WesBanco (WSBC) 10-Q 7 May 15 2015 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2015	Apr. 30, 2015
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	FALSE
Document Period End Date	31-Mar-15
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Trading Symbol	WSBC
Entity Registrant Name	WESBANCO INC
Entity Central Index Key	203596
Current Fiscal Year End Date	-19
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		38,449,812

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
ASSETS
Cash and due from banks, including interest bearing amounts of $17,871 and $8,405, respectively	$92,974	$94,002
Securities:
Available-for-sale, at fair value	1,654,264	917,424
Held-to-maturity (fair values of $772,843 and $619,617, respectively)	743,925	593,670
Total securities	2,398,189	1,511,094
Loans held for sale	6,064	5,865
Portfolio loans, net of unearned income	4,873,721	4,086,766
Allowance for loan losses	-44,173	-44,654
Net portfolio loans	4,829,548	4,042,112
Premises and equipment, net	110,900	93,135
Accrued interest receivable	25,232	18,481
Goodwill and other intangible assets, net	493,176	319,506
Bank-owned life insurance	153,991	123,298
Other assets	123,205	89,072
Total Assets	8,233,279	6,296,565
Deposits:
Non-interest bearing demand	1,249,521	1,061,075
Interest bearing demand	1,199,801	885,037
Money market	1,018,184	954,957
Savings deposits	1,064,808	842,818
Certificates of deposit	1,883,888	1,305,096
Total deposits	6,416,202	5,048,983
Federal Home Loan Bank borrowings	432,456	223,126
Other short-term borrowings	76,630	80,690
Junior subordinated debt owed to unconsolidated subsidiary trusts	142,269	106,176
Total borrowings	651,355	409,992
Accrued interest payable	2,297	1,620
Other liabilities	72,041	47,780
Total Liabilities	7,141,895	5,508,375
SHAREHOLDERS' EQUITY
Preferred stock, no par value; 1,000,000 shares authorized; none outstanding
Common stock, $2.0833 par value; 50,000,000 shares authorized; 38,546,042 and 29,367,511 issued in 2015 and 2014, respectively; outstanding: 38,449,812 and 29,298,188 shares in 2015 and 2014, respectively	80,304	61,182
Capital surplus	520,596	244,661
Retained earnings	509,622	504,578
Treasury stock (96,230 and 69,323 shares in 2015 and 2014, respectively, at cost)	-3,061	-2,151
Accumulated other comprehensive loss	-13,624	-18,825
Deferred benefits for directors	-2,453	-1,255
Total Shareholders' Equity	1,091,384	788,190
Total Liabilities and Shareholders' Equity	$8,233,279	$6,296,565

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, except Share data, unless otherwise specified
Statement of Financial Position [Abstract]
Interest bearing deposits, banks	$17,871	$8,405
Held-to-maturity securities, fair values	$772,843	$619,617
Preferred stock, no par value	$0	$0
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares outstanding	0	0
Common stock, par value	$2.08	$2.08
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	38,546,042	29,367,511
Common stock, shares outstanding	38,449,812	29,298,188
Treasury stock, shares	96,230	69,323

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
INTEREST AND DIVIDEND INCOME
Loans, including fees	$47,713	$42,746
Interest and dividends on securities:
Taxable	8,498	7,225
Tax-exempt	3,533	3,385
Total interest and dividends on securities	12,031	10,610
Other interest income	635	101
Total interest and dividend income	60,379	53,457
INTEREST EXPENSE
Interest bearing demand deposits	422	374
Money market deposits	456	440
Savings deposits	148	130
Certificates of deposit	2,872	3,630
Total interest expense on deposits	3,898	4,574
Federal Home Loan Bank borrowings	557	211
Other short-term borrowings	75	557
Junior subordinated debt owed to unconsolidated subsidiary trusts	894	790
Total interest expense	5,424	6,132
NET INTEREST INCOME	54,955	47,325
Provision for credit losses	1,289	2,199
Net interest income after provision for credit losses	53,666	45,126
NON-INTEREST INCOME
Trust fees	6,053	5,648
Service charges on deposits	3,652	3,860
Electronic banking fees	3,325	3,013
Net securities brokerage revenue	2,059	1,829
Bank-owned life insurance	1,251	875
Net gains on sales of mortgage loans	272	154
Net securities gains	22	10
Net gain on other real estate owned and other assets	122	113
Other income	1,434	1,547
Total non-interest income	18,190	17,049
NON-INTEREST EXPENSE
Salaries and wages	18,357	16,467
Employee benefits	7,316	5,708
Net occupancy	3,490	3,491
Equipment	2,973	2,783
Marketing	965	1,003
FDIC insurance	910	877
Amortization of intangible assets	566	495
Restructuring and merger-related expense	9,733
Other operating expenses	9,131	9,271
Total non-interest expense	53,441	40,095
Income before provision for income taxes	18,415	22,080
Provision for income taxes	4,528	5,659
NET INCOME	13,887	16,421
EARNINGS PER COMMON SHARE
Basic	$0.40	$0.56
Diluted	$0.40	$0.56
AVERAGE COMMON SHARES OUTSTANDING
Basic	34,393,137	29,182,183
Diluted	34,478,335	29,262,680
DIVIDENDS DECLARED PER COMMON SHARE	$0.23	$0.22
COMPREHENSIVE INCOME	$19,088	$19,694

Consolidated_Statements_of_Cha

Consolidated Statements of Changes in Shareholders' Equity (USD $)	Total	Common Stock [Member]	Capital Surplus [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Deferred Benefits for Directors [Member]
In Thousands, except Share data
Beginning Balance at Dec. 31, 2013	$746,595	$61,182	$244,974	$460,351	($5,969)	($12,734)	($1,209)
Beginning Balance, shares at Dec. 31, 2013		29,175,236
Net income	16,421			16,421
Other comprehensive income	3,273					3,273
Comprehensive income	19,694
Common dividends declared ($0.22 per share in Mar 31, 2015 and 2014 respectively	-6,420			-6,420
Treasury shares acquired	-19		49		-68
Treasury shares acquired, shares		-2,258
Stock options exercised	976		-176		1,152
Stock options exercised, shares		37,092
Restricted stock granted			-63		63
Restricted stock granted, shares		2,040
Stock compensation expense	291		291
Deferred benefits for directors- net			10				-10
Ending Balance at Mar. 31, 2014	761,117	61,182	245,085	470,352	-4,822	-9,461	-1,219
Ending Balance, shares at Mar. 31, 2014		29,212,110
Beginning Balance at Dec. 31, 2014	788,190	61,182	244,661	504,578	-2,151	-18,825	-1,255
Beginning Balance, shares at Dec. 31, 2014		29,298,188
Net income	13,887			13,887
Other comprehensive income	5,201					5,201
Comprehensive income	19,088
Common dividends declared ($0.22 per share in Mar 31, 2015 and 2014 respectively	-8,843			-8,843
Shares issued for acquisition	293,629	19,122	274,507
Shares issued for acquisition, shares		9,178,531
Treasury shares acquired	-1,262				-1,262
Treasury shares acquired, shares		-38,237
Stock options exercised	308		-44		352
Stock options exercised, shares		11,330
Stock compensation expense	274		274
Deferred benefits for directors- net			1,198				-1,198
Ending Balance at Mar. 31, 2015	$1,091,384	$80,304	$520,596	$509,622	($3,061)	($13,624)	($2,453)
Ending Balance, shares at Mar. 31, 2015		38,449,812

Consolidated_Statements_of_Cha1

Consolidated Statements of Changes in Shareholders' Equity (Parenthetical) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Common dividends declared, per share	$0.23	$0.22
Retained Earnings [Member]
Common dividends declared, per share	$0.23	$0.22

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Statement of Cash Flows [Abstract]
NET CASH PROVIDED BY OPERATING ACTIVITIES	$36,064	$23,985
INVESTING ACTIVITIES
Net (increase) decrease in loans	-94,812	3,446
Securities available-for-sale:
Proceeds from sales	560,676	3,155
Proceeds from maturities, prepayments and calls	52,783	53,631
Purchases of securities	-405,998	-77,725
Securities held-to-maturity:
Proceeds from maturities, prepayments and calls	9,430	12,325
Purchases of securities	-51,246	-12,240
Proceeds from bank-owned life insurance	1,185
Cash paid to acquire a business, net of cash acquired	-28,551
Purchases of premises and equipment - net	-2,033	-1,485
Net cash provided by (used in) investing activities	41,434	-18,893
FINANCING ACTIVITIES
Increase in deposits	120,954	153,387
Proceeds from Federal Home Loan Bank borrowings	325,000
Repayment of Federal Home Loan Bank borrowings	-507,982	-16,181
Decrease in other short-term borrowings	-9,060	-37,682
Decrease in federal funds purchased		-20,000
Dividends paid to common shareholders	-6,446	-5,833
Treasury shares (purchased) sold - net	-992	862
Net cash (used in) provided by financing activities	-78,526	74,553
Net (decrease) increase in cash and cash equivalents	-1,028	79,645
Cash and cash equivalents at beginning of the period	94,002	95,551
Cash and cash equivalents at end of the period	92,974	175,196
SUPPLEMENTAL DISCLOSURES
Interest paid on deposits and other borrowings	5,522	6,589
Income taxes paid	100
Transfers of loans to other real estate owned	344	1,287
Non-cash transactions related to ESB acquisition	$301,933

Summary_of_Significant_Account

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	NOTE 1. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
	Basis of presentation — The accompanying unaudited interim financial statements of WesBanco, Inc. and its consolidated subsidiaries (“WesBanco”) have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and 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.
	WesBanco’s interim financial statements have been prepared following the significant accounting policies disclosed in Note 1 of the Notes to the Consolidated Financial Statements of its 2014 Annual Report on Form 10-K filed with the Securities and Exchange Commission. In the opinion of management, the accompanying interim financial information reflects all adjustments, including normal recurring adjustments, necessary to present fairly WesBanco’s financial position and 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.
	Recent accounting pronouncements — In April 2015, the Financial Accounting Standards Board (the “FASB”) issued an Accounting Standards Update (“ASU”) (ASU 2015-05) that provides guidance on when to account for a cloud computing arrangement as a software license. The guidance applies only to internal-use software that a customer obtains access to in a hosting arrangement if both of the following criteria are met: (1) The customer has the contractual right to take possession of the software at any time during the hosting period without significant penalty, (2) it is feasible for the customer to either run the software on its own hardware or contract with another party unrelated to the vendor to host the software. The pronouncement is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2015. Early adoption is permitted. The adoption of this pronouncement is not expected to have a material impact on WesBanco’s Consolidated Financial Statements.
	In February 2015, the FASB issued ASU 2015-02 that revised the consolidation model, requiring reporting entities to reevaluate whether they should consolidate certain legal entities under the revised model. The amendments in this Update modify the evaluation of whether limited partnerships and similar legal entities are variable interest entities (VIEs) or voting interest entities, and eliminate the presumption that a general partner should consolidate and affect the consolidation analysis of reporting entities that are involved with VIEs, particularly those that have fee arrangements and related party relationships. The pronouncement also provides for 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 similar to those in Rule 2a-7 of the Investment Company Act of 1940 for registered money market funds. The pronouncement is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2015. Early adoption is permitted. The adoption of this pronouncement is not expected to have a material impact on WesBanco’s Consolidated Financial Statements.
	In August 2014, the FASB issued ASU 2014-14 related to the classification of certain government-guaranteed mortgage loans upon foreclosure. The amendments in this update require that a mortgage loan be derecognized and that a separate other receivable be recognized upon foreclosure if the following conditions are met: (1) The loan has a government guarantee that is not separable from the loan before foreclosure, (2) at the time of foreclosure, the creditor has the intent to convey the real estate property to the guarantor and make a claim on the guarantee, and the creditor has the ability to recover under that claim, (3) at the time of foreclosure, any amount of the claim that is determined on the basis of the fair value of the real estate is fixed. Upon foreclosure, the separate other receivable should be measured based upon the amount of the loan balance (principal and interest) expected to be recovered from the guarantor. The pronouncement is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2014 and may be adopted under either a modified retrospective transition method or a prospective transition method. However, the same method of transition as elected under ASU 2014-04 must be applied. Early adoption is permitted. The adoption of this pronouncement did not have a material impact on WesBanco’s Consolidated Financial Statements.
	In June 2014, the FASB issued ASU 2014-11 related to repurchase-to-maturity transactions, repurchase financing and disclosures. The pronouncement changes the accounting for repurchase-to-maturity transactions and linked repurchase financings to secured borrowing accounting, which is consistent with the accounting for other repurchase agreements. The pronouncement also requires two new disclosures. The first disclosure requires an entity to disclose information on transfers accounted for as sales in transactions that are economically similar to repurchase agreements. The second disclosure provides increased transparency about the types of collateral pledged in repurchase agreements and similar transactions accounted for as secured borrowings. The pronouncement is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2014. Early adoption is not permitted. The adoption of this pronouncement did not have a material impact on WesBanco’s Consolidated Financial Statements.
	In May 2014, the FASB issued ASU 2014-09 related to the recognition of revenue from contracts with customers. The new revenue pronouncement creates a single source of revenue guidance for all companies in all industries and is more principles-based than current revenue guidance. The pronouncement provides a five-step model for a company to recognize revenue when it transfers control of goods or services to customers at an amount that reflects the consideration to which it expects to be entitled in exchange for those goods or services. The five steps are (1) identify the contract with the customer, (2) identify the separate performance obligations in the contract, (3) determine the transaction price, (4) allocate the transaction price to the separate performance obligations and (5) recognize revenue when each performance obligation is satisfied. The pronouncement is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2016 using either a full retrospective approach for all periods presented in the period of adoption or a modified retrospective approach. Early adoption is not permitted. In April 2015, the FASB issued an exposure draft of a proposed ASU that would delay by one year the effective date of ASU 2014-11. Under the proposal, the standard would be effective for annual reporting periods beginning after December 15, 2017 and interim periods therein. WesBanco is currently evaluating the impact of the adoption of this pronouncement on its Consolidated Financial Statements.

Mergers_and_Acquisitions

Mergers and Acquisitions	3 Months Ended
	Mar. 31, 2015
Business Combinations [Abstract]
Mergers and Acquisitions	NOTE 2. MERGERS AND ACQUISITIONS
	On February 10, 2015, WesBanco completed its acquisition of ESB Financial Corporation (“ESB”), and its wholly-owned banking subsidiary, ESB Bank (“ESB Bank”), a Pennsylvania-chartered stock savings bank headquartered in Ellwood City, Pennsylvania. The transaction expanded WesBanco’s franchise in the Pittsburgh region of western Pennsylvania from 16 to 38 offices.
	On the acquisition date, ESB had $1.9 billion in assets, excluding goodwill, which included $700.8 million in loans, and $486.9 million in securities. The ESB acquisition was valued at $339.0 million, based on WesBanco’s closing stock price on February 10, 2015 of $32.00, and resulted in WesBanco issuing 9,178,531 shares of its common stock and $45.0 million in cash and other assets in exchange for ESB common stock. The assets and liabilities of ESB were recorded on WesBanco’s balance sheet at their preliminary estimated fair values as of February 10, 2015, the acquisition date, and ESB’s results of operations have been included in WesBanco’s Consolidated Statements of Income since that date. ESB was merged into WesBanco and ESB Bank was merged into WesBanco Bank, Inc. (the “Bank”) on February 10, 2015. Based on a preliminary purchase price allocation, WesBanco recorded $168.9 million in goodwill and $5.3 million in core deposit intangibles in its community banking segment. The fair values for the assets acquired and liabilities assumed are provisional amounts and are currently under review. Due to the timing of the ESB acquisition, WesBanco is still in the process of completing its fair market valuation, including the valuation of certain tangible and intangible assets as well as deferred income taxes. None of the goodwill is deductible for income tax purposes as the acquisition is accounted for as a tax-free exchange for tax purposes.
	For the three months ended March 31, 2015, WesBanco recorded merger-related expenses of $9.7 million associated with the ESB acquisition. In 2014 WesBanco recognized $1.3 million in merger-related expenses in connection with the ESB acquisition.
	The total of net interest income and non-interest income of the acquired operations of ESB was approximately $6.5 million and net income was approximately $2.7 million from February 11, 2015 through March 31, 2015. If the ESB acquisition had occurred on January 1, 2014, unaudited proforma net interest income and non-interest income of the combined entity for the three months ended March 31, 2014 would have totaled approximately $76.1 million and unaudited proforma net income would have been approximately $19.8 million as compared to proforma results of $78.2 million and $22.2 million, respectively, for the three months ended March 31, 2015. Merger-related expenses were excluded from the pro-forma results.
	The purchase price of the ESB acquisition and resulting goodwill is summarized as follows:
	(unaudited, in thousands)		February 10, 2015
	Purchase Price:
	Fair value of WesBanco shares issued, (net of equity issuance costs of $0.1 million)		$	293,933
	Cash consideration for outstanding ESB shares, options and restricted stock			37,036
	Settlement of pre-existing loan to ESB			8,000
	Total purchase price		$	338,969
	Fair value of:
	Tangible assets acquired		$	1,859,865
	Core deposit and other intangible assets acquired			5,346
	Liabilities assumed			(1,703,616	)
	Net cash received in the acquisition			8,485
	Fair value of net assets acquired			170,080
	Goodwill recognized		$	168,889
	The following table presents the preliminary allocation of the purchase price of the assets acquired and the liabilities assumed at the date of acquisition, as WesBanco intends to finalize its accounting for the acquisition of ESB during 2015:
	(unaudited, in thousands)		February 10, 2015
	Assets
	Cash and due from banks		$	8,485
	Securities			486,891
	Loans			700,849
	Goodwill and other intangible assets			174,235
	Accrued income and other assets (1)			672,125
	Total Assets		$	2,042,585
	Liabilities
	Deposits		$	1,246,992
	Borrowings			433,454
	Accrued expenses and other liabilities			23,170
	Total liabilities			1,703,616
	Purchase price		$	338,969
	(1)	Includes receivables of $560.7 million from the sale of available-for-sale securities prior to the acquisition date.
	At March 31, 2015 the carrying value of goodwill increased by $168.9 million from December 31, 2014 to $481.0 million.

EARNINGS_PER_COMMON_SHARE

EARNINGS PER COMMON SHARE	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
EARNINGS PER COMMON SHARE	NOTE 3. EARNINGS PER COMMON SHARE
	Earnings per common share are calculated as follows:
		For the Three Months Ended
		March 31,
	(unaudited, in thousands, except shares and per share amounts)	2015		2014
	Numerator for both basic and diluted earnings per common share:
	Net income	$	13,887	$	16,421
	Denominator:
	Total average basic common shares outstanding		34,393,137		29,182,183
	Effect of dilutive stock options and warrant		85,198		80,497
	Total diluted average common shares outstanding		34,478,335		29,262,680
	Earnings per common share - basic	$	0.4	$	0.56
	Earnings per common share - diluted	$	0.4	$	0.56
	All stock options outstanding were included in the computation of diluted earnings per share for the three months ended March 31, 2015 as all were considered dilutive, while 33,000 were not included in March 31, 2014, because to do so would have been anti-dilutive.
	On February 10, 2015, WesBanco issued 9,178,531 shares to complete its acquisition of ESB. These shares are included in average shares outstanding beginning on that date. For additional information relating to the ESB acquisition, refer to Note 2, “Mergers and Acquisitions.”

