United Bankshares (UBSI) 10-K 3 Mar 14 2013 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2013	Jan. 31, 2014	Jun. 30, 2013
Document And Entity Information [Abstract]	'	'	'
Document Type	'10-K	'	'
Amendment Flag	'false	'	'
Document Period End Date	31-Dec-13	'	'
Document Fiscal Year Focus	'2013	'	'
Document Fiscal Period Focus	'FY	'	'
Entity Registrant Name	'UNITED BANKSHARES INC/WV	'	'
Entity Central Index Key	'0000729986	'	'
Current Fiscal Year End Date	'--12-31	'	'
Entity Well-known Seasoned Issuer	'Yes	'	'
Entity Current Reporting Status	'Yes	'	'
Entity Voluntary Filers	'No	'	'
Entity Filer Category	'Large Accelerated Filer	'	'
Entity Common Stock, Shares Outstanding	'	68,767,594	'
Entity Public Float	'	'	$1,213,705,516

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Assets	'	'
Cash and due from banks	$134,808	$157,539
Interest-bearing deposits with other banks	281,090	273,517
Federal funds sold	719	1,021
Total cash and cash equivalents	416,617	432,077
Securities available for sale at estimated fair value (amortized cost-$813,049 at December 31, 2013 and $673,315 at December 31, 2012)	775,284	625,625
Securities held to maturity (estimated fair value-$38,293 at December 31, 2013 and $42,695 at December 31, 2012)	40,965	43,467
Other investment securities	73,093	60,310
Loans held for sale	4,236	17,762
Loans	6,713,599	6,517,780
Less: Unearned income	-9,016	-6,364
Loans net of unearned income	6,704,583	6,511,416
Less: Allowance for loan losses	-74,198	-73,901
Net loans	6,630,385	6,437,515
Bank premises and equipment	69,897	72,170
Goodwill	375,547	375,583
Accrued interest receivable	26,666	26,302
Other assets	322,634	329,202
Total Assets	8,735,324	8,420,013
Deposits:	'	'
Noninterest-bearing	1,874,520	1,824,411
Interest-bearing	4,747,051	4,928,575
Total deposits	6,621,571	6,752,986
Borrowings:	'	'
Federal funds purchased	27,685	5,446
Securities sold under agreements to repurchase	188,069	209,516
Federal Home Loan Bank borrowings	592,069	186,411
Other long-term borrowings	198,628	198,515
Allowance for lending-related commitments	2,143	1,656
Accrued expenses and other liabilities	63,427	73,232
TOTAL LIABILITIES	7,693,592	7,427,762
Shareholders' Equity	'	'
Preferred stock, $1.00 par value; Authorized-50,000,000 shares; none issued	0	0
Common stock, $2.50 par value; Authorized-100,000,000 shares; issued- 50,867,630 at December 31, 2013 and 2012, including 437,363 and 591,057 shares in treasury at December 31, 2013 and 2012, respectively	127,169	127,169
Surplus	237,674	238,739
Retained earnings	734,945	712,299
Accumulated other comprehensive loss	-43,047	-65,748
Treasury stock, at cost	-15,009	-20,208
TOTAL SHAREHOLDERS' EQUITY	1,041,732	992,251
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$8,735,324	$8,420,013

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, except Share data, unless otherwise specified
Statement Of Financial Position [Abstract]	'	'
Securities available for sale, amortized cost	$813,049	$673,315
Securities held to maturity	$38,293	$42,695
Preferred stock, par value	$1	$1
Preferred stock, shares authorized	50,000,000	50,000,000
Preferred stock, shares issued	'	'
Common stock, par value	$2.50	$2.50
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	50,867,630	50,867,630
Common stock, shares in treasury	437,363	591,057

