,200 — — (127 ) 4,073 Net interest income 49,425 1 108 62 49,596 Provision for loan losses 3,206 — — — 3,206 Noninterest income 8,651 1,197 2,806 (173 ) 12,481 Noninterest expense 28,941 1,098 2,210 (111 ) 32,138 Depreciation expense 1,192 13 6 — 1,211 Amortization of intangible assets 460 13 7 — 480 Provision for income taxes 6,139 26 242 — 6,407 Net Income $ 18,138 $ 48 $ 449 $ — $ 18,635 Three Months Ended September 30, 2014 (dollars in thousands) Community Banking Insurance Wealth Management Eliminations Consolidated Interest income $ 40,581 $ — $ 109 $ (85 ) $ 40,605 Interest expense 3,435 — — (359 ) 3,076 Net interest income 37,146 — 109 274 37,529 Provision for loan losses 1,454 — — — 1,454 Noninterest income 7,742 1,496 2,748 (55 ) 11,931 Noninterest expense 23,691 1,127 2,245 219 27,282 Depreciation expense 878 13 7 — 898 Amortization of intangible assets 238 13 9 — 260 Provision for income taxes 4,577 120 209 — 4,906 Net Income $ 14,050 $ 223 $ 387 $ — $ 14,660 Nine Months Ended September 30, 2015 (dollars in thousands) Community Banking Insurance Wealth Management Eliminations Consolidated Interest income $ 150,108 $ 2 $ 406 $ (321 ) $ 150,195 Interest expense 12,144 — — (615 ) 11,529 Net interest income 137,964 2 406 294 138,666 Provision for loan losses 6,473 — — — 6,473 Noninterest income 25,056 4,079 8,639 174 37,948 Noninterest expense 87,542 3,288 6,716 468 98,014 Depreciation expense 3,482 39 19 — 3,540 Amortization of intangible assets 1,283 38 24 — 1,345 Provision for income taxes 16,534 250 800 — 17,584 Net Income $ 47,706 $ 466 $ 1,486 $ — $ 49,658 Nine Months Ended September 30, 2014 (dollars in thousands) Community Banking Insurance Wealth Management Eliminations Consolidated Interest income $ 119,055 $ 1 $ 419 $ (333 ) $ 119,142 Interest expense 10,332 — — (1,165 ) 9,167 Net interest income 108,723 1 419 832 109,975 Provision for loan losses 608 — — — 608 Noninterest income 22,118 4,262 8,511 227 35,118 Noninterest expense 72,756 3,327 6,961 1,059 84,103 Depreciation expense 2,485 38 20 — 2,543 Amortization of intangible assets 805 38 30 — 873 Provision for income taxes 12,579 301 672 — 13,552 Net Income $ 41,608 $ 559 $ 1,247 $ — $ 43,414

Qualified Affordable Housing Pr

Qualified Affordable Housing Projects	9 Months Ended
	Sep. 30, 2015
Investments in Affordable Housing Projects [Abstract]
Qualified Affordable Housing Projects	We invest in affordable housing projects primarily to satisfy our Community Reinvestment Act requirements. As a limited partner in these operating partnerships, we receive tax credits and tax deductions for losses incurred by the underlying properties. We use the cost method to account for these partnerships. Our total investment in qualified affordable housing projects totaled $15.9 million at September 30, 2015 and $18.6 million at December 31, 2014. We had no open commitments to fund current or future investments in qualified affordable housing projects at September 30, 2015 or December 31, 2014. Amortization expense included in noninterest expense was $0.9 million and $2.8 million for the three and nine months ended September 30, 2015 and $1.0 million and $3.1 million for the three and nine months ended September 30, 2014. The amortization expense was offset by tax credits of $1.0 million and $3.0 million for the three and nine months ended September 30, 2015 and $1.1 million and $3.3 million for the three and nine months ended September 30, 2014 as a reduction to our federal tax provision.

Basis of Presentation (Policies

Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2015
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation The interim Consolidated Financial Statements include the accounts of S&T Bancorp, Inc., or S&T, and its wholly owned subsidiaries. All significant intercompany transactions have been eliminated in consolidation. Investments of 20 percent to 50 percent of the outstanding common stock of investees are accounted for using the equity method of accounting.
Basis of Presentation	Basis of Presentation The accompanying unaudited interim Consolidated Financial Statements of S&T have been prepared in accordance with generally accepted accounting principles, or GAAP, in the United States for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements and should be read in conjunction with our annual report on Form 10-K for the year ended December 31, 2014 , filed with the Securities and Exchange Commission, or SEC, on February 20, 2015. In the opinion of management, the accompanying interim financial information reflects all adjustments, including normal recurring adjustments, necessary to present fairly our financial position and the results of operations for each of the interim periods presented. Results of operations for interim periods are not necessarily indicative of the results of operations that may be expected for a full year or any future period.
Reclassification	Reclassification Certain amounts in the prior periods’ financial statements and footnotes have been reclassified to conform to the current period’s presentation. The reclassifications had no significant effect on our results of operations or financial condition.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements. Actual results could differ from those estimates.
Recently Adopted Accounting Standards and Recently Issued Accounting Updates not yet Adopted	Recently Adopted Accounting Standards Updates, or ASU Repurchase-To-Maturity Transactions, Repurchase Financings, and Disclosures In June 2014, the Financial Accounting Standards Board, or FASB, issued ASU No. 2014-11, Repurchase-to-Maturity Transactions, Repurchase Financings, and Disclosures which introduces two accounting changes to the Transfers and Servicing guidance (Topic 860). Repurchase-to-maturity transactions will be accounted for as secured borrowing transactions on the balance sheet and for repurchase financing arrangements, an entity will account separately for a transfer of a financial asset executed contemporaneously with a repurchase agreement with the same counterparty. This will also generally result in secured borrowing accounting for the repurchase agreement. With respect to disclosures, a transferor is required to disclose information about transactions accounted for as a sale in which the transferor retains substantially all of the exposure to the economic return on the transferred financial assets through an agreement with the transferee. Additionally, new disclosures are required for repurchase agreements, securities lending transactions, and repurchase-to-maturity transactions that are accounted for as secured borrowings. The new disclosure for transactions accounted for as secured borrowings is required for interim periods beginning after March 15, 2015. These new disclosures are included in Note 9. Borrowings. The adoption of this ASU had no impact on our results of operations or financial position. Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity In April 2014, the FASB issued ASU No. 2014-08, Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity, which changes the criteria for determining which disposals can be presented as discontinued operations and modifies related disclosure requirements. The guidance applies to all entities that dispose of components. It will significantly change current practices for assessing discontinued operations and affect an entity’s income and earnings per share from continuing operations. An entity is required to reclassify assets and liabilities of a discontinued operation that are classified as held for sale or disposed of in the current period for all comparative periods presented. The ASU requires that an entity present in the statement of cash flows or disclose in a note either total operating and investing cash flows for discontinued operations, or depreciation, amortization, capital expenditures and significant operating and investing noncash items related to discontinued operations. Additional disclosures are required when an entity retains significant continuing involvement with a discontinued operation after its disposal, including the amount of cash flows to and from a discontinued operation. The new standard applies prospectively after the effective date of December 15, 2014, and early adoption was permitted. The adoption of this ASU had no impact on our results of operations or financial position. Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans upon Foreclosure In January 2014, the FASB issued ASU No. 2014-04, Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans upon Foreclosure. The ASU clarifies that an in substance repossession or foreclosure has occurred and a creditor is considered to have received physical possession of residential real estate property collateralizing a consumer mortgage loan, upon either the creditor obtaining legal title to the residential real estate property upon completion of a foreclosure or the borrower conveying all interest in the residential real estate property to the creditor to satisfy that loan through completion of a deed in lieu of foreclosure. Interim and annual disclosure is required of both the amount of foreclosed residential real estate property held by the creditor and the recorded investment in consumer mortgage loans collateralized by residential real estate property that are in the process of foreclosure. The new standard is effective using either the modified retrospective transition method or a prospective transition method for fiscal years and interim periods within those years, beginning after December 15, 2014, and early adoption was permitted. The adoption of this ASU had no impact on our results of operations or financial position. Accounting for Investments in Qualified Affordable Housing Projects In January 2014, the FASB issued ASU No. 2014-01, Accounting for Investments in Qualified Affordable Housing Projects. The ASU permits reporting entities to make an accounting policy election to account for investments in qualified affordable housing projects using the proportional amortization method if certain conditions are met. The proportional amortization method permits the amortization of the initial cost of the investment in proportion to the tax credits and other tax benefits received, and recognizes the net investment performance in the income statement as a component of income tax expense (benefit). The new standard is effective retrospectively for fiscal years and interim periods within those years, beginning after December 15, 2014, and early adoption was permitted. This ASU did not have a material impact on our results of operations or financial position. We did not adopt the proportional amortization method. Refer to Note 14 for additional disclosure. Recently Issued Accounting Standards Updates not yet Adopted Business Combinations – Simplifying the Accounting for Measurement Period Adjustments In September 2015, the FASB issued ASU No. 2015-16, Business Combinations – Simplifying the Accounting for Measurement Period Adjustments (Topic 805): The amendments in this ASU 2015-16 eliminate the requirement to retrospectively adjust the financial statements for measurement-period adjustments as if they were known at the acquisition date, but are recognized in the reporting period in which they are determined. Additional disclosures are required about the impact on current-period income statement line items of adjustments that would have been recognized in prior periods if that information had been revised. The measurement period is a reasonable time period after the acquisition date when the acquirer may adjust the provisional amounts recognized for a business combination if the necessary information is not available by the end of the reporting period in which the acquisition occurs. The measurement periods cannot continue for more than one year from the acquisition date. The standard is effective for annual periods and interim periods beginning after December 15, 2015. We do not expect that this ASU will have a material impact on our results of operations or financial position. Intangibles – Goodwill and Other – Internal-Use Software: Customer's Accounting for Fees Paid in a Cloud Computing Arrangement In April 2015, the FASB issued ASU No. 2015-05, Intangibles – Goodwill and Other – Internal-Use Software (Subtopic 350-40): Customer's Accounting for Fees Paid in a Cloud Computing Arrangement. The main provisions of ASU 2015-05 provide a basis for evaluating whether a cloud computing arrangement 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, then the arrangement should be accounted for as a service contract. The standard is effective for annual periods and interim periods beginning after December 15, 2015. We do not expect that this ASU will have a material impact on our results of operations or financial position. Interest – Imputation of Interest: Simplifying the Presentation of Debt Issuance Costs In April 2015, the FASB issued ASU No. 2015-03, Interest – Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs. The amendments in this ASU require 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 standard is required to be adopted by public business entities in annual periods beginning on or after December 15, 2016. We do not expect that this ASU will have a material impact on our results of operations or financial position. Consolidation: Amendments to the Consolidation Analysis In April 2015, the FASB issued ASU No. 2015-02, Consolidation (Topic 810): Amendments to the Consolidation Analysis. The amendments in this ASU affect reporting entities that are required to evaluate whether they should consolidate certain legal entities. All legal entities are subject to reevaluation under the revised consolidation model. Specifically, the amendments: 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 ASU are effective for public business entities for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2015. We are currently evaluating the impact that these amendments may have on our consolidated financial statements. We do not expect that this ASU will have a material impact on our results of operations or financial position. Income Statement – Extraordinary and Unusual Items: Simplifying Income Statement Presentation by Eliminating the Concept of Extraordinary In January 2015, the FASB issued ASU No. 2015-01, Income Statement – Extraordinary and Unusual Items (Subtopic 225-20): Simplifying Income Statement Presentation by Eliminating the Concept of Extraordinary. The amendments in this ASU eliminate from GAAP the concept of extraordinary items and eliminate the requirements for reporting entities to consider whether an underlying event or transaction is extraordinary. The presentation and disclosure guidance for items that are unusual in nature or occur infrequently will be retained and will be expanded to include items that are both unusual in nature and infrequently occurring. The standard is required to be adopted by public business entities in annual periods beginning on or after December 15, 2015. We do not expect that this ASU will have a material impact on our results of operations or financial position.

Business Combinations (Tables)

Business Combinations (Tables)	9 Months Ended
	Sep. 30, 2015
Business Combinations [Abstract]
Summary of Consideration, Assets Acquired and Liabilities Assumed	The following table summarizes total consideration, assets acquired and liabilities assumed as of September 30, 2015: (dollars in thousands) Consideration Paid Cash $ 29,510 Common stock 142,469 Fair Value of Total Consideration $ 171,979 Fair Value of Assets Acquired Cash and cash equivalents $ 13,163 Securities and other investments 11,502 Loans 788,687 Bank owned life insurance 15,974 Premises and equipment 10,855 Core deposit intangible 5,713 Other assets 19,076 Total Assets Acquired 864,970 Fair Value of Liabilities Assumed Deposits 722,308 Borrowings 82,286 Other liabilities 4,259 Total Liabilities Assumed 808,853 Total Fair Value of Identifiable Net Assets 56,117 Goodwill $ 115,862
Schedule of Pro Forma Information	The following table presents unaudited pro forma financial information which combines the historical consolidated statements of income of S&T and Integrity to give effect to the Merger as if it had occurred on January 1, 2014, for the periods presented. Unaudited Pro Forma Information Three Months Ended September 30, Nine Months Ended September 30, (dollars in thousands, except per share data) 2015 2014 2015 2014 Total revenue (1) $ 59,819 $ 58,875 $ 179,559 $ 174,097 Net income (2) $ 18,527 $ 18,250 $ 51,406 $ 51,651 Earnings per common share: (2) Basic $ 0.53 $ 0.53 $ 1.49 $ 1.49 Diluted $ 0.53 $ 0.53 $ 1.48 $ 1.49 (1) Total pro forma revenue is defined as net interest income plus non-interest income, excluding gains and losses on sales of investment securities available-for-sale. ( 2) Excludes merger expenses

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2015
Earnings Per Share [Abstract]
Reconciles Numerators and Denominators of Basic Earnings Per Share with Diluted Earnings Per Share	The following table reconciles the components of basic earnings per share with that of diluted earnings per share for the periods presented: Three Months Ended September 30, Nine Months Ended September 30, (in thousands, except shares and per share data) 2015 2014 2015 2014 Numerator for Earnings per Share—Basic: Net income $ 18,635 $ 14,660 $ 49,658 $ 43,414 Less: Income allocated to participating shares 81 51 204 115 Net Income Allocated to Shareholders $ 18,554 $ 14,609 $ 49,454 $ 43,299 Numerator for Earnings per Share—Diluted: Net income 18,635 14,660 $ 49,658 $ 43,414 Net Income Available to Shareholders $ 18,635 $ 14,660 $ 49,658 $ 43,414 Denominators for Earnings per Share: Weighted Average Shares Outstanding—Basic 34,660,007 29,693,417 33,527,549 29,679,623 Add: Potentially dilutive shares 32,985 21,195 33,980 25,732 Denominator for Treasury Stock Method—Diluted 34,692,992 29,714,612 33,561,529 29,705,355 Weighted Average Shares Outstanding—Basic 34,660,007 29,693,417 33,527,549 29,679,623 Add: Average participating shares outstanding 151,972 102,980 138,441 78,835 Denominator for Two-Class Method—Diluted 34,811,979 29,796,397 33,665,990 29,758,458 Earnings per share—basic $ 0.54 $ 0.49 $ 1.48 $ 1.46 Earnings per share—diluted $ 0.54 $ 0.49 $ 1.48 $ 1.46 Warrants considered anti-dilutive excluded from potentially dilutive shares - exercise price $31.53 per share, expires January 2019 517,012 517,012 517,012 517,012 Stock options considered anti-dilutive excluded from potentially dilutive shares 155,500 427,362 155,500 428,233 Restricted stock considered anti-dilutive excluded from potentially dilutive shares 118,987 81,785 104,461 53,103

Fair Value Measurement (Tables)