Securities

Securities	3 Months Ended
	Mar. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Securities	NOTE 4. SECURITIES
	The following table presents the fair value and amortized cost of available-for-sale and held-to-maturity securities:
			March 31, 2015											December 31, 2014
	(unaudited, in thousands)		Amortized			Gross			Gross			Estimated		Amortized			Gross		Gross			Estimated
			Cost			Unrealized			Unrealized			Fair		Cost			Unrealized		Unrealized			Fair
						Gains			Losses			Value					Gains		Losses			Value
	Available-for-sale
	Obligations of government agencies		$	79,315		$	1,486		$	(33	)	$	80,768	$	86,964		$	1,087	$	(315	)	$	87,736
	Residential mortgage-backed securities and collateralized mortgage obligations of government agencies			1,279,350			8,091			(3,996	)		1,283,445		703,535			4,336		(6,758	)		701,113
	Obligations of states and political subdivisions			89,977			5,693			(17	)		95,653		86,073			5,365		(5	)		91,433
	Corporate debt securities			182,781			430			(121	)		183,090		25,974			141		(119	)		25,996
	Total debt securities		$	1,631,423		$	15,700		$	(4,167	)	$	1,642,956	$	902,546		$	10,929	$	(7,197	)	$	906,278
	Equity securities			10,702			606			—			11,308		10,304			842		—			11,146
	Total available-for-sale securities		$	1,642,125		$	16,306		$	(4,167	)	$	1,654,264	$	912,850		$	11,771	$	(7,197	)	$	917,424
	Held-to-maturity
	Residential mortgage-backed securities and collateralized mortgage obligations of government agencies		$	126,935		$	3,244		$	(208	)	$	129,971	$	79,004		$	3,262	$	(246	)	$	82,020
	Obligations of states and political subdivisions			610,249			26,560			(878	)		635,931		507,927			23,917		(1,043	)		530,801
	Corporate debt securities			6,741			200			—			6,941		6,739			106		(49	)		6,796
	Total held-to-maturity securities		$	743,925		$	30,004		$	(1,086	)	$	772,843	$	593,670		$	27,285	$	(1,338	)	$	619,617
	Total securities		$	2,386,050		$	46,310		$	(5,253	)	$	2,427,107	$	1,506,520		$	39,056	$	(8,535	)	$	1,537,041
	At March 31, 2015, and December 31, 2014, there were no holdings of any one issuer, other than the U.S. government and its agencies, in an amount greater than 10% of WesBanco’s shareholders’ equity.
	The following table presents the fair value of available-for-sale and held-to-maturity securities by contractual maturity at March 31, 2015. In some instances, the issuers may have the right to call or prepay obligations without penalty prior to the contractual maturity date.
			March 31, 2015
	(unaudited, in thousands)		One Year			One to			Five to			After		Mortgage-backed			Total
			or less			Five Years			Ten Years			Ten Years		and Equity
	Available-for-sale
	Obligations of government agencies		$	—		$	23,276		$	40,297		$	17,195	$	—		$	80,768
	Residential mortgage-backed securities and collateralized mortgage obligations of government agencies (1)			—			—			—			—		1,283,445			1,283,445
	Obligations of states and political subdivisions			5,254			33,049			21,417			35,933		—			95,653
	Corporate debt securities			82,193			62,312			33,658			4,927		—			183,090
	Equity securities (2)			—			—			—			—		11,308			11,308
	Total available-for-sale securities		$	87,447		$	118,637		$	95,372		$	58,055	$	1,294,753		$	1,654,264
	Held-to-maturity (3)
	Residential mortgage-backed securities and collateralized mortgage obligations of government agencies (1)		$	—		$	—		$	—		$	—	$	129,971		$	129,971
	Obligations of states and political subdivisions			2,852			17,024			259,231			356,824		—			635,931
	Corporate debt securities			—			—			6,941			—		—			6,941
	Total held-to-maturity securities		$	2,852		$	17,024		$	266,172		$	356,824	$	129,971		$	772,843
	Total securities		$	90,299		$	135,661		$	361,544		$	414,879	$	1,424,724		$	2,427,107
	-1	Mortgage-backed and collateralized mortgage securities, which have prepayment provisions, are not assigned to maturity categories due to fluctuations in their prepayment speeds.
	-2	Equity securities, which have no stated maturity, are not assigned a maturity category.
	(3)	The held-to-maturity portfolio is carried at an amortized cost of $743.9 million.
	Securities with aggregate fair values of $1.1 billion and $706.5 million at March 31, 2015 and December 31, 2014, respectively, were pledged as security for public and trust funds, and securities sold under agreements to repurchase. Proceeds from the sale of available-for-sale securities were $560.7 million, entirely due to the ESB portfolio restructuring, and $3.2 million for the three months ended March 31, 2015 and 2014, respectively. Net unrealized gains on available-for-sale securities included in accumulated other comprehensive income net of tax, as of March 31, 2015 and December 31, 2014 were $7.7 million and $2.9 million, respectively.
	The following table presents the gross realized gains and losses on sales and calls of securities for the three months ended March 31, 2015 and 2014, respectively.
			For the Three Months Ended
			March 31,
	(unaudited, in thousands)		2015			2014
	Gross realized gains		$	24		$	195
	Gross realized losses			(2	)		(185	)
	Net realized gains (losses)		$	22		$	10
	The following tables provide information on unrealized losses on investment securities that have been in an unrealized loss position for less than twelve months and twelve months or more as of March 31, 2015 and December 31, 2014:
			March 31, 2015
			Less than 12 months									12 months or more							Total
	(unaudited, dollars in thousands)		Fair			Unrealized			# of			Fair		Unrealized			# of		Fair			Unrealized			# of
			Value			Losses			Securities			Value		Losses			Securities		Value			Losses			Securities
	Obligations of government agencies			17,953			(33	)		3			—		—			0		17,953			(33	)		3
	Residential mortgage-backed securities and collateralized mortgage obligations of government agencies			260,103			(681	)		55			168,693		(3,523	)		32		428,796			(4,204	)		87
	Obligations of states and political subdivisions			68,439			(450	)		79			20,777		(445	)		31		89,216			(895	)		110
	Corporate debt securities			53,122			(113	)		16			1,978		(8	)		1		55,100			(121	)		17
	Total temporarily impaired securities			399,617			(1,277	)		153			191,448		(3,976	)		64		591,065			(5,253	)		217
			31-Dec-14
			Less than 12 months									12 months or more							Total
	(unaudited, dollars in thousands)		Fair			Unrealized			# of			Fair		Unrealized			# of		Fair			Unrealized			# of
			Value			Losses			Securities			Value		Losses			Securities		Value			Losses			Securities
	Obligations of government agencies		$	19,362		$	(77	)		5		$	19,757	$	(238	)		4	$	39,119		$	(315	)		9
Residential mortgage-backed securities and collateralized mortgage obligations of government agencies			78,786			(386	)		19			240,055		(6,618	)		43		318,841			(7,004	)		62
Obligations of states and political subdivisions			12,615			(96	)		15			61,548		(952	)		93		74,163			(1,048	)		108
Corporate debt securities			2,969			(31	)		1			4,573		(137	)		2		7,542			(168	)		3
Total temporarily impaired securities		$	113,732		$	(590	)		40		$	325,933	$	(7,945	)		142	$	439,665		$	(8,535	)		182
Unrealized losses on debt securities in the tables represent temporary fluctuations resulting from changes in market rates in relation to fixed yields. Unrealized losses in the available-for-sale portfolio are accounted for as an adjustment, net of taxes, to other comprehensive income in shareholders’ equity.
WesBanco does not believe the securities presented above are impaired due to reasons of credit quality, as there are no debt securities rated below investment grade and all are paying principal and interest according to their contractual terms. WesBanco does not intend to sell, nor is it more likely than not that it will be required to sell, loss position securities prior to recovery of their cost, and therefore, management believes the unrealized losses detailed above are temporary and no impairment loss relating to these securities has been recognized.
Securities that do not have readily determinable fair values and for which WesBanco does not exercise significant influence are carried at cost. Cost method investments consist primarily of FHLB of Pittsburgh and FHLB of Cincinnati stock totaling $20.9 million and $11.6 million at March 31, 2015 and December 31, 2014, respectively, and are included in other assets in the Consolidated Balance Sheets. Cost method investments are evaluated for impairment whenever events or circumstances suggest that their carrying value may not be recoverable.

Loans_and_the_Allowance_for_Cr

Loans and the Allowance for Credit Losses	3 Months Ended
	Mar. 31, 2015
Receivables [Abstract]
Loans and the Allowance for Credit Losses	NOTE 5. LOANS AND THE ALLOWANCE FOR CREDIT LOSSES
	The recorded investment in loans is presented in the Consolidated Balance Sheets net of deferred loan fees and costs of $2.2 million and $2.4 million at March 31, 2015 and December 31, 2014, respectively.
	(unaudited, in thousands)		March 31,			December 31,
			2015			2014
	Commercial real estate:
	Land and construction		$	288,075		$	262,643
	Improved property			1,908,869			1,682,817
	Total commercial real estate			2,196,944			1,945,460
	Commercial and industrial			709,621			638,410
	Residential real estate			1,239,163			928,770
	Home equity			362,163			330,031
	Consumer			365,830			244,095
	Total portfolio loans			4,873,721			4,086,766
	Loans held for sale			6,064			5,865
	Total loans		$	4,879,785		$	4,092,631
	The following tables summarize changes in the allowance for credit losses applicable to each category of the loan portfolio:
			Allowance for Credit Losses By Category
			For the Three Months Ended March 31, 2015 and 2014
	(unaudited, in thousands)		Commercial			Commercial			Commercial			Residential			Home			Consumer			Deposit			Total
			Real Estate-			Real Estate-			& Industrial			Real Estate			Equity						Overdraft
			Land and			Improved
			Construction			Property
	Balance at December 31, 2014:
	Allowance for loan losses		$	5,654		$	17,573		$	9,063		$	5,382		$	2,329		$	4,078		$	575		$	44,654
	Allowance for loan commitments			194			10			112			9			90			40			—			455
	Total beginning allowance for credit losses			5,848			17,583			9,175			5,391			2,419			4,118			575			45,109
	Provision for credit losses:
	Provision for loan losses			(323	)		903			(44	)		(208	)		747			133			58			1,266
	Provision for loan commitments			(16	)		8			8			4			17			2			—			23
	Total provision for credit losses			(339	)		911			(36	)		(204	)		764			135			58			1,289
	Charge-offs			—			(577	)		(122	)		(358	)		(589	)		(717	)		(154	)		(2,517	)
	Recoveries			—			136			114			218			10			229			63			770
	Net charge-offs			—			(441	)		(8	)		(140	)		(579	)		(488	)		(91	)		(1,747	)
	Balance at March 31, 2015:
	Allowance for loan losses			5,331			18,035			9,011			5,034			2,497			3,723			542			44,173
	Allowance for loan commitments			178			18			120			13			107			42			—			478
	Total ending allowance for credit losses		$	5,509		$	18,053		$	9,131		$	5,047		$	2,604		$	3,765		$	542		$	44,651
	Balance at December 31, 2013:
	Allowance for loan losses		$	6,056		$	18,157		$	9,925		$	5,673		$	2,017		$	5,020		$	520		$	47,368
	Allowance for loan commitments			301			62			130			5			85			19			—			602
	Total beginning allowance for credit losses			6,357			18,219			10,055			5,678			2,102			5,039			520			47,970
	Provision for credit losses:
	Provision for loan losses			(1,051	)		(509	)		2,128			869			153			305			361			2,256
	Provision for loan commitments			(8	)		(53	)		3			—			1			—			—			(57	)
	Total provision for credit losses			(1,059	)		(562	)		2,131			869			154			305			361			2,199
	Charge-offs			—			(493	)		(2,276	)		(879	)		(155	)		(752	)		(180	)		(4,735	)
	Recoveries			—			120			65			109			11			227			62			594
	Net charge-offs			—			(373	)		(2,211	)		(770	)		(144	)		(525	)		(118	)		(4,141	)
	Balance at March 31, 2014:
	Allowance for loan losses			5,005			17,275			9,842			5,772			2,026			4,800			763			45,483
	Allowance for loan commitments			293			9			133			5			86			19			—			545
	Total ending allowance for credit losses		$	5,298		$	17,284		$	9,975		$	5,777		$	2,112		$	4,819		$	763		$	46,028
	The following tables present the allowance for credit losses and recorded investments in loans by category:
			Allowance for Credit Losses and Recorded Investment in Loans
	(unaudited, in thousands)		Commercial			Commercial			Commercial			Residential			Home			Consumer			Over-draft			Total
			Real Estate-			Real Estate-			and Industrial			Real Estate			Equity
			Land and			Improved
			Construction			Property
	March 31, 2015
	Allowance for credit losses:
	Allowance for loans individually evaluated for impairment		$	—		$	2,828		$	873		$	—		$	—		$	—		$	—		$	3,701
	Allowance for loans collectively evaluated for impairment			5,331			15,207			8,138			5,034			2,497			3,723			542			40,472
	Allowance for loan commitments			178			18			120			13			107			42			—			478
	Total allowance for credit losses		$	5,509		$	18,053		$	9,131		$	5,047		$	2,604		$	3,765		$	542		$	44,651
Portfolio loans:
Individually evaluated for impairment (1)		$	—		$	9,822		$	2,722		$	—		$	—		$	—		$	—		$	12,544
Collectively evaluated for impairment			288,075			1,899,047			706,899			1,239,163			362,163			365,830			—			4,861,177
Total portfolio loans		$	288,075		$	1,908,869		$	709,621		$	1,239,163		$	362,163		$	365,830		$	—		$	4,873,721
December 31, 2014
Allowance for credit losses:
Allowance for loans individually evaluated for impairment		$	—		$	2,765		$	1,033		$	—		$	—		$	—		$	—		$	3,798
Allowance for loans collectively evaluated for impairment			5,654			14,808			8,030			5,382			2,329			4,078			575			40,856
Allowance for loan commitments			194			10			112			9			90			40			—			455
Total allowance for credit losses		$	5,848		$	17,583		$	9,175		$	5,391		$	2,419		$	4,118		$	575		$	45,109
Portfolio loans:
Individually evaluated for impairment (1)		$	—		$	11,469		$	2,844		$	—		$	—		$	—		$	—		$	14,313
Collectively evaluated for impairment			262,643			1,671,348			635,566			928,770			330,031			244,095			—			4,072,453
Total portfolio loans		$	262,643		$	1,682,817		$	638,410		$	928,770		$	330,031		$	244,095		$	—		$	4,086,766
(1)	Commercial loans greater than $1 million that are reported as non-accrual or as a troubled debt restructuring (“TDR”) are individually evaluated for impairment.
WesBanco maintains an internal loan grading system to reflect the credit quality of commercial loans. Commercial loan risk grades are determined based on an evaluation of the relevant characteristics of each loan, assigned at the inception of each loan and adjusted thereafter at any time to reflect changes in the risk profile throughout the life of each loan. The primary factors used to determine the risk grade are the reliability and sustainability of the primary source of repayment and overall financial strength of the borrower. This includes an analysis of cash flow available to repay debt, profitability, liquidity, leverage, and overall financial trends. Other factors include management, industry or property type risks, an assessment of secondary sources of repayment such as collateral or guarantees, other terms and conditions of the loan that may increase or reduce its risk, and economic conditions and other external factors that may influence repayment capacity and financial condition.
Commercial real estate — land and construction consists of loans to finance investments in vacant land, land development, construction of residential housing, and construction of commercial buildings. Commercial real estate – improved property consists of loans for the purchase or refinance of all types of improved owner-occupied and investment properties. Factors that are considered in assigning the risk grade vary depending on the type of property financed. The risk grade assigned to construction and development loans is based on the overall viability of the project, the experience and financial capacity of the developer or builder to successfully complete the project, project specific and market absorption rates and comparable property values, and the amount of pre-sales for residential housing construction or pre-leases for commercial investment property. The risk grade assigned to commercial investment property loans is based primarily on the adequacy of net rental income generated by the property to service the debt, the type, quality, industry and mix of tenants, and the terms of leases, but also considers the overall financial capacity of the investors and their experience in owning and managing investment property. The risk grade assigned to owner-occupied commercial real estate and commercial and industrial loans is based primarily on historical and projected earnings, the adequacy of operating cash flow to service all of the business’ debt, and the capital resources, liquidity and leverage of the business, but also considers the industry in which the business operates, the business’ specific competitive advantages or disadvantages, the quality and experience of management, and external influences on the business such as economic conditions. Other factors that are considered for commercial and industrial loans include the type, quality and marketability of non-real estate collateral and whether the structure of the loan increases or reduces its risk. The type, age, condition, location and any environmental risks associated with a property are also considered for all types of commercial real estate. The overall financial condition and repayment capacity of any guarantors is also evaluated to determine the extent to which they mitigate other risks of the loan. The following descriptions of risk grades apply to commercial real estate and commercial and industrial loans:
Pass loans are those that exhibit a history of positive financial results that are at least comparable to the average for their industry or type of real estate. The primary source of repayment is acceptable and these loans are expected to perform satisfactorily during most economic cycles. Pass loans typically have no significant external factors that are expected to adversely affect these borrowers more than others in the same industry or property type. Any minor unfavorable characteristics of these loans are outweighed or mitigated by other positive factors including but not limited to adequate secondary or tertiary sources of repayment.
Criticized or compromised loans are currently protected but have weaknesses, which, if not corrected, may inadequately protect the Bank at some future date. These loans represent an unwarranted credit risk and would generally not be extended in the normal course of lending. Specific issues which may warrant this grade include declining financial results, increased reliance on secondary sources of repayment or guarantor support and adverse external influences that may negatively impact the business or property.
Substandard and doubtful loans are equivalent to the classifications used by banking regulators. Substandard loans are inadequately protected by the current repayment capacity and equity of the borrower or collateral pledged, if any. Substandard loans have one or more well-defined weaknesses that jeopardize their repayment or collection in full. These loans may or may not be reported as non-accrual. Doubtful loans have all the weaknesses inherent to a substandard loan with the added characteristic that full repayment is highly questionable or improbable on the basis of currently existing facts, conditions and collateral values. However, recognition of loss may be deferred if there are reasonably specific pending factors that will reduce the risk if they occur.
The following tables summarize commercial loans by their assigned risk grade:
		Commerical Loans by Internally Assigned Risk Grade
(unaudited, in thousands)		Commercial			Commercial			Commercial			Total
		Real Estate-			Real Estate-			& Industrial			Commercial
		Land and			Improved						Loans
		Construction			Property
As of March 31, 2015
Pass		$	281,730		$	1,848,655		$	683,226		$	2,813,611
Criticized - compromised			3,653			18,049			18,957			40,659
Classified - substandard			2,692			42,165			7,438			52,295
Classified - doubtful			—			—			—			—
Total		$	288,075		$	1,908,869		$	709,621		$	2,906,565
As of December 31, 2014
Pass		$	257,218		$	1,627,771		$	617,742		$	2,502,731
Criticized - compromised			3,645			17,873			12,770			34,288
Classified - substandard			1,780			37,173			7,898			46,851
Classified - doubtful			—			—			—			—
Total		$	262,643		$	1,682,817		$	638,410		$	2,583,870
Residential real estate, home equity and consumer loans are not assigned internal risk grades other than as required by regulatory guidelines that are based primarily on the age of past due loans. WesBanco primarily evaluates the credit quality of residential real estate, home equity and consumer loans based on repayment performance and historical loss rates. The aggregate amount of residential real estate, home equity and consumer loans classified as substandard in accordance with regulatory guidelines were $15.5 million at March 31, 2015 and $15.2 million at December 31, 2014, of which $1.5 and $2.2 million were accruing, for each period, respectively. The aggregate amount of residential real estate, home equity and consumer loans classified as substandard are not included in the tables above.
Acquired Loans — Loans acquired in connection with acquisitions are recorded at their acquisition-date fair value in accordance with ASC 805, Business Combinations, with no carryover of related allowance for credit losses. Determining the fair value of the acquired loans involves estimating the principal and interest cash flows expected to be collected on the loans and discounting those cash flows at a market rate of interest. Management considers a number of factors in evaluating the acquisition-date fair value including the remaining life of the acquired loans, delinquency status, estimated prepayments, payment options and other loan features, internal risk grade, estimated value of the underlying collateral and interest rate environment.
Loans acquired with deteriorated credit quality are accounted for in accordance with ASC 310-30, Loans and Debt Securities Acquired with Deteriorated Credit Quality (ASC 310-30), and therefore impaired if, at acquisition, the loans have evidence of credit quality deterioration since origination and it is probable that all contractually required payments will not be collected. At acquisition, WesBanco considers several factors as indicators that an acquired loan has evidence of deterioration in credit quality. These factors include loans 90 days or more past due, loans with an internal risk grade of substandard or below, loans classified as non-accrual by the acquired institution, and loans that have been previously modified as a TDR.
Acquired loans that were not individually determined to be impaired are considered performing and are accounted for in accordance with ASC 310-20, Nonrefundable Fees and Other Costs (ASC 310-20), whereby the premium or discount derived from the fair market value adjustment, on a loan-by-loan or pooled basis, is recognized into interest income on a level yield over the remaining expected life of the loan or pool.
Under the ASC 310-30 model, the excess of cash flows expected to be collected at acquisition over recorded fair value is referred to as the accretable yield and is the interest component of expected cash flow. The accretable yield is recognized into income over the remaining life of the loan if the timing and/or amount of cash flows expected to be collected can be reasonably estimated. If the timing or amount of cash flows expected to be collected cannot be reasonably estimated, the cost recovery method of income recognition is used. The difference between the loan’s total scheduled principal and interest payments over all cash flows expected to be collected at acquisition, considering the impact of prepayments, is referred to as the non-accretable difference. The non-accretable difference represents contractually required principal and interest payments which WesBanco does not expect to collect.
Over the life of the loan, management continues to estimate cash flows expected to be collected. Decreases in expected cash flows are recognized as impairments through a charge to the provision for loan losses resulting in an increase in the allowance for loan losses. Subsequent improvements in cash flows result in first, reversal of existing valuation allowances recognized subsequent to acquisition, if any, and next, an increase in the amount of accretable yield to be subsequently recognized in interest income on a prospective basis over the loan’s remaining life.
In conjunction with the ESB acquisition, WesBanco acquired loans with a book value of $716.1 million. These loans were recorded at their fair value of $700.8 million, with $691.1 million categorized as performing. The fair market value adjustment on performing loans of $9.0 million at acquisition date is expected to be recognized into interest income on a level yield over the remaining expected life of the performing loans. Loans acquired with deteriorated credit quality with a book value of $16.0 million were recorded at their estimated fair value of $9.7 million. The accretable yield on the acquired impaired loans is estimated at $2.4 million, while the non-accretable difference is estimated at $3.9 million. The balance of these loans acquired with deteriorated credit quality at March 31, 2015, was $9.3 million, of which $3.6 million were categorized as non-accrual and $5.7 million were categorized as accruing TDRs.
The following tables summarize the age analysis of all categories of loans:
		Age Analysis of Loans
(unaudited, in thousands)		Current			30-59			60-89			90 Days			Total			Total Loans			90 Days or
					Days			Days			or More			Past Due						More
					Past Due			Past Due			Past Due									Past Due and
																				Accruing (1)
As of March 31, 2015
Commercial real estate:
Land and construction		$	286,883		$	—		$	—		$	1,192		$	1,192		$	288,075		$	—
Improved property			1,889,451			1,093			1,435			16,890			19,418			1,908,869			—
Total commercial real estate			2,176,334			1,093			1,435			18,082			20,610			2,196,944			—
Commercial and industrial			705,380			916			1,518			1,807			4,241			709,621			3
Residential real estate			1,226,131			4,981			1,673			6,378			13,032			1,239,163			74
Home equity			357,545			1,982			508			2,128			4,618			362,163			684
Consumer			362,338			2,117			868			507			3,492			365,830			270
Total portfolio loans			4,827,728			11,089			6,002			28,902			45,993			4,873,721			1,031
Loans held for sale			6,064			—			—			—			—			6,064			—
Total loans		$	4,833,792		$	11,089		$	6,002		$	28,902		$	45,993		$	4,879,785		$	1,031
Impaired loans included above are as follows:
Non-accrual loans		$	9,209		$	2,008		$	2,319		$	27,838		$	32,165		$	41,374
TDRs accruing interest (1)			16,536			582			179			33			794			17,330
Total impaired		$	25,745		$	2,590		$	2,498		$	27,871		$	32,959		$	58,704
As of December 31, 2014
Commercial real estate:
Land and construction		$	261,356		$	20		$	—		$	1,267		$	1,287		$	262,643		$	71
Improved property			1,665,363			961			4,772			11,721			17,454			1,682,817			—
Total commercial real estate			1,926,719			981			4,772			12,988			18,741			1,945,460			71
Commercial and industrial			634,482			1,834			240			1,854			3,928			638,410			22
Residential real estate			915,968			1,237			3,384			8,181			12,802			928,770			1,306
Home equity			325,291			1,877			895			1,968			4,740			330,031			570
Consumer			240,365			2,571			685			474			3,730			244,095			319
Total portfolio loans			4,042,825			8,500			9,976			25,465			43,941			4,086,766			2,288
Loans held for sale			5,865			—			—			—			—			5,865			—
Total loans		$	4,048,690		$	8,500		$	9,976		$	25,465		$	43,941		$	4,092,631		$	2,288
Impaired loans included above are as follows:
Non-accrual loans		$	7,562		$	2,884		$	5,552		$	22,820		$	31,256		$	38,818
TDRs accruing interest (1)			11,016			151			542			357			1,050			12,066
Total impaired		$	18,578		$	3,035		$	6,094		$	23,177		$	32,306		$	50,884
-1	Loans 90 days or more past due and accruing interest exclude TDRs 90 days or more past due and accruing interest.
Impaired Loans — A loan is considered impaired, based on current information and events, if it is probable that WesBanco will be unable to collect the payments of principal and interest when due according to the contractual terms of the loan agreement. Impaired loans generally included all non-accrual loans and TDRs.
Loans are generally placed on non-accrual when they are 90 days past due unless the loan is well-secured and in the process of collection. Loans may also be placed on non-accrual when full collection of principal is in doubt even if payments on such loans remain current, or may remain on non-accrual if they were past due but subsequently brought current.
Loans are categorized as TDRs when the Bank, for economic or legal reasons related to a borrower’s financial difficulties, grants a concession to the borrower that it would not otherwise consider.
Acquired loans that have experienced a deterioration of credit quality from origination to acquisition for which it is probable that WesBanco will be unable to collect all contractually required payments receivable, including both principal and interest, are considered impaired.
The following tables summarize impaired loans:
		Impaired Loans
		March 31, 2015									December 31, 2014
(unaudited, in thousands)		Unpaid			Recorded			Related			Unpaid			Recorded			Related
		Principal			Investment			Allowance			Principal			Investment			Allowance
		Balance (1)									Balance (1)
With no related specific allowance recorded:
Commercial real estate:
Land and construction		$	3,101		$	2,476		$	—		$	1,588		$	1,488		$	—
Improved property			30,138			22,481			—			16,480			14,684			—
Commercial and industrial			3,094			2,432			—			3,152			2,597			—
Residential real estate			20,943			19,132			—			20,077			18,544			—
Home equity			2,824			2,617			—			2,890			2,663			—
Consumer			1,659			1,332			—			1,287			1,086			—
Total impaired loans without a specific allowance			61,759			50,470			—			45,474			41,062			—
With a specific allowance recorded:
Commercial real estate:
Land and construction			—			—			—			—			—			—
Improved property			6,466			6,466			2,828			7,980			7,980			2,765
Commercial and industrial			1,768			1,768			873			1,842			1,842			1,033
Total impaired loans with a specific allowance			8,234			8,234			3,701			9,822			9,822			3,798
Total impaired loans		$	69,993		$	58,704		$	3,701		$	55,296		$	50,884		$	3,798
-1	The difference between the unpaid principal balance and the recorded investment generally reflects amounts that have been previously charged-off and fair market value adjustments on acquired impaired loans.
		Impaired Loans
		For the Three Months Ended						For the Three Months Ended
		March 31, 2015						March 31, 2014
(unaudited, in thousands)		Average			Interest			Average			Interest
		Recorded			Income			Recorded			Income
		Investment			Recognized			Investment			Recognized
With no related specific allowance recorded:
Commercial real estate:
Land and construction		$	2,128		$	16		$	2,450		$	2
Improved property			18,932			223			19,158			20
Commercial and industrial			2,513			13			3,532			32
Residential real estate			18,715			230			19,463			182
Home equity			2,641			20			2,367			19
Consumer			1,194			20			1,174			28
Total impaired loans without a specific allowance			46,123			522			48,144			283
With a specific allowance recorded:
Commercial real estate:
Land and construction			—			—			—			—
Improved property			7,223			—			729			1
Commercial and industrial			1,805			19			2,329			12
Total impaired loans with a specific allowance			9,028			19			3,058			13
Total impaired loans		$	55,151		$	541		$	51,202		$	296
The following tables present the recorded investment in non-accrual loans and TDRs:
		Non-accrual Loans (1)
(unaudited, in thousands)		March 31,			December 31,
		2015			2014
Commercial real estate:
Land and construction		$	1,463		$	1,488
Improved property			22,143			20,227
Total commercial real estate			23,606			21,715
Commercial and industrial			3,849			4,110
Residential real estate			11,249			10,329
Home equity			1,899			1,923
Consumer			771			741
Total		$	41,374		$	38,818
(1)	Total non-accrual loans include loans that are also restructured. Such loans are also set forth in the following table as non-accrual TDRs.
		TDRs
		March 31, 2015									December 31, 2014
(unaudited, in thousands)		Accruing			Non-Accrual			Total			Accruing			Non-Accrual			Total
Commercial real estate:
Land and construction		$	1,013		$	504		$	1,517		$	—		$	464		$	464
Improved property			6,804			5,399			12,203			2,437			1,850			4,287
Total commercial real estate			7,817			5,903			13,720			2,437			2,314			4,751
Commercial and industrial			351			376			727			329			478			807
Residential real estate			7,883			2,386			10,269			8,215			2,074			10,289
Home equity			718			285			1,003			740			245			985
Consumer			561			274			835			345			309			654
Total		$	17,330		$	9,224		$	26,554		$	12,066		$	5,420		$	17,486
As of March 31, 2015, there were three TDRs greater than $1.0 million. The concessions granted in the majority of loans reported as accruing and non-accrual TDRs are extensions of the maturity date or the amortization period, reductions in the interest rate below the prevailing market rate for loans with comparable characteristics, and/or permitting interest-only payments for longer than three months.
The following table presents details related to loans identified as TDRs during the three months ended March 31, 2015 and 2014, respectively:
		New TDRs (1)
		For the Three Months Ended
		March 31, 2015									March 31, 2014
(unaudited, dollars in thousands)		Number of			Pre-			Post-			Number of			Pre-			Post-
		Modifications			Modification			Modification			Modifications			Modification			Modification
					Outstanding			Outstanding						Outstanding			Outstanding
					Recorded			Recorded						Recorded			Recorded
					Investment			Investment						Investment			Investment
Commercial real estate:
Land and construction			11		$	1,414		$	1,056			—		$	—		$	—
Improved Property			7			8,568			8,289			1			91			90
Total commercial real estate			18			9,982			9,345			1			91			90
Commercial and industrial			2			42			57			—			—			—
Residential real estate			7			424			421			4			121			118
Home equity			1			7			6			—			—			—
Consumer			21			269			303			2			33			31
Total			49		$	10,724		$	10,132			7		$	245		$	239
(1)	Excludes loans that were either paid off or charged-off by period end. The pre-modification balance represents the balance outstanding at the beginning of the period. The post-modification balance represents the outstanding balance at period end.
The following table summarizes TDRs which defaulted (defined as past due 90 days) during the three months ended March 31, 2015 and 2014, respectively, that were restructured within the last twelve months prior to March 31, 2015 and 2014, respectively:
		Defaulted TDRs (1)						Defaulted TDRs (1)
		For the Three Months Ended						For the Three Months Ended
		March 31, 2015						March 31, 2014
(unaudited, dollars in thousands)		Number of			Recorded			Number of			Recorded
		Defaults			Investment			Defaults			Investment
Commercial real estate:
Land and construction			—		$	—			—		$	—
Improved property			—			—			—			—
Total commercial real estate			—			—			—			—
Commercial and industrial			—			—			—			—
Residential real estate			—			—			8			481
Home equity			1			42			1			3
Consumer			1			27			—			—
Total			2		$	69			9		$	484
(1)	Excludes loans that were either charged-off or cured by period end. The recorded investment is as of March 31, 2014 and 2013, respectively.
TDRs that defaulted during the three month period that were restructured within the last twelve months represented 0.3% of the total TDR balance at March 31, 2015. These loans are placed on non-accrual status unless they are both well-secured and in the process of collection. At March 31, 2015, none of the loans in the table above were accruing interest.
The following table summarizes other real estate owned and repossessed assets included in other assets:
(unaudited, in thousands)		March 31,			December 31,
		2015			2014
Other real estate owned		$	5,886		$	4,920
Repossessed assets			340			162
Total other real estate owned and repossessed assets		$	6,226		$	5,082
Residential real estate included in other real estate owned at March 31, 2015 and December 31, 2014 was $0.8 million and $0.6 million, respectively. At March 31, 2015, formal foreclosure proceedings were in process on residential real estate loans totaling $4.3 million.