Consolidated_Statements_of_Inc

Consolidated Statements of Income (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Interest income	'	'	'
Interest and fees on loans	$286,033	$301,840	$288,213
Interest on federal funds sold and other short-term investments	613	1,169	1,255
Interest and dividends on securities:	'	'	'
Taxable	16,646	17,364	23,069
Tax-exempt	2,862	3,524	3,985
Total interest income	306,154	323,897	316,522
Interest expense	'	'	'
Interest on deposits	26,531	32,248	39,075
Interest on short-term borrowings	895	303	166
Interest on long-term borrowings	8,887	13,639	16,553
Total interest expense	36,313	46,190	55,794
Net interest income	269,841	277,707	260,728
Provision for loan losses	19,267	17,862	17,141
Net interest income after provision for loan losses	250,574	259,845	243,587
Other income	'	'	'
Fees from trust and brokerage services	16,447	15,845	13,343
Fees from deposit services	40,245	41,832	42,110
Bankcard fees and merchant discounts	3,591	2,996	2,572
Other service charges, commissions, and fees	2,247	2,229	1,849
Income from bank-owned life insurance	5,788	5,039	5,286
Income from mortgage banking	2,571	2,471	952
Other income	2,748	2,810	3,563
Total other-than-temporary impairment losses	-860	-4,955	-20,958
Portion of loss recognized in other comprehensive income	-6,472	-2,421	544
Net other-than-temporary impairment losses	-7,332	-7,376	-20,414
Net gains on sales/calls of investment securities	1,523	446	1,576
Net investment securities losses	-5,809	-6,930	-18,838
Total other income	67,828	66,292	50,837
Other expense	'	'	'
Employee compensation	68,074	71,402	64,611
Employee benefits	22,970	21,178	17,358
Net occupancy expense	19,818	20,428	18,596
Other real estate owned (OREO) expense	6,441	8,556	7,008
Equipment expense	7,748	8,307	7,976
Data processing expense	11,394	12,532	11,637
Bankcard processing expense	1,332	1,315	1,051
FDIC insurance expense	6,188	6,064	8,468
Other expense	49,393	54,874	47,343
Total other expense	193,358	204,656	184,048
Income before income taxes	125,044	121,481	110,376
Income taxes	39,416	38,874	34,766
Net income	$85,628	$82,607	$75,610
Earnings per common share:	'	'	'
Basic	$1.70	$1.64	$1.62
Diluted	$1.70	$1.64	$1.61
Dividends per common share	$1.25	$1.24	$1.21
Average outstanding shares:	'	'	'
Basic	50,353,452	50,265,620	46,803,432
Diluted	50,426,078	50,298,019	46,837,363

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Statement Of Income And Comprehensive Income [Abstract]	'	'	'
Net income	$85,628	$82,607	$75,610
Change in net unrealized (loss) gain on available-for-sale (AFS) securities, net of tax	6,452	5,120	5,820
Accretion of the net unrealized loss on the transfer of AFS securities to held-to-maturity (HTM) securities, net of tax	5	4	5
Change in defined benefit pension plan, net of tax	16,244	-4,114	-11,927
Comprehensive income, net of tax	$108,329	$83,617	$69,508

Consolidated_Statement_of_Chan

Consolidated Statement of Changes in Shareholders' Equity (USD $)	Total	Common Stock [Member]	Surplus [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]
In Thousands, except Share data
Beginning Balance at Dec. 31, 2010	$793,012	$110,798	$93,431	$673,260	($60,656)	($23,821)
Beginning Balance, shares at Dec. 31, 2010	'	44,319,157	'	'	'	'
Net income	75,610	0	0	75,610	0	0
Other comprehensive income, net of tax	-6,102	0	0	0	-6,102	0
Comprehensive income, net of tax	69,508	'	'	'	'	'
Acquisition of Centra Financial Holdings, Inc.	161,420	16,371	145,049	0	0	0
Acquisition of Centra Financial Holdings, Inc., shares	'	6,548,473	'	'	'	'
Stock based compensation expense	1,133	0	1,133	0	0	0
Purchase of treasury stock	-18	0	0	0	0	-18
Distribution of treasury stock for deferred compensation