Fair Value Measurement (Tables)	9 Months Ended
	Sep. 30, 2015
Fair Value Disclosures [Abstract]
Assets and Liabilities Measured at Fair Value on Recurring Basis	The following tables present our assets and liabilities that are measured at fair value on a recurring basis by fair value hierarchy level at September 30, 2015 and December 31, 2014 . Due to limited trading volume, we transferred marketable equity securities with a fair value of $0.2 million from Level 1 to Level 2 during the nine month period ended September 30, 2015. There were no other transfers between Level 1 and Level 2 for items measured at fair value on a recurring basis during the periods presented. September 30, 2015 (dollars in thousands) Level 1 Level 2 Level 3 Total ASSETS Securities available-for-sale: U.S. Treasury securities $ — $ 15,062 $ — $ 15,062 Obligations of U.S. government corporations and agencies — 271,332 — 271,332 Collateralized mortgage obligations of U.S. government corporations and agencies — 135,216 — 135,216 Residential mortgage-backed securities of U.S. government corporations and agencies — 42,065 — 42,065 Commercial mortgage-backed securities of U.S. government corporations and agencies — 50,223 — 50,223 Obligations of states and political subdivisions — 137,335 — 137,335 Marketable equity securities — 8,813 — 8,813 Total securities available-for-sale — 660,046 — 660,046 Trading securities held in a Rabbi Trust 3,690 — — 3,690 Total securities 3,690 660,046 — 663,736 Derivative financial assets: Interest rate swaps — 14,232 — 14,232 Interest rate lock commitments — 574 — 574 Total Assets $ 3,690 $ 674,852 $ — $ 678,542 LIABILITIES Derivative financial liabilities: Interest rate swaps $ — $ 14,184 $ — $ 14,184 Forward sale contracts — 126 — 126 Total Liabilities $ — $ 14,310 $ — $ 14,310 December 31, 2014 (dollars in thousands) Level 1 Level 2 Level 3 Total ASSETS Securities available-for-sale: U.S. Treasury securities $ — $ 14,880 $ — $ 14,880 Obligations of U.S. government corporations and agencies — 269,285 — 269,285 Collateralized mortgage obligations of U.S. government corporations and agencies — 118,006 — 118,006 Residential mortgage-backed securities of U.S. government corporations and agencies — 46,668 — 46,668 Commercial mortgage-backed securities of U.S. government corporations and agencies — 39,673 — 39,673 Obligations of states and political subdivisions — 142,702 — 142,702 Marketable equity securities 178 8,881 — 9,059 Total securities available-for-sale 178 640,095 — 640,273 Trading securities held in a Rabbi Trust 3,456 — — 3,456 Total securities 3,634 640,095 — 643,729 Derivative financial assets: Interest rate swaps — 12,981 — 12,981 Interest rate lock commitments — 235 — 235 Total Assets $ 3,634 $ 653,311 $ — $ 656,945 LIABILITIES Derivative financial liabilities: Interest rate swaps $ — $ 12,953 $ — $ 12,953 Forward sale contracts — 57 — 57 Total Liabilities $ — $ 13,010 $ — $ 13,010
Assets Measured at Estimated Fair Value on Nonrecurring Basis by Fair Value Hierarchy	The following table presents our assets that were measured at fair value on a nonrecurring basis by the fair value hierarchy level at September 30, 2015 and December 31, 2014 . There were no liabilities measured at fair value on a nonrecurring basis during these periods. September 30, 2015 December 31, 2014 (dollars in thousands) Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total ASSETS (1) Loans held for sale $ — $ — $ 216 $ 216 $ — $ — $ — $ — Impaired loans — — 8,870 8,870 — — 12,916 12,916 Other real estate owned — — 439 439 — — 117 117 Mortgage servicing rights — — 1,827 1,827 — — 2,934 2,934 Total Assets $ — $ — $ 11,352 $ 11,352 $ — $ — $ 15,967 $ 15,967 (1) This table presents only the nonrecurring items that are recorded at fair value in our financial statements.
Carrying Values and Fair Values of Financial Instruments	The carrying values and fair values of our financial instruments at September 30, 2015 and December 31, 2014 are presented in the following tables: Carrying Value (1) Fair Value Measurements at September 30, 2015 (dollars in thousands) Total Level 1 Level 2 Level 3 ASSETS Cash and due from banks, including interest-bearing deposits $ 115,347 $ 115,347 $ 115,347 $ — $ — Securities available-for-sale 660,046 660,046 — 660,046 — Loans held for sale 13,794 14,134 — — 14,134 Portfolio loans, net of unearned income 4,925,963 4,902,661 — — 4,902,661 Bank owned life insurance 79,894 79,894 — 79,894 — FHLB and other restricted stock 20,352 20,352 — — 20,352 Trading securities held in a Rabbi Trust 3,690 3,690 3,690 — — Mortgage servicing rights 3,083 3,170 — — 3,170 Interest rate swaps 14,232 14,232 — 14,232 — Interest rate lock commitments 574 574 — 574 — LIABILITIES Deposits $ 4,877,409 $ 4,883,132 $ — $ — $ 4,883,132 Securities sold under repurchase agreements 42,971 42,971 — — 42,971 Short-term borrowings 280,000 280,000 — — 280,000 Long-term borrowings 117,613 118,646 — — 118,646 Junior subordinated debt securities 45,619 45,619 — — 45,619 Interest rate swaps 14,184 14,184 — 14,184 — Forward sale contracts 126 126 — 126 — (1) As reported in the Consolidated Balance Sheets Carrying Value (1) Fair Value Measurements at December 31, 2014 (dollars in thousands) Total Level 1 Level 2 Level 3 ASSETS Cash and due from banks, including interest-bearing deposits $ 109,580 $ 109,580 $ 109,580 $ — $ — Securities available-for-sale 640,273 640,273 178 640,095 — Loans held for sale 2,970 2,991 — — 2,991 Portfolio loans, net of unearned income 3,868,746 3,827,634 — — 3,827,634 Bank owned life insurance 62,252 62,252 — 62,252 — FHLB and other restricted stock 15,135 15,135 — — 15,135 Trading securities held in a Rabbi Trust 3,456 3,456 3,456 — — Mortgage servicing rights 2,817 2,934 — — 2,934 Interest rate swaps 12,981 12,981 — 12,981 — Interest rate lock commitments 235 235 — 235 — LIABILITIES Deposits $ 3,908,842 $ 3,910,342 $ — $ — $ 3,910,342 Securities sold under repurchase agreements 30,605 30,605 — — 30,605 Short-term borrowings 290,000 290,000 — — 290,000 Long-term borrowings 19,442 20,462 — — 20,462 Junior subordinated debt securities 45,619 45,619 — — 45,619 Interest rate swaps 12,953 12,953 — 12,953 — Forward sale contracts 57 57 — 57 — (1) As reported in the Consolidated Balance Sheets

Securities Available-for-Sale (

Securities Available-for-Sale (Tables)	9 Months Ended
	Sep. 30, 2015
Investments, Debt and Equity Securities [Abstract]
Composition of Securities Available-for-Sale	The following tables present the amortized cost and fair value of available-for-sale securities as of the dates presented: September 30, 2015 December 31, 2014 (dollars in thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value U.S. Treasury securities $ 14,903 $ 159 $ — $ 15,062 $ 14,873 $ 7 $ — $ 14,880 Obligations of U.S. government corporations and agencies 267,328 4,032 (28 ) 271,332 268,029 2,334 (1,078 ) 269,285 Collateralized mortgage obligations of U.S. government corporations and agencies 132,691 2,536 (11 ) 135,216 116,897 1,257 (148 ) 118,006 Residential mortgage-backed securities of U.S. government corporations and agencies 40,678 1,467 (80 ) 42,065 45,274 1,548 (154 ) 46,668 Commercial mortgage-backed securities of U.S. government corporations and agencies 49,596 669 (42 ) 50,223 39,834 232 (393 ) 39,673 Obligations of states and political subdivisions 132,139 5,249 (53 ) 137,335 136,977 5,789 (64 ) 142,702 Debt Securities 637,335 14,112 (214 ) 651,233 621,884 11,167 (1,837 ) 631,214 Marketable equity securities 7,579 1,234 — 8,813 7,579 1,480 — 9,059 Total $ 644,914 $ 15,346 $ (214 ) $ 660,046 $ 629,463 $ 12,647 $ (1,837 ) $ 640,273
Schedule of Realized Gain (Loss)	Realized gains and losses on the sale of securities are determined using the specific-identification method. The following table shows the composition of gross and net realized gains and losses for the periods presented: Three Months Ended September 30, Nine Months Ended September 30, (dollars in thousands) 2015 2014 2015 2014 Gross realized gains $ — $ — $ — $ 41 Gross realized losses — — (34 ) — Net Realized Gains $ — $ — $ (34 ) $ 41
Fair Value and Age of Gross Unrealized Losses by Investment Category	The following tables present the fair value and the age of gross unrealized losses by investment category as of the dates presented: September 30, 2015 Less Than 12 Months 12 Months or More Total (dollars in thousands) Number of Securities Fair Value Unrealized Number of Securities Fair Value Unrealized Number of Securities Fair Value Unrealized Obligations of U.S. government corporations and agencies — $ — $ — 2 $ 14,720 $ (28 ) 2 $ 14,720 $ (28 ) Collateralized mortgage obligations of U.S. government corporations and agencies 1 10,694 (11 ) — — — 1 10,694 (11 ) Residential mortgage-backed securities of U.S. government corporations and agencies 1 8,377 (80 ) — — — 1 8,377 (80 ) Commercial mortgage-backed securities of U.S. government corporations and agencies — — — 1 9,709 (42 ) 1 9,709 (42 ) Obligations of states and political subdivisions 2 10,666 (53 ) — — — 2 10,666 (53 ) Total Temporarily Impaired Securities 4 $ 29,737 $ (144 ) 3 $ 24,429 $ (70 ) 7 $ 54,166 $ (214 ) December 31, 2014 Less Than 12 Months 12 Months or More Total (dollars in thousands) Number of Securities Fair Value Unrealized Losses Number of Securities Fair Value Unrealized Losses Number of Securities Fair Value Unrealized Losses Obligations of U.S. government corporations and agencies 4 $ 39,745 $ (207 ) 8 $ 63,149 $ (871 ) 12 $ 102,894 $ (1,078 ) Collateralized mortgage obligations of U.S. government corporations and agencies 1 9,323 (148 ) — — — 1 9,323 (148 ) Residential mortgage-backed securities of U.S. government corporations and agencies — — — 1 8,982 (154 ) 1 8,982 (154 ) Commercial mortgage-backed securities of U.S. government corporations and agencies 1 9,998 (25 ) 2 20,640 (368 ) 3 30,638 (393 ) Obligations of states and political subdivisions 1 263 (1 ) 2 10,756 (63 ) 3 11,019 (64 ) Total Temporarily Impaired Securities 7 $ 59,329 $ (381 ) 13 $ 103,527 $ (1,456 ) 20 $ 162,856 $ (1,837 )
Unrealized Gains and Losses, Net of Tax on Securities Available for Sale	The following table displays net unrealized gains and losses, net of tax on securities available for sale included in accumulated other comprehensive (loss)/income for the periods presented: September 30, 2015 December 31, 2014 (dollars in thousands) Gross Unrealized Gains Gross Unrealized Losses Net Unrealized Gains/ (Losses) Gross Unrealized Gains Gross Unrealized Losses Net Unrealized Gains/ (Losses) Total unrealized gains/(losses) on securities available-for-sale $ 15,346 $ (214 ) $ 15,132 $ 12,647 $ (1,837 ) $ 10,810 Income tax expense/(benefit) 5,371 (75 ) 5,296 4,426 (643 ) 3,783 Net unrealized gains/(losses), net of tax included in accumulated other comprehensive income/(loss) $ 9,975 $ (139 ) $ 9,836 $ 8,221 $ (1,194 ) $ 7,027
Amortized Cost and Fair Value of Available-for-Sale Securities	The amortized cost and fair value of securities available-for-sale at September 30, 2015 by contractual maturity are included in the table below. Actual maturities may differ from contractual maturities because issuers may have the right to call or prepay obligations with or without call or prepayment penalties. September 30, 2015 (dollars in thousands) Amortized Cost Fair Value Obligations of the U.S. Treasury, U.S. government corporations and agencies, and obligations of states and political subdivisions Due in one year or less $ 37,404 $ 37,767 Due after one year through five years 224,669 228,005 Due after five years through ten years 65,260 67,613 Due after ten years 87,037 90,344 414,370 423,729 Collateralized mortgage obligations of U.S. government corporations and agencies 132,691 135,216 Residential mortgage-backed securities of U.S. government corporations and agencies 40,678 42,065 Commercial mortgage-backed securities of U.S. government corporations and agencies 49,596 50,223 Debt Securities 637,335 651,233 Marketable equity securities 7,579 8,813 Total $ 644,914 $ 660,046

Loans and Loans Held for Sale (

Loans and Loans Held for Sale (Tables)	9 Months Ended
	Sep. 30, 2015
Receivables [Abstract]
Composition of Loans	The following table indicates the composition of the loans as of the dates presented: (dollars in thousands) September 30, 2015 December 31, 2014 Commercial Commercial real estate $ 2,111,585 $ 1,682,236 Commercial and industrial 1,237,915 994,138 Commercial construction 384,328 216,148 Total Commercial Loans 3,733,828 2,892,522 Consumer Residential mortgage 625,251 489,586 Home equity 467,698 418,563 Installment and other consumer 91,122 65,567 Consumer construction 8,064 2,508 Total Consumer Loans 1,192,135 976,224 Total Portfolio Loans 4,925,963 3,868,746 Loans held for sale 13,794 2,970 Total Loans $ 4,939,757 $ 3,871,716
Restructured Loans for Periods Presented	The following table summarizes the restructured loans as of the dates presented: September 30, 2015 December 31, 2014 (dollars in thousands) Performing TDRs Nonperforming TDRs Total TDRs Performing TDRs Nonperforming TDRs Total TDRs Commercial real estate $ 8,062 $ 3,552 $ 11,614 $ 16,939 $ 2,180 $ 19,119 Commercial and industrial 6,360 1,839 8,199 8,074 356 8,430 Commercial construction 5,627 1,610 7,237 5,736 1,869 7,605 Residential mortgage 2,609 591 3,200 2,839 459 3,298 Home equity 3,363 412 3,775 3,342 562 3,904 Installment and other consumer 28 88 116 53 10 63 Total $ 26,049 $ 8,092 $ 34,141 $ 36,983 $ 5,436 $ 42,419
Restructured Loans for Periods Stated	The following tables present the restructured loans during the periods presented: Three Months Ended September 30, 2015 Three Months Ended September 30, 2014 (dollars in thousands) Number of Loans Pre-Modification Outstanding Recorded Investment ( 1) Post-Modification Outstanding Recorded Investment (1) Total Difference in Recorded Investment Number of Loans Pre-Modification Outstanding Recorded Investment (1) Post-Modification Outstanding Recorded Investment (1) Total Difference in Recorded Investment Commercial real estate Principal deferral — $ — $ — $ — 1 $ 487 $ 475 $ (12 ) Chapter 7 bankruptcy (2) — — — — 1 83 83 — Maturity date extension 1 264 260 (4 ) — — — — Commercial and industrial Principal deferral — — — — 2 381 366 (15 ) Commercial Construction Maturity date extension 2 813 812 (1 ) — — — — Residential mortgage Chapter 7 bankruptcy (2) 2 74 74 — 2 135 134 (1 ) Maturity date extension 1 180 180 — — — — — Home equity Chapter 7 bankruptcy (2) 5 115 110 (5 ) 2 14 14 — Maturity date extension and interest rate reduction 2 138 138 — 2 96 96 — Installment and other consumer Chapter 7 bankruptcy (2) 1 9 4 $ (5 ) 2 14 11 $ (3 ) Total by Concession Type Principal deferral — — — — 3 868 841 (27 ) Maturity date extension and interest rate reduction 2 138 138 — 2 96 96 — Chapter 7 bankruptcy (2) 8 198 188 (10 ) 7 246 242 (4 ) Maturity date extension 4 1,257 1,252 (5 ) — — — — Total 14 $ 1,593 $ 1,578 $ (15 ) 12 $ 1,210 $ 1,179 $ (31 ) (1) Excludes loans that were fully paid off or fully charged-off by period end. The pre-modification balance represents the balance outstanding prior to modification. The post-modification balance represents the outstanding balance at period end. (2) Chapter 7 bankruptcy loans where the debt has been legally discharged through the bankruptcy court and not reaffirmed. Nine Months Ended September 30, 2015 Nine Months Ended September 30, 2014 (dollars in thousands) Number of Pre-Modification (1) Post-Modification (1) Total Difference Number of Pre-Modification ( 1) Post-Modification (1) Total Difference Commercial real estate Principal deferral 2 $ 2,851 $ 1,841 $ (1,010 ) 2 $ 616 $ 602 $ (14 ) Chapter 7 bankruptcy (2) — — — — 1 83 83 — Maturity date extension 1 264 260 (4 ) — — — — Commercial and industrial Principal forgiveness 1 400 273 (127 ) — — — — Principal deferral 6 661 363 (298 ) 2 381 366 (15 ) Chapter 7 bankruptcy (2) 1 3 — (3 ) 1 287 286 (1 ) Maturity date extension 1 780 720 (60 ) — — — — Commercial Construction Principal deferral 1 104 — (104 ) — — — — Maturity date extension 2 813 812 (1 ) 1 1,019 1,019 — Residential mortgage Chapter 7 bankruptcy (2) 2 74 74 — 7 464 461 (3 ) Maturity date extension 1 180 180 — — — — — Maturity date extension and interest rate reduction 2 225 229 4 — — — — Home equity Chapter 7 bankruptcy (2) 17 428 389 (39 ) 12 283 265 (18 ) Maturity date extension and interest rate reduction 2 138 138 — 2 96 96 — Maturity date extension 1 71 70 (1 ) — — — — Installment and other consumer Chapter 7 bankruptcy (2) 1 9 4 $ (5 ) 3 23 20 $ (3 ) Total by Concession Type Principal forgiveness 1 $ 400 $ 273 $ (127 ) — $ — $ — $ — Principal deferral 9 3,616 2,204 (1,412 ) 4 997 968 (29 ) Chapter 7 bankruptcy (2) 21 514 467 (47 ) 24 1,140 1,115 (25 ) Maturity date extension and interest rate reduction 4 363 367 4 2 96 96 — Maturity date extension 6 2,108 2,042 (66 ) 1 1,019 1,019 — Total 41 7,001 5,353 $ (1,648 ) 31 $ 3,252 $ 3,198 $ (54 ) (1) Excludes loans that were fully paid off or fully charged-off by period end. The pre-modification balance represents the balance outstanding prior to modification. The post-modification balance represents the outstanding balance at period end. (2) Chapter 7 bankruptcy loans where the debt has been legally discharged through the bankruptcy court and not reaffirmed.
Summary of Nonperforming Assets of Defaulted TDRs	The following tables present a summary of TDRs which defaulted during the periods presented that had been restructured within the last 12 months prior to defaulting: Defaulted TDRs Three Months Ended Three Months Ended (dollars in thousands) Number of Defaults Recorded Investment Number of Defaults Recorded Investment Commercial real estate — $ — — $ — Commercial and Industrial — — — — Commercial construction — — — — Residential mortgage — — — — Home equity — $ — — $ — Installment and other consumer — — — — Consumer construction — — — — Total — $ — — $ — Defaulted TDRs Nine Months Ended Nine Months Ended (dollars in thousands) Number of Defaults Recorded Investment Number of Defaults Recorded Investment Commercial real estate — $ — — $ — Commercial and Industrial — — — — Commercial construction — — — — Residential mortgage 1 $ 183 1 $ 72 Home equity 3 124 — — Installment and other consumer — — — — Consumer construction — — — — Total 4 $ 307 1 $ 72
Summary of Nonperforming Assets	The following table is a summary of nonperforming assets as of the dates presented: Nonperforming Assets (dollars in thousands) September 30, 2015 December 31, 2014 Nonperforming Assets Nonaccrual loans $ 15,716 $ 7,021 Nonaccrual TDRs 8,092 5,436 Total nonaccrual loans 23,808 12,457 OREO 472 166 Total Nonperforming Assets $ 24,280 $ 12,623