Pension_Plan

Pension Plan	3 Months Ended
	Mar. 31, 2015
Compensation and Retirement Disclosure [Abstract]
Pension Plan	NOTE 6. PENSION PLAN
	The following table presents the net periodic pension cost for WesBanco’s Defined Benefit Pension Plan (the “Plan”) and the related components:
		For the Three Months Ended
		March 31,
	(unaudited, in thousands)	2015			2014
	Service cost - benefits earned during year	$	827		$	717
	Interest cost on projected benefit obligation		1,201			1,170
	Expected return on plan assets		(1,907	)		(1,783	)
	Amortization of prior service cost		6			11
	Amortization of net loss		784			363
	Net periodic pension cost	$	911		$	478
	The Plan covers all employees of WesBanco and its subsidiaries who were hired on or before August 1, 2007 who satisfy minimum age and length of service requirements, and is not available to employees hired after such date.
	A minimum required contribution of $3.1 million is due for 2015 which could be all or partially offset by the Plan’s $34.9 million available credit balance. WesBanco expects to make a voluntary contribution of $7.5 million to the Plan in 2015.

Fair_Value_Measurement

Fair Value Measurement	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurement	NOTE 7. FAIR VALUE MEASUREMENT
	Fair value estimates are based on quoted market prices, if available, quoted market prices of similar assets or liabilities, or the present value of expected future cash flows and other valuation techniques. These valuations are significantly affected by discount rates, cash flow assumptions, and risk assumptions used. Therefore, fair value estimates may not be substantiated by comparison to independent markets and are not intended to reflect the proceeds that may be realizable in an immediate settlement of the instruments.
	Fair value is determined at one point in time and is not representative of future value. These amounts do not reflect the total value of a going concern organization. Management does not have the intention to dispose of a significant portion of its assets and liabilities and therefore, the unrealized gains or losses should not be interpreted as a forecast of future earnings and cash flows.
	The following is a discussion of assets and liabilities measured at fair value on a recurring basis and valuation techniques applied:
	Securities available-for-sale: The fair value of securities available-for-sale which are measured on a recurring basis are determined primarily by obtaining quoted prices on nationally recognized securities exchanges or matrix pricing, which is a mathematical technique used widely in the industry to value debt securities without relying exclusively on quoted prices for the specific securities but rather by relying on the securities’ relationship to other similar securities. These securities are classified within level 1 or 2 in the fair value hierarchy. Certain equity securities that are lightly traded in over-the-counter markets are classified as level 2 in the fair value hierarchy, as quoted market prices may not be available on the fair value measurement date. Positions that are not traded in active markets for which valuations are generated using assumptions not observable in the market or management’s best estimate are classified within level 3 of the fair value hierarchy. This includes certain specific municipal debt issues for which the credit quality and discount rate must be estimated.
	We may be required from time to time to measure certain assets at fair value on a nonrecurring basis in accordance with GAAP. These adjustments to fair value usually result from application of lower of cost or market accounting or write-downs of individual assets.
	Impaired loans: Impaired loans are carried at the lower of cost or the fair value of the collateral for collateral-dependent loans. Collateral may be in the form of real estate or business assets including equipment, inventory and accounts receivable. The use of independent appraisals, discounted cash flow models and management’s best judgment are significant inputs in arriving at the fair value measure of the underlying collateral and impaired loans are therefore classified within level 3 of the fair value hierarchy.
	Other real estate owned and repossessed assets: Other real estate owned and repossessed assets are carried at the lower of the investment in the assets or the fair value of the assets less estimated selling costs. The use of independent appraisals and management’s best judgment are significant inputs in arriving at the fair value measure of the underlying collateral, and therefore other real estate owned and repossessed assets are classified within level 3 of the fair value hierarchy.
	Loans held for sale: Loans held for sale are carried, in aggregate, at the lower of cost or fair value. The use of a valuation model using quoted prices of similar instruments are significant inputs in arriving at the fair value and therefore loans held for sale are classified within level 2 of the fair value hierarchy.
	The following tables set forth WesBanco’s financial assets and liabilities that were accounted for at fair value on a recurring and nonrecurring basis by level within the fair value hierarchy as of March 31, 2015 and December 31, 2014:
					March 31, 2015
					Fair Value Measurements Using:
	(unaudited, in thousands)		March 31,		Quoted Prices in			Significant Other		Significant
			2015		Active Markets			Observable		Unobservable
					for Identical			Inputs		Inputs
					Assets (level  1)			(level 2)		(level 3)
	Recurring fair value measurements
	Securities - available-for-sale
	Obligations of government agencies		$	80,768	$	—		$	80,768	$	—
	Residential mortgage-backed securities and collateralized mortgage obligations of government agencies			1,283,445		—			1,283,445		—
	Obligations of state and political subdivisions			95,653		—			95,653		—
	Corporate debt securities			183,090		—			183,090		—
	Equity securities			11,308		8,538			2,770		—
	Total securities - available-for-sale		$	1,654,264	$	8,538		$	1,645,726	$	—
	Total recurring fair value measurements		$	1,654,264	$	8,538		$	1,645,726	$	—
	Nonrecurring fair value measurements
	Impaired loans		$	4,533	$	—		$	—	$	4,533
	Other real estate owned and repossessed assets			6,226		—			—		6,226
	Loans held for sale			6,064		—			6,064		—
	Total nonrecurring fair value measurements		$	16,823	$	—		$	6,064	$	10,759
					December 31, 2014
					Fair Value Measurements Using:
	(unaudited, in thousands)		December 31,		Quoted Prices in			Significant Other		Significant
			2014		Active Markets			Observable		Unobservable
					for Identical			Inputs		Inputs
					Assets (level 1)			(level 2)		(level 3)
	Recurring fair value measurements
	Securities - available-for-sale
	Obligations of government agencies		$	87,736	$	—		$	87,736	$	—
	Residential mortgage-backed securities and collateralized mortgage obligations of government agencies			701,113		—			701,113		—
	Obligations of state and political subdivisions			91,433		—			91,433		—
	Corporate debt securities			25,996		—			25,996		—
	Equity securities			11,146		8,440			2,706		—
	Total securities - available-for-sale		$	917,424	$	8,440		$	908,984	$	—
	Total recurring fair value measurements		$	917,424	$	8,440		$	908,984	$	—
	Nonrecurring fair value measurements
	Impaired loans		$	6,024	$	—		$	—	$	6,024
	Other real estate owned and repossessed assets			5,082		—			—		5,082
	Loans held for sale			5,865		—			5,865		—
	Total nonrecurring fair value measurements		$	16,971	$	—		$	5,865	$	11,106
	WesBanco’s policy is to recognize transfers between levels as of the actual date of the event or change in circumstances that caused the transfer. There were no transfers between level 1, 2 or 3 for the three months ended March 31, 2015 or 2014.
	The following table presents additional quantitative information about assets measured at fair value on a nonrecurring basis and for which WesBanco has utilized level 3 inputs to determine fair value:
			Quantitative Information about Level 3 Fair Value Measurements
	(unaudited, in thousands)		Fair Value		Valuation Techniques		Unobservable Input	Range (Weighted Average)
			Estimate
	March 31, 2015:
	Impaired loans		$	4,533	Appraisal of collateral (1)		Appraisal adjustments (2)	0% to (38.5%) / (6.9%)
							Liquidation expenses (2)	(3.1%) to (8.0%) / (7.4%)
	Other real estate owned and repossessed assets			6,226	Appraisal of collateral (1), (3)
	December 31, 2014:
	Impaired loans		$	6,024	Appraisal of collateral (1)		Appraisal adjustments (2)	0% to (39.7%) / (6.7%)
							Liquidation expenses (2)	(1.2%) to (8.0%) / (6.7%)
	Other real estate owned and repossessed assets			5,082	Appraisal of collateral (1), (3)
	-1	Fair value is generally determined through independent appraisals of the underlying collateral, which generally include various level 3 inputs which are not identifiable.
(2)	Appraisals may be adjusted by management for qualitative factors such as economic conditions and estimated liquidation expenses. The range and weighted average of appraisal adjustments and liquidation expenses are presented as a percent of the appraisal.
(3)	Includes estimated liquidation expenses and numerous dissimilar qualitative adjustments by management which are not identifiable.
The estimated fair values of WesBanco’s financial instruments are summarized below:
							Fair Value Measurements at
							March 31, 2015
(unaudited, in thousands)		Carrying		Fair Value			Quoted Prices in		Significant Other		Significant
		Amount		Estimate			Active Markets		Observable		Unobservable
							for Identical		Inputs		Inputs
							Assets (level 1)		(level 2)		(level 3)
Financial Assets
Cash and due from banks		$	92,974	$	92,974		$	92,974	$	—	$	—
Securities available-for-sale			1,654,264		1,654,264			8,538		1,645,726		—
Securities held-to-maturity			743,925		772,843			—		772,088		755
Net loans			4,829,548		4,820,779			—		—		4,820,779
Loans held for sale			6,064		6,064			—		6,064		—
Accrued interest receivable			25,232		25,232			25,232		—		—
Bank-owned life insurance			153,991		153,991			153,991		—		—
Financial Liabilities
Deposits			6,416,202		6,423,499			4,532,314		1,891,185		—
Federal Home Loan Bank borrowings			432,456		435,089			—		435,089		—
Other borrowings			76,630		76,621			73,589		3,032		—
Junior subordinated debt			142,269		116,070			—		116,070		—
Accrued interest payable			2,297		2,297			2,297		—		—
							Fair Value Measurements at
							December 31, 2014
(unaudited, in thousands)		Carrying		Fair Value			Quoted Prices in		Significant Other		Significant
		Amount		Estimate			Active Markets		Observable		Unobservable
							for Identical		Inputs		Inputs
							Assets (level 1)		(level 2)		(level 3)
Financial Assets
Cash and due from banks		$	94,002	$	94,002		$	94,002	$	—	$	—
Securities available-for-sale			917,424		917,424			8,440		908,984		—
Securities held-to-maturity			593,670		619,617			—		618,895		722
Net loans			4,042,112		4,047,648			—		—		4,047,648
Loans held for sale			5,865		5,865			—		5,865		—
Accrued interest receivable			18,481		18,481			18,481		—		—
Bank-owned life insurance			123,298		123,298			123,298		—		—
Financial Liabilities
Deposits			5,048,983		5,056,828			3,743,887		1,312,941		—
Federal Home Loan Bank borrowings			223,126		225,456			—		225,456		—
Other borrowings			80,690		80,696			77,534		3,162		—
Junior subordinated debt			106,176		79,212			—		79,212		—
Accrued interest payable			1,620		1,620			1,620		—		—
The following methods and assumptions were used to measure the fair value of financial instruments recorded at cost on WesBanco’s consolidated balance sheets:
Cash and due from banks: The carrying amount for cash and due from banks is a reasonable estimate of fair value.
Securities held-to-maturity: Fair values for securities held-to-maturity are determined in the same manner as securities available-for-sale which is described above.
Net loans: Fair values for loans are estimated using a discounted cash flow methodology. The discount rates take into account interest rates currently being offered to customers for loans with similar terms, the credit risk associated with the loan and other market factors, including liquidity. The valuation of the loan portfolio reflects discounts that WesBanco believes are consistent with transactions occurring in the marketplace for both performing and distressed loan types. The carrying value that fair value is compared to is net of the allowance for loan losses and other associated premiums and discounts. Due to the significant judgment involved in evaluating credit quality, loans are classified within level 3 of the fair value hierarchy.
Accrued interest receivable: The carrying amount of accrued interest receivable approximates its fair value.
Bank-owned life insurance: The carrying value of bank-owned life insurance represents the net cash surrender value of the underlying insurance policies, should these policies be terminated. Management believes that the carrying value approximates its fair value.
Deposits: The carrying amount is considered a reasonable estimate of fair value for demand, savings and other variable rate deposit accounts. The fair value of fixed maturity certificates of deposit is estimated by a discounted cash flow method using rates currently offered for deposits of similar remaining maturities.
Federal Home Loan Bank borrowings: The fair value of FHLB borrowings is based on rates currently available to WesBanco for borrowings with similar terms and remaining maturities.
Other borrowings: The carrying amount of federal funds purchased and overnight sweep accounts generally approximate fair value. Other repurchase agreements are based on quoted market prices if available. If market prices are not available, for certain fixed and adjustable rate repurchase agreements, then quoted market prices of similar instruments are used.
Junior subordinated debt owed to unconsolidated subsidiary trusts: Due to the pooled nature of these instruments, which are not actively traded, estimated fair value is based on recent similar transactions of single-issuer trust preferred securities.
Accrued interest payable: The carrying amount of accrued interest payable approximates its fair value.
Off-balance sheet financial instruments: Off-balance sheet financial instruments consist of commitments to extend credit, including letters of credit. Fair values for commitments to extend credit are estimated using the fees currently charged to enter into similar agreements, taking into account the remaining terms of the agreements and the present credit standing of the counterparties. The estimated fair value of the commitments to extend credit and letters of credit are insignificant and therefore are not presented in the above tables.

Comprehensive_Income

Comprehensive Income	3 Months Ended
	Mar. 31, 2015
Equity [Abstract]
Comprehensive Income	NOTE 8. COMPREHENSIVE INCOME
	The activity in accumulated other comprehensive income for the three months ended March 31, 2015 and 2014 is as follows:
			Accumulated Other Comprehensive Income(1)
	(unaudited, in thousands)		Defined			Unrealized Gains			Unrealized Gains			Total
			Benefit			(Losses) on			on Securities
			Pension			Securities			Transferred from
			Plan			Available-for-Sale			Available-for-
									Sale to
									Held-to-Maturity
	Balance at December 31, 2014		$	(22,776	)	$	2,892		$	1,059		$	(18,825	)
	Other comprehensive income before reclassifications			—			4,804			—			4,804
	Amounts reclassified from accumulated other comprehensive income			475			(11	)		(67	)		397
	Period change			475			4,793			(67	)		5,201
	Balance at March 31, 2015		$	(22,301	)	$	7,685		$	992		$	(13,624	)
	Balance at December 31, 2013		$	(7,966	)	$	(6,126	)	$	1,358		$	(12,734	)
	Other comprehensive income before reclassifications			—			3,075			—			3,075
	Amounts reclassified from accumulated other comprehensive income			236			49			(87	)		198
	Period change			236			3,124			(87	)		3,273
	Balance at March 31, 2014		$	(7,730	)	$	(3,002	)	$	1,271		$	(9,461	)
	(1)	All amounts are net of tax. Related income tax expense or benefit is calculated using a combined Federal and State income tax rate approximating 37%.
	The following table provides details about amounts reclassified from accumulated other comprehensive income for the three months ended March 31, 2015 and 2014:
	Details about Accumulated Other Comprehensive Income/(Loss)		Amounts Reclassified from						Affected Line Item in the
	Components		Accumulated Other						Statement of Net Income
			Comprehensive Income/(Loss)
			For the Three Months Ended
			March 31,
	(unaudited, in thousands)		2015			2014
	Securities available-for-sale (1):
	Net securities (gains) losses reclassified into earnings			(18	)	$	78		Net securities gains (Non-interest income)
	Related income tax expense (benefit)			7			(29	)	Provision for income taxes
	Net effect on accumulated other comprehensive income for the period			(11	)		49
	Securities held-to-maturity (1):
	Amortization of unrealized gain transferred from available-for-sale			(107	)		(138	)	Interest and dividends on securities (Interest and dividend income)
	Related income tax expense			40			51		Provision for income taxes
	Net effect on accumulated other comprehensive income for the period			(67	)		(87	)
	Defined benefit pension plan (2):
	Amortization of net loss and prior service costs			790			374		Employee benefits (Non-interest expense)
	Related income tax benefit			(315	)		(138	)	Provision for income taxes
	Net effect on accumulated other comprehensive income for the period			475			236
	Total reclassifications for the period			397		$	198
	-1	For additional detail related to unrealized gains on securities and related amounts reclassified from accumulated other comprehensive income see Note 4, “Securities.”
	-2	Included in the computation of net periodic pension cost. See Note 6, “Pension Plan” for additional detail.

Commitments_and_Contingent_Lia

Commitments and Contingent Liabilities	3 Months Ended
	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingent Liabilities	NOTE 9. COMMITMENTS AND CONTINGENT LIABILITIES
	Commitments — In the normal course of business, WesBanco offers off-balance sheet credit arrangements to enable its customers to meet their financing objectives. Those instruments involve, to varying degrees, elements of credit and interest rate risk in excess of the amount recognized in the financial statements. WesBanco’s exposure to credit losses in the event of non-performance by the other parties to the financial instruments for commitments to extend credit and standby letters of credit is limited to the contractual amount of those instruments. WesBanco uses the same credit policies in making commitments and conditional obligations as for all other lending. Commitments generally have fixed expiration dates or other termination clauses and may require payment of a fee. Since many of the commitments are expected to expire without being drawn upon, the total commitment amounts do not necessarily represent future cash requirements. The allowance for credit losses associated with commitments was $0.5 million as of March 31, 2015 and December 31, 2014, respectively, and is included in other liabilities on the Consolidated Balance Sheets.
	Letters of credit are conditional commitments issued by banks to guarantee the performance of a customer to a third party. Those guarantees are primarily issued to support public and private borrowing arrangements, including normal business activities, bond financing and similar transactions. Letters of credit are considered guarantees. The liability associated with letters of credit was $0.2 million as of March 31, 2015 and December 31, 2014, respectively.
	Contingent obligations to purchase loans funded by other entities include affordable housing plan guarantees and credit card guarantees. Affordable housing plan guarantees are performance guarantees for various building project loans. The guarantee amortizes as the loan balances decrease. Credit card guarantees are credit card balances not owned by WesBanco, whereby the Bank guarantees the performance of the cardholder.
	The following table presents total commitments to extend credit, guarantees and various letters of credit outstanding:
	(unaudited, in thousands)	March 31,		December 31,
		2015		2014
	Lines of credit	$	1,032,235	$	984,352
	Loans approved but not closed		295,702		116,757
	Overdraft limits		110,389		95,965
	Letters of credit		26,910		23,362
	Contingent obligations to purchase loans funded by other entities		8,457		8,312
	Contingent Liabilities — WesBanco is a party to various legal and administrative proceedings and claims. While any litigation contains an element of uncertainty, management does not believe that a material loss related to such proceedings or claims pending or known to be threatened is reasonably possible.

Business_Segments

Business Segments	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Business Segments	NOTE 10. BUSINESS SEGMENTS
	WesBanco operates two reportable segments: community banking and trust and investment services. WesBanco’s community banking segment offers services traditionally offered by full-service commercial banks, including commercial demand, individual demand and time deposit accounts, as well as commercial, mortgage and individual installment loans, and certain non-traditional offerings, such as insurance and securities brokerage services. The trust and investment services segment offers trust services as well as various alternative investment products including mutual funds. The market value of assets managed or held in custody by the trust and investment services segment was approximately $3.9 billion and $3.8 billion at March 31, 2015 and 2014, respectively. These assets are held by WesBanco in fiduciary or agency capacities for their customers and therefore are not included as assets on WesBanco’s Consolidated Balance Sheets.
	Condensed financial information by business segment is presented below:
	(unaudited, in thousands)	Community		Trust and		Consolidated
		Banking		Investment
				Services
	For the Three Months ended March 31, 2015:
	Interest income	$	60,379	$	—	$	60,379
	Interest expense		5,424		—		5,424
	Net interest income		54,955		—		54,955
	Provision for credit losses		1,289		—		1,289
	Net interest income after provision for credit losses		53,666		—		53,666
	Non-interest income		12,137		6,053		18,190
	Non-interest expense		50,278		3,163		53,441
	Income before provision for income taxes		15,525		2,890		18,415
	Provision for income taxes		3,372		1,156		4,528
	Net income	$	12,153	$	1,734	$	13,887
	For the Three Months ended March 31, 2014:
	Interest income	$	53,457	$	—	$	53,457
	Interest expense		6,132		—		6,132
	Net interest income		47,325		—		47,325
	Provision for credit losses		2,199		—		2,199
	Net interest income after provision for credit losses		45,126		—		45,126
	Non-interest income		11,401		5,648		17,049
	Non-interest expense		36,827		3,268		40,095
	Income before provision for income taxes		19,700		2,380		22,080
	Provision for income taxes		4,707		952		5,659
	Net income	$	14,993	$	1,428	$	16,421
	Total non-fiduciary assets of the trust and investment services segment were $3.7 million and $4.0 million at March 31, 2015 and 2014, respectively. All other assets, including goodwill and other intangible assets, were allocated to the community banking segment.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Basis of Presentation	Basis of presentation — The accompanying unaudited interim financial statements of WesBanco, Inc. and its consolidated subsidiaries (“WesBanco”) have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and 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.
	WesBanco’s interim financial statements have been prepared following the significant accounting policies disclosed in Note 1 of the Notes to the Consolidated Financial Statements of its 2014 Annual Report on Form 10-K filed with the Securities and Exchange Commission. In the opinion of management, the accompanying interim financial information reflects all adjustments, including normal recurring adjustments, necessary to present fairly WesBanco’s financial position and 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.
Recent Accounting Pronouncements	Recent accounting pronouncements — In April 2015, the Financial Accounting Standards Board (the “FASB”) issued an Accounting Standards Update (“ASU”) (ASU 2015-05) that provides guidance on when to account for a cloud computing arrangement as a software license. The guidance applies only to internal-use software that a customer obtains access to in a hosting arrangement if both of the following criteria are met: (1) The customer has the contractual right to take possession of the software at any time during the hosting period without significant penalty, (2) it is feasible for the customer to either run the software on its own hardware or contract with another party unrelated to the vendor to host the software. The pronouncement is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2015. Early adoption is permitted. The adoption of this pronouncement is not expected to have a material impact on WesBanco’s Consolidated Financial Statements.
	In February 2015, the FASB issued ASU 2015-02 that revised the consolidation model, requiring reporting entities to reevaluate whether they should consolidate certain legal entities under the revised model. The amendments in this Update modify the evaluation of whether limited partnerships and similar legal entities are variable interest entities (VIEs) or voting interest entities, and eliminate the presumption that a general partner should consolidate and affect the consolidation analysis of reporting entities that are involved with VIEs, particularly those that have fee arrangements and related party relationships. The pronouncement also provides for 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 similar to those in Rule 2a-7 of the Investment Company Act of 1940 for registered money market funds. The pronouncement is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2015. Early adoption is permitted. The adoption of this pronouncement is not expected to have a material impact on WesBanco’s Consolidated Financial Statements.
	In August 2014, the FASB issued ASU 2014-14 related to the classification of certain government-guaranteed mortgage loans upon foreclosure. The amendments in this update require that a mortgage loan be derecognized and that a separate other receivable be recognized upon foreclosure if the following conditions are met: (1) The loan has a government guarantee that is not separable from the loan before foreclosure, (2) at the time of foreclosure, the creditor has the intent to convey the real estate property to the guarantor and make a claim on the guarantee, and the creditor has the ability to recover under that claim, (3) at the time of foreclosure, any amount of the claim that is determined on the basis of the fair value of the real estate is fixed. Upon foreclosure, the separate other receivable should be measured based upon the amount of the loan balance (principal and interest) expected to be recovered from the guarantor. The pronouncement is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2014 and may be adopted under either a modified retrospective transition method or a prospective transition method. However, the same method of transition as elected under ASU 2014-04 must be applied. Early adoption is permitted. The adoption of this pronouncement did not have a material impact on WesBanco’s Consolidated Financial Statements.
	In June 2014, the FASB issued ASU 2014-11 related to repurchase-to-maturity transactions, repurchase financing and disclosures. The pronouncement changes the accounting for repurchase-to-maturity transactions and linked repurchase financings to secured borrowing accounting, which is consistent with the accounting for other repurchase agreements. The pronouncement also requires two new disclosures. The first disclosure requires an entity to disclose information on transfers accounted for as sales in transactions that are economically similar to repurchase agreements. The second disclosure provides increased transparency about the types of collateral pledged in repurchase agreements and similar transactions accounted for as secured borrowings. The pronouncement is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2014. Early adoption is not permitted. The adoption of this pronouncement did not have a material impact on WesBanco’s Consolidated Financial Statements.
	In May 2014, the FASB issued ASU 2014-09 related to the recognition of revenue from contracts with customers. The new revenue pronouncement creates a single source of revenue guidance for all companies in all industries and is more principles-based than current revenue guidance. The pronouncement provides a five-step model for a company to recognize revenue when it transfers control of goods or services to customers at an amount that reflects the consideration to which it expects to be entitled in exchange for those goods or services. The five steps are (1) identify the contract with the customer, (2) identify the separate performance obligations in the contract, (3) determine the transaction price, (4) allocate the transaction price to the separate performance obligations and (5) recognize revenue when each performance obligation is satisfied. The pronouncement is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2016 using either a full retrospective approach for all periods presented in the period of adoption or a modified retrospective approach. Early adoption is not permitted. In April 2015, the FASB issued an exposure draft of a proposed ASU that would delay by one year the effective date of ASU 2014-11. Under the proposal, the standard would be effective for annual reporting periods beginning after December 15, 2017 and interim periods therein. WesBanco is currently evaluating the impact of the adoption of this pronouncement on its Consolidated Financial Statements.

Mergers_and_Acquisitions_Table

Mergers and Acquisitions (Tables)	3 Months Ended
	Mar. 31, 2015
Business Combinations [Abstract]
Calculation of Purchase Price and Resulting Goodwill Relating to ESB Acquisition	The purchase price of the ESB acquisition and resulting goodwill is summarized as follows:
	(unaudited, in thousands)		February 10, 2015
	Purchase Price:
	Fair value of WesBanco shares issued, (net of equity issuance costs of $0.1 million)		$	293,933
	Cash consideration for outstanding ESB shares, options and restricted stock			37,036
	Settlement of pre-existing loan to ESB			8,000
	Total purchase price		$	338,969
	Fair value of:
	Tangible assets acquired		$	1,859,865
	Core deposit and other intangible assets acquired			5,346
	Liabilities assumed			(1,703,616	)
	Net cash received in the acquisition			8,485
	Fair value of net assets acquired			170,080
	Goodwill recognized		$	168,889
Summary of Fair Value of Net Assets that Wesbanco Acquired from ESB	The following table presents the preliminary allocation of the purchase price of the assets acquired and the liabilities assumed at the date of acquisition, as WesBanco intends to finalize its accounting for the acquisition of ESB during 2015:
	(unaudited, in thousands)		February 10, 2015
	Assets
	Cash and due from banks		$	8,485
	Securities			486,891
	Loans			700,849
	Goodwill and other intangible assets			174,235
	Accrued income and other assets (1)			672,125
	Total Assets		$	2,042,585
	Liabilities
	Deposits		$	1,246,992
	Borrowings			433,454
	Accrued expenses and other liabilities			23,170
	Total liabilities			1,703,616
	Purchase price		$	338,969
	(1)	Includes receivables of $560.7 million from the sale of available-for-sale securities prior to the acquisition date.

EARNINGS_PER_COMMON_SHARE_Tabl

EARNINGS PER COMMON SHARE (Tables)	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
Summary of Earnings Per Common Share	Earnings per common share are calculated as follows:
		For the Three Months Ended
		March 31,
	(unaudited, in thousands, except shares and per share amounts)	2015		2014
	Numerator for both basic and diluted earnings per common share:
	Net income	$	13,887	$	16,421
	Denominator:
	Total average basic common shares outstanding		34,393,137		29,182,183
	Effect of dilutive stock options and warrant		85,198		80,497
	Total diluted average common shares outstanding		34,478,335		29,262,680
	Earnings per common share - basic	$	0.4	$	0.56
	Earnings per common share - diluted	$	0.4	$	0.56

Securities_Tables

Securities (Tables)	3 Months Ended
	Mar. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Schedule of Fair Value and Amortized Cost of Available-for-sale and Held-to-maturity Securities	The following table presents the fair value and amortized cost of available-for-sale and held-to-maturity securities:
			March 31, 2015											December 31, 2014
	(unaudited, in thousands)		Amortized			Gross			Gross			Estimated		Amortized			Gross		Gross			Estimated
			Cost			Unrealized			Unrealized			Fair		Cost			Unrealized		Unrealized			Fair
						Gains			Losses			Value					Gains		Losses			Value
	Available-for-sale
	Obligations of government agencies		$	79,315		$	1,486		$	(33	)	$	80,768	$	86,964		$	1,087	$	(315	)	$	87,736
	Residential mortgage-backed securities and collateralized mortgage obligations of government agencies			1,279,350			8,091			(3,996	)		1,283,445		703,535			4,336		(6,758	)		701,113
	Obligations of states and political subdivisions			89,977			5,693			(17	)		95,653		86,073			5,365		(5	)		91,433
	Corporate debt securities			182,781			430			(121	)		183,090		25,974			141		(119	)		25,996
	Total debt securities		$	1,631,423		$	15,700		$	(4,167	)	$	1,642,956	$	902,546		$	10,929	$	(7,197	)	$	906,278
	Equity securities			10,702			606			—			11,308		10,304			842		—			11,146
	Total available-for-sale securities		$	1,642,125		$	16,306		$	(4,167	)	$	1,654,264	$	912,850		$	11,771	$	(7,197	)	$	917,424
	Held-to-maturity
	Residential mortgage-backed securities and collateralized mortgage obligations of government agencies		$	126,935		$	3,244		$	(208	)	$	129,971	$	79,004		$	3,262	$	(246	)	$	82,020
	Obligations of states and political subdivisions			610,249			26,560			(878	)		635,931		507,927			23,917		(1,043	)		530,801
	Corporate debt securities			6,741			200			—			6,941		6,739			106		(49	)		6,796
	Total held-to-maturity securities		$	743,925		$	30,004		$	(1,086	)	$	772,843	$	593,670		$	27,285	$	(1,338	)	$	619,617
	Total securities		$	2,386,050		$	46,310		$	(5,253	)	$	2,427,107	$	1,506,520		$	39,056	$	(8,535	)	$	1,537,041
Schedule of Fair Value of Available-for-sale and Held-to-maturity Securities by Contractual Maturity	The following table presents the fair value of available-for-sale and held-to-maturity securities by contractual maturity at March 31, 2015. In some instances, the issuers may have the right to call or prepay obligations without penalty prior to the contractual maturity date.
			March 31, 2015
	(unaudited, in thousands)		One Year			One to			Five to			After		Mortgage-backed			Total
			or less			Five Years			Ten Years			Ten Years		and Equity
	Available-for-sale
	Obligations of government agencies		$	—		$	23,276		$	40,297		$	17,195	$	—		$	80,768
	Residential mortgage-backed securities and collateralized mortgage obligations of government agencies (1)			—			—			—			—		1,283,445			1,283,445
	Obligations of states and political subdivisions			5,254			33,049			21,417			35,933		—			95,653
	Corporate debt securities			82,193			62,312			33,658			4,927		—			183,090
	Equity securities (2)			—			—			—			—		11,308			11,308
	Total available-for-sale securities		$	87,447		$	118,637		$	95,372		$	58,055	$	1,294,753		$	1,654,264
	Held-to-maturity (3)
	Residential mortgage-backed securities and collateralized mortgage obligations of government agencies (1)		$	—		$	—		$	—		$	—	$	129,971		$	129,971
	Obligations of states and political subdivisions			2,852			17,024			259,231			356,824		—			635,931
	Corporate debt securities			—			—			6,941			—		—			6,941
	Total held-to-maturity securities		$	2,852		$	17,024		$	266,172		$	356,824	$	129,971		$	772,843
	Total securities		$	90,299		$	135,661		$	361,544		$	414,879	$	1,424,724		$	2,427,107
	-1	Mortgage-backed and collateralized mortgage securities, which have prepayment provisions, are not assigned to maturity categories due to fluctuations in their prepayment speeds.
	-2	Equity securities, which have no stated maturity, are not assigned a maturity category.
	(3)	The held-to-maturity portfolio is carried at an amortized cost of $743.9 million.
Schedule of Gross Realized Gains and Losses on the Sales and Calls of Securities	The following table presents the gross realized gains and losses on sales and calls of securities for the three months ended March 31, 2015 and 2014, respectively.
			For the Three Months Ended
			March 31,
	(unaudited, in thousands)		2015			2014
	Gross realized gains		$	24		$	195
	Gross realized losses			(2	)		(185	)
	Net realized gains (losses)		$	22		$	10
Schedule of Unrealized Losses on Investment Securities	The following tables provide information on unrealized losses on investment securities that have been in an unrealized loss position for less than twelve months and twelve months or more as of March 31, 2015 and December 31, 2014:
			March 31, 2015
			Less than 12 months									12 months or more							Total
	(unaudited, dollars in thousands)		Fair			Unrealized			# of			Fair		Unrealized			# of		Fair			Unrealized			# of
			Value			Losses			Securities			Value		Losses			Securities		Value			Losses			Securities
	Obligations of government agencies			17,953			(33	)		3			—		—			0		17,953			(33	)		3
	Residential mortgage-backed securities and collateralized mortgage obligations of government agencies			260,103			(681	)		55			168,693		(3,523	)		32		428,796			(4,204	)		87
	Obligations of states and political subdivisions			68,439			(450	)		79			20,777		(445	)		31		89,216			(895	)		110
	Corporate debt securities			53,122			(113	)		16			1,978		(8	)		1		55,100			(121	)		17
	Total temporarily impaired securities			399,617			(1,277	)		153			191,448		(3,976	)		64		591,065			(5,253	)		217
			31-Dec-14
			Less than 12 months									12 months or more							Total
	(unaudited, dollars in thousands)		Fair			Unrealized			# of			Fair		Unrealized			# of		Fair			Unrealized			# of
			Value			Losses			Securities			Value		Losses			Securities		Value			Losses			Securities
	Obligations of government agencies		$	19,362		$	(77	)		5		$	19,757	$	(238	)		4	$	39,119		$	(315	)		9
	Residential mortgage-backed securities and collateralized mortgage obligations of government agencies			78,786			(386	)		19			240,055		(6,618	)		43		318,841			(7,004	)		62
	Obligations of states and political subdivisions			12,615			(96	)		15			61,548		(952	)		93		74,163			(1,048	)		108
	Corporate debt securities			2,969			(31	)		1			4,573		(137	)		2		7,542			(168	)		3
	Total temporarily impaired securities		$	113,732		$	(590	)		40		$	325,933	$	(7,945	)		142	$	439,665		$	(8,535	)		182