Allowance for Loan Losses (Tabl

Allowance for Loan Losses (Tables)	9 Months Ended
	Sep. 30, 2015
Receivables [Abstract]
Age Analysis of Past Due Loans Segregated by Class of Loans	The following tables present the age analysis of past due loans segregated by class of loans as of September 30, 2015 and December 31, 2014 : September 30, 2015 (dollars in thousands) Current 30-59 Days Past Due 60-89 Days Past Due 90 Days Past Due (1) Nonaccrual Total Past Due Total Loans Commercial real estate $ 2,092,139 $ 8,987 $ 1,567 $ 973 $ 7,919 $ 19,446 $ 2,111,585 Commercial and industrial 1,228,571 2,183 1,791 — 5,370 9,344 1,237,915 Commercial construction 374,001 3,955 1,364 — 5,008 10,327 384,328 Residential mortgage 614,609 3,563 3,281 556 3,242 10,642 625,251 Home equity 463,145 2,144 262 — 2,147 4,553 467,698 Installment and other consumer 90,624 344 32 — 122 498 91,122 Consumer construction 8,064 — — — — — 8,064 Loans held for sale 13,794 — — — — — 13,794 Totals $ 4,884,947 $ 21,176 $ 8,297 $ 1,529 $ 23,808 $ 54,810 $ 4,939,757 (1) Represents acquired loans that were recorded at fair value at the acquisition date. December 31, 2014 (dollars in thousands) Current 30-59 Days Past Due 60-89 Days Past Due 90 Days Past Due Nonaccrual Total Past Due Total Loans Commercial real estate $ 1,674,930 $ 2,548 $ 323 $ — $ 4,435 $ 7,306 $ 1,682,236 Commercial and industrial 991,136 1,227 153 — 1,622 3,002 994,138 Commercial construction 214,174 — — — 1,974 1,974 216,148 Residential mortgage 485,465 565 1,220 — 2,336 4,121 489,586 Home equity 414,303 1,756 445 — 2,059 4,260 418,563 Installment and other consumer 65,111 352 73 — 31 456 65,567 Consumer construction 2,508 — — — — — 2,508 Loans held for sale 2,970 — — — — — 2,970 Totals $ 3,850,597 $ 6,448 $ 2,214 $ — $ 12,457 $ 21,119 $ 3,871,716
Recorded Investment in Commercial Loan Classes by Internally Assigned Risk Ratings	The following tables present the recorded investment in commercial loan classes by internally assigned risk ratings as of the dates presented: September 30, 2015 (dollars in thousands) Commercial Real Estate % of Total Commercial and Industrial % of Total Commercial Construction % of Total Total % of Total Pass $ 2,036,905 96.5 % $ 1,169,828 94.5 % $ 344,513 89.6 % $ 3,551,246 95.1 % Special mention 32,371 1.5 % 45,750 3.7 % 18,771 4.9 % 96,892 2.6 % Substandard 42,309 2.0 % 22,337 1.8 % 21,044 5.5 % 85,690 2.3 % Total $ 2,111,585 100 % $ 1,237,915 100.0 % $ 384,328 100.0 % $ 3,733,828 100.0 % December 31, 2014 (dollars in thousands) Commercial Real Estate % of Total Commercial and Industrial % of Total Commercial Construction % of Total Total % of Total Pass $ 1,635,132 97.2 % $ 948,663 95.4 % $ 196,520 90.9 % $ 2,780,315 96.1 % Special mention 23,597 1.4 % 30,357 3.1 % 12,014 5.6 % 65,968 2.3 % Substandard 23,507 1.4 % 15,118 1.5 % 7,614 3.5 % 46,239 1.6 % Total $ 1,682,236 100.0 % $ 994,138 100.0 % $ 216,148 100.0 % $ 2,892,522 100.0 %
Recorded Investment in Consumer Loan Classes by Performing and Nonperforming Status	The following tables present the recorded investment in consumer loan classes by performing and nonperforming status as of the dates presented: September 30, 2015 (dollars in thousands) Residential Mortgage % of Total Home Equity % of Total Installment and other consumer % of Total Consumer Construction % of Total Total % of Total Performing $ 622,009 99.5 % $ 465,551 99.5 % $ 91,000 99.9 % $ 8,064 100.0 % $ 1,186,624 99.5 % Nonperforming 3,242 0.5 % 2,147 0.5 % 122 0.1 % — — % 5,511 0.5 % Total $ 625,251 100.0 % $ 467,698 100.0 % $ 91,122 100.0 % $ 8,064 100.0 % $ 1,192,135 100.0 % December 31, 2014 (dollars in thousands) Residential Mortgage % of Total Home Equity % of Total Installment and other consumer % of Total Consumer Construction % of Total Total % of Total Performing $ 487,250 99.5 % $ 416,504 99.5 % $ 65,536 99.9 % $ 2,508 100.0 % $ 971,798 99.5 % Nonperforming 2,336 0.5 % 2,059 0.5 % 31 0.1 % — — % 4,426 0.5 % Total $ 489,586 100.0 % $ 418,563 100.0 % $ 65,567 100.0 % $ 2,508 100.0 % $ 976,224 100.0 %
Investments in Loans Considered to be Impaired and Related Information on Impaired Loans	The following tables summarize investments in loans considered to be impaired and related information on those impaired loans for the periods presented: Three Months Ended September 30, 2015 September 30, 2014 (dollars in thousands) Average Recorded Investment Interest Income Recognized Average Recorded Investment Interest Income Recognized Without a related allowance recorded: Commercial real estate $ 14,101 $ 352 $ 21,110 $ 159 Commercial and industrial 8,993 44 9,702 63 Commercial construction 11,034 67 8,160 58 Consumer real estate 6,829 92 7,034 100 Other consumer 183 — 115 1 Total without a Related Allowance Recorded 41,140 555 46,121 381 With a related allowance recorded: Commercial real estate — — — — Commercial and industrial 1,977 7 — — Commercial construction — — — — Consumer real estate 119 2 47 1 Other consumer 2 — 23 — Total with a Related Allowance Recorded 2,098 9 70 1 Total: Commercial real estate 14,101 352 21,110 159 Commercial and industrial 10,970 51 9,702 63 Commercial construction 11,034 67 8,160 58 Consumer real estate 6,948 94 7,081 101 Other consumer 185 — 138 1 Total $ 43,238 $ 564 $ 46,191 $ 382 Nine Months Ended September 30, 2015 September 30, 2014 (dollars in thousands) Average Recorded Investment Interest Income Recognized Average Recorded Investment Interest Income Recognized Without a related allowance recorded: Commercial real estate $ 14,994 $ 731 $ 21,593 $ 512 Commercial and industrial 9,742 131 9,477 177 Commercial construction 8,920 200 8,254 172 Consumer real estate 6,856 279 7,181 306 Other consumer 119 1 122 3 Total without a Related Allowance Recorded 40,631 1,342 46,627 1,170 With a related allowance recorded: Commercial real estate $ — $ — $ — $ — Commercial and industrial 1,980 42 — — Commercial construction — — — — Consumer real estate 121 5 49 2 Other consumer 2 — 24 2 Total with a Related Allowance Recorded 2,103 47 73 4 Total: Commercial real estate 14,994 731 21,593 512 Commercial and industrial 11,722 173 9,477 177 Commercial construction 8,920 200 8,254 172 Consumer real estate 6,977 284 7,230 308 Other consumer 121 1 146 5 Total $ 42,734 $ 1,389 $ 46,700 $ 1,174 The following tables summarize investments in loans considered to be impaired and the related information on those impaired loans as of the dates presented: September 30, 2015 December 31, 2014 (dollars in thousands) Recorded Investment Unpaid Principal Balance Related Allowance Recorded Investment Unpaid Principal Balance Related Allowance Without a related allowance recorded: Commercial real estate $ 14,080 $ 14,576 $ — $ 19,890 $ 25,262 $ — Commercial and industrial 8,746 10,918 — 9,218 9,449 — Commercial construction 9,315 12,977 — 7,605 11,293 — Consumer real estate 6,852 7,401 — 7,159 7,733 — Other consumer 119 191 — 42 48 — Total without a Related Allowance Recorded 39,112 46,063 — 43,914 53,785 — With a related allowance recorded: Commercial real estate — — — — — — Commercial and industrial 1,969 1,969 1,224 — — — Commercial construction — — — — — — Consumer real estate 118 118 34 43 43 43 Other consumer 2 2 2 20 20 11 Total with a Related Allowance Recorded 2,089 2,089 1,260 63 63 54 Total: Commercial real estate 14,080 14,576 — 19,890 25,262 — Commercial and industrial 10,715 12,887 1,224 9,218 9,449 — Commercial construction 9,315 12,977 — 7,605 11,293 — Consumer real estate 6,970 7,519 34 7,202 7,776 43 Other consumer 121 193 2 62 68 11 Total $ 41,201 $ 48,152 $ 1,260 $ 43,977 $ 53,848 $ 54
Summary of Allowance for Loan Losses	The following tables detail activity in the ALL for the periods presented: Three Months Ended September 30, 2015 (dollars in thousands) Commercial Real Estate Commercial and Industrial Commercial Construction Consumer Real Estate Other Consumer Total Loans Balance at beginning of period $ 19,018 $ 13,308 $ 7,671 $ 7,027 $ 1,790 $ 48,814 Charge-offs (2,361 ) (1,121 ) (1,247 ) (445 ) (467 ) (5,641 ) Recoveries 2,896 272 129 132 99 3,528 Net (Charge-offs)/ Recoveries 535 (849 ) (1,118 ) (313 ) (368 ) (2,113 ) Provision for loan losses (2,575 ) 12 4,983 302 484 3,206 Balance at End of Period $ 16,978 $ 12,471 $ 11,536 $ 7,016 $ 1,906 $ 49,907 Three Months Ended September 30, 2014 (dollars in thousands) Commercial Real Estate Commercial and Industrial Commercial Construction Consumer Real Estate Other Consumer Total Loans Balance at beginning of period $ 20,733 $ 13,004 $ 4,759 $ 6,705 $ 1,379 $ 46,580 Charge-offs — (37 ) (234 ) (436 ) (295 ) (1,002 ) Recoveries (154 ) 315 — 48 75 284 Net (Charge-offs)/ Recoveries (154 ) 278 (234 ) (388 ) (220 ) (718 ) Provision for loan losses (602 ) 616 653 446 341 1,454 Balance at End of Period $ 19,977 $ 13,898 $ 5,178 $ 6,763 $ 1,500 $ 47,316 Nine Months Ended September 30, 2015 (dollars in thousands) Commercial Real Estate Commercial and Industrial Commercial Construction Consumer Real Estate Other Consumer Total Loans Balance at beginning of period $ 20,164 $ 13,668 $ 6,093 $ 6,333 $ 1,653 $ 47,911 Charge-offs (2,738 ) (2,819 ) (1,247 ) (997 ) (1,046 ) (8,847 ) Recoveries 3,072 475 132 379 312 4,370 Net (Charge-offs)/Recoveries 334 (2,344 ) (1,115 ) (618 ) (734 ) (4,477 ) Provision for loan losses (3,520 ) 1,147 6,558 1,301 987 6,473 Balance at End of Period $ 16,978 $ 12,471 $ 11,536 $ 7,016 $ 1,906 $ 49,907 Nine Months Ended September 30, 2014 (dollars in thousands) Commercial Real Estate Commercial and Industrial Commercial Construction Consumer Real Estate Other Consumer Total Loans Balance at beginning of period $ 18,921 $ 14,433 $ 5,374 $ 6,362 $ 1,165 $ 46,255 Charge-offs (2,002 ) (1,070 ) (693 ) (983 ) (740 ) (5,488 ) Recoveries 1,681 3,564 140 272 284 5,941 Net (Charge-offs)/Recoveries (321 ) 2,494 (553 ) (711 ) (456 ) 453 Provision for loan losses 1,377 (3,029 ) 357 1,112 791 608 Balance at End of Period $ 19,977 $ 13,898 $ 5,178 $ 6,763 $ 1,500 $ 47,316
Summary of Allowance for Loan Losses and Recorded Investments	The following tables present the ALL and recorded investments in loans by category as of the periods presented: September 30, 2015 Allowance for Loan Losses Portfolio Loans (dollars in thousands) Individually Evaluated for Impairment Collectively Evaluated for Impairment Total Individually Evaluated for Impairment Collectively Evaluated for Impairment Total (1) Commercial real estate $ — $ 16,978 $ 16,978 $ 14,080 $ 2,097,505 $ 2,111,585 Commercial and industrial 1,224 11,247 12,471 10,715 1,227,200 1,237,915 Commercial construction — 11,536 11,536 9,315 375,013 384,328 Consumer real estate 34 6,982 7,016 6,970 1,094,043 1,101,013 Other consumer 2 1,904 1,906 121 91,001 91,122 Total $ 1,260 $ 48,647 $ 49,907 $ 41,201 $ 4,884,762 $ 4,925,963 (1) Includes acquired loans. December 31, 2014 Allowance for Loan Losses Portfolio Loans (dollars in thousands) Individually Evaluated for Impairment Collectively Evaluated for Impairment Total Individually Evaluated for Impairment Collectively Evaluated for Impairment Total (1) Commercial real estate $ — $ 20,164 $ 20,164 $ 19,890 $ 1,662,346 $ 1,682,236 Commercial and industrial — 13,668 13,668 9,218 984,920 994,138 Commercial construction — 6,093 6,093 7,605 208,543 216,148 Consumer real estate 43 6,290 6,333 7,202 903,455 910,657 Other consumer 11 1,642 1,653 62 65,505 65,567 Total $ 54 $ 47,857 $ 47,911 $ 43,977 $ 3,824,769 $ 3,868,746 (1) Includes acquired loans.

Derivative Instruments and He29

Derivative Instruments and Hedging Activities (Tables)	9 Months Ended
	Sep. 30, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Value of Derivative Assets and Derivative Liabilities	The following table indicates the amounts representing the value of derivative assets and derivative liabilities as of the dates presented: Derivatives (included in Other Assets) Derivatives (included in Other Liabilities) (dollars in thousands) September 30, 2015 December 31, 2014 September 30, 2015 December 31, 2014 Derivatives not Designated as Hedging Instruments: Interest Rate Swap Contracts- Commercial Loans Fair value $ 14,232 $ 12,981 $ 14,184 $ 12,953 Notional amount 239,277 245,152 239,277 245,152 Collateral posted — — 12,548 12,059 Interest Rate Lock Commitments- Mortgage Loans Fair value 574 235 — — Notional amount 16,969 8,822 — — Forward Sale Contracts- Mortgage Loans Fair value — — 126 57 Notional amount $ — $ — $ 14,320 $ 7,789
Schedule of Gross Amounts of Derivative Assets and Derivative Liabilities	The following table indicates the gross amounts of commercial loan swap derivative assets and derivative liabilities, the amounts offset and the carrying values in the Consolidated Balance Sheets as of the dates presented: Derivatives (included in Other Assets) Derivatives (included in Other Liabilities) (dollars in thousands) September 30, 2015 December 31, 2014 September 30, 2015 December 31, 2014 Derivatives not Designated as Hedging Instruments: Gross amounts recognized $ 14,232 $ 13,203 $ 14,184 $ 13,175 Gross amounts offset — (222 ) — (222 ) Net amounts presented in the Consolidated Balance Sheets 14,232 12,981 14,184 12,953 Gross amounts not offset (1) — — (12,548 ) (12,059 ) Net Amount $ 14,232 $ 12,981 $ 1,636 $ 894 (1) Amounts represent posted collateral.
Amount of Gain or Loss Recognized in Income on Derivatives	The following table indicates the gain or loss recognized in income on derivatives for the periods presented: Three Months Ended September 30, Nine Months Ended September 30, (dollars in thousands) 2015 2014 2015 2014 Derivatives not Designated as Hedging Instruments Interest rate swap contracts—commercial loans $ 29 $ (10 ) $ 20 $ (29 ) Interest rate lock commitments—mortgage loans 208 (105 ) 339 102 Forward sale contracts—mortgage loans (143 ) 49 (69 ) (43 ) Total Derivatives Gain (Loss) $ 94 $ (66 ) $ 290 $ 30

Borrowings (Tables)

Borrowings (Tables)	9 Months Ended
	Sep. 30, 2015
Debt Disclosure [Abstract]
Summary of Information Pertaining to Borrowings	Information pertaining to borrowings is summarized in the table below as of the dates presented: September 30, 2015 December 31, 2014 (dollars in thousands) Balance Weighted Average Rate Balance Weighted Average Rate Short-term borrowings Securities sold under repurchase agreements $ 42,971 0.01 % $ 30,605 0.01 % Short-term borrowings 280,000 0.37 % 290,000 0.31 % Total short-term borrowings 322,971 0.32 % 320,605 0.27 % Long-term borrowings Other long-term borrowings 117,613 0.76 % 19,442 3.00 % Junior subordinated debt securities 45,619 2.80 % 45,619 2.70 % Total long-term borrowings 163,232 1.33 % 65,061 2.79 % Total Borrowings $ 486,203 0.66 % $ 385,666 0.70 %