Loans_and_the_Allowance_for_Cr1

Loans and the Allowance for Credit Losses (Tables)	3 Months Ended
	Mar. 31, 2015
Receivables [Abstract]
Schedule of Recorded Investment in Loans by Category	The recorded investment in loans is presented in the Consolidated Balance Sheets net of deferred loan fees and costs of $2.2 million and $2.4 million at March 31, 2015 and December 31, 2014, respectively.
	(unaudited, in thousands)		March 31,			December 31,
			2015			2014
	Commercial real estate:
	Land and construction		$	288,075		$	262,643
	Improved property			1,908,869			1,682,817
	Total commercial real estate			2,196,944			1,945,460
	Commercial and industrial			709,621			638,410
	Residential real estate			1,239,163			928,770
	Home equity			362,163			330,031
	Consumer			365,830			244,095
	Total portfolio loans			4,873,721			4,086,766
	Loans held for sale			6,064			5,865
	Total loans		$	4,879,785		$	4,092,631
Summary of Changes in Allowance for Credit Losses	The following tables summarize changes in the allowance for credit losses applicable to each category of the loan portfolio:
			Allowance for Credit Losses By Category
			For the Three Months Ended March 31, 2015 and 2014
	(unaudited, in thousands)		Commercial			Commercial			Commercial			Residential			Home			Consumer			Deposit			Total
			Real Estate-			Real Estate-			& Industrial			Real Estate			Equity						Overdraft
			Land and			Improved
			Construction			Property
	Balance at December 31, 2014:
	Allowance for loan losses		$	5,654		$	17,573		$	9,063		$	5,382		$	2,329		$	4,078		$	575		$	44,654
	Allowance for loan commitments			194			10			112			9			90			40			—			455
	Total beginning allowance for credit losses			5,848			17,583			9,175			5,391			2,419			4,118			575			45,109
	Provision for credit losses:
	Provision for loan losses			(323	)		903			(44	)		(208	)		747			133			58			1,266
	Provision for loan commitments			(16	)		8			8			4			17			2			—			23
	Total provision for credit losses			(339	)		911			(36	)		(204	)		764			135			58			1,289
	Charge-offs			—			(577	)		(122	)		(358	)		(589	)		(717	)		(154	)		(2,517	)
	Recoveries			—			136			114			218			10			229			63			770
	Net charge-offs			—			(441	)		(8	)		(140	)		(579	)		(488	)		(91	)		(1,747	)
	Balance at March 31, 2015:
	Allowance for loan losses			5,331			18,035			9,011			5,034			2,497			3,723			542			44,173
	Allowance for loan commitments			178			18			120			13			107			42			—			478
	Total ending allowance for credit losses		$	5,509		$	18,053		$	9,131		$	5,047		$	2,604		$	3,765		$	542		$	44,651
	Balance at December 31, 2013:
	Allowance for loan losses		$	6,056		$	18,157		$	9,925		$	5,673		$	2,017		$	5,020		$	520		$	47,368
	Allowance for loan commitments			301			62			130			5			85			19			—			602
	Total beginning allowance for credit losses			6,357			18,219			10,055			5,678			2,102			5,039			520			47,970
	Provision for credit losses:
	Provision for loan losses			(1,051	)		(509	)		2,128			869			153			305			361			2,256
	Provision for loan commitments			(8	)		(53	)		3			—			1			—			—			(57	)
	Total provision for credit losses			(1,059	)		(562	)		2,131			869			154			305			361			2,199
	Charge-offs			—			(493	)		(2,276	)		(879	)		(155	)		(752	)		(180	)		(4,735	)
	Recoveries			—			120			65			109			11			227			62			594
	Net charge-offs			—			(373	)		(2,211	)		(770	)		(144	)		(525	)		(118	)		(4,141	)
	Balance at March 31, 2014:
	Allowance for loan losses			5,005			17,275			9,842			5,772			2,026			4,800			763			45,483
	Allowance for loan commitments			293			9			133			5			86			19			—			545
	Total ending allowance for credit losses		$	5,298		$	17,284		$	9,975		$	5,777		$	2,112		$	4,819		$	763		$	46,028
Allowance for Credit Losses and Recorded Investments in Loans	The following tables present the allowance for credit losses and recorded investments in loans by category:
			Allowance for Credit Losses and Recorded Investment in Loans
	(unaudited, in thousands)		Commercial			Commercial			Commercial			Residential			Home			Consumer			Over-draft			Total
			Real Estate-			Real Estate-			and Industrial			Real Estate			Equity
			Land and			Improved
			Construction			Property
	March 31, 2015
	Allowance for credit losses:
	Allowance for loans individually evaluated for impairment		$	—		$	2,828		$	873		$	—		$	—		$	—		$	—		$	3,701
	Allowance for loans collectively evaluated for impairment			5,331			15,207			8,138			5,034			2,497			3,723			542			40,472
	Allowance for loan commitments			178			18			120			13			107			42			—			478
	Total allowance for credit losses		$	5,509		$	18,053		$	9,131		$	5,047		$	2,604		$	3,765		$	542		$	44,651
	Portfolio loans:
	Individually evaluated for impairment (1)		$	—		$	9,822		$	2,722		$	—		$	—		$	—		$	—		$	12,544
	Collectively evaluated for impairment			288,075			1,899,047			706,899			1,239,163			362,163			365,830			—			4,861,177
	Total portfolio loans		$	288,075		$	1,908,869		$	709,621		$	1,239,163		$	362,163		$	365,830		$	—		$	4,873,721
	December 31, 2014
	Allowance for credit losses:
	Allowance for loans individually evaluated for impairment		$	—		$	2,765		$	1,033		$	—		$	—		$	—		$	—		$	3,798
	Allowance for loans collectively evaluated for impairment			5,654			14,808			8,030			5,382			2,329			4,078			575			40,856
	Allowance for loan commitments			194			10			112			9			90			40			—			455
	Total allowance for credit losses		$	5,848		$	17,583		$	9,175		$	5,391		$	2,419		$	4,118		$	575		$	45,109
	Portfolio loans:
	Individually evaluated for impairment (1)		$	—		$	11,469		$	2,844		$	—		$	—		$	—		$	—		$	14,313
	Collectively evaluated for impairment			262,643			1,671,348			635,566			928,770			330,031			244,095			—			4,072,453
	Total portfolio loans		$	262,643		$	1,682,817		$	638,410		$	928,770		$	330,031		$	244,095		$	—		$	4,086,766
	(1)	Commercial loans greater than $1 million that are reported as non-accrual or as a troubled debt restructuring (“TDR”) are individually evaluated for impairment.
Summary of Commercial Loans by Risk Grade	The following tables summarize commercial loans by their assigned risk grade:
			Commerical Loans by Internally Assigned Risk Grade
	(unaudited, in thousands)		Commercial			Commercial			Commercial			Total
			Real Estate-			Real Estate-			& Industrial			Commercial
			Land and			Improved						Loans
			Construction			Property
	As of March 31, 2015
	Pass		$	281,730		$	1,848,655		$	683,226		$	2,813,611
	Criticized - compromised			3,653			18,049			18,957			40,659
	Classified - substandard			2,692			42,165			7,438			52,295
	Classified - doubtful			—			—			—			—
	Total		$	288,075		$	1,908,869		$	709,621		$	2,906,565
	As of December 31, 2014
	Pass		$	257,218		$	1,627,771		$	617,742		$	2,502,731
	Criticized - compromised			3,645			17,873			12,770			34,288
	Classified - substandard			1,780			37,173			7,898			46,851
	Classified - doubtful			—			—			—			—
	Total		$	262,643		$	1,682,817		$	638,410		$	2,583,870
Summary of Age Analysis of Loan Categories	The following tables summarize the age analysis of all categories of loans:
			Age Analysis of Loans
	(unaudited, in thousands)		Current			30-59			60-89			90 Days			Total			Total Loans			90 Days or
						Days			Days			or More			Past Due						More
						Past Due			Past Due			Past Due									Past Due and
																					Accruing (1)
	As of March 31, 2015
	Commercial real estate:
	Land and construction		$	286,883		$	—		$	—		$	1,192		$	1,192		$	288,075		$	—
	Improved property			1,889,451			1,093			1,435			16,890			19,418			1,908,869			—
	Total commercial real estate			2,176,334			1,093			1,435			18,082			20,610			2,196,944			—
	Commercial and industrial			705,380			916			1,518			1,807			4,241			709,621			3
	Residential real estate			1,226,131			4,981			1,673			6,378			13,032			1,239,163			74
	Home equity			357,545			1,982			508			2,128			4,618			362,163			684
	Consumer			362,338			2,117			868			507			3,492			365,830			270
	Total portfolio loans			4,827,728			11,089			6,002			28,902			45,993			4,873,721			1,031
	Loans held for sale			6,064			—			—			—			—			6,064			—
	Total loans		$	4,833,792		$	11,089		$	6,002		$	28,902		$	45,993		$	4,879,785		$	1,031
	Impaired loans included above are as follows:
	Non-accrual loans		$	9,209		$	2,008		$	2,319		$	27,838		$	32,165		$	41,374
	TDRs accruing interest (1)			16,536			582			179			33			794			17,330
	Total impaired		$	25,745		$	2,590		$	2,498		$	27,871		$	32,959		$	58,704
	As of December 31, 2014
	Commercial real estate:
	Land and construction		$	261,356		$	20		$	—		$	1,267		$	1,287		$	262,643		$	71
	Improved property			1,665,363			961			4,772			11,721			17,454			1,682,817			—
	Total commercial real estate			1,926,719			981			4,772			12,988			18,741			1,945,460			71
	Commercial and industrial			634,482			1,834			240			1,854			3,928			638,410			22
	Residential real estate			915,968			1,237			3,384			8,181			12,802			928,770			1,306
	Home equity			325,291			1,877			895			1,968			4,740			330,031			570
	Consumer			240,365			2,571			685			474			3,730			244,095			319
	Total portfolio loans			4,042,825			8,500			9,976			25,465			43,941			4,086,766			2,288
	Loans held for sale			5,865			—			—			—			—			5,865			—
	Total loans		$	4,048,690		$	8,500		$	9,976		$	25,465		$	43,941		$	4,092,631		$	2,288
	Impaired loans included above are as follows:
	Non-accrual loans		$	7,562		$	2,884		$	5,552		$	22,820		$	31,256		$	38,818
	TDRs accruing interest (1)			11,016			151			542			357			1,050			12,066
	Total impaired		$	18,578		$	3,035		$	6,094		$	23,177		$	32,306		$	50,884
	-1	Loans 90 days or more past due and accruing interest exclude TDRs 90 days or more past due and accruing interest.
Summary of Impaired Loans	The following tables summarize impaired loans:
			Impaired Loans
			March 31, 2015									December 31, 2014
	(unaudited, in thousands)		Unpaid			Recorded			Related			Unpaid			Recorded			Related
			Principal			Investment			Allowance			Principal			Investment			Allowance
			Balance (1)									Balance (1)
	With no related specific allowance recorded:
	Commercial real estate:
	Land and construction		$	3,101		$	2,476		$	—		$	1,588		$	1,488		$	—
	Improved property			30,138			22,481			—			16,480			14,684			—
	Commercial and industrial			3,094			2,432			—			3,152			2,597			—
	Residential real estate			20,943			19,132			—			20,077			18,544			—
	Home equity			2,824			2,617			—			2,890			2,663			—
	Consumer			1,659			1,332			—			1,287			1,086			—
	Total impaired loans without a specific allowance			61,759			50,470			—			45,474			41,062			—
	With a specific allowance recorded:
	Commercial real estate:
	Land and construction			—			—			—			—			—			—
	Improved property			6,466			6,466			2,828			7,980			7,980			2,765
	Commercial and industrial			1,768			1,768			873			1,842			1,842			1,033
	Total impaired loans with a specific allowance			8,234			8,234			3,701			9,822			9,822			3,798
	Total impaired loans		$	69,993		$	58,704		$	3,701		$	55,296		$	50,884		$	3,798
	-1	The difference between the unpaid principal balance and the recorded investment generally reflects amounts that have been previously charged-off and fair market value adjustments on acquired impaired loans.
			Impaired Loans
			For the Three Months Ended						For the Three Months Ended
			March 31, 2015						March 31, 2014
	(unaudited, in thousands)		Average			Interest			Average			Interest
			Recorded			Income			Recorded			Income
			Investment			Recognized			Investment			Recognized
	With no related specific allowance recorded:
	Commercial real estate:
	Land and construction		$	2,128		$	16		$	2,450		$	2
	Improved property			18,932			223			19,158			20
	Commercial and industrial			2,513			13			3,532			32
	Residential real estate			18,715			230			19,463			182
	Home equity			2,641			20			2,367			19
	Consumer			1,194			20			1,174			28
	Total impaired loans without a specific allowance			46,123			522			48,144			283
	With a specific allowance recorded:
	Commercial real estate:
	Land and construction			—			—			—			—
	Improved property			7,223			—			729			1
	Commercial and industrial			1,805			19			2,329			12
	Total impaired loans with a specific allowance			9,028			19			3,058			13
	Total impaired loans		$	55,151		$	541		$	51,202		$	296
Recorded Investment in Non-Accrual Loans and TDRs	The following tables present the recorded investment in non-accrual loans and TDRs:
			Non-accrual Loans (1)
	(unaudited, in thousands)		March 31,			December 31,
			2015			2014
	Commercial real estate:
	Land and construction		$	1,463		$	1,488
	Improved property			22,143			20,227
	Total commercial real estate			23,606			21,715
	Commercial and industrial			3,849			4,110
	Residential real estate			11,249			10,329
	Home equity			1,899			1,923
	Consumer			771			741
	Total		$	41,374		$	38,818
	(1)	Total non-accrual loans include loans that are also restructured. Such loans are also set forth in the following table as non-accrual TDRs.
			TDRs
			March 31, 2015									December 31, 2014
	(unaudited, in thousands)		Accruing			Non-Accrual			Total			Accruing			Non-Accrual			Total
	Commercial real estate:
	Land and construction		$	1,013		$	504		$	1,517		$	—		$	464		$	464
	Improved property			6,804			5,399			12,203			2,437			1,850			4,287
	Total commercial real estate			7,817			5,903			13,720			2,437			2,314			4,751
	Commercial and industrial			351			376			727			329			478			807
	Residential real estate			7,883			2,386			10,269			8,215			2,074			10,289
	Home equity			718			285			1,003			740			245			985
	Consumer			561			274			835			345			309			654
	Total		$	17,330		$	9,224		$	26,554		$	12,066		$	5,420		$	17,486
Loans Identified as TDRs	The following table presents details related to loans identified as TDRs during the three months ended March 31, 2015 and 2014, respectively:
			New TDRs (1)
			For the Three Months Ended
			March 31, 2015									March 31, 2014
	(unaudited, dollars in thousands)		Number of			Pre-			Post-			Number of			Pre-			Post-
			Modifications			Modification			Modification			Modifications			Modification			Modification
						Outstanding			Outstanding						Outstanding			Outstanding
						Recorded			Recorded						Recorded			Recorded
						Investment			Investment						Investment			Investment
	Commercial real estate:
	Land and construction			11		$	1,414		$	1,056			—		$	—		$	—
	Improved Property			7			8,568			8,289			1			91			90
	Total commercial real estate			18			9,982			9,345			1			91			90
	Commercial and industrial			2			42			57			—			—			—
	Residential real estate			7			424			421			4			121			118
	Home equity			1			7			6			—			—			—
	Consumer			21			269			303			2			33			31
	Total			49		$	10,724		$	10,132			7		$	245		$	239
	(1)	Excludes loans that were either paid off or charged-off by period end. The pre-modification balance represents the balance outstanding at the beginning of the period. The post-modification balance represents the outstanding balance at period end.
TDRs Defaulted Later Restructured	The following table summarizes TDRs which defaulted (defined as past due 90 days) during the three months ended March 31, 2015 and 2014, respectively, that were restructured within the last twelve months prior to March 31, 2015 and 2014, respectively:
			Defaulted TDRs (1)						Defaulted TDRs (1)
			For the Three Months Ended						For the Three Months Ended
			March 31, 2015						March 31, 2014
	(unaudited, dollars in thousands)		Number of			Recorded			Number of			Recorded
			Defaults			Investment			Defaults			Investment
	Commercial real estate:
	Land and construction			—		$	—			—		$	—
	Improved property			—			—			—			—
	Total commercial real estate			—			—			—			—
	Commercial and industrial			—			—			—			—
	Residential real estate			—			—			8			481
	Home equity			1			42			1			3
	Consumer			1			27			—			—
	Total			2		$	69			9		$	484
	(1)	Excludes loans that were either charged-off or cured by period end. The recorded investment is as of March 31, 2014 and 2013, respectively.
Summary of Other Real Estate Owned and Repossessed Assets	The following table summarizes other real estate owned and repossessed assets included in other assets:
	(unaudited, in thousands)		March 31,			December 31,
			2015			2014
	Other real estate owned		$	5,886		$	4,920
	Repossessed assets			340			162
	Total other real estate owned and repossessed assets		$	6,226		$	5,082

Pension_Plan_Tables

Pension Plan (Tables)	3 Months Ended
	Mar. 31, 2015
Compensation and Retirement Disclosure [Abstract]
Components of Net Periodic Pension Cost	The following table presents the net periodic pension cost for WesBanco’s Defined Benefit Pension Plan (the “Plan”) and the related components:
		For the Three Months Ended
		March 31,
	(unaudited, in thousands)	2015			2014
	Service cost - benefits earned during year	$	827		$	717
	Interest cost on projected benefit obligation		1,201			1,170
	Expected return on plan assets		(1,907	)		(1,783	)
	Amortization of prior service cost		6			11
	Amortization of net loss		784			363
	Net periodic pension cost	$	911		$	478

Fair_Value_Measurement_Tables

Fair Value Measurement (Tables)	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Schedule of Fair Value of Assets and Liabilities Measured on Recurring and Nonrecurring Basis	The following tables set forth WesBanco’s financial assets and liabilities that were accounted for at fair value on a recurring and nonrecurring basis by level within the fair value hierarchy as of March 31, 2015 and December 31, 2014:
					March 31, 2015
					Fair Value Measurements Using:
	(unaudited, in thousands)		March 31,		Quoted Prices in			Significant Other		Significant
			2015		Active Markets			Observable		Unobservable
					for Identical			Inputs		Inputs
					Assets (level  1)			(level 2)		(level 3)
	Recurring fair value measurements
	Securities - available-for-sale
	Obligations of government agencies		$	80,768	$	—		$	80,768	$	—
	Residential mortgage-backed securities and collateralized mortgage obligations of government agencies			1,283,445		—			1,283,445		—
	Obligations of state and political subdivisions			95,653		—			95,653		—
	Corporate debt securities			183,090		—			183,090		—
	Equity securities			11,308		8,538			2,770		—
	Total securities - available-for-sale		$	1,654,264	$	8,538		$	1,645,726	$	—
	Total recurring fair value measurements		$	1,654,264	$	8,538		$	1,645,726	$	—
	Nonrecurring fair value measurements
	Impaired loans		$	4,533	$	—		$	—	$	4,533
	Other real estate owned and repossessed assets			6,226		—			—		6,226
	Loans held for sale			6,064		—			6,064		—
	Total nonrecurring fair value measurements		$	16,823	$	—		$	6,064	$	10,759
					December 31, 2014
					Fair Value Measurements Using:
	(unaudited, in thousands)		December 31,		Quoted Prices in			Significant Other		Significant
			2014		Active Markets			Observable		Unobservable
					for Identical			Inputs		Inputs
					Assets (level 1)			(level 2)		(level 3)
	Recurring fair value measurements
	Securities - available-for-sale
	Obligations of government agencies		$	87,736	$	—		$	87,736	$	—
	Residential mortgage-backed securities and collateralized mortgage obligations of government agencies			701,113		—			701,113		—
	Obligations of state and political subdivisions			91,433		—			91,433		—
	Corporate debt securities			25,996		—			25,996		—
	Equity securities			11,146		8,440			2,706		—
	Total securities - available-for-sale		$	917,424	$	8,440		$	908,984	$	—
	Total recurring fair value measurements		$	917,424	$	8,440		$	908,984	$	—
	Nonrecurring fair value measurements
	Impaired loans		$	6,024	$	—		$	—	$	6,024
	Other real estate owned and repossessed assets			5,082		—			—		5,082
	Loans held for sale			5,865		—			5,865		—
	Total nonrecurring fair value measurements		$	16,971	$	—		$	5,865	$	11,106
Schedule of Assets Measured at Fair Value on Nonrecurring Basis	The following table presents additional quantitative information about assets measured at fair value on a nonrecurring basis and for which WesBanco has utilized level 3 inputs to determine fair value:
			Quantitative Information about Level 3 Fair Value Measurements
	(unaudited, in thousands)		Fair Value		Valuation Techniques		Unobservable Input	Range (Weighted Average)
			Estimate
	March 31, 2015:
	Impaired loans		$	4,533	Appraisal of collateral (1)		Appraisal adjustments (2)	0% to (38.5%) / (6.9%)
							Liquidation expenses (2)	(3.1%) to (8.0%) / (7.4%)
	Other real estate owned and repossessed assets			6,226	Appraisal of collateral (1), (3)
	December 31, 2014:
	Impaired loans		$	6,024	Appraisal of collateral (1)		Appraisal adjustments (2)	0% to (39.7%) / (6.7%)
							Liquidation expenses (2)	(1.2%) to (8.0%) / (6.7%)
	Other real estate owned and repossessed assets			5,082	Appraisal of collateral (1), (3)
	-1	Fair value is generally determined through independent appraisals of the underlying collateral, which generally include various level 3 inputs which are not identifiable.
	(2)	Appraisals may be adjusted by management for qualitative factors such as economic conditions and estimated liquidation expenses. The range and weighted average of appraisal adjustments and liquidation expenses are presented as a percent of the appraisal.
	(3)	Includes estimated liquidation expenses and numerous dissimilar qualitative adjustments by management which are not identifiable.
Estimates Fair Values of Financial Instruments	The estimated fair values of WesBanco’s financial instruments are summarized below:
								Fair Value Measurements at
								March 31, 2015
	(unaudited, in thousands)		Carrying		Fair Value			Quoted Prices in		Significant Other		Significant
			Amount		Estimate			Active Markets		Observable		Unobservable
								for Identical		Inputs		Inputs
								Assets (level 1)		(level 2)		(level 3)
	Financial Assets
	Cash and due from banks		$	92,974	$	92,974		$	92,974	$	—	$	—
	Securities available-for-sale			1,654,264		1,654,264			8,538		1,645,726		—
	Securities held-to-maturity			743,925		772,843			—		772,088		755
	Net loans			4,829,548		4,820,779			—		—		4,820,779
	Loans held for sale			6,064		6,064			—		6,064		—
	Accrued interest receivable			25,232		25,232			25,232		—		—
	Bank-owned life insurance			153,991		153,991			153,991		—		—
	Financial Liabilities
	Deposits			6,416,202		6,423,499			4,532,314		1,891,185		—
	Federal Home Loan Bank borrowings			432,456		435,089			—		435,089		—
	Other borrowings			76,630		76,621			73,589		3,032		—
	Junior subordinated debt			142,269		116,070			—		116,070		—
	Accrued interest payable			2,297		2,297			2,297		—		—
								Fair Value Measurements at
								December 31, 2014
	(unaudited, in thousands)		Carrying		Fair Value			Quoted Prices in		Significant Other		Significant
			Amount		Estimate			Active Markets		Observable		Unobservable
								for Identical		Inputs		Inputs
								Assets (level 1)		(level 2)		(level 3)
	Financial Assets
	Cash and due from banks		$	94,002	$	94,002		$	94,002	$	—	$	—
	Securities available-for-sale			917,424		917,424			8,440		908,984		—
	Securities held-to-maturity			593,670		619,617			—		618,895		722
	Net loans			4,042,112		4,047,648			—		—		4,047,648
	Loans held for sale			5,865		5,865			—		5,865		—
	Accrued interest receivable			18,481		18,481			18,481		—		—
	Bank-owned life insurance			123,298		123,298			123,298		—		—
	Financial Liabilities
	Deposits			5,048,983		5,056,828			3,743,887		1,312,941		—
	Federal Home Loan Bank borrowings			223,126		225,456			—		225,456		—
	Other borrowings			80,690		80,696			77,534		3,162		—
	Junior subordinated debt			106,176		79,212			—		79,212		—
	Accrued interest payable			1,620		1,620			1,620		—		—

Comprehensive_Income_Tables

Comprehensive Income (Tables)	3 Months Ended
	Mar. 31, 2015
Equity [Abstract]
Components of Accumulated Other Comprehensive Income	The activity in accumulated other comprehensive income for the three months ended March 31, 2015 and 2014 is as follows:
			Accumulated Other Comprehensive Income(1)
	(unaudited, in thousands)		Defined			Unrealized Gains			Unrealized Gains			Total
			Benefit			(Losses) on			on Securities
			Pension			Securities			Transferred from
			Plan			Available-for-Sale			Available-for-
									Sale to
									Held-to-Maturity
	Balance at December 31, 2014		$	(22,776	)	$	2,892		$	1,059		$	(18,825	)
	Other comprehensive income before reclassifications			—			4,804			—			4,804
	Amounts reclassified from accumulated other comprehensive income			475			(11	)		(67	)		397
	Period change			475			4,793			(67	)		5,201
	Balance at March 31, 2015		$	(22,301	)	$	7,685		$	992		$	(13,624	)
	Balance at December 31, 2013		$	(7,966	)	$	(6,126	)	$	1,358		$	(12,734	)
	Other comprehensive income before reclassifications			—			3,075			—			3,075
	Amounts reclassified from accumulated other comprehensive income			236			49			(87	)		198
	Period change			236			3,124			(87	)		3,273
	Balance at March 31, 2014		$	(7,730	)	$	(3,002	)	$	1,271		$	(9,461	)
	(1)	All amounts are net of tax. Related income tax expense or benefit is calculated using a combined Federal and State income tax rate approximating 37%.
Schedule of Amounts Reclassified from Accumulated Other Comprehensive Income	The following table provides details about amounts reclassified from accumulated other comprehensive income for the three months ended March 31, 2015 and 2014:
	Details about Accumulated Other Comprehensive Income/(Loss)		Amounts Reclassified from						Affected Line Item in the
	Components		Accumulated Other						Statement of Net Income
			Comprehensive Income/(Loss)
			For the Three Months Ended
			March 31,
	(unaudited, in thousands)		2015			2014
	Securities available-for-sale (1):
	Net securities (gains) losses reclassified into earnings			(18	)	$	78		Net securities gains (Non-interest income)
	Related income tax expense (benefit)			7			(29	)	Provision for income taxes
	Net effect on accumulated other comprehensive income for the period			(11	)		49
	Securities held-to-maturity (1):
	Amortization of unrealized gain transferred from available-for-sale			(107	)		(138	)	Interest and dividends on securities (Interest and dividend income)
	Related income tax expense			40			51		Provision for income taxes
	Net effect on accumulated other comprehensive income for the period			(67	)		(87	)
	Defined benefit pension plan (2):
	Amortization of net loss and prior service costs			790			374		Employee benefits (Non-interest expense)
	Related income tax benefit			(315	)		(138	)	Provision for income taxes
	Net effect on accumulated other comprehensive income for the period			475			236
	Total reclassifications for the period			397		$	198
	-1	For additional detail related to unrealized gains on securities and related amounts reclassified from accumulated other comprehensive income see Note 4, “Securities.”
	-2	Included in the computation of net periodic pension cost. See Note 6, “Pension Plan” for additional detail.

Commitments_and_Contingent_Lia1

Commitments and Contingent Liabilities (Tables)	3 Months Ended
	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments to Extend Credit, Guarantees and Various Letters of Credit Outstanding	The following table presents total commitments to extend credit, guarantees and various letters of credit outstanding:
	(unaudited, in thousands)	March 31,		December 31,
		2015		2014
	Lines of credit	$	1,032,235	$	984,352
	Loans approved but not closed		295,702		116,757
	Overdraft limits		110,389		95,965
	Letters of credit		26,910		23,362
	Contingent obligations to purchase loans funded by other entities		8,457		8,312

Business_Segments_Tables

Business Segments (Tables)	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Financial Information by Business Segment	Condensed financial information by business segment is presented below:
	(unaudited, in thousands)	Community		Trust and		Consolidated
		Banking		Investment
				Services
	For the Three Months ended March 31, 2015:
	Interest income	$	60,379	$	—	$	60,379
	Interest expense		5,424		—		5,424
	Net interest income		54,955		—		54,955
	Provision for credit losses		1,289		—		1,289
	Net interest income after provision for credit losses		53,666		—		53,666
	Non-interest income		12,137		6,053		18,190
	Non-interest expense		50,278		3,163		53,441
	Income before provision for income taxes		15,525		2,890		18,415
	Provision for income taxes		3,372		1,156		4,528
	Net income	$	12,153	$	1,734	$	13,887
	For the Three Months ended March 31, 2014:
	Interest income	$	53,457	$	—	$	53,457
	Interest expense		6,132		—		6,132
	Net interest income		47,325		—		47,325
	Provision for credit losses		2,199		—		2,199
	Net interest income after provision for credit losses		45,126		—		45,126
	Non-interest income		11,401		5,648		17,049
	Non-interest expense		36,827		3,268		40,095
	Income before provision for income taxes		19,700		2,380		22,080
	Provision for income taxes		4,707		952		5,659
	Net income	$	14,993	$	1,428	$	16,421

Mergers_and_Acquisitions_Addit

Mergers and Acquisitions - Additional Information (Detail) (USD $)	3 Months Ended		12 Months Ended	0 Months Ended	2 Months Ended	3 Months Ended	1 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Feb. 10, 2015	Mar. 31, 2015	Dec. 31, 2014	Feb. 10, 2015
							Office
Business Acquisition [Line Items]
Loans	$700,800,000				$700,800,000
Goodwill increase	168,900,000
Net income	13,887,000	16,421,000	16,421,000
Unaudited proforma net interest income and non - interest income	78,200,000	76,100,000
Approximate unaudited proforma net income	22,200,000	19,800,000
Carrying value of goodwill	481,000,000				481,000,000
ESB Financial Corporation [Member]
Business Acquisition [Line Items]
Total Assets				1,900,000,000			1,900,000,000
Loans				700,849,000			700,849,000
Securities				486,891,000			486,891,000
Value of acquisition				338,969,000
Common shares issued				9,178,531
Cash consideration for outstanding shares				45,000,000
Goodwill increase				168,889,000
Purchase price allocation in core deposit intangible				5,346,000			5,346,000
Closing stock price				$32			32
Merger related expense	9,700,000					1,300,000
Total of net interest income and non-interest income					6,500,000
Net income					$2,700,000
Pennsylvania
Business Acquisition [Line Items]
Number of offices					38		16
Common Stock [Member]
Business Acquisition [Line Items]
Common shares issued	9,178,531
Common Stock [Member] | ESB Financial Corporation [Member]
Business Acquisition [Line Items]
Common shares issued				9,178,531

Mergers_and_Acquisitions_Calcu

Mergers and Acquisitions - Calculation of Purchase Price and Resulting Goodwill Relating to ESB Acquisition (Detail) (USD $)	3 Months Ended	0 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Feb. 10, 2015
Fair value of:
Goodwill recognized	$168,900
ESB Financial Corporation [Member]
Purchase Price:
Fair value of WesBanco shares issued, (net of equity issuance costs of $0.1 million)		293,933
Cash consideration for outstanding ESB shares, options and restricted stock		37,036
Settlement of pre-existing loan to ESB		8,000
Total purchase price		338,969
Fair value of:
Tangible assets acquired		1,859,865
Core deposit and other intangible assets acquired		5,346
Liabilities assumed		-1,703,616
Net cash received in the acquisition		8,485
Fair value of net assets acquired		170,080
Goodwill recognized		$168,889

Mergers_and_Acquisitions_Calcu1

Mergers and Acquisitions - Calculation of Purchase Price and Resulting Goodwill Relating to ESB Acquisition (Parenthetical) (Detail) (ESB Financial Corporation [Member], USD $)	0 Months Ended
In Millions, unless otherwise specified	Feb. 10, 2015
ESB Financial Corporation [Member]
Business Acquisition [Line Items]
Equity issuance costs	$0.10

Mergers_and_Acquisitions_Summa

Mergers and Acquisitions - Summary of Fair Value of Net Assets that Wesbanco Acquired from ESB (Detail) (USD $)	Mar. 31, 2015	Feb. 10, 2015
In Thousands, unless otherwise specified
Assets
Loans	$700,800
ESB Financial Corporation [Member]
Assets
Cash and due from banks		8,485
Securities		486,891
Loans		700,849
Goodwill and other intangible assets		174,235
Accrued income and other assets		672,125
Total Assets		2,042,585
Liabilities
Deposits		1,246,992
Borrowings		433,454
Accrued expenses and other liabilities		23,170
Total liabilities		1,703,616
Purchase price		$338,969

Mergers_and_Acquisitions_Summa1

Mergers and Acquisitions - Summary of Fair Value of Net Assets that Wesbanco Acquired from ESB (Parenthetical) (Detail) (ESB Financial Corporation [Member], USD $)	Mar. 31, 2015
In Millions, unless otherwise specified
ESB Financial Corporation [Member]
Business Acquisition [Line Items]
Recievables from sale of available-for-sale securities	$560.70

Earnings_Per_Common_Share_Summ

Earnings Per Common Share - Summary of Earnings Per Common Share (Detail) (USD $)	3 Months Ended		12 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Numerator for both basic and diluted earnings per common share:
Net income	$13,887	$16,421	$16,421
Denominator:
Total average basic common shares outstanding	34,393,137	29,182,183
Effect of dilutive stock options and warrant	85,198	80,497
Total diluted average common shares outstanding	34,478,335	29,262,680
Earnings per common share - basic	$0.40	$0.56
Earnings per common share - diluted	$0.40	$0.56

Earnings_Per_Common_Share_Addi

Earnings Per Common Share - Additional Information (Detail)	3 Months Ended	0 Months Ended
	Mar. 31, 2014	Feb. 10, 2015
Stock Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stock options excluded from computation of diluted earnings per share	33,000
ESB Financial Corporation [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Common shares issued		9,178,531

Securities_Schedule_of_Fair_Va

Securities - Schedule of Fair Value and Amortized Cost of Available-for-sale and Held-to-maturity Securities (Detail) (USD $)	3 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Schedule of Trading Securities and Other Trading Assets [Line Items]
Available-for-sale, Amortized Cost	$1,642,125	$912,850
Available-for-sale, Gross Unrealized Gains	16,306	11,771
Available-for-sale, Gross Unrealized Losses	-4,167	-7,197
Available-for-sale, Estimated Fair Value	1,654,264	917,424
Held-to-maturity, Amortized Cost	743,925	593,670
Held-to-maturity, Gross Unrealized Gains	30,004	27,285
Held-to-maturity, Gross Unrealized Losses	-1,086	-1,338
Held-to-maturity securities, Fair value	772,843	619,617
Total securities, Amortized Cost	2,386,050	1,506,520
Total securities, Gross Unrealized Gains	46,310	39,056
Total securities, Gross Unrealized Losses	-5,253	-8,535
Total securities, Estimated Fair Value	2,427,107	1,537,041
Residential Mortgage-Backed Securities and Collateralized Mortgage Obligations of Government Agencies [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Available-for-sale, Amortized Cost	1,279,350	703,535
Available-for-sale, Gross Unrealized Gains	8,091	4,336
Available-for-sale, Gross Unrealized Losses	-3,996	-6,758
Available-for-sale, Estimated Fair Value	1,283,445	701,113
Held-to-maturity, Amortized Cost	126,935	79,004
Held-to-maturity, Gross Unrealized Gains	3,244	3,262
Held-to-maturity, Gross Unrealized Losses	-208	-246
Held-to-maturity securities, Fair value	129,971	82,020
Obligations of State and Political Subdivisions [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Available-for-sale, Amortized Cost	89,977	86,073
Available-for-sale, Gross Unrealized Gains	5,693	5,365
Available-for-sale, Gross Unrealized Losses	-17	-5
Available-for-sale, Estimated Fair Value	95,653	91,433
Held-to-maturity, Amortized Cost	610,249	507,927
Held-to-maturity, Gross Unrealized Gains	26,560	23,917
Held-to-maturity, Gross Unrealized Losses	-878	-1,043
Held-to-maturity securities, Fair value	635,931	530,801
Corporate Debt Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Available-for-sale, Amortized Cost	182,781	25,974
Available-for-sale, Gross Unrealized Gains	430	141
Available-for-sale, Gross Unrealized Losses	-121	-119
Available-for-sale, Estimated Fair Value	183,090	25,996
Held-to-maturity, Amortized Cost	6,741	6,739
Held-to-maturity, Gross Unrealized Gains	200	106
Held-to-maturity, Gross Unrealized Losses		-49
Held-to-maturity securities, Fair value	6,941	6,796
Obligations of Government Agencies [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Available-for-sale, Amortized Cost	79,315	86,964
Available-for-sale, Gross Unrealized Gains	1,486	1,087
Available-for-sale, Gross Unrealized Losses	-33	-315
Available-for-sale, Estimated Fair Value	80,768	87,736
Debt Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Available-for-sale, Amortized Cost	1,631,423	902,546
Available-for-sale, Gross Unrealized Gains	15,700	10,929
Available-for-sale, Gross Unrealized Losses	-4,167	-7,197
Available-for-sale, Estimated Fair Value	1,642,956	906,278
Equity Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Available-for-sale, Amortized Cost	10,702	10,304
Available-for-sale, Gross Unrealized Gains	606	842
Available-for-sale, Estimated Fair Value	$11,308	$11,146

Securities_Additional_Informat

Securities - Additional Information (Detail) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013
	Holdings		Holdings
Amortized Cost and Fair Value Debt Securities [Abstract]
Maximum percentage of equity of one issuer	10.00%
Number of holdings greater than specified percentage of equity	0		0
Securities with aggregate fair values	$1,100,000,000		$706,500,000
Proceeds from sale of available-for-sale securities	560,676,000	3,155,000	3,200,000
Net unrealized gains (losses) on available-for-sale securities included in AOCI	7,685,000	-3,002,000	2,892,000	-6,126,000
Impaired loss relating to securities	0
Federal home loan bank stock, Total	$20,900,000		$11,600,000

Securities_Schedule_of_Fair_Va1

Securities - Schedule of Fair Value of Available-for-Sale and Held-to-Maturity Securities by Contractual Maturity (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total available-for-sale securities, One Year or less	$87,447
Total available-for-sale securities, One to Five Years	118,637
Total available-for-sale securities, Five to Ten Years	95,372
Total available-for-sale securities, After Ten Years	58,055
Total available-for-sale securities, Mortgage-backed and Equity	1,294,753
Available-for-sale, Estimated Fair Value	1,654,264	917,424
Total held-to-maturity securities, One Year or less	2,852
Total held-to-maturity securities, One to Five Years	17,024
Total held-to-maturity securities, Five to Ten Years	266,172
Total held-to-maturity securities, After Ten Years	356,824
Total held-to-maturity securities, Mortgage-backed and Equity	129,971
Held-to-maturity securities, Fair value	772,843	619,617
Total securities, One Year or less	90,299
Total securities, One to Five Years	135,661
Total securities, Five to Ten Years	361,544
Total securities, After Ten Years, Fair value	414,879
Total securities, Mortgage- backed and Equity	1,424,724
Total securities, Fair value	2,427,107
Residential Mortgage-Backed Securities and Collateralized Mortgage Obligations of Government Agencies [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total available-for-sale securities, Mortgage-backed and Equity	1,283,445
Available-for-sale, Estimated Fair Value	1,283,445	701,113
Total held-to-maturity securities, Mortgage-backed and Equity	129,971
Held-to-maturity securities, Fair value	129,971	82,020
Obligations of State and Political Subdivisions [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total available-for-sale securities, One Year or less	5,254
Total available-for-sale securities, One to Five Years	33,049
Total available-for-sale securities, Five to Ten Years	21,417
Total available-for-sale securities, After Ten Years	35,933
Available-for-sale, Estimated Fair Value	95,653	91,433
Total held-to-maturity securities, One Year or less	2,852
Total held-to-maturity securities, One to Five Years	17,024
Total held-to-maturity securities, Five to Ten Years	259,231
Total held-to-maturity securities, After Ten Years	356,824
Held-to-maturity securities, Fair value	635,931	530,801
Corporate Debt Securities [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total available-for-sale securities, One Year or less	82,193
Total available-for-sale securities, One to Five Years	62,312
Total available-for-sale securities, Five to Ten Years	33,658
Total available-for-sale securities, After Ten Years	4,927
Available-for-sale, Estimated Fair Value	183,090	25,996
Total held-to-maturity securities, Five to Ten Years	6,941
Held-to-maturity securities, Fair value	6,941	6,796
Obligations of Government Agencies [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total available-for-sale securities, One to Five Years	23,276
Total available-for-sale securities, Five to Ten Years	40,297
Total available-for-sale securities, After Ten Years	17,195
Available-for-sale, Estimated Fair Value	80,768	87,736
Equity Securities [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total available-for-sale securities, Mortgage-backed and Equity	11,308
Available-for-sale, Estimated Fair Value	$11,308	$11,146