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Letters of Credit	The following table sets forth the commitments and letters of credit as of the dates presented: (dollars in thousands) September 30, 2015 December 31, 2014 Commitments to extend credit $ 1,538,397 $ 1,158,628 Standby letters of credit 96,612 73,584 Total $ 1,635,009 $ 1,232,212

Other Comprehensive Income (Tab

Other Comprehensive Income (Tables)	9 Months Ended
	Sep. 30, 2015
Equity [Abstract]
Other Comprehensive Income	The following table presents the tax effects of the components of other comprehensive income (loss) for the periods presented: Three Months Ended September 30, 2015 Three Months Ended September 30, 2014 (dollars in thousands) Pre-Tax Amount Tax (Expense) Benefit Net of Tax Amount Pre-Tax Amount Tax (Expense) Benefit Net of Tax Amount Change in net unrealized gains/(losses) on securities available-for-sale $ 5,177 $ (1,812 ) $ 3,365 $ (2,032 ) $ 712 $ (1,320 ) Reclassification adjustment for net (gains)/losses on securities available-for-sale included in net income (1) — — — — — — Adjustment to funded status of employee benefit plans 647 (227 ) 420 269 (94 ) 175 Other Comprehensive Income/(Loss) $ 5,824 $ (2,039 ) $ 3,785 $ (1,763 ) $ 618 $ (1,145 ) (1) Reclassification adjustments are comprised of realized security gains or losses. The realized gains or losses have been reclassified out of accumulated other comprehensive income/(loss) and have affected certain lines in the Consolidated Statements of Comprehensive Income as follows; the pre-tax amount is included in securities gains/losses-net, the tax expense amount is included in the provision for income taxes and the net of tax amount is included in net income. Nine Months Ended September 30, 2015 Nine Months Ended September 30, 2014 (dollars in thousands) Pre-Tax Amount Tax (Expense) Benefit Net of Tax Amount Pre-Tax Amount Tax (Expense) Benefit Net of Tax Amount Change in net unrealized gains/(losses) on securities available-for-sale $ 4,288 $ (1,501 ) $ 2,787 $ 7,844 $ (2,746 ) $ 5,098 Reclassification adjustment for net (gains)/losses on securities available-for-sale included in net income (1) 34 (12 ) 22 (41 ) 15 (26 ) Adjustment to funded status of employee benefit plans 1,839 (551 ) 1,288 692 (242 ) 450 Other Comprehensive Income $ 6,161 $ (2,064 ) $ 4,097 $ 8,495 $ (2,973 ) $ 5,522 (1) Reclassification adjustments are comprised of realized security gains or losses. The realized gains or losses have been reclassified out of accumulated other comprehensive income and have affected certain lines in the consolidated statement of comprehensive income as follows; the pre-tax amount is included in securities gains/losses-net, the tax expense amount is included in the provision for income taxes and the net of tax amount is included in net income.

Employee Benefits (Tables)

Employee Benefits (Tables)	9 Months Ended
	Sep. 30, 2015
Compensation and Retirement Disclosure [Abstract]
Components of Net Periodic Pension Cost and Other Changes in Plan Assets and Benefit	The following table summarizes the components of net periodic pension cost for the periods presented: Three Months Ended September 30, Nine Months Ended September 30, (dollars in thousands) 2015 2014 2015 2014 Components of Net Periodic Pension Cost Service cost—benefits earned during the period $ 606 $ 516 $ 1,951 $ 1,778 Interest cost on projected benefit obligation 1,120 1,141 3,319 3,353 Expected return on plan assets (1,772 ) (1,710 ) (5,385 ) (5,180 ) Amortization of prior service (credit) cost (34 ) (34 ) (104 ) (104 ) Recognized net actuarial loss 586 287 1,521 705 Net Periodic Pension Expense $ 506 $ 200 $ 1,302 $ 552

Segments (Tables)

Segments (Tables)	9 Months Ended
	Sep. 30, 2015
Segment Reporting [Abstract]
Total Assets by Reportable Operating Segment	The following table represents total assets by reportable operating segment as of the dates presented: (dollars in thousands) September 30, 2015 December 31, 2014 Community Banking $ 6,203,446 $ 4,954,728 Insurance 8,255 7,468 Wealth Management 3,637 2,490 Total Assets $ 6,215,338 $ 4,964,686
Financial Information of Segments	The following tables provide financial information for our three operating segments for the three and nine month periods ended September 30, 2015 and 2014 . The financial results of the business segments include allocations for shared services based on an internal analysis that supports line of business and branch performance measurement. Shared services include expenses such as employee benefits, occupancy expense, computer support and other corporate overhead. Even with these allocations, the financial results are not necessarily indicative of the business segments’ financial condition and results of operations as if they existed as independent entities. The information provided under the caption “Eliminations” represents operations not considered to be reportable segments and/or general operating expenses and eliminations and adjustments, which are necessary for purposes of reconciling to the Consolidated Financial Statements. Three Months Ended September 30, 2015 (dollars in thousands) Community Banking Insurance Wealth Management Eliminations Consolidated Interest income $ 53,625 $ 1 $ 108 $ (65 ) $ 53,669 Interest expense 4,200 — — (127 ) 4,073 Net interest income 49,425 1 108 62 49,596 Provision for loan losses 3,206 — — — 3,206 Noninterest income 8,651 1,197 2,806 (173 ) 12,481 Noninterest expense 28,941 1,098 2,210 (111 ) 32,138 Depreciation expense 1,192 13 6 — 1,211 Amortization of intangible assets 460 13 7 — 480 Provision for income taxes 6,139 26 242 — 6,407 Net Income $ 18,138 $ 48 $ 449 $ — $ 18,635 Three Months Ended September 30, 2014 (dollars in thousands) Community Banking Insurance Wealth Management Eliminations Consolidated Interest income $ 40,581 $ — $ 109 $ (85 ) $ 40,605 Interest expense 3,435 — — (359 ) 3,076 Net interest income 37,146 — 109 274 37,529 Provision for loan losses 1,454 — — — 1,454 Noninterest income 7,742 1,496 2,748 (55 ) 11,931 Noninterest expense 23,691 1,127 2,245 219 27,282 Depreciation expense 878 13 7 — 898 Amortization of intangible assets 238 13 9 — 260 Provision for income taxes 4,577 120 209 — 4,906 Net Income $ 14,050 $ 223 $ 387 $ — $ 14,660 Nine Months Ended September 30, 2015 (dollars in thousands) Community Banking Insurance Wealth Management Eliminations Consolidated Interest income $ 150,108 $ 2 $ 406 $ (321 ) $ 150,195 Interest expense 12,144 — — (615 ) 11,529 Net interest income 137,964 2 406 294 138,666 Provision for loan losses 6,473 — — — 6,473 Noninterest income 25,056 4,079 8,639 174 37,948 Noninterest expense 87,542 3,288 6,716 468 98,014 Depreciation expense 3,482 39 19 — 3,540 Amortization of intangible assets 1,283 38 24 — 1,345 Provision for income taxes 16,534 250 800 — 17,584 Net Income $ 47,706 $ 466 $ 1,486 $ — $ 49,658 Nine Months Ended September 30, 2014 (dollars in thousands) Community Banking Insurance Wealth Management Eliminations Consolidated Interest income $ 119,055 $ 1 $ 419 $ (333 ) $ 119,142 Interest expense 10,332 — — (1,165 ) 9,167 Net interest income 108,723 1 419 832 109,975 Provision for loan losses 608 — — — 608 Noninterest income 22,118 4,262 8,511 227 35,118 Noninterest expense 72,756 3,327 6,961 1,059 84,103 Depreciation expense 2,485 38 20 — 2,543 Amortization of intangible assets 805 38 30 — 873 Provision for income taxes 12,579 301 672 — 13,552 Net Income $ 41,608 $ 559 $ 1,247 $ — $ 43,414

Basis of Presentation - Additio

Basis of Presentation - Additional Information (Detail)	Sep. 30, 2015
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage of outstanding common stock of investees accounted for using equity method of accounting	20.00%
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage of outstanding common stock of investees accounted for using equity method of accounting	50.00%

Business Combinations - Additio

Business Combinations - Additional Information (Details) - USD ($)	Mar. 04, 2015	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Business Acquisition [Line Items]
Goodwill		$ 291,683,000		$ 291,683,000	$ 291,683,000		$ 175,820,000
Discount on loans acquired		12,000,000		12,000,000	12,000,000		$ 2,000,000
Merger related expenses		0	$ 0		3,167,000	$ 0
Professional services and legal		946,000	$ 950,000		2,270,000	$ 2,488,000
Integrity Bancshares, Inc. [Member]
Business Acquisition [Line Items]
Business acquisition, percentage of voting interests acquired	100.00%
Business acquisition, cash per share offered in exchange of share	$ 52.50
Shares of S&T offered for each share of Integrity (shares)	2.0627
Fair value of total consideration	$ 172,000,000				171,979,000
Cash	$ 29,500,000				29,510,000
S&T common shares issued (shares)	4,933,115
S&T common shares issued, fair value (in USD per share)	$ 28.88
Purchase accounting adjustments, increase to goodwill				1,100,000
Purchase accounting adjustments, decrease to land				800,000
Purchase accounting adjustments, decrease to deferred taxes				300,000
Goodwill	$ 115,900,000	115,862,000		115,862,000	115,862,000
Carryover of allowance for loan losses	0
Fair value of loans acquired	788,700,000	$ 788,687,000		$ 788,687,000	788,687,000
Discount on loans acquired	14,800,000
Merger related expenses					3,200,000
Data processing, contract termination and conversion cost expenses					1,300,000
Professional services and legal					1,200,000
Severance payments					400,000
Other expenses					$ 300,000
Commercial Real Estate [Member] | Integrity Bancshares, Inc. [Member]
Business Acquisition [Line Items]
Fair value of loans acquired	331,600,000
Commercial Construction [Member] | Integrity Bancshares, Inc. [Member]
Business Acquisition [Line Items]
Fair value of loans acquired	92,400,000
Residential Mortgage [Member] | Integrity Bancshares, Inc. [Member]
Business Acquisition [Line Items]
Fair value of loans acquired	116,900,000
Home Equity [Member] | Integrity Bancshares, Inc. [Member]
Business Acquisition [Line Items]
Fair value of loans acquired	25,600,000
Installment and Other Consumer [Member] | Integrity Bancshares, Inc. [Member]
Business Acquisition [Line Items]
Fair value of loans acquired	36,100,000
Consumer Construction [Member] | Integrity Bancshares, Inc. [Member]
Business Acquisition [Line Items]
Fair value of loans acquired	1,900,000
Commercial and Industrial [Member] | Integrity Bancshares, Inc. [Member]
Business Acquisition [Line Items]
Fair value of loans acquired	$ 184,200,000

Business Combinations - Conside

Business Combinations - Consideration, Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Mar. 04, 2015	Sep. 30, 2015	Dec. 31, 2014
Fair Value of Liabilities Assumed
Goodwill		$ 291,683	$ 175,820
Integrity Bancshares, Inc. [Member]
Business Acquisition [Line Items]
Cash	$ 29,500	29,510
Common stock		142,469
Fair value of total consideration	172,000	171,979
Fair Value of Assets Acquired
Cash and cash equivalents		13,163
Securities and other investments		11,502
Loans	788,700	788,687
Bank owned life insurance		15,974
Premises and equipment		10,855
Core deposit intangible		5,713
Other assets		19,076
Total Assets Acquired		864,970
Fair Value of Liabilities Assumed
Deposits		722,308
Borrowings		82,286
Other liabilities		4,259
Total Liabilities Assumed		808,853
Total Fair Value of Identifiable Net Assets		56,117
Goodwill	$ 115,900	$ 115,862

Business Combinations - Pro For

Business Combinations - Pro Forma Information (Details) - Integrity Bancshares, Inc. [Member] - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Business Acquisition, Pro Forma Information [Abstract]
Total revenue	[1]	$ 59,819	$ 58,875	$ 179,559	$ 174,097
Net income	[2]	$ 18,527	$ 18,250	$ 51,406	$ 51,651
Earnings per common share:
Basic (in USD per share)	[2]	$ 0.53	$ 0.53	$ 1.49	$ 1.49
Diluted (in USD per share)	[2]	$ 0.53	$ 0.53	$ 1.48	$ 1.49
[1]	Total pro forma revenue is defined as net interest income plus non-interest income, excluding gains and losses on sales of investment securities available-for-sale.
[2]	Excludes merger expenses

Earnings Per Share - Reconciles

Earnings Per Share - Reconciles Numerators and Denominators of Basic Earnings Per Share with Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Numerator for Earnings per Share-Basic:
Net income	$ 18,635	$ 14,660	$ 49,658	$ 43,414
Less: Income allocated to participating shares	81	51	204	115
Net Income Allocated to Shareholders	18,554	14,609	49,454	43,299
Numerator for Earnings per Share-Diluted:
Net income	18,635	14,660	49,658	43,414
Net Income Available to Shareholders	$ 18,635	$ 14,660	$ 49,658	$ 43,414
Denominators:
Weighted Average Shares Outstanding-Basic	34,660,007	29,693,417	33,527,549	29,679,623
Add: Potentially dilutive shares	32,985	21,195	33,980	25,732
Denominator for Treasury Stock Method-Diluted	34,692,992	29,714,612	33,561,529	29,705,355
Weighted Average Shares Outstanding-Basic	34,660,007	29,693,417	33,527,549	29,679,623
Add: Average participating shares outstanding	151,972	102,980	138,441	78,835
Denominator for Two-Class Method-Diluted	34,811,979	29,796,397	33,665,990	29,758,458
Earnings per share—basic (in dollars per share)	$ 0.54	$ 0.49	$ 1.48	$ 1.46
Earnings per share—diluted (in dollars per share)	0.54	$ 0.49	1.48	$ 1.46
Anti-dilutive warrants - exercise price (in USD per share)	$ 31.53		$ 31.53
Warrants [Member]
Denominators:
Anti-dilutive excluded from potentially dilutive shares	517,012	517,012	517,012	517,012
Stock Options [Member]
Denominators:
Anti-dilutive excluded from potentially dilutive shares	155,500	427,362	155,500	428,233
Restricted Stock [Member]
Denominators:
Anti-dilutive excluded from potentially dilutive shares	118,987	81,785	104,461	53,103

Fair Value Measurement - Additi

Fair Value Measurement - Additional Information (Detail) - USD ($)	Sep. 30, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of asset transfer from Level 1 to Level 2 on recurring basis	$ 200,000	$ 0
Fair value of asset transfer from Level 2 to Level 1 on recurring basis	0	0
Fair value of liabilities transfer from Level 1 to Level 2 on recurring basis	0	0
Fair value of liabilities transfer from Level 2 to Level 1 recurring basis	0	0
Liabilities measured at estimated fair value on nonrecurring basis		0
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at estimated fair value on a recurring basis		0
Liabilities measured at estimated fair value on a recurring basis	0	$ 0
Fair Value Measurements, Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at estimated fair value on a recurring basis	0
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities measured at estimated fair value on nonrecurring basis	$ 0