Securities_Schedule_of_Fair_Va2

Securities - Schedule of Fair Value of Available-for-Sale and Held-to-Maturity Securities by Contractual Maturity (Parenthetical) (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Amortized Cost and Fair Value Debt Securities [Abstract]
Held-to-maturity, Amortized Cost	$743,925	$593,670

Securities_Schedule_of_Gross_R

Securities - Schedule of Gross Realized Gains and Losses on the Sales and Calls of Securities (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Securities Gross Realized Gain Loss [Abstract]
Gross realized gains	$24	$195
Gross realized losses	-2	-185
Net realized gains (losses)	$22	$10

Securities_Schedule_of_Unreali

Securities - Schedule of Unrealized Losses on Investment Securities (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified	Security	Security
Obligations of Government Agencies [Member]
Net Unrealized Gains And Losses On Investments [Line Items]
Less than 12 months, Fair Value	$17,953	$19,362
Less than 12 months, Unrealized Losses	-33	-77
Less than 12 months, Number of Securities	3	5
12 months or more, Fair Value		19,757
12 months or more, Unrealized Losses		-238
12 months or more, Number of Securities	0	4
Fair Value, Total	17,953	39,119
Unrealized Losses, Total	-33	-315
Number of Securities Total	3	9
Residential Mortgage-Backed Securities and Collateralized Mortgage Obligations of Government Agencies [Member]
Net Unrealized Gains And Losses On Investments [Line Items]
Less than 12 months, Fair Value	260,103	78,786
Less than 12 months, Unrealized Losses	-681	-386
Less than 12 months, Number of Securities	55	19
12 months or more, Fair Value	168,693	240,055
12 months or more, Unrealized Losses	-3,523	-6,618
12 months or more, Number of Securities	32	43
Fair Value, Total	428,796	318,841
Unrealized Losses, Total	-4,204	-7,004
Number of Securities Total	87	62
Obligations of State and Political Subdivisions [Member]
Net Unrealized Gains And Losses On Investments [Line Items]
Less than 12 months, Fair Value	68,439	12,615
Less than 12 months, Unrealized Losses	-450	-96
Less than 12 months, Number of Securities	79	15
12 months or more, Fair Value	20,777	61,548
12 months or more, Unrealized Losses	-445	-952
12 months or more, Number of Securities	31	93
Fair Value, Total	89,216	74,163
Unrealized Losses, Total	-895	-1,048
Number of Securities Total	110	108
Corporate Debt Securities [Member]
Net Unrealized Gains And Losses On Investments [Line Items]
Less than 12 months, Fair Value	53,122	2,969
Less than 12 months, Unrealized Losses	-113	-31
Less than 12 months, Number of Securities	16	1
12 months or more, Fair Value	1,978	4,573
12 months or more, Unrealized Losses	-8	-137
12 months or more, Number of Securities	1	2
Fair Value, Total	55,100	7,542
Unrealized Losses, Total	-121	-168
Number of Securities Total	17	3
Total Temporarily Impaired Securities [Member]
Net Unrealized Gains And Losses On Investments [Line Items]
Less than 12 months, Fair Value	399,617	113,732
Less than 12 months, Unrealized Losses	-1,277	-590
Less than 12 months, Number of Securities	153	40
12 months or more, Fair Value	191,448	325,933
12 months or more, Unrealized Losses	-3,976	-7,945
12 months or more, Number of Securities	64	142
Fair Value, Total	591,065	439,665
Unrealized Losses, Total	($5,253)	($8,535)
Number of Securities Total	217	182

Loans_and_the_Allowance_for_Cr2

Loans and the Allowance for Credit Losses - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
	Contract
Financing Receivable, Recorded Investment [Line Items]
Deferred loan fees and costs	$2,200,000	$2,400,000
Aggregate amount of residential real estate, home equity and consumer loans classified as substandard	15,500,000	15,200,000
Internally assigned loan grades to residential real estate, home equity and consumer loans	1,500,000	2,200,000
Book value of acquired loans	716,100,000
Fair value of acquired loans	700,800,000
Loans acquired accretable	2,400,000
Book value, acquired loans with deteriorated credit quality	16,000,000
Fair value of acquired loans with deteriorated credit quality	9,700,000
Deteriorated credit quality loans acquired non-accretable difference	3,900,000
Balance loans acquired with deteriorated credit quality	9,300,000
Certain loans acquired in transfer not accounted for as debt securities acquired during period at acquisition non accrual	3,600,000
Certain loans acquired in transfer not accounted for as debt securities acquired during period at acquisition accrual amount	5,700,000
Non-accrual status period	90 days
Number of restructured contracts greater than $1 million	3
Accruing and non accrual TDR permitted interest-only payment period	3 months
Percentage of TDRs defaulted during the period that were restructured within the last twelve months	0.30%
Other real estate owned	5,886,000	4,920,000
Performing Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Fair value of acquired loans	691,100,000
Loans acquired accretable	9,000,000
Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Other real estate owned	800,000	600,000
Foreclosure proceedings in process on residential real estate loans	$4,300,000

Loans_and_the_Allowance_for_Cr3

Loans and the Allowance for Credit Losses - Schedule of Recorded Investment in Loans by Category (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Financing Receivable, Recorded Investment [Line Items]
Total portfolio loans	$4,873,721	$4,086,766
Loans held for sale	6,064	5,865
Total loans	4,879,785	4,092,631
Commercial Real Estate - Land and Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total portfolio loans	288,075	262,643
Commercial Real Estate - Improved Property [Member]
Financing Receivable, Recorded Investment [Line Items]
Total portfolio loans	1,908,869	1,682,817
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total portfolio loans	2,196,944	1,945,460
Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total portfolio loans	709,621	638,410
Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total portfolio loans	1,239,163	928,770
Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total portfolio loans	362,163	330,031
Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Total portfolio loans	$365,830	$244,095

Loans_and_the_Allowance_for_Cr4

Loans and the Allowance for Credit Losses - Summary of Changes in Allowance for Credit Losses (Detail) (USD $)	3 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses, beginning balance	$44,654	$47,368	$47,368
Allowance for loan commitments, beginning balance	455	602	602
Total beginning allowance for credit losses	45,109	47,970	47,970
Provision for loan losses	1,266	2,256
Provision for loan commitments	23	-57
Total provision for credit losses	1,289	2,199	2,199
Charge-offs	-2,517	-4,735
Recoveries	770	594
Net charge-offs	-1,747	-4,141
Allowance for loan losses, ending balance	44,173	45,483	44,654
Allowance for loan commitments, ending balance	478	545	455
Total ending allowance for credit losses	44,651	46,028	45,109
Commercial Real Estate - Land and Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses, beginning balance	5,654	6,056	6,056
Allowance for loan commitments, beginning balance	194	301	301
Total beginning allowance for credit losses	5,848	6,357	6,357
Provision for loan losses	-323	-1,051
Provision for loan commitments	-16	-8
Total provision for credit losses	-339	-1,059
Allowance for loan losses, ending balance	5,331	5,005
Allowance for loan commitments, ending balance	178	293
Total ending allowance for credit losses	5,509	5,298
Commercial Real Estate - Improved Property [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses, beginning balance	17,573	18,157	18,157
Allowance for loan commitments, beginning balance	10	62	62
Total beginning allowance for credit losses	17,583	18,219	18,219
Provision for loan losses	903	-509
Provision for loan commitments	8	-53
Total provision for credit losses	911	-562
Charge-offs	-577	-493
Recoveries	136	120
Net charge-offs	-441	-373
Allowance for loan losses, ending balance	18,035	17,275
Allowance for loan commitments, ending balance	18	9
Total ending allowance for credit losses	18,053	17,284
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses, beginning balance	9,063	9,925	9,925
Allowance for loan commitments, beginning balance	112	130	130
Total beginning allowance for credit losses	9,175	10,055	10,055
Provision for loan losses	-44	2,128
Provision for loan commitments	8	3
Total provision for credit losses	-36	2,131
Charge-offs	-122	-2,276
Recoveries	114	65
Net charge-offs	-8	-2,211
Allowance for loan losses, ending balance	9,011	9,842
Allowance for loan commitments, ending balance	120	133
Total ending allowance for credit losses	9,131	9,975
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses, beginning balance	5,382	5,673	5,673
Allowance for loan commitments, beginning balance	9	5	5
Total beginning allowance for credit losses	5,391	5,678	5,678
Provision for loan losses	-208	869
Provision for loan commitments	4
Total provision for credit losses	-204	869
Charge-offs	-358	-879
Recoveries	218	109
Net charge-offs	-140	-770
Allowance for loan losses, ending balance	5,034	5,772
Allowance for loan commitments, ending balance	13	5
Total ending allowance for credit losses	5,047	5,777
Home Equity [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses, beginning balance	2,329	2,017	2,017
Allowance for loan commitments, beginning balance	90	85	85
Total beginning allowance for credit losses	2,419	2,102	2,102
Provision for loan losses	747	153
Provision for loan commitments	17	1
Total provision for credit losses	764	154
Charge-offs	-589	-155
Recoveries	10	11
Net charge-offs	-579	-144
Allowance for loan losses, ending balance	2,497	2,026
Allowance for loan commitments, ending balance	107	86
Total ending allowance for credit losses	2,604	2,112
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses, beginning balance	4,078	5,020	5,020
Allowance for loan commitments, beginning balance	40	19	19
Total beginning allowance for credit losses	4,118	5,039	5,039
Provision for loan losses	133	305
Provision for loan commitments	2
Total provision for credit losses	135	305
Charge-offs	-717	-752
Recoveries	229	227
Net charge-offs	-488	-525
Allowance for loan losses, ending balance	3,723	4,800
Allowance for loan commitments, ending balance	42	19
Total ending allowance for credit losses	3,765	4,819
Deposit Overdraft [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses, beginning balance	575	520	520
Total beginning allowance for credit losses	575	520	520
Provision for loan losses	58	361
Total provision for credit losses	58	361
Charge-offs	-154	-180
Recoveries	63	62
Net charge-offs	-91	-118
Allowance for loan losses, ending balance	542	763
Total ending allowance for credit losses	$542	$763

Loans_and_the_Allowance_for_Cr5

Loans and the Allowance for Credit Losses - Allowance for Credit Losses and Recorded Investments in Loans (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loans individually evaluated for impairment	$3,701	$3,798
Allowance for loans collectively evaluated for impairment	40,472	40,856
Allowance for loan commitments	478	455	545	602
Total allowance for credit losses	44,651	45,109	46,028	47,970
Individually evaluated for impairment	12,544	14,313
Collectively evaluated for impairment	4,861,177	4,072,453
Total Loans	4,873,721	4,086,766
Commercial Real Estate - Land and Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loans collectively evaluated for impairment	5,331	5,654
Allowance for loan commitments	178	194	293	301
Total allowance for credit losses	5,509	5,848	5,298	6,357
Collectively evaluated for impairment	288,075	262,643
Total Loans	288,075	262,643
Commercial Real Estate - Improved Property [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loans individually evaluated for impairment	2,828	2,765
Allowance for loans collectively evaluated for impairment	15,207	14,808
Allowance for loan commitments	18	10	9	62
Total allowance for credit losses	18,053	17,583	17,284	18,219
Individually evaluated for impairment	9,822	11,469
Collectively evaluated for impairment	1,899,047	1,671,348
Total Loans	1,908,869	1,682,817
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loans individually evaluated for impairment	873	1,033
Allowance for loans collectively evaluated for impairment	8,138	8,030
Allowance for loan commitments	120	112	133	130
Total allowance for credit losses	9,131	9,175	9,975	10,055
Individually evaluated for impairment	2,722	2,844
Collectively evaluated for impairment	706,899	635,566
Total Loans	709,621	638,410
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loans collectively evaluated for impairment	5,034	5,382
Allowance for loan commitments	13	9	5	5
Total allowance for credit losses	5,047	5,391	5,777	5,678
Collectively evaluated for impairment	1,239,163	928,770
Total Loans	1,239,163	928,770
Home Equity [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loans collectively evaluated for impairment	2,497	2,329
Allowance for loan commitments	107	90	86	85
Total allowance for credit losses	2,604	2,419	2,112	2,102
Collectively evaluated for impairment	362,163	330,031
Total Loans	362,163	330,031
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loans collectively evaluated for impairment	3,723	4,078
Allowance for loan commitments	42	40	19	19
Total allowance for credit losses	3,765	4,118	4,819	5,039
Collectively evaluated for impairment	365,830	244,095
Total Loans	365,830	244,095
Deposit Overdraft [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loans collectively evaluated for impairment	542	575
Total allowance for credit losses	$542	$575	$763	$520

Loans_and_the_Allowance_for_Cr6

Loans and the Allowance for Credit Losses - Allowance for Credit Losses and Recorded Investments in Loans (Parenthetical) (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015
Receivables [Abstract]
Troubled debt restructuring threshold	$1

Loans_and_the_Allowance_for_Cr7

Loans and the Allowance for Credit Losses - Summary of Commercial Loans by Risk Grade (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Summary of commercial loans by risk grade
Commercial loans	$2,906,565	$2,583,870
Pass [Member]
Summary of commercial loans by risk grade
Commercial loans	2,813,611	2,502,731
Criticized - Compromised [Member]
Summary of commercial loans by risk grade
Commercial loans	40,659	34,288
Classified - Substandard [Member]
Summary of commercial loans by risk grade
Commercial loans	52,295	46,851
Commercial Real Estate - Land and Construction [Member]
Summary of commercial loans by risk grade
Commercial loans	288,075	262,643
Commercial Real Estate - Land and Construction [Member] | Pass [Member]
Summary of commercial loans by risk grade
Commercial loans	281,730	257,218
Commercial Real Estate - Land and Construction [Member] | Criticized - Compromised [Member]
Summary of commercial loans by risk grade
Commercial loans	3,653	3,645
Commercial Real Estate - Land and Construction [Member] | Classified - Substandard [Member]
Summary of commercial loans by risk grade
Commercial loans	2,692	1,780
Commercial Real Estate - Improved Property [Member]
Summary of commercial loans by risk grade
Commercial loans	1,908,869	1,682,817
Commercial Real Estate - Improved Property [Member] | Pass [Member]
Summary of commercial loans by risk grade
Commercial loans	1,848,655	1,627,771
Commercial Real Estate - Improved Property [Member] | Criticized - Compromised [Member]
Summary of commercial loans by risk grade
Commercial loans	18,049	17,873
Commercial Real Estate - Improved Property [Member] | Classified - Substandard [Member]
Summary of commercial loans by risk grade
Commercial loans	42,165	37,173
Commercial and Industrial [Member]
Summary of commercial loans by risk grade
Commercial loans	709,621	638,410
Commercial and Industrial [Member] | Pass [Member]
Summary of commercial loans by risk grade
Commercial loans	683,226	617,742
Commercial and Industrial [Member] | Criticized - Compromised [Member]
Summary of commercial loans by risk grade
Commercial loans	18,957	12,770
Commercial and Industrial [Member] | Classified - Substandard [Member]
Summary of commercial loans by risk grade
Commercial loans	$7,438	$7,898

Loans_and_the_Allowance_for_Cr8

Loans and the Allowance for Credit Losses - Summary of Age Analysis of Loan Categories (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Financing Receivable, Recorded Investment [Line Items]
Current	$4,827,728	$4,042,825
30-59 Days Past Due	11,089	8,500
60-89 Days Past Due	6,002	9,976
90 Days or More Past Due	28,902	25,465
Total Past Due	45,993	43,941
Total Loans	4,873,721	4,086,766
90 Days or More Past Due and Accruing	1,031	2,288
Loans held for sale, current	6,064	5,865
Loans held for sale	6,064	5,865
Total loans, current	4,833,792	4,048,690
Total loans	4,879,785	4,092,631
Commercial Real Estate - Land and Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	286,883	261,356
30-59 Days Past Due		20
90 Days or More Past Due	1,192	1,267
Total Past Due	1,192	1,287
Total Loans	288,075	262,643
90 Days or More Past Due and Accruing		71
Commercial Real Estate - Improved Property [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	1,889,451	1,665,363
30-59 Days Past Due	1,093	961
60-89 Days Past Due	1,435	4,772
90 Days or More Past Due	16,890	11,721
Total Past Due	19,418	17,454
Total Loans	1,908,869	1,682,817
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	2,176,334	1,926,719
30-59 Days Past Due	1,093	981
60-89 Days Past Due	1,435	4,772
90 Days or More Past Due	18,082	12,988
Total Past Due	20,610	18,741
Total Loans	2,196,944	1,945,460
90 Days or More Past Due and Accruing		71
Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	705,380	634,482
30-59 Days Past Due	916	1,834
60-89 Days Past Due	1,518	240
90 Days or More Past Due	1,807	1,854
Total Past Due	4,241	3,928
Total Loans	709,621	638,410
90 Days or More Past Due and Accruing	3	22
Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	1,226,131	915,968
30-59 Days Past Due	4,981	1,237
60-89 Days Past Due	1,673	3,384
90 Days or More Past Due	6,378	8,181
Total Past Due	13,032	12,802
Total Loans	1,239,163	928,770
90 Days or More Past Due and Accruing	74	1,306
Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	357,545	325,291
30-59 Days Past Due	1,982	1,877
60-89 Days Past Due	508	895
90 Days or More Past Due	2,128	1,968
Total Past Due	4,618	4,740
Total Loans	362,163	330,031
90 Days or More Past Due and Accruing	684	570
Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	362,338	240,365
30-59 Days Past Due	2,117	2,571
60-89 Days Past Due	868	685
90 Days or More Past Due	507	474
Total Past Due	3,492	3,730
Total Loans	365,830	244,095
90 Days or More Past Due and Accruing	270	319
Non-Accrual Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	9,209	7,562
30-59 Days Past Due	2,008	2,884
60-89 Days Past Due	2,319	5,552
90 Days or More Past Due	27,838	22,820
Total Past Due	32,165	31,256
Total Loans	41,374	38,818
TDRs Accruing Interest [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	16,536	11,016
30-59 Days Past Due	582	151
60-89 Days Past Due	179	542
90 Days or More Past Due	33	357
Total Past Due	794	1,050
Total Loans	17,330	12,066
Total Impaired [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	25,745	18,578
30-59 Days Past Due	2,590	3,035
60-89 Days Past Due	2,498	6,094
90 Days or More Past Due	27,871	23,177
Total Past Due	32,959	32,306
Total Loans	$58,704	$50,884

Loans_and_the_Allowance_for_Cr9

Loans and the Allowance for Credit Losses - Summary of Age Analysis of Loan Categories (Parenthetical) (Detail)	3 Months Ended
	Mar. 31, 2015
Receivables [Abstract]
Past due loans excluded TDRs past due and accruing	90 days

Recovered_Sheet1

Loans and the Allowance for Credit Losses - Summary of Impaired Loans (Detail) (USD $)	3 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance, With no specific allowance recorded	$61,759	$45,474
Total impaired loans, Unpaid principal balance	69,993	55,296
Recorded Investment, With no specific allowance recorded	50,470	41,062
Total impaired loans, Recorded investment	58,704	50,884
Unpaid Principal Balance, With a specific allowance recorded	8,234	9,822
Recorded Investment, With a specific allowance recorded	8,234	9,822
Related Allowance, With a specific allowance recorded	3,701	3,798
Average recorded investment, with no related specific allowance	46,123	48,144
Interest income recognized, With no related specific allowance	522	283
Average recorded investment, With a specific allowance recorded	9,028	3,058
Interest income recognized, With a specific allowance recorded	19	13
Total impaired loans, Average recorded investment	55,151	51,202
Total impaired loans, Interest income recognized	541	296
Commercial Real Estate - Land and Construction [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance, With no specific allowance recorded	3,101	1,588
Recorded Investment, With no specific allowance recorded	2,476	1,488
Average recorded investment, with no related specific allowance	2,128	2,450
Interest income recognized, With no related specific allowance	16	2
Commercial Real Estate - Improved Property [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance, With no specific allowance recorded	30,138	16,480
Recorded Investment, With no specific allowance recorded	22,481	14,684
Unpaid Principal Balance, With a specific allowance recorded	6,466	7,980
Recorded Investment, With a specific allowance recorded	6,466	7,980
Related Allowance, With a specific allowance recorded	2,828	2,765
Average recorded investment, with no related specific allowance	18,932	19,158
Interest income recognized, With no related specific allowance	223	20
Average recorded investment, With a specific allowance recorded	7,223	729
Interest income recognized, With a specific allowance recorded		1
Commercial and Industrial [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance, With no specific allowance recorded	3,094	3,152
Recorded Investment, With no specific allowance recorded	2,432	2,597
Unpaid Principal Balance, With a specific allowance recorded	1,768	1,842
Recorded Investment, With a specific allowance recorded	1,768	1,842
Related Allowance, With a specific allowance recorded	873	1,033
Average recorded investment, with no related specific allowance	2,513	3,532
Interest income recognized, With no related specific allowance	13	32
Average recorded investment, With a specific allowance recorded	1,805	2,329
Interest income recognized, With a specific allowance recorded	19	12
Residential Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance, With no specific allowance recorded	20,943	20,077
Recorded Investment, With no specific allowance recorded	19,132	18,544
Average recorded investment, with no related specific allowance	18,715	19,463
Interest income recognized, With no related specific allowance	230	182
Home Equity [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance, With no specific allowance recorded	2,824	2,890
Recorded Investment, With no specific allowance recorded	2,617	2,663
Average recorded investment, with no related specific allowance	2,641	2,367
Interest income recognized, With no related specific allowance	20	19
Consumer [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Principal Balance, With no specific allowance recorded	1,659	1,287
Recorded Investment, With no specific allowance recorded	1,332	1,086
Average recorded investment, with no related specific allowance	1,194	1,174
Interest income recognized, With no related specific allowance	$20	$28

Recovered_Sheet2

Loans and the Allowance for Credit Losses - Recorded Investment in Non-Accrual Loans and TDRs (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Financing Receivable, Impaired [Line Items]
Non-accrual loans	$41,374	$38,818
TDRs	26,554	17,486
Accruing TDRs [Member]
Financing Receivable, Impaired [Line Items]
TDRs	17,330	12,066
Non-Accrual TDRs [Member]
Financing Receivable, Impaired [Line Items]
TDRs	9,224	5,420
Commercial Real Estate - Land and Construction [Member]
Financing Receivable, Impaired [Line Items]
Non-accrual loans	1,463	1,488
TDRs	1,517	464
Commercial Real Estate - Land and Construction [Member] | Accruing TDRs [Member]
Financing Receivable, Impaired [Line Items]
TDRs	1,013
Commercial Real Estate - Land and Construction [Member] | Non-Accrual TDRs [Member]
Financing Receivable, Impaired [Line Items]
TDRs	504	464
Commercial Real Estate - Improved Property [Member]
Financing Receivable, Impaired [Line Items]
Non-accrual loans	22,143	20,227
TDRs	12,203	4,287
Commercial Real Estate - Improved Property [Member] | Accruing TDRs [Member]
Financing Receivable, Impaired [Line Items]
TDRs	6,804	2,437
Commercial Real Estate - Improved Property [Member] | Non-Accrual TDRs [Member]
Financing Receivable, Impaired [Line Items]
TDRs	5,399	1,850
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Non-accrual loans	23,606	21,715
TDRs	13,720	4,751
Commercial Real Estate [Member] | Accruing TDRs [Member]
Financing Receivable, Impaired [Line Items]
TDRs	7,817	2,437
Commercial Real Estate [Member] | Non-Accrual TDRs [Member]
Financing Receivable, Impaired [Line Items]
TDRs	5,903	2,314
Commercial and Industrial [Member]
Financing Receivable, Impaired [Line Items]
Non-accrual loans	3,849	4,110
TDRs	727	807
Commercial and Industrial [Member] | Accruing TDRs [Member]
Financing Receivable, Impaired [Line Items]
TDRs	351	329
Commercial and Industrial [Member] | Non-Accrual TDRs [Member]
Financing Receivable, Impaired [Line Items]
TDRs	376	478
Residential Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Non-accrual loans	11,249	10,329
TDRs	10,269	10,289
Residential Real Estate [Member] | Accruing TDRs [Member]
Financing Receivable, Impaired [Line Items]
TDRs	7,883	8,215
Residential Real Estate [Member] | Non-Accrual TDRs [Member]
Financing Receivable, Impaired [Line Items]
TDRs	2,386	2,074
Home Equity [Member]
Financing Receivable, Impaired [Line Items]
Non-accrual loans	1,899	1,923
TDRs	1,003	985
Home Equity [Member] | Accruing TDRs [Member]
Financing Receivable, Impaired [Line Items]
TDRs	718	740
Home Equity [Member] | Non-Accrual TDRs [Member]
Financing Receivable, Impaired [Line Items]
TDRs	285	245
Consumer [Member]
Financing Receivable, Impaired [Line Items]
Non-accrual loans	771	741
TDRs	835	654
Consumer [Member] | Accruing TDRs [Member]
Financing Receivable, Impaired [Line Items]
TDRs	561	345
Consumer [Member] | Non-Accrual TDRs [Member]
Financing Receivable, Impaired [Line Items]
TDRs	$274	$309

Recovered_Sheet3

Loans and the Allowance for Credit Losses - Loans Identified as TDRs (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
	Contract	Contract
Financing Receivable, Modifications [Line Items]
Number of Modifications	49	7
Pre-Modification Outstanding Recorded Investment	$10,724	$245
Post-Modification Outstanding Recorded Investment	10,132	239
Commercial Real Estate - Land and Construction [Member]
Financing Receivable, Modifications [Line Items]
Number of Modifications	11
Pre-Modification Outstanding Recorded Investment	1,414
Post-Modification Outstanding Recorded Investment	1,056
Commercial Real Estate - Improved Property [Member]
Financing Receivable, Modifications [Line Items]
Number of Modifications	7	1
Pre-Modification Outstanding Recorded Investment	8,568	91
Post-Modification Outstanding Recorded Investment	8,289	90
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Modifications	18	1
Pre-Modification Outstanding Recorded Investment	9,982	91
Post-Modification Outstanding Recorded Investment	9,345	90
Commercial and Industrial [Member]
Financing Receivable, Modifications [Line Items]
Number of Modifications	2
Pre-Modification Outstanding Recorded Investment	42
Post-Modification Outstanding Recorded Investment	57
Residential Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Modifications	7	4
Pre-Modification Outstanding Recorded Investment	424	121
Post-Modification Outstanding Recorded Investment	421	118
Home Equity [Member]
Financing Receivable, Modifications [Line Items]
Number of Modifications	1
Pre-Modification Outstanding Recorded Investment	7
Post-Modification Outstanding Recorded Investment	6
Consumer [Member]
Financing Receivable, Modifications [Line Items]
Number of Modifications	21	2
Pre-Modification Outstanding Recorded Investment	269	33
Post-Modification Outstanding Recorded Investment	$303	$31

Recovered_Sheet4

Loans and the Allowance for Credit Losses - TDRs Defaulted Later Restructured (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
	Defaults	Defaults
Financing Receivable, Modifications [Line Items]
Number of Defaults	2	9
Recorded Investment	$69	$484
Residential Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Defaults		8
Recorded Investment		481
Home Equity [Member]
Financing Receivable, Modifications [Line Items]
Number of Defaults	1	1
Recorded Investment	42	3
Consumer [Member]
Financing Receivable, Modifications [Line Items]
Number of Defaults	1
Recorded Investment	$27

Recovered_Sheet5

Loans and the Allowance for Credit Losses - Summary of Other Real Estate Owned and Repossessed Assets (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Receivables [Abstract]
Other real estate owned	$5,886	$4,920
Repossessed assets	340	162
Total other real estate owned and repossessed assets	$6,226	$5,082

Pension_Plan_Components_of_Net

Pension Plan - Components of Net Periodic Cost (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost - benefits earned during year	$827	$717
Interest cost on projected benefit obligation	1,201	1,170
Expected return on plan assets	-1,907	-1,783
Amortization of prior service cost	6	11
Amortization of net loss	784	363
Net periodic pension cost	$911	$478

Pension_Plan_Additional_Inform

Pension Plan - Additional Information (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015
Compensation and Retirement Disclosure [Abstract]
Minimum required pension plan contribution	$3.10
Partial credit balance utilized for minimum required contribution	34.9
Employer contribution	$7.50

Fair_Value_Measurement_Schedul

Fair Value Measurement - Schedule of Fair Value of Assets and Liabilities Measured on Recurring and Nonrecurring Basis (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities - available-for-sale	$1,654,264	$917,424
Other real estate owned and repossessed assets	6,226	5,082
Loans held for sale	6,064	5,865
Recurring Fair Value Measurements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities - available-for-sale	1,654,264	917,424
Total recurring fair value measurements	1,654,264	917,424
Nonrecurring Fair Value Measurements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	4,533	6,024
Other real estate owned and repossessed assets	6,226	5,082
Loans held for sale	6,064	5,865
Total nonrecurring fair value measurements	16,823	16,971
Obligations of Government Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities - available-for-sale	80,768	87,736
Obligations of Government Agencies [Member] | Recurring Fair Value Measurements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities - available-for-sale	80,768	87,736
Residential Mortgage-Backed Securities and Collateralized Mortgage Obligations of Government Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities - available-for-sale	1,283,445	701,113
Residential Mortgage-Backed Securities and Collateralized Mortgage Obligations of Government Agencies [Member] | Recurring Fair Value Measurements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities - available-for-sale	1,283,445	701,113
Obligations of State and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities - available-for-sale	95,653	91,433
Obligations of State and Political Subdivisions [Member] | Recurring Fair Value Measurements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities - available-for-sale	95,653	91,433
Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities - available-for-sale	183,090	25,996
Corporate Debt Securities [Member] | Recurring Fair Value Measurements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities - available-for-sale	183,090	25,996
Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities - available-for-sale	11,308	11,146
Equity Securities [Member] | Recurring Fair Value Measurements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities - available-for-sale	11,308	11,146
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities - available-for-sale	8,538	8,440
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Recurring Fair Value Measurements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities - available-for-sale	8,538	8,440
Total recurring fair value measurements	8,538	8,440
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Equity Securities [Member] | Recurring Fair Value Measurements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities - available-for-sale	8,538	8,440
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities - available-for-sale	1,645,726	908,984
Loans held for sale	6,064	5,865
Significant Other Observable Inputs (Level 2) [Member] | Recurring Fair Value Measurements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities - available-for-sale	1,645,726	908,984
Total recurring fair value measurements	1,645,726	908,984
Significant Other Observable Inputs (Level 2) [Member] | Nonrecurring Fair Value Measurements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale	6,064	5,865
Total nonrecurring fair value measurements	6,064	5,865
Significant Other Observable Inputs (Level 2) [Member] | Obligations of Government Agencies [Member] | Recurring Fair Value Measurements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities - available-for-sale	80,768	87,736
Significant Other Observable Inputs (Level 2) [Member] | Residential Mortgage-Backed Securities and Collateralized Mortgage Obligations of Government Agencies [Member] | Recurring Fair Value Measurements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities - available-for-sale	1,283,445	701,113
Significant Other Observable Inputs (Level 2) [Member] | Obligations of State and Political Subdivisions [Member] | Recurring Fair Value Measurements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities - available-for-sale	95,653	91,433
Significant Other Observable Inputs (Level 2) [Member] | Corporate Debt Securities [Member] | Recurring Fair Value Measurements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities - available-for-sale	183,090	25,996
Significant Other Observable Inputs (Level 2) [Member] | Equity Securities [Member] | Recurring Fair Value Measurements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total securities - available-for-sale	2,770	2,706
Significant Unobservable Inputs (Level 3) [Member] | Nonrecurring Fair Value Measurements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	4,533	6,024
Other real estate owned and repossessed assets	6,226	5,082
Total nonrecurring fair value measurements	$10,759	$11,106

Fair_Value_Measurement_Additio

Fair Value Measurement - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Fair Value Disclosures [Abstract]
Fair value transfer amount	$0	$0

Fair_Value_Measurement_Schedul1

Fair Value Measurement - Schedule of Assets Measured at Fair Value on Nonrecurring Basis (Detail) (USD $)	3 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Other real estate owned and repossessed assets	6,226	5,082
Nonrecurring Fair Value Measurements [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Impaired loans	4,533	6,024
Other real estate owned and repossessed assets	6,226	5,082
Significant Unobservable Inputs (Level 3) [Member] | Nonrecurring Fair Value Measurements [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Impaired loans	4,533	6,024
Other real estate owned and repossessed assets	6,226	5,082
Minimum [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Impaired loans, Appraisal adjustments	0.00%	0.00%
Impaired loans, Liquidation expenses	-3.10%	-1.20%
Maximum [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Impaired loans, Appraisal adjustments	-38.50%	-39.70%
Impaired loans, Liquidation expenses	-8.00%	-8.00%
Weighted Average [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Impaired loans, Appraisal adjustments	-6.90%	-6.70%
Impaired loans, Liquidation expenses	-7.40%	-6.70%

Fair_Value_Measurement_Estimat

Fair Value Measurement - Estimates Fair Value of Financial Instruments (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Financial Assets
Cash and due from banks	$92,974	$94,002	$175,196	$95,551
Securities available-for-sale	1,654,264	917,424
Securities held-to-maturity	743,925	593,670
Net loans	4,829,548	4,042,112
Loans held for sale	6,064	5,865
Accrued interest receivable	25,232	18,481
Bank-owned life insurance	153,991	123,298
Financial Liabilities
Deposits	6,416,202	5,048,983
Federal Home Loan Bank borrowings	432,456	223,126
Other borrowings	76,630	80,690
Junior subordinated debt	142,269	106,176
Accrued interest payable	2,297	1,620
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Financial Assets
Cash and due from banks	92,974	94,002
Securities available-for-sale	8,538	8,440
Accrued interest receivable	25,232	18,481
Bank-owned life insurance	153,991	123,298
Financial Liabilities
Deposits	4,532,314	3,743,887
Other borrowings	73,589	77,534
Accrued interest payable	2,297	1,620
Significant Other Observable Inputs (Level 2) [Member]
Financial Assets
Securities available-for-sale	1,645,726	908,984
Securities held-to-maturity	772,088	618,895
Loans held for sale	6,064	5,865
Financial Liabilities
Deposits	1,891,185	1,312,941
Federal Home Loan Bank borrowings	435,089	225,456
Other borrowings	3,032	3,162
Junior subordinated debt	116,070	79,212
Significant Unobservable Inputs (Level 3) [Member]
Financial Assets
Securities held-to-maturity	755	722
Net loans	4,820,779	4,047,648
Carrying Amount [Member]
Financial Assets
Cash and due from banks	92,974	94,002
Securities available-for-sale	1,654,264	917,424
Securities held-to-maturity	743,925	593,670
Net loans	4,829,548	4,042,112
Loans held for sale	6,064	5,865
Accrued interest receivable	25,232	18,481
Bank-owned life insurance	153,991	123,298
Financial Liabilities
Deposits	6,416,202	5,048,983
Federal Home Loan Bank borrowings	432,456	223,126
Other borrowings	76,630	80,690
Junior subordinated debt	142,269	106,176
Accrued interest payable	2,297	1,620
Fair Value Estimate [Member]
Financial Assets
Cash and due from banks	92,974	94,002
Securities available-for-sale	1,654,264	917,424
Securities held-to-maturity	772,843	619,617
Net loans	4,820,779	4,047,648
Loans held for sale	6,064	5,865
Accrued interest receivable	25,232	18,481
Bank-owned life insurance	153,991	123,298
Financial Liabilities
Deposits	6,423,499	5,056,828
Federal Home Loan Bank borrowings	435,089	225,456
Other borrowings	76,621	80,696
Junior subordinated debt	116,070	79,212
Accrued interest payable	$2,297	$1,620

Comprehensive_Income_Component

Comprehensive Income - Components of Accumulated Other Comprehensive Income (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
Beginning Balance, Defined Benefit Pension Plan	($22,776)	($7,966)
Defined Benefit Pension Plan, Other comprehensive income before reclassifications	0	0
Defined Benefit Pension Plan, Amounts reclassified from accumulated other comprehensive income	475	236
Defined Benefit Pension Plan, Period change	475	236
Ending Balance, Defined Benefit Pension Plan	-22,301	-7,730
Beginning Balance, Unrealized Gains (Losses) on Securities Available-for-Sale	2,892	-6,126
Unrealized Gains (Losses) on Securities Available-for-Sale, Other comprehensive income before reclassifications	4,804	3,075
Unrealized Gains (Losses) on Securities Available-for-Sale, Amounts reclassified from accumulated other comprehensive income	-11	49
Net effect on accumulated other comprehensive income for the period	4,793	3,124
Ending Balance, Unrealized Gains (Losses) on Securities Available-for-Sale	7,685	-3,002
Beginning Balance, Unrealized Gains on Securities Transferred from Available-for-Sale to Held-to-Maturity	1,059	1,358
Unrealized Gains on Securities Transferred from Available-for-Sale to Held-to-Maturity, Other comprehensive income before reclassifications	0	0
Unrealized Gains on Securities Transferred from Available-for-Sale to Held-to-Maturity, Amounts reclassified from accumulated other comprehensive income	-67	-87
Unrealized Gains on Securities Transferred from Available-for-Sale to Held-to-Maturity, Period change	-67	-87
Ending Balance, Unrealized Gains on Securities Transferred from Available-for-Sale to Held-to-Maturity	992	1,271
Beginning Balance, Accumulated Other Comprehensive Income	-18,825	-12,734
Other comprehensive income before reclassifications	4,804	3,075
Amounts reclassified from accumulated other comprehensive income	397	198
Total other comprehensive income	5,201	3,273
Ending Balance, Accumulated Other Comprehensive Income	($13,624)	($9,461)

Comprehensive_Income_Component1

Comprehensive Income - Components of Accumulated Other Comprehensive Income (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Percentage of Federal and State income tax rate	37.00%	37.00%	37.00%

Comprehensive_Income_Schedule_

Comprehensive Income - Schedule of Amounts Reclassified from Accumulated Other Comprehensive Income (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net effect on accumulated other comprehensive income for the period	$4,793	$3,124
Defined benefit pension plan (2):
Total reclassifications for the period	-397	-198
Amounts Reclassified From Accumulated Other Comprehensive Income/(Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net securities (gains) losses reclassified into earnings	-18	78
Related income tax expense (benefit)	7	-29
Net effect on accumulated other comprehensive income for the period	-11	49
Amortization of unrealized gain transferred from available-for-sale	-107	-138
Related income tax expense	40	51
Net effect on accumulated other comprehensive income for the period	-67	-87
Defined benefit pension plan (2):
Amortization of net loss and prior service costs	790	374
Related income tax benefit	-315	-138
Net effect on accumulated other comprehensive income for the period	475	236
Total reclassifications for the period	$397	$198

Commitments_and_Contingent_Lia2

Commitments and Contingent Liabilities - Additional Information (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
Commitments and Contingencies Disclosure [Abstract]
Allowance for credit losses associated with loan commitments	$478,000	$455,000	$545,000	$602,000
Liability associated with letters of credit	$200,000	$200,000

Commitments_and_Contingent_Lia3

Commitments and Contingent Liabilities - Commitments to Extend Credit, Guarantees and Various Letters of Credit Outstanding (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Commitments and Contingencies Disclosure [Abstract]
Lines of credit	$1,032,235	$984,352
Loans approved but not closed	295,702	116,757
Overdraft limits	110,389	95,965
Letters of credit	26,910	23,362
Contingent obligations to purchase loans funded by other entities	$8,457	$8,312

Business_Segments_Additional_I

Business Segments - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
	Segment
Segment Reporting Information [Line Items]
Operating segments	2
Trust and Investment Services [Member]
Segment Reporting Information [Line Items]
Market value of assets held by trust and investment services segment	3,900,000,000	$3,800,000,000
Total non-fiduciary assets of the trust and investment services segment	3,700,000	$4,000,000

Business_Segments_Financial_In

Business Segments - Financial Information by Business Segment (Detail) (USD $)	3 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Segment Reporting Information [Line Items]
Interest income	$60,379	$53,457	$53,457
Interest expense	5,424	6,132	6,132
Net interest income	54,955	47,325	47,325
Provision for credit losses	1,289	2,199	2,199
Net interest income after provision for credit losses	53,666	45,126	45,126
Non-interest income	18,190	17,049	17,049
Non-interest expense	53,441	40,095	40,095
Income before provision for income taxes	18,415	22,080	22,080
Provision for income taxes	4,528	5,659	5,659
Net income	13,887	16,421	16,421
Community Banking [Member]
Segment Reporting Information [Line Items]
Interest income	60,379		53,457
Interest expense	5,424		6,132
Net interest income	54,955		47,325
Provision for credit losses	1,289		2,199
Net interest income after provision for credit losses	53,666		45,126
Non-interest income	12,137		11,401
Non-interest expense	50,278		36,827
Income before provision for income taxes	15,525		19,700
Provision for income taxes	3,372		4,707
Net income	12,153		14,993
Trust and Investment Services [Member]
Segment Reporting Information [Line Items]
Non-interest income	6,053		5,648
Non-interest expense	3,163		3,268
Income before provision for income taxes	2,890		2,380
Provision for income taxes	1,156		952
Net income	$1,734		$1,428