Fair Value Measurement - Assets

Fair Value Measurement - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
ASSETS
Total securities available-for-sale	$ 660,046	$ 640,273
US Treasury Securities [Member]
ASSETS
Total securities available-for-sale	15,062	14,880
Obligations of U.S. Government Corporations and Agencies [Member]
ASSETS
Total securities available-for-sale	271,332	269,285
Collateralized Mortgage Obligations of U.S. Government Corporations and Agencies [Member]
ASSETS
Total securities available-for-sale	135,216	118,006
Residential Mortgage-Backed Securities of U.S. Government Corporations and Agencies [Member]
ASSETS
Total securities available-for-sale	42,065	46,668
Commercial Mortgage-Backed Securities of U.S. Government Corporations and Agencies [Member]
ASSETS
Total securities available-for-sale	50,223	39,673
Obligations of States and Political Subdivisions [Member]
ASSETS
Total securities available-for-sale	137,335	142,702
Marketable Equity Securities [Member]
ASSETS
Total securities available-for-sale	8,813	9,059
Fair Value Measurements, Recurring [Member]
ASSETS
Total securities available-for-sale	660,046	640,273
Trading securities held in a Rabbi Trust	3,690	3,456
Total securities	663,736	643,729
Total Assets	678,542	656,945
LIABILITIES
Total Liabilities	14,310	13,010
Fair Value Measurements, Recurring [Member] | Interest Rate Swaps [Member]
ASSETS
Derivative financial assets	14,232	12,981
LIABILITIES
Derivative financial liabilities	14,184	12,953
Fair Value Measurements, Recurring [Member] | Interest Rate Lock Commitments [Member]
ASSETS
Derivative financial assets	574	235
Fair Value Measurements, Recurring [Member] | Forward Sale Contracts [Member]
LIABILITIES
Derivative financial liabilities	126	57
Fair Value Measurements, Recurring [Member] | US Treasury Securities [Member]
ASSETS
Total securities available-for-sale	15,062	14,880
Fair Value Measurements, Recurring [Member] | Obligations of U.S. Government Corporations and Agencies [Member]
ASSETS
Total securities available-for-sale	271,332	269,285
Fair Value Measurements, Recurring [Member] | Collateralized Mortgage Obligations of U.S. Government Corporations and Agencies [Member]
ASSETS
Total securities available-for-sale	135,216	118,006
Fair Value Measurements, Recurring [Member] | Residential Mortgage-Backed Securities of U.S. Government Corporations and Agencies [Member]
ASSETS
Total securities available-for-sale	42,065	46,668
Fair Value Measurements, Recurring [Member] | Commercial Mortgage-Backed Securities of U.S. Government Corporations and Agencies [Member]
ASSETS
Total securities available-for-sale	50,223	39,673
Fair Value Measurements, Recurring [Member] | Obligations of States and Political Subdivisions [Member]
ASSETS
Total securities available-for-sale	137,335	142,702
Fair Value Measurements, Recurring [Member] | Marketable Equity Securities [Member]
ASSETS
Total securities available-for-sale	8,813	9,059
Level 1 [Member] | Fair Value Measurements, Recurring [Member]
ASSETS
Total securities available-for-sale	0	178
Trading securities held in a Rabbi Trust	3,690	3,456
Total securities	3,690	3,634
Total Assets	3,690	3,634
LIABILITIES
Total Liabilities	0	0
Level 1 [Member] | Fair Value Measurements, Recurring [Member] | US Treasury Securities [Member]
ASSETS
Total securities available-for-sale		0
Level 1 [Member] | Fair Value Measurements, Recurring [Member] | Marketable Equity Securities [Member]
ASSETS
Total securities available-for-sale	0	178
Level 2 [Member] | Fair Value Measurements, Recurring [Member]
ASSETS
Total securities available-for-sale	660,046	640,095
Total securities	660,046	640,095
Total Assets	674,852	653,311
LIABILITIES
Total Liabilities	14,310	13,010
Level 2 [Member] | Fair Value Measurements, Recurring [Member] | Interest Rate Swaps [Member]
ASSETS
Derivative financial assets	14,232	12,981
LIABILITIES
Derivative financial liabilities	14,184	12,953
Level 2 [Member] | Fair Value Measurements, Recurring [Member] | Interest Rate Lock Commitments [Member]
ASSETS
Derivative financial assets	574	235
Level 2 [Member] | Fair Value Measurements, Recurring [Member] | Forward Sale Contracts [Member]
LIABILITIES
Derivative financial liabilities	126	57
Level 2 [Member] | Fair Value Measurements, Recurring [Member] | US Treasury Securities [Member]
ASSETS
Total securities available-for-sale	15,062	14,880
Level 2 [Member] | Fair Value Measurements, Recurring [Member] | Obligations of U.S. Government Corporations and Agencies [Member]
ASSETS
Total securities available-for-sale	271,332	269,285
Level 2 [Member] | Fair Value Measurements, Recurring [Member] | Collateralized Mortgage Obligations of U.S. Government Corporations and Agencies [Member]
ASSETS
Total securities available-for-sale	135,216	118,006
Level 2 [Member] | Fair Value Measurements, Recurring [Member] | Residential Mortgage-Backed Securities of U.S. Government Corporations and Agencies [Member]
ASSETS
Total securities available-for-sale	42,065	46,668
Level 2 [Member] | Fair Value Measurements, Recurring [Member] | Commercial Mortgage-Backed Securities of U.S. Government Corporations and Agencies [Member]
ASSETS
Total securities available-for-sale	50,223	39,673
Level 2 [Member] | Fair Value Measurements, Recurring [Member] | Obligations of States and Political Subdivisions [Member]
ASSETS
Total securities available-for-sale	137,335	142,702
Level 2 [Member] | Fair Value Measurements, Recurring [Member] | Marketable Equity Securities [Member]
ASSETS
Total securities available-for-sale	8,813	8,881
Level 3 [Member] | Fair Value Measurements, Recurring [Member]
LIABILITIES
Total Liabilities	$ 0
Level 3 [Member] | Fair Value Measurements, Recurring [Member] | US Treasury Securities [Member]
ASSETS
Total securities available-for-sale		$ 0

Fair Value Measurement - Asse42

Fair Value Measurement - Assets Measured at Estimated Fair Value on Nonrecurring Basis by Fair Value Hierarchy (Detail) - Fair Value, Measurements, Nonrecurring [Member] - USD ($) $ in Thousands		Sep. 30, 2015	Dec. 31, 2014
ASSETS
Loans held for sale	[1]	$ 216
Impaired loans	[1]	8,870	$ 12,916
Other real estate owned	[1]	439	117
Mortgage servicing rights	[1]	1,827	2,934
Total Assets	[1]	11,352	15,967
Level 3 [Member]
ASSETS
Loans held for sale	[1]	216
Impaired loans	[1]	8,870	12,916
Other real estate owned	[1]	439	117
Mortgage servicing rights	[1]	1,827	2,934
Total Assets	[1]	$ 11,352	$ 15,967
[1]	This table represents only the nonrecurring items that are recorded at fair value in our financial statements.

Fair Value Measurement - Carryi

Fair Value Measurement - Carrying Values and Fair Values of Financial Instruments (Detail) - USD ($) $ in Thousands		Sep. 30, 2015	Dec. 31, 2014
ASSETS
Securities available-for-sale		$ 660,046	$ 640,273
FHLB and other restricted stock		20,352	15,135
LIABILITIES
Junior subordinated debt securities		45,619	45,619
Carrying Value [Member]
ASSETS
Cash and due from banks, including interest-bearing deposits	[1]	115,347	109,580
Securities available-for-sale	[1]	660,046	640,273
Loans held for sale	[1]	13,794	2,970
Portfolio loans, net of unearned income	[1]	4,925,963	3,868,746
Bank owned life insurance	[1]	79,894	62,252
FHLB and other restricted stock	[1]	20,352	15,135
Trading securities held in a Rabbi Trust	[1]	3,690	3,456
Mortgage servicing rights	[1]	3,083	2,817
LIABILITIES
Deposits	[1]	4,877,409	3,908,842
Securities sold under repurchase agreements	[1]	42,971	30,605
Short-term borrowings	[1]	280,000	290,000
Long-term borrowings	[1]	117,613	19,442
Junior subordinated debt securities	[1]	45,619	45,619
Carrying Value [Member] | Interest Rate Swaps [Member]
ASSETS
Derivative financial assets	[1]	14,232	12,981
LIABILITIES
Derivative financial liabilities	[1]	14,184	12,953
Carrying Value [Member] | Interest Rate Lock Commitments [Member]
ASSETS
Derivative financial assets	[1]	574	235
Carrying Value [Member] | Forward Sale Contracts [Member]
LIABILITIES
Derivative financial liabilities	[1]	126	57
Fair Value Measurements [Member]
ASSETS
Cash and due from banks, including interest-bearing deposits		115,347	109,580
Securities available-for-sale		660,046	640,273
Loans held for sale		14,134	2,991
Portfolio loans, net of unearned income		4,902,661	3,827,634
Bank owned life insurance		79,894	62,252
FHLB and other restricted stock		20,352	15,135
Trading securities held in a Rabbi Trust		3,690	3,456
Mortgage servicing rights		3,170	2,934
LIABILITIES
Deposits		4,883,132	3,910,342
Securities sold under repurchase agreements		42,971	30,605
Short-term borrowings		280,000	290,000
Long-term borrowings		118,646	20,462
Junior subordinated debt securities		45,619	45,619
Fair Value Measurements [Member] | Level 1 [Member]
ASSETS
Cash and due from banks, including interest-bearing deposits		115,347	109,580
Securities available-for-sale		0	178
Loans held for sale		0	0
Portfolio loans, net of unearned income		0	0
Bank owned life insurance		0	0
FHLB and other restricted stock		0	0
Trading securities held in a Rabbi Trust		3,690	3,456
Mortgage servicing rights		0	0
LIABILITIES
Deposits		0	0
Securities sold under repurchase agreements		0	0
Short-term borrowings		0	0
Long-term borrowings		0	0
Junior subordinated debt securities		0	0
Fair Value Measurements [Member] | Level 2 [Member]
ASSETS
Cash and due from banks, including interest-bearing deposits		0	0
Securities available-for-sale		660,046	640,095
Loans held for sale		0	0
Portfolio loans, net of unearned income		0	0
Bank owned life insurance		79,894	62,252
FHLB and other restricted stock		0	0
Trading securities held in a Rabbi Trust		0	0
Mortgage servicing rights		0	0
LIABILITIES
Deposits		0	0
Securities sold under repurchase agreements		0	0
Short-term borrowings		0	0
Long-term borrowings		0	0
Junior subordinated debt securities		0	0
Fair Value Measurements [Member] | Level 3 [Member]
ASSETS
Cash and due from banks, including interest-bearing deposits		0	0
Securities available-for-sale		0	0
Loans held for sale		14,134	2,991
Portfolio loans, net of unearned income		4,902,661	3,827,634
Bank owned life insurance		0	0
FHLB and other restricted stock		20,352	15,135
Trading securities held in a Rabbi Trust		0	0
Mortgage servicing rights		3,170	2,934
LIABILITIES
Deposits		4,883,132	3,910,342
Securities sold under repurchase agreements		42,971	30,605
Short-term borrowings		280,000	290,000
Long-term borrowings		118,646	20,462
Junior subordinated debt securities		45,619	45,619
Fair Value Measurements [Member] | Interest Rate Swaps [Member]
ASSETS
Derivative financial assets		14,232	12,981
LIABILITIES
Derivative financial liabilities		14,184	12,953
Fair Value Measurements [Member] | Interest Rate Swaps [Member] | Level 1 [Member]
ASSETS
Derivative financial assets		0	0
LIABILITIES
Derivative financial liabilities		0	0
Fair Value Measurements [Member] | Interest Rate Swaps [Member] | Level 2 [Member]
ASSETS
Derivative financial assets		14,232	12,981
LIABILITIES
Derivative financial liabilities		14,184	12,953
Fair Value Measurements [Member] | Interest Rate Swaps [Member] | Level 3 [Member]
ASSETS
Derivative financial assets		0	0
LIABILITIES
Derivative financial liabilities		0	0
Fair Value Measurements [Member] | Interest Rate Lock Commitments [Member]
ASSETS
Derivative financial assets		574	235
Fair Value Measurements [Member] | Interest Rate Lock Commitments [Member] | Level 1 [Member]
ASSETS
Derivative financial assets		0	0
Fair Value Measurements [Member] | Interest Rate Lock Commitments [Member] | Level 2 [Member]
ASSETS
Derivative financial assets		574	235
Fair Value Measurements [Member] | Interest Rate Lock Commitments [Member] | Level 3 [Member]
ASSETS
Derivative financial assets		0	0
Fair Value Measurements [Member] | Forward Sale Contracts [Member]
LIABILITIES
Derivative financial liabilities		126	57
Fair Value Measurements [Member] | Forward Sale Contracts [Member] | Level 1 [Member]
LIABILITIES
Derivative financial liabilities		0	0
Fair Value Measurements [Member] | Forward Sale Contracts [Member] | Level 2 [Member]
LIABILITIES
Derivative financial liabilities		126	57
Fair Value Measurements [Member] | Forward Sale Contracts [Member] | Level 3 [Member]
LIABILITIES
Derivative financial liabilities		$ 0	$ 0
[1]	As reported in the Consolidated Balance Sheets.

Securities Available-for-Sale -

Securities Available-for-Sale - Composition of Securities Available-for-Sale (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 644,914	$ 629,463
Gross Unrealized Gains	15,346	12,647
Gross Unrealized Losses	(214)	(1,837)
Fair Value	660,046	640,273
US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	14,903	14,873
Gross Unrealized Gains	159	7
Fair Value	15,062	14,880
Obligations of U.S. Government Corporations and Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	267,328	268,029
Gross Unrealized Gains	4,032	2,334
Gross Unrealized Losses	(28)	(1,078)
Fair Value	271,332	269,285
Collateralized Mortgage Obligations of U.S. Government Corporations and Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	132,691	116,897
Gross Unrealized Gains	2,536	1,257
Gross Unrealized Losses	(11)	(148)
Fair Value	135,216	118,006
Residential Mortgage-Backed Securities of U.S. Government Corporations and Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	40,678	45,274
Gross Unrealized Gains	1,467	1,548
Gross Unrealized Losses	(80)	(154)
Fair Value	42,065	46,668
Commercial Mortgage-Backed Securities of U.S. Government Corporations and Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	49,596	39,834
Gross Unrealized Gains	669	232
Gross Unrealized Losses	(42)	(393)
Fair Value	50,223	39,673
Obligations of States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	132,139	136,977
Gross Unrealized Gains	5,249	5,789
Gross Unrealized Losses	(53)	(64)
Fair Value	137,335	142,702
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	637,335	621,884
Gross Unrealized Gains	14,112	11,167
Gross Unrealized Losses	(214)	(1,837)
Fair Value	651,233	631,214
Marketable Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	7,579	7,579
Gross Unrealized Gains	1,234	1,480
Fair Value	$ 8,813	$ 9,059

Securities Available-for-Sale45

Securities Available-for-Sale - Schedule of Gross and Net Realized Gains and Losses on Sale of Securities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Investments, Debt and Equity Securities [Abstract]
Gross realized gains		$ 0		$ 41
Gross realized losses	$ 0		$ (34)
Net Realized Gains	$ 0	$ 0	$ (34)	$ 41

Securities Available-for-Sale46

Securities Available-for-Sale - Fair Value and Age of Gross Unrealized Losses by Investment Category (Detail) $ in Thousands	Sep. 30, 2015USD ($)security	Dec. 31, 2014USD ($)security
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale, Securities, Less Than 12 Months, Number of Positions | security	4	7
Available-for-sale Securities, Less Than 12 Months, Fair Value	$ 29,737	$ 59,329
Available-for-sale Securities, Less Than 12 Months, Unrealized Losses	$ (144)	$ (381)
Available-for-sale, Securities, 12 Months or More, Number of Positions | security	3	13
Available-for-sale Securities, 12 Months or More, Fair Value	$ 24,429	$ 103,527
Available-for-sale Securities, 12 Months or More, Unrealized Losses	$ (70)	$ (1,456)
Available-for-sale, Securities, Number of Positions | security	7	20
Available-for-sale Securities, Fair Value, Total	$ 54,166	$ 162,856
Available-for-sale Securities, Unrealized Losses, Total	$ (214)	$ (1,837)
Obligations of U.S. Government Corporations and Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale, Securities, Less Than 12 Months, Number of Positions | security	0	4
Available-for-sale Securities, Less Than 12 Months, Fair Value	$ 0	$ 39,745
Available-for-sale Securities, Less Than 12 Months, Unrealized Losses	$ 0	$ (207)
Available-for-sale, Securities, 12 Months or More, Number of Positions | security	2	8
Available-for-sale Securities, 12 Months or More, Fair Value	$ 14,720	$ 63,149
Available-for-sale Securities, 12 Months or More, Unrealized Losses	$ (28)	$ (871)
Available-for-sale, Securities, Number of Positions | security	2	12
Available-for-sale Securities, Fair Value, Total	$ 14,720	$ 102,894
Available-for-sale Securities, Unrealized Losses, Total	$ (28)	$ (1,078)
Collateralized Mortgage Obligations of U.S. Government Corporations and Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale, Securities, Less Than 12 Months, Number of Positions | security	1	1
Available-for-sale Securities, Less Than 12 Months, Fair Value	$ 10,694	$ 9,323
Available-for-sale Securities, Less Than 12 Months, Unrealized Losses	$ (11)	$ (148)
Available-for-sale, Securities, Number of Positions | security	1	1
Available-for-sale Securities, Fair Value, Total	$ 10,694	$ 9,323
Available-for-sale Securities, Unrealized Losses, Total	$ (11)	$ (148)
Residential Mortgage-Backed Securities of U.S. Government Corporations and Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale, Securities, Less Than 12 Months, Number of Positions | security	1
Available-for-sale Securities, Less Than 12 Months, Fair Value	$ 8,377
Available-for-sale Securities, Less Than 12 Months, Unrealized Losses	$ (80)
Available-for-sale, Securities, 12 Months or More, Number of Positions | security		1
Available-for-sale Securities, 12 Months or More, Fair Value		$ 8,982
Available-for-sale Securities, 12 Months or More, Unrealized Losses		$ (154)
Available-for-sale, Securities, Number of Positions | security	1	1
Available-for-sale Securities, Fair Value, Total	$ 8,377	$ 8,982
Available-for-sale Securities, Unrealized Losses, Total	$ (80)	$ (154)
Commercial Mortgage-Backed Securities of U.S. Government Corporations and Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale, Securities, Less Than 12 Months, Number of Positions | security		1
Available-for-sale Securities, Less Than 12 Months, Fair Value		$ 9,998
Available-for-sale Securities, Less Than 12 Months, Unrealized Losses		$ (25)
Available-for-sale, Securities, 12 Months or More, Number of Positions | security	1	2
Available-for-sale Securities, 12 Months or More, Fair Value	$ 9,709	$ 20,640
Available-for-sale Securities, 12 Months or More, Unrealized Losses	$ (42)	$ (368)
Available-for-sale, Securities, Number of Positions | security	1	3
Available-for-sale Securities, Fair Value, Total	$ 9,709	$ 30,638
Available-for-sale Securities, Unrealized Losses, Total	$ (42)	$ (393)
Obligations of States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale, Securities, Less Than 12 Months, Number of Positions | security	2	1
Available-for-sale Securities, Less Than 12 Months, Fair Value	$ 10,666	$ 263
Available-for-sale Securities, Less Than 12 Months, Unrealized Losses	$ (53)	$ (1)
Available-for-sale, Securities, 12 Months or More, Number of Positions | security		2
Available-for-sale Securities, 12 Months or More, Fair Value		$ 10,756
Available-for-sale Securities, 12 Months or More, Unrealized Losses		$ (63)
Available-for-sale, Securities, Number of Positions | security	2	3
Available-for-sale Securities, Fair Value, Total	$ 10,666	$ 11,019
Available-for-sale Securities, Unrealized Losses, Total	$ (53)	$ (64)

Securities Available-for-Sale47

Securities Available-for-Sale - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2015USD ($)security	Dec. 31, 2014USD ($)
Schedule of Available-for-sale Securities [Line Items]
Number of debt securities on which unrealized losses were primarily attributable to changes in interest | security	7
Carrying values of securities	$ 296,100,000	$ 289,100,000
Marketable Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses reclassified out of accumulated other comprehensive income into earnings	$ 0

Securities Available-for-sale48

Securities Available-for-sale - Unrealized Gains (Losses) (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Total unrealized gains/(losses) on securities available for sale, Gross Unrealized Gains	$ 15,346	$ 12,647
Total unrealized gains/(losses) on securities available for sale, Gross Unrealized Losses	(214)	(1,837)
Total unrealized gains/(losses) on securities available for sale, Net Unrealized Gains/(Losses)	15,132	10,810
Income tax expense/(benefit), Gross Unrealized Gains	5,371	4,426
Income tax expense/(benefit), Gross Unrealized Losses	(75)	(643)
Income tax expense/(benefit), Net Unrealized Gains/ (Losses)	5,296	3,783
Net unrealized gains/(losses), net of tax included in accumulated other comprehensive income/(loss), Gross Unrealized Gains	9,975	8,221
Net unrealized gains/(losses), net of tax included in accumulated other comprehensive income/(loss), Gross Unrealized Losses	(139)	(1,194)
Net unrealized gains/(losses), net of tax included in accumulated other comprehensive income/(loss), Net Unrealized Gains/ (Losses)	$ 9,836	$ 7,027

Securities Available-for-Sale49

Securities Available-for-Sale - 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]
Amortized Cost	$ 644,914	$ 629,463
Fair Value	660,046	640,273
Obligations of the U.S. Treasury and U.S. government corporations and agencies, and obligations of states and political subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Due in one year or less, Amortized Cost	37,404
Due after one year through five years, Amortized Cost	224,669
Due after five years through ten years, Amortized Cost	65,260
Due after ten years, Amortized Cost	87,037
Available-for-sale Securities, Debt Maturities, Amortized Cost	414,370
Due in one year or less, Fair Value	37,767
Due after one year through five years, Fair Value	228,005
Due after five years through ten years, Fair Value	67,613
Due after ten years, Fair Value	90,344
Fair Value, Debt securities	423,729
Collateralized Mortgage Obligations of U.S. Government Corporations and Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	132,691	116,897
Fair Value	135,216	118,006
Residential Mortgage-Backed Securities of U.S. Government Corporations and Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	40,678	45,274
Fair Value	42,065	46,668
Commercial Mortgage-Backed Securities of U.S. Government Corporations and Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	49,596	39,834
Fair Value	50,223	39,673
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	637,335	621,884
Fair Value	651,233	631,214
Marketable Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	7,579	7,579
Fair Value	$ 8,813	$ 9,059

Loans and Loans Held for Sale -

Loans and Loans Held for Sale - Additional Information (Detail) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2015USD ($)SecurityLoan	Sep. 30, 2015USD ($)SecurityLoan	Mar. 04, 2015USD ($)	Dec. 31, 2014USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, unearned income	$ 2,700	$ 2,700		$ 2,100
Discount on loans related to purchase accounting fair value adjustments	$ 12,000	$ 12,000		$ 2,000
Percentage of commercial loans in total portfolio loans	76.00%	76.00%		75.00%
Commercial Loans	$ 3,733,828	$ 3,733,828		$ 2,892,522
Concentration Risk, Product		no
Maximum concentration of commercial real estate and commercial construction portfolio in loans (in excess of)	7.00%	7.00%		7.00%
Minimum period of loan payment defaults following restructure for TDRs to be in default		90 days
Commercial Real Estate and Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial Loans	$ 2,500,000	$ 2,500,000
Combined percentage of commercial real estate and commercial construction in total commercial loans	67.00%	67.00%		66.00%
Combined percentage of commercial real estate and commercial construction in total portfolio loans	51.00%	51.00%		49.00%
Out of market exposure of combined portfolio (percent)	6.40%	6.40%		8.00%
Percentage of total loans out-of-state excluding contiguous states	3.30%	3.30%		3.90%
Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial Loans	$ 384,328	$ 384,328		$ 216,148
Number Of Loans Modified Not Considered To Be Troubled Debt Restructuring | SecurityLoan	11	13
Loans modified not considered to be troubled debt restructuring	$ 7,100	$ 8,400
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial Loans	$ 2,111,585	$ 2,111,585		1,682,236
Number Of Loans Modified Not Considered To Be Troubled Debt Restructuring | SecurityLoan	3	6
Loans modified not considered to be troubled debt restructuring	$ 4,300	$ 5,300
Home Equity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number Of Loans Modified Not Considered To Be Troubled Debt Restructuring | SecurityLoan	1	3
Loans modified not considered to be troubled debt restructuring	$ 100	$ 300
Residential Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number Of Loans Modified Not Considered To Be Troubled Debt Restructuring | SecurityLoan	1	1
Loans modified not considered to be troubled debt restructuring	$ 100	$ 100
Integrity Bancshares, Inc. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Discount on loans related to purchase accounting fair value adjustments			$ 14,800
Integrity Bancshares, Inc. [Member] | Commercial Real Estate and Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial Loans	424,000	424,000
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial Loans	$ 1,237,915	$ 1,237,915		$ 994,138
Number Of Loans Modified Not Considered To Be Troubled Debt Restructuring | SecurityLoan	2	8
Loans modified not considered to be troubled debt restructuring	$ 1,100	$ 6,800

Loans and Loans Held for Sale51

Loans and Loans Held for Sale - Composition of Loans (Detail) - USD ($) $ in Thousands		Sep. 30, 2015	Dec. 31, 2014
Composition of the loans
Commercial Loans		$ 3,733,828	$ 2,892,522
Consumer Loans		1,192,135	976,224
Total Portfolio Loans	[1]	4,925,963	3,868,746
Loans held for sale		13,794	2,970
Total Loans		4,939,757	3,871,716
Commercial Real Estate [Member]
Composition of the loans
Commercial Loans		2,111,585	1,682,236
Total Portfolio Loans	[1]	2,111,585	1,682,236
Total Loans		2,111,585	1,682,236
Commercial Construction [Member]
Composition of the loans
Commercial Loans		384,328	216,148
Total Portfolio Loans	[1]	384,328	216,148
Total Loans		384,328	216,148
Residential Mortgage [Member]
Composition of the loans
Consumer Loans		625,251	489,586
Total Loans		625,251	489,586
Home Equity [Member]
Composition of the loans
Consumer Loans		467,698	418,563
Total Loans		467,698	418,563
Installment and Other Consumer [Member]
Composition of the loans
Consumer Loans		91,122	65,567
Total Loans		91,122	65,567
Consumer Construction [Member]
Composition of the loans
Consumer Loans		8,064	2,508
Total Loans		8,064	2,508
Commercial and Industrial [Member]
Composition of the loans
Commercial Loans		1,237,915	994,138
Total Portfolio Loans	[1]	1,237,915	994,138
Total Loans		$ 1,237,915	$ 994,138
[1]	Includes acquired loans.

Loans and Loans Held for Sale52

Loans and Loans Held for Sale - Restructured Loans for Periods Presented (Detail) $ in Thousands	3 Months Ended				9 Months Ended				12 Months Ended
	Sep. 30, 2015USD ($)SecurityLoan		Sep. 30, 2014USD ($)SecurityLoan		Sep. 30, 2015USD ($)SecurityLoan		Sep. 30, 2014USD ($)SecurityLoan		Dec. 31, 2014USD ($)
Financing Receivable, Modifications [Line Items]
Threshold period of satisfactory performance for TDR to be restored to accruing status					6 months
Restructured loans	$ 1,578	[1]	$ 1,179	[1]	$ 5,353	[2]	$ 3,198	[2]
Number of TDRs returned to accruing status | SecurityLoan	3		5		9		10
TDRs returned to accruing status	$ 200		$ 500		$ 500		$ 2,000
Performing Financial Instruments [Member]
Financing Receivable, Modifications [Line Items]
Restructured loans					26,049				$ 36,983
Performing Financial Instruments [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Restructured loans					8,062				16,939
Performing Financial Instruments [Member] | Commercial Construction [Member]
Financing Receivable, Modifications [Line Items]
Restructured loans					5,627				5,736
Performing Financial Instruments [Member] | Residential Mortgage [Member]
Financing Receivable, Modifications [Line Items]
Restructured loans					2,609				2,839
Performing Financial Instruments [Member] | Home Equity [Member]
Financing Receivable, Modifications [Line Items]
Restructured loans					3,363				3,342
Performing Financial Instruments [Member] | Installment and Other Consumer [Member]
Financing Receivable, Modifications [Line Items]
Restructured loans					28				53
Nonperforming Financial Instruments [Member]
Financing Receivable, Modifications [Line Items]
Restructured loans					8,092				5,436
Nonperforming Financial Instruments [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Restructured loans					3,552				2,180
Nonperforming Financial Instruments [Member] | Commercial Construction [Member]
Financing Receivable, Modifications [Line Items]
Restructured loans					1,610				1,869
Nonperforming Financial Instruments [Member] | Residential Mortgage [Member]
Financing Receivable, Modifications [Line Items]
Restructured loans					591				459
Nonperforming Financial Instruments [Member] | Home Equity [Member]
Financing Receivable, Modifications [Line Items]
Restructured loans					412				562
Nonperforming Financial Instruments [Member] | Installment and Other Consumer [Member]
Financing Receivable, Modifications [Line Items]
Restructured loans					88				10
Financing Receivable [Member]
Financing Receivable, Modifications [Line Items]
Restructured loans					34,141				42,419
Financing Receivable [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Restructured loans					11,614				19,119
Financing Receivable [Member] | Commercial Construction [Member]
Financing Receivable, Modifications [Line Items]
Restructured loans					7,237				7,605
Financing Receivable [Member] | Residential Mortgage [Member]
Financing Receivable, Modifications [Line Items]
Restructured loans					3,200				3,298
Financing Receivable [Member] | Home Equity [Member]
Financing Receivable, Modifications [Line Items]
Restructured loans					3,775				3,904
Financing Receivable [Member] | Installment and Other Consumer [Member]
Financing Receivable, Modifications [Line Items]
Restructured loans					116				63
Commercial and Industrial [Member] | Performing Financial Instruments [Member]
Financing Receivable, Modifications [Line Items]
Restructured loans					6,360				8,074
Commercial and Industrial [Member] | Nonperforming Financial Instruments [Member]
Financing Receivable, Modifications [Line Items]
Restructured loans					1,839				356
Commercial and Industrial [Member] | Financing Receivable [Member]
Financing Receivable, Modifications [Line Items]
Restructured loans					$ 8,199				$ 8,430
[1]	Excludes loans that were fully paid off or fully charged-off by period end. The pre-modification balance represents the balance outstanding prior to modification. The post-modification balance represents the outstanding balance at period end.
[2]	Excludes loans that were fully paid off or fully charged-off by period end. The pre-modification balance represents the balance outstanding prior to modification. The post-modification balance represents the outstanding balance at period end.

Loans and Loans Held for Sale53

Loans and Loans Held for Sale - Restructured Loans for Periods Stated (Detail) $ in Thousands		3 Months Ended				9 Months Ended
		Sep. 30, 2015USD ($)SecurityLoan		Sep. 30, 2014USD ($)SecurityLoan		Sep. 30, 2015USD ($)SecurityLoan		Sep. 30, 2014USD ($)SecurityLoan
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan		14		12		41		31
Pre-Modification Outstanding Recorded Investment		$ 1,593	[1]	$ 1,210	[1]	$ 7,001	[2]	$ 3,252	[2]
Post-Modification Outstanding Recorded Investment		1,578	[1]	1,179	[1]	5,353	[2]	3,198	[2]
Total Difference in Recorded Investment		$ (15)		$ (31)		$ (1,648)		$ (54)
Principal Forgiveness [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan						1		0
Pre-Modification Outstanding Recorded Investment	[2]					$ 400		$ 0
Post-Modification Outstanding Recorded Investment	[2]					273		0
Total Difference in Recorded Investment						$ (127)		$ 0
Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan				3		9		4
Pre-Modification Outstanding Recorded Investment				$ 868	[1]	$ 3,616	[2]	$ 997	[2]
Post-Modification Outstanding Recorded Investment				841	[1]	2,204	[2]	968	[2]
Total Difference in Recorded Investment				$ (27)		$ (1,412)		$ (29)
Principal Deferral [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan				1		2		2
Pre-Modification Outstanding Recorded Investment				$ 487	[1]	$ 2,851	[2]	$ 616	[2]
Post-Modification Outstanding Recorded Investment				475	[1]	1,841	[2]	602	[2]
Total Difference in Recorded Investment				$ (12)		$ (1,010)		(14)
Principal Deferral [Member] | Commercial Construction [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan						1
Pre-Modification Outstanding Recorded Investment	[2]					$ 104		0
Post-Modification Outstanding Recorded Investment	[2]					0		$ 0
Total Difference in Recorded Investment						$ (104)
Chapter 7 Bankruptcy [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan		8	[3]	7	[3]	21	[4]	24	[4]
Pre-Modification Outstanding Recorded Investment		$ 198	[1],[3]	$ 246	[1],[3]	$ 514	[2],[4]	$ 1,140	[2],[4]
Post-Modification Outstanding Recorded Investment		188	[1],[3]	242	[1],[3]	467	[2],[4]	1,115	[2],[4]
Total Difference in Recorded Investment		$ (10)	[3]	$ (4)	[3]	$ (47)		$ (25)	[4]
Chapter 7 Bankruptcy [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan		0	[3]	1	[3]	0	[4]	1	[4]
Pre-Modification Outstanding Recorded Investment		$ 0	[1],[3]	$ 83	[1],[3]	$ 0	[2],[4]	$ 83	[2],[4]
Post-Modification Outstanding Recorded Investment		$ 0	[1],[3]	$ 83	[1],[3]	$ 0	[2],[4]	83	[2],[4]
Total Difference in Recorded Investment	[4]							$ 0
Chapter 7 Bankruptcy [Member] | Residential Mortgage [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan		2	[3]	2	[3]	2	[4]	7	[4]
Pre-Modification Outstanding Recorded Investment		$ 74	[1],[3]	$ 135	[1],[3]	$ 74	[2],[4]	$ 464	[2],[4]
Post-Modification Outstanding Recorded Investment		$ 74	[1],[3]	134	[1],[3]	$ 74	[2],[4]	461	[2],[4]
Total Difference in Recorded Investment				$ (1)	[3]			$ (3)	[4]
Chapter 7 Bankruptcy [Member] | Home Equity [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan		5	[3]	2	[3]	17	[4]	12	[4]
Pre-Modification Outstanding Recorded Investment		$ 115	[1],[3]	$ 14	[1],[3]	$ 428	[2],[4]	$ 283	[2],[4]
Post-Modification Outstanding Recorded Investment		110	[1],[3]	$ 14	[1],[3]	389	[2],[4]	265	[2],[4]
Total Difference in Recorded Investment		$ (5)	[3]			$ (39)	[4]	$ (18)	[4]
Chapter 7 Bankruptcy [Member] | Installment and Other Consumer [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan		1	[3]	2	[3]	1	[4]	3	[4]
Pre-Modification Outstanding Recorded Investment		$ 9	[1],[3]	$ 14	[1],[3]	$ 9	[2],[4]	$ 23	[2],[4]
Post-Modification Outstanding Recorded Investment		4	[1],[3]	11	[1],[3]	4	[2],[4]	20	[2],[4]
Total Difference in Recorded Investment		$ (5)	[3]	$ (3)	[3]	$ (5)	[4]	$ (3)	[4]
Interest Rate Reduction and Maturity Date Extension [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan		2		2		4		2
Pre-Modification Outstanding Recorded Investment		$ 138		$ 96		$ 363	[2]	$ 96	[2]
Post-Modification Outstanding Recorded Investment		$ 138		$ 96		367	[2]	96	[2]
Total Difference in Recorded Investment						$ 4
Interest Rate Reduction and Maturity Date Extension [Member] | Residential Mortgage [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan						2
Pre-Modification Outstanding Recorded Investment	[2]					$ 225		0
Post-Modification Outstanding Recorded Investment	[2]					229		$ 0
Total Difference in Recorded Investment						$ 4
Interest Rate Reduction and Maturity Date Extension [Member] | Home Equity [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan		2		2		2		2
Pre-Modification Outstanding Recorded Investment		$ 138	[1]	$ 96	[1]	$ 138	[2]	$ 96	[2]
Post-Modification Outstanding Recorded Investment		$ 138	[1]	$ 96	[1]	138	[2]	96	[2]
Total Difference in Recorded Investment						$ 0		$ 0
Maturity Date Extension [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan		4		0		6		1
Pre-Modification Outstanding Recorded Investment		$ 1,257	[1]	$ 0	[1]	$ 2,108	[2]	$ 1,019	[2]
Post-Modification Outstanding Recorded Investment		1,252	[1]	0	[1]	2,042	[2]	$ 1,019	[2]
Total Difference in Recorded Investment		$ (5)		$ 0		$ (66)
Maturity Date Extension [Member] | Commercial Construction [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan		2		0
Pre-Modification Outstanding Recorded Investment	[1]	$ 813		$ 0
Post-Modification Outstanding Recorded Investment	[1]	812		0
Total Difference in Recorded Investment		$ (1)		$ 0
Maturity Date Extension [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan		1		0		1		0
Pre-Modification Outstanding Recorded Investment		$ 264	[1]	$ 0	[1]	$ 264	[2]	$ 0	[2]
Post-Modification Outstanding Recorded Investment		260	[1]	0	[1]	260	[2]	0	[2]
Total Difference in Recorded Investment		$ (4)		$ 0		$ (4)		$ 0
Maturity Date Extension [Member] | Commercial Construction [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan						2		1
Pre-Modification Outstanding Recorded Investment	[2]					$ 813		$ 1,019
Post-Modification Outstanding Recorded Investment	[2]					812		1,019
Total Difference in Recorded Investment						$ (1)
Maturity Date Extension [Member] | Residential Mortgage [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan		1		0
Pre-Modification Outstanding Recorded Investment		$ 180	[2]	$ 0	[1]
Post-Modification Outstanding Recorded Investment		$ 180	[2]	$ 0	[1]
Maturity Date Extension [Member] | Home Equity [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan						1
Pre-Modification Outstanding Recorded Investment	[2]					$ 71		0
Post-Modification Outstanding Recorded Investment	[2]					70		$ 0
Total Difference in Recorded Investment						$ (1)
Commercial and Industrial [Member] | Principal Forgiveness [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan						1		0
Pre-Modification Outstanding Recorded Investment	[2]					$ 400		$ 0
Post-Modification Outstanding Recorded Investment	[2]					273		$ 0
Total Difference in Recorded Investment						$ (127)
Commercial and Industrial [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan		0		2		6		2
Pre-Modification Outstanding Recorded Investment		$ 0	[1]	$ 381	[1]	$ 661	[2]	$ 381	[2]
Post-Modification Outstanding Recorded Investment		0	[1]	366	[1]	363	[2]	366	[2]
Total Difference in Recorded Investment		$ 0		$ (15)		$ (298)		$ (15)
Commercial and Industrial [Member] | Chapter 7 Bankruptcy [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan	[4]					1		1
Pre-Modification Outstanding Recorded Investment	[2],[4]					$ 3		$ 287
Post-Modification Outstanding Recorded Investment	[2],[4]					0		286
Total Difference in Recorded Investment	[4]					$ (3)		(1)
Commercial and Industrial [Member] | Maturity Date Extension [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan						1
Pre-Modification Outstanding Recorded Investment	[2]					$ 780		0
Post-Modification Outstanding Recorded Investment	[2]					720		$ 0
Total Difference in Recorded Investment						$ (60)
[1]	Excludes loans that were fully paid off or fully charged-off by period end. The pre-modification balance represents the balance outstanding prior to modification. The post-modification balance represents the outstanding balance at period end.
[2]	Excludes loans that were fully paid off or fully charged-off by period end. The pre-modification balance represents the balance outstanding prior to modification. The post-modification balance represents the outstanding balance at period end.
[3]	Chapter 7 bankruptcy loans where the debt has been legally discharged through the bankruptcy court and not reaffirmed.
[4]	Chapter 7 bankruptcy loans where the debt has been legally discharged through the bankruptcy court and not reaffirmed.

Loans and Loans Held for Sale54

Loans and Loans Held for Sale - Summary of Nonperforming Assets of Defaulted TDRs (Detail) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015USD ($)Contract	Sep. 30, 2014USD ($)Contract	Sep. 30, 2015USD ($)Contract	Sep. 30, 2014USD ($)Contract
Financing Receivable, Modifications [Line Items]
Number of Defaults	0	0	4	1
Recorded Investment | $	$ 0	$ 0	$ 307	$ 72
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Defaults	0		0
Recorded Investment | $	$ 0	0	$ 0
Commercial and Industrial [Member]
Financing Receivable, Modifications [Line Items]
Number of Defaults	0		0
Recorded Investment | $	$ 0		$ 0
Commercial Construction [Member]
Financing Receivable, Modifications [Line Items]
Number of Defaults	0		0
Recorded Investment | $	$ 0	$ 0	$ 0
Residential Mortgage [Member]
Financing Receivable, Modifications [Line Items]
Number of Defaults	0	0	1	1
Recorded Investment | $	$ 0	$ 0	$ 183	$ 72
Home Equity [Member]
Financing Receivable, Modifications [Line Items]
Number of Defaults	0		3
Recorded Investment | $	$ 0		$ 124
Installment and Other Consumer [Member]
Financing Receivable, Modifications [Line Items]
Number of Defaults	0		0
Recorded Investment | $	$ 0		$ 0
Consumer Construction [Member]
Financing Receivable, Modifications [Line Items]
Number of Defaults	0		0
Recorded Investment | $	$ 0		$ 0

Loans and Loans Held for Sale55

Loans and Loans Held for Sale - Summary of Nonperforming Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Nonperforming Assets
Nonaccrual loans	$ 15,716	$ 7,021
Nonaccrual TDRs	8,092	5,436
Total nonaccrual loans	23,808	12,457
OREO	472	166
Total Nonperforming Assets	$ 24,280	$ 12,623

Allowance for Loan Losses - Age

Allowance for Loan Losses - Age Analysis of Past Due Loans Segregated by Class of Loans (Detail) - USD ($) $ in Thousands		Sep. 30, 2015		Dec. 31, 2014
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, Current		$ 4,884,947		$ 3,850,597
Total nonaccrual loans		23,808		12,457
Total past due		54,810		21,119
Total Loans		4,939,757		3,871,716
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, Current		2,092,139		1,674,930
Total nonaccrual loans		7,919		4,435
Total past due		19,446		7,306
Total Loans		2,111,585		1,682,236
Commercial Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, Current		374,001		214,174
Total nonaccrual loans		5,008		1,974
Total past due		10,327		1,974
Total Loans		384,328		216,148
Residential Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, Current		614,609		485,465
Total nonaccrual loans		3,242		2,336
Total past due		10,642		4,121
Total Loans		625,251		489,586
Home Equity [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, Current		463,145		414,303
Total nonaccrual loans		2,147		2,059
Total past due		4,553		4,260
Total Loans		467,698		418,563
Installment and Other Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, Current		90,624		65,111
Total nonaccrual loans		122		31
Total past due		498		456
Total Loans		91,122		65,567
Consumer Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, Current		8,064		2,508
Total Loans		8,064		2,508
Loans Held for Sale [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, Current		13,794		2,970
Total Loans		13,794		2,970
30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		21,176		6,448
30 to 59 Days Past Due [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		8,987		2,548
30 to 59 Days Past Due [Member] | Commercial Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		3,955
30 to 59 Days Past Due [Member] | Residential Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		3,563		565
30 to 59 Days Past Due [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		2,144		1,756
30 to 59 Days Past Due [Member] | Installment and Other Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		344		352
60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		8,297		2,214
60 to 89 Days Past Due [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		1,567		323
60 to 89 Days Past Due [Member] | Commercial Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		1,364		0
60 to 89 Days Past Due [Member] | Residential Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		3,281		1,220
60 to 89 Days Past Due [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		262		445
60 to 89 Days Past Due [Member] | Installment and Other Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		32		73
90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		1,529	[1]	0
90 Days Past Due [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	[1]	973
90 Days Past Due [Member] | Commercial Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	[1]	0
90 Days Past Due [Member] | Residential Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	[1]	556
90 Days Past Due [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	[1]	0
Commercial and Industrial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, Current		1,228,571		991,136
Total nonaccrual loans		5,370		1,622
Total past due		9,344		3,002
Total Loans		1,237,915		994,138
Commercial and Industrial [Member] | 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		2,183		1,227
Commercial and Industrial [Member] | 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		$ 1,791		$ 153
[1]	Represents acquired loans that were recorded at fair value at the acquisition date.

Allowance for Loan Losses - Rec

Allowance for Loan Losses - Recorded Investment in Commercial Loan Classes by Internally Assigned Risk Ratings (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in commercial loan	$ 3,733,828	$ 2,892,522
Total percentage of recorded investment in commercial loan	100.00%	100.00%
Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in commercial loan	$ 3,551,246	$ 2,780,315
Total percentage of recorded investment in commercial loan	95.10%	96.10%
Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in commercial loan	$ 96,892	$ 65,968
Total percentage of recorded investment in commercial loan	2.60%	2.30%
Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in commercial loan	$ 85,690	$ 46,239
Total percentage of recorded investment in commercial loan	2.30%	1.60%
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in commercial loan	$ 2,111,585	$ 1,682,236
Total percentage of recorded investment in commercial loan	100.00%	100.00%
Commercial Real Estate [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in commercial loan	$ 2,036,905	$ 1,635,132
Total percentage of recorded investment in commercial loan	96.50%	97.20%
Commercial Real Estate [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in commercial loan	$ 32,371	$ 23,597
Total percentage of recorded investment in commercial loan	1.50%	1.40%
Commercial Real Estate [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in commercial loan	$ 42,309	$ 23,507
Total percentage of recorded investment in commercial loan	2.00%	1.40%
Commercial Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in commercial loan	$ 384,328	$ 216,148
Total percentage of recorded investment in commercial loan	100.00%	100.00%
Commercial Construction [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in commercial loan	$ 344,513	$ 196,520
Total percentage of recorded investment in commercial loan	89.60%	90.90%
Commercial Construction [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in commercial loan	$ 18,771	$ 12,014
Total percentage of recorded investment in commercial loan	4.90%	5.60%
Commercial Construction [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in commercial loan	$ 21,044	$ 7,614
Total percentage of recorded investment in commercial loan	5.50%	3.50%
Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in commercial loan	$ 1,237,915	$ 994,138
Total percentage of recorded investment in commercial loan	100.00%	100.00%
Commercial and Industrial [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in commercial loan	$ 1,169,828	$ 948,663
Total percentage of recorded investment in commercial loan	94.50%	95.40%
Commercial and Industrial [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in commercial loan	$ 45,750	$ 30,357
Total percentage of recorded investment in commercial loan	3.70%	3.10%
Commercial and Industrial [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total recorded investment in commercial loan	$ 22,337	$ 15,118
Total percentage of recorded investment in commercial loan	1.80%	1.50%

Allowance for Loan Losses - Add

Allowance for Loan Losses - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2015USD ($)
Financing Receivable, Impaired [Line Items]
Evaluation for impairment of substandard and nonaccrual commercial loans	$ 500,000
Minimum [Member]
Financing Receivable, Impaired [Line Items]
Loans considered nonperforming (in days)	90 days

Allowance for Loan Losses - R59

Allowance for Loan Losses - Recorded Investment in Consumer Loan Classes by Performing and Nonperforming Status (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in consumer loan	$ 1,192,135	$ 976,224
Percentage of Total	100.00%	100.00%
Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in consumer loan	$ 1,186,624	$ 971,798
Percentage of Total	99.50%	99.50%
Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in consumer loan	$ 5,511	$ 4,426
Percentage of Total	0.50%	0.50%
Residential Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in consumer loan	$ 625,251	$ 489,586
Percentage of Total	100.00%	100.00%
Residential Mortgage [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in consumer loan	$ 622,009	$ 487,250
Percentage of Total	99.50%	99.50%
Residential Mortgage [Member] | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in consumer loan	$ 3,242	$ 2,336
Percentage of Total	0.50%	0.50%
Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in consumer loan	$ 467,698	$ 418,563
Percentage of Total	100.00%	100.00%
Home Equity [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in consumer loan	$ 465,551	$ 416,504
Percentage of Total	99.50%	99.50%
Home Equity [Member] | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in consumer loan	$ 2,147	$ 2,059
Percentage of Total	0.50%	0.50%
Consumer Borrower [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in consumer loan	$ 91,122	$ 65,567
Percentage of Total	100.00%	100.00%
Consumer Borrower [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in consumer loan	$ 91,000	$ 65,536
Percentage of Total	99.90%	99.90%
Consumer Borrower [Member] | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in consumer loan	$ 122	$ 31
Percentage of Total	0.10%	0.10%
Consumer Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in consumer loan	$ 8,064	$ 2,508
Percentage of Total	100.00%	100.00%
Consumer Construction [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded investment in consumer loan	$ 8,064	$ 2,508
Percentage of Total	100.00%	100.00%

Allowance for Loan Losses - Inv

Allowance for Loan Losses - Investments in Loans Considered to be Impaired and Related Information on Impaired Loans (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Financing Receivable, Impaired [Line Items]
Without a related allowance recorded, Recorded Investment	$ 39,112		$ 39,112		$ 43,914
Without a related allowance, Unpaid Principal Balance	46,063		46,063		53,785
Without a related allowance recorded, Related Allowance	0		0		0
With a related allowance recorded, Recorded Investment	2,089		2,089		63
With a related allowance recorded, Unpaid Principal Balance	2,089		2,089		63
Impaired Financing Receivable, Recorded Investment, Total	41,201		41,201		43,977
Impaired Financing Receivable, Unpaid Principal Balance, Total	48,152		48,152		53,848
Impaired Financing Receivable, Related Allowance	1,260		1,260		54
Without a related allowance recorded, Average Recorded Investment	41,140	$ 46,121	40,631	$ 46,627
Without a related allowance recorded, Interest Income Recognized	555	381	1,342	1,170
With a related allowance recorded, Average Recorded Investment	2,098	70	2,103	73
With a related allowance recorded, Interest Income Recognized	9	1	47	4
Impaired Financing Receivable, Average Recorded Investment, Total	43,238	46,191	42,734	46,700
Impaired Financing Receivable, Interest Income Recognized, Total	564	382	1,389	1,174
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Without a related allowance recorded, Recorded Investment	14,080		14,080		19,890
Without a related allowance, Unpaid Principal Balance	14,576		14,576		25,262
With a related allowance recorded, Recorded Investment	0		0
With a related allowance recorded, Unpaid Principal Balance	0		0
Impaired Financing Receivable, Recorded Investment, Total	14,080		14,080		19,890
Impaired Financing Receivable, Unpaid Principal Balance, Total	14,576		14,576		25,262
Impaired Financing Receivable, Related Allowance	0		0
Without a related allowance recorded, Average Recorded Investment	14,101	21,110	14,994	21,593
Without a related allowance recorded, Interest Income Recognized	352	159	731	512
With a related allowance recorded, Average Recorded Investment	0		0
Impaired Financing Receivable, Average Recorded Investment, Total	14,101	21,110	14,994	21,593
Impaired Financing Receivable, Interest Income Recognized, Total	352	159	731	512
Commercial Construction [Member]
Financing Receivable, Impaired [Line Items]
Without a related allowance recorded, Recorded Investment	9,315		9,315		7,605
Without a related allowance, Unpaid Principal Balance	12,977		12,977		11,293
Impaired Financing Receivable, Recorded Investment, Total	9,315		9,315		7,605
Impaired Financing Receivable, Unpaid Principal Balance, Total	12,977		12,977		11,293
Without a related allowance recorded, Average Recorded Investment	11,034	8,160	8,920	8,254
Without a related allowance recorded, Interest Income Recognized	67	58	200	172
Impaired Financing Receivable, Average Recorded Investment, Total	11,034	8,160	8,920	8,254
Impaired Financing Receivable, Interest Income Recognized, Total	67	58	200	172
Consumer Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Without a related allowance recorded, Recorded Investment	6,852		6,852		7,159
Without a related allowance, Unpaid Principal Balance	7,401		7,401		7,733
With a related allowance recorded, Recorded Investment	118		118		43
With a related allowance recorded, Unpaid Principal Balance	118		118		43
Impaired Financing Receivable, Recorded Investment, Total	6,970		6,970		7,202
Impaired Financing Receivable, Unpaid Principal Balance, Total	7,519		7,519		7,776
Impaired Financing Receivable, Related Allowance	34		34		43
Without a related allowance recorded, Average Recorded Investment	6,829	7,034	6,856	7,181
Without a related allowance recorded, Interest Income Recognized	92	100	279	306
With a related allowance recorded, Average Recorded Investment	119	47	121	49
With a related allowance recorded, Interest Income Recognized	2	1	5	2
Impaired Financing Receivable, Average Recorded Investment, Total	6,948	7,081	6,977	7,230
Impaired Financing Receivable, Interest Income Recognized, Total	94	101	284	308
Other Consumer [Member]
Financing Receivable, Impaired [Line Items]
Without a related allowance recorded, Recorded Investment	119		119		42
Without a related allowance, Unpaid Principal Balance	191		191		48
With a related allowance recorded, Recorded Investment	2		2		20
With a related allowance recorded, Unpaid Principal Balance	2		2		20
Impaired Financing Receivable, Recorded Investment, Total	121		121		62
Impaired Financing Receivable, Unpaid Principal Balance, Total	193		193		68
Impaired Financing Receivable, Related Allowance	2		2		11
Without a related allowance recorded, Average Recorded Investment	183	115	119	122
Without a related allowance recorded, Interest Income Recognized	0	1	1	3
With a related allowance recorded, Average Recorded Investment	2	23	2	24
With a related allowance recorded, Interest Income Recognized				2
Impaired Financing Receivable, Average Recorded Investment, Total	185	138	121	146
Impaired Financing Receivable, Interest Income Recognized, Total	0	1	1	5
Commercial and Industrial [Member]
Financing Receivable, Impaired [Line Items]
Without a related allowance recorded, Recorded Investment	8,746		8,746		9,218
Without a related allowance, Unpaid Principal Balance	10,918		10,918		9,449
With a related allowance recorded, Recorded Investment	1,969		1,969
With a related allowance recorded, Unpaid Principal Balance	1,969		1,969
Impaired Financing Receivable, Recorded Investment, Total	10,715		10,715		9,218
Impaired Financing Receivable, Unpaid Principal Balance, Total	12,887		12,887		$ 9,449
Impaired Financing Receivable, Related Allowance	1,224		1,224
Without a related allowance recorded, Average Recorded Investment	8,993	9,702	9,742	9,477
Without a related allowance recorded, Interest Income Recognized	44	63	131	177
With a related allowance recorded, Average Recorded Investment	1,977		1,980
With a related allowance recorded, Interest Income Recognized	7		42
Impaired Financing Receivable, Average Recorded Investment, Total	10,970	9,702	11,722	9,477
Impaired Financing Receivable, Interest Income Recognized, Total	$ 51	$ 63	$ 173	$ 177

Allowance for Loan Losses - Sum

Allowance for Loan Losses - Summary of Allowance for Loan Losses (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	$ 48,814	$ 46,580	$ 47,911	$ 46,255
Charge-offs	(5,641)	(1,002)	(8,847)	(5,488)
Recoveries	3,528	284	4,370	5,941
Net (Charge-offs)/ Recoveries	(2,113)	(718)	(4,477)	453
Provision for loan losses	3,206	1,454	6,473	608
Balance at End of Period	49,907	47,316	49,907	47,316
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	19,018	20,733	20,164	18,921
Charge-offs	(2,361)	0	(2,738)	(2,002)
Recoveries	2,896	(154)	3,072	1,681
Net (Charge-offs)/ Recoveries	535	(154)	334	(321)
Provision for loan losses	(2,575)	(602)	(3,520)	1,377
Balance at End of Period	16,978	19,977	16,978	19,977
Commercial Construction [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	7,671	4,759	6,093	5,374
Charge-offs	(1,247)	(234)	(1,247)	(693)
Recoveries	129	0	132	140
Net (Charge-offs)/ Recoveries	(1,118)	(234)	(1,115)	(553)
Provision for loan losses	4,983	653	6,558	357
Balance at End of Period	11,536	5,178	11,536	5,178
Consumer Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	7,027	6,705	6,333	6,362
Charge-offs	(445)	(436)	(997)	(983)
Recoveries	132	48	379	272
Net (Charge-offs)/ Recoveries	(313)	(388)	(618)	(711)
Provision for loan losses	302	446	1,301	1,112
Balance at End of Period	7,016	6,763	7,016	6,763
Other Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	1,790	1,379	1,653	1,165
Charge-offs	(467)	(295)	(1,046)	(740)
Recoveries	99	75	312	284
Net (Charge-offs)/ Recoveries	(368)	(220)	(734)	(456)
Provision for loan losses	484	341	987	791
Balance at End of Period	1,906	1,500	1,906	1,500
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	13,308	13,004	13,668	14,433
Charge-offs	(1,121)	(37)	(2,819)	(1,070)
Recoveries	272	315	475	3,564
Net (Charge-offs)/ Recoveries	(849)	278	(2,344)	2,494
Provision for loan losses	12	616	1,147	(3,029)
Balance at End of Period	$ 12,471	$ 13,898	$ 12,471	$ 13,898

Allowance for Loan Losses - S62

Allowance for Loan Losses - Summary of Allowance for Loan Losses and Recorded Investments (Detail) - USD ($)		Sep. 30, 2015	Jun. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Dec. 31, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment		$ 1,260,000		$ 54,000
Allowance for Loan Losses, Collectively Evaluated for Impairment		48,647,000		47,857,000
Total Allowance for Loan Losses		49,907,000	$ 48,814,000	47,911,000	$ 47,316,000	$ 46,580,000	$ 46,255,000
Portfolio Loans, Individually Evaluated for Impairment		41,201,000		43,977,000
Portfolio Loans, Collectively Evaluated for Impairment		4,884,762,000		3,824,769,000
Total Portfolio Loans	[1]	4,925,963,000		3,868,746,000
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment		0
Allowance for Loan Losses, Collectively Evaluated for Impairment		16,978,000		20,164,000
Total Allowance for Loan Losses		16,978,000	19,018,000	20,164,000	19,977,000	20,733,000	18,921,000
Portfolio Loans, Individually Evaluated for Impairment		14,080,000		19,890,000
Portfolio Loans, Collectively Evaluated for Impairment		2,097,505,000		1,662,346,000
Total Portfolio Loans	[1]	2,111,585,000		1,682,236,000
Commercial Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Collectively Evaluated for Impairment		11,536,000		6,093,000
Total Allowance for Loan Losses		11,536,000	7,671,000	6,093,000	5,178,000	4,759,000	5,374,000
Portfolio Loans, Individually Evaluated for Impairment		9,315,000		7,605,000
Portfolio Loans, Collectively Evaluated for Impairment		375,013,000		208,543,000
Total Portfolio Loans	[1]	384,328,000		216,148,000
Consumer Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment		34,000		43,000
Allowance for Loan Losses, Collectively Evaluated for Impairment		6,982,000		6,290,000
Total Allowance for Loan Losses		7,016,000	7,027,000	6,333,000	6,763,000	6,705,000	6,362,000
Portfolio Loans, Individually Evaluated for Impairment		6,970,000		7,202,000
Portfolio Loans, Collectively Evaluated for Impairment		1,094,043,000		903,455,000
Total Portfolio Loans	[1]	1,101,013,000		910,657,000
Other Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment		2,000		11,000
Allowance for Loan Losses, Collectively Evaluated for Impairment		1,904,000		1,642,000
Total Allowance for Loan Losses		1,906,000	1,790,000	1,653,000	1,500,000	1,379,000	1,165,000
Portfolio Loans, Individually Evaluated for Impairment		121,000		62,000
Portfolio Loans, Collectively Evaluated for Impairment		91,001,000		65,505,000
Total Portfolio Loans	[1]	91,122,000		65,567,000
Fair Value Measurements [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses on acquired loans		0
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment		1,224,000
Allowance for Loan Losses, Collectively Evaluated for Impairment		11,247,000		13,668,000
Total Allowance for Loan Losses		12,471,000	$ 13,308,000	13,668,000	$ 13,898,000	$ 13,004,000	$ 14,433,000
Portfolio Loans, Individually Evaluated for Impairment		10,715,000		9,218,000
Portfolio Loans, Collectively Evaluated for Impairment		1,227,200,000		984,920,000
Total Portfolio Loans	[1]	$ 1,237,915,000		$ 994,138,000
[1]	Includes acquired loans.

Derivative Instruments and He63

Derivative Instruments and Hedging Activities - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Period for commitments	60 days

Derivative Instruments and He64

Derivative Instruments and Hedging Activities - Value of Derivative Assets and Derivative Liabilities (Detail) - Not Designated as Hedging Instruments [Member] - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Assets)	$ 14,232	$ 12,981
Fair value, Derivatives (included in Other Liabilities)	14,184	12,953
Other Assets [Member] | Interest Rate Swaps [Member]
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Assets)	14,232	12,981
Notional amount, Derivatives (included in Other Assets)	239,277	245,152
Other Assets [Member] | Interest Rate Lock Commitments [Member]
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Assets)	574	235
Notional amount, Derivatives (included in Other Assets)	16,969	8,822
Other Assets [Member] | Forward Sale Contracts [Member]
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Assets)	0
Notional amount, Derivatives (included in Other Assets)	0
Other Liabilities [Member] | Interest Rate Swap Contracts-Commercial Loans [Member]
Derivatives not Designated as Hedging Instruments
Collateral posted	12,548	12,059
Other Liabilities [Member] | Interest Rate Swaps [Member]
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Liabilities)	14,184	12,953
Notional amount, Derivatives (included in Other Liabilities)	239,277	245,152
Other Liabilities [Member] | Forward Sale Contracts [Member]
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Liabilities)	126	57
Notional amount, Derivatives (included in Other Liabilities)	$ 14,320	$ 7,789

Derivative Instruments and He65

Derivative Instruments and Hedging Activities - Schedule of Gross Amounts of Derivative Assets and Derivative Liabilities (Detail) - Not Designated as Hedging Instruments [Member] - USD ($) $ in Thousands		Sep. 30, 2015	Dec. 31, 2014
Derivative Asset [Abstract]
Gross amounts recognized		$ 14,232	$ 13,203
Gross amounts offset		0	(222)
Net amounts presented in the Consolidated Balance Sheets		14,232	12,981
Gross amounts not offset	[1]	0	0
Net Amount		14,232	12,981
Derivative Liability [Abstract]
Gross amounts recognized		14,184	13,175
Gross amounts offset		0	(222)
Net amounts presented in the Consolidated Balance Sheets		14,184	12,953
Gross amounts not offset	[1]	(12,548)	(12,059)
Net Amount		$ 1,636	$ 894
[1]	Amounts represent posted collateral.

Derivative Instruments and He66

Derivative Instruments and Hedging Activities - Amount of Gain or Loss Recognized in Income on Derivatives (Detail) - Not Designated as Hedging Instruments [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Total Derivatives Gain (Loss)	$ 94	$ (66)	$ 290	$ 30
Interest Rate Swap Contracts - Commercial Loans [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total Derivatives Gain (Loss)	29	(10)	20	(29)
Interest Rate Lock Commitments - Mortgage Loans [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total Derivatives Gain (Loss)	208	(105)	339	102
Forward Sale Contracts - Mortgage Loans [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total Derivatives Gain (Loss)	$ (143)	$ 49	$ (69)	$ (43)

Borrowings - Additional Informa

Borrowings - Additional Information (Detail) - USD ($)	Jun. 18, 2015	Mar. 05, 2015	Sep. 30, 2015	Sep. 30, 2014	Mar. 04, 2015	Dec. 31, 2014
Long Term And Short Term Debt [Line Items]
Total long-term debt outstanding at a fixed rate			$ 14,400,000
Total long-term debt outstanding at a variable rate			148,900,000
Capital lease			200,000
Repayment of junior subordinated debt			13,500,000	$ 0
Total borrowings			397,500,000			$ 309,300,000
Short-term borrowings			280,000,000
Long-term borrowings			117,600,000
Federal Home Loan Bank Advances [Member]
Long Term And Short Term Debt [Line Items]
Maximum borrowing capacity			1,900,000,000
Remaining borrowing capacity			1,400,000,000
Borrowing capacity utilized			500,000,000
Letter of credit to collateralize public funds			152,800,000
Junior Subordinated Debt [Member]
Long Term And Short Term Debt [Line Items]
Repayment of junior subordinated debt	$ 5,000,000	$ 8,500,000
Borrowings					$ 13,500,000
Mortgage Backed Securities [Member]
Long Term And Short Term Debt [Line Items]
Mortgage backed securities pledged as collateral			$ 46,200,000			$ 35,600,000

Borrowings - Summary of Informa

Borrowings - Summary of Information Pertaining to Borrowings (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Long Term And Short Term Debt [Line Items]
Short-term borrowings	$ 322,971	$ 320,605
Long-term borrowings	163,232	65,061
Total Borrowings	$ 486,203	$ 385,666
Short-term borrowings, Weighted Average Rate	0.32%	0.27%
Long-term borrowings, Weighted Average Rate	1.33%	2.79%
Total Borrowings, Weighted Average Rate	0.66%	0.70%
Securities Sold under Repurchase Agreements [Member]
Long Term And Short Term Debt [Line Items]
Short-term borrowings	$ 42,971	$ 30,605
Short-term borrowings, Weighted Average Rate	0.01%	0.01%
Short-Term Borrowings [Member]
Long Term And Short Term Debt [Line Items]
Short-term borrowings	$ 280,000	$ 290,000
Short-term borrowings, Weighted Average Rate	0.37%	0.31%
Other Long-Term Borrowings [Member]
Long Term And Short Term Debt [Line Items]
Long-term borrowings	$ 117,613	$ 19,442
Long-term borrowings, Weighted Average Rate	0.76%	3.00%
Junior Subordinated Debt Securities [Member]
Long Term And Short Term Debt [Line Items]
Long-term borrowings	$ 45,619	$ 45,619
Long-term borrowings, Weighted Average Rate	2.80%	2.70%

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Allowance for unfunded commitments	$ 3	$ 2.3

Commitments and Contingencies70

Commitments and Contingencies - Commitments and Letters of Credit (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Other Commitments [Line Items]
Commitments and letters of credit	$ 1,635,009	$ 1,232,212
Commitments to Extend Credit [Member]
Other Commitments [Line Items]
Commitments and letters of credit	1,538,397	1,158,628
Standby Letters of Credit [Member]
Other Commitments [Line Items]
Commitments and letters of credit	$ 96,612	$ 73,584

Other Comprehensive Income (Det

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
Pre-Tax Amount
Change in net unrealized gains/(losses) on securities available-for-sale		$ 5,177	$ (2,032)	$ 4,288	$ 7,844
Reclassification adjustment for net (gains)/losses on securities available-for-sale included in net income	[1]	0	0	34	(41)
Adjustment to funded status of employee benefit plans		647	269	1,839	692
Other Comprehensive Income/(Loss)		5,824	(1,763)	6,161	8,495
Tax (Expense) Benefit
Change in net unrealized gains/(losses) on securities available-for-sale		(1,812)	712	(1,501)	(2,746)
Reclassification adjustment for net (gains)/losses on securities available-for-sale included in net income	[1]	0	0	(12)	15
Adjustment to funded status of employee benefit plans		(227)	(94)	(551)	(242)
Other Comprehensive (Loss)/Income		(2,039)	618	(2,064)	(2,973)
Net of Tax Amount
Change in net unrealized gains/(losses) on securities available-for-sale		3,365	(1,320)	2,787	5,098
Reclassification adjustment for net (gains)/losses on securities available-for-sale included in net income	[1]	0	0	22	(26)
Adjustment to funded status of employee benefit plans		420	175	1,288	450
Other Comprehensive Income/(Loss)		$ 3,785	$ (1,145)	$ 4,097	$ 5,522
[1]	Reclassification adjustments are comprised of realized security gains. The gains have been reclassified out of accumulated other comprehensive income (loss) and have affected certain lines in the Consolidated Statements of Comprehensive Income as follows; the pre-tax amount is included in securities gains-net, the tax expense amount is included in the provision for income taxes and the net of tax amount is included in net income.

Employee Benefits - Additional

Employee Benefits - Additional Information (Detail)	Jan. 01, 2015	Sep. 30, 2015
Compensation and Retirement Disclosure [Abstract]
Number of consecutive years of employee's compensation		5 years
Number of total years of employee's compensation		10 years
Expected long-term rate of return on plan assets		8.00%
Lump sum death benefit to unmarried beneficiary as percent of accrued benefit payable (percent)	80.00%

Employee Benefits - Components

Employee Benefits - Components of Net Periodic Pension Cost and Other Changes in Plan Assets and Benefit (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Components of Net Periodic Pension Cost
Service cost—benefits earned during the period	$ 606	$ 516	$ 1,951	$ 1,778
Interest cost on projected benefit obligation	1,120	1,141	3,319	3,353
Expected return on plan assets	(1,772)	(1,710)	(5,385)	(5,180)
Amortization of prior service (credit) cost	(34)	(34)	(104)	(104)
Recognized net actuarial loss	586	287	1,521	705
Net Periodic Pension Expense	$ 506	$ 200	$ 1,302	$ 552

Segments - Additional Informati

Segments - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2015segment
Segment Reporting [Abstract]
Number of Reportable Segments	3

Segments - Total Assets by Repo

Segments - Total Assets by Reportable Operating Segment (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Segment Reporting, Asset Reconciling Item [Line Items]
Total Assets	$ 6,215,338	$ 4,964,686
Operating Segments [Member] | Community Banking [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total Assets	6,203,446	4,954,728
Operating Segments [Member] | Insurance [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total Assets	8,255	7,468
Operating Segments [Member] | Wealth Management [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total Assets	$ 3,637	$ 2,490

Segments - Financial Informatio

Segments - Financial Information of Segments (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Segment Reporting, Asset Reconciling Item [Line Items]
Interest income	$ 53,669	$ 40,605	$ 150,195	$ 119,142
Interest expense	4,073	3,076	11,529	9,167
NET INTEREST INCOME	49,596	37,529	138,666	109,975
Provision for loan losses	3,206	1,454	6,473	608
Noninterest income	12,481	11,931	37,948	35,118
Noninterest expense	32,138	27,282	98,014	84,103
Depreciation expense	1,211	898	3,540	2,543
Amortization of intangible assets	480	260	1,345	873
Provision for income taxes	6,407	4,906	17,584	13,552
Net Income	18,635	14,660	49,658	43,414
Operating Segments [Member] | Community Banking [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Interest income	53,625	40,581	150,108	119,055
Interest expense	4,200	3,435	12,144	10,332
NET INTEREST INCOME	49,425	37,146	137,964	108,723
Provision for loan losses	3,206	1,454	6,473	608
Noninterest income	8,651	7,742	25,056	22,118
Noninterest expense	28,941	23,691	87,542	72,756
Depreciation expense	1,192	878	3,482	2,485
Amortization of intangible assets	460	238	1,283	805
Provision for income taxes	6,139	4,577	16,534	12,579
Net Income	18,138	14,050	47,706	41,608
Operating Segments [Member] | Insurance [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Interest income	1		2	1
NET INTEREST INCOME	1		2	1
Noninterest income	1,197	1,496	4,079	4,262
Noninterest expense	1,098	1,127	3,288	3,327
Depreciation expense	13	13	39	38
Amortization of intangible assets	13	13	38	38
Provision for income taxes	26	120	250	301
Net Income	48	223	466	559
Operating Segments [Member] | Wealth Management [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Interest income	108	109	406	419
NET INTEREST INCOME	108	109	406	419
Noninterest income	2,806	2,748	8,639	8,511
Noninterest expense	2,210	2,245	6,716	6,961
Depreciation expense	6	7	19	20
Amortization of intangible assets	7	9	24	30
Provision for income taxes	242	209	800	672
Net Income	449	387	1,486	1,247
Eliminations [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Interest income	(65)	(85)	(321)	(333)
Interest expense	(127)	(359)	(615)	(1,165)
NET INTEREST INCOME	62	274	294	832
Noninterest income	(173)	(55)	174	227
Noninterest expense	$ (111)	$ 219	$ 468	$ 1,059

Qualified Affordable Housing 77

Qualified Affordable Housing Projects (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Investments in Affordable Housing Projects [Abstract]
Investment in qualified affordable housing projects	$ 15,900,000		$ 15,900,000		$ 18,600,000
Open commitments	0		0		$ 0
Amortization expense included in noninterest expense	900,000	$ 1,000,000	2,800,000	$ 3,100,000
Tax credits	$ 1,000,000	$ 1,100,000	$ 3,000,000	$ 3,300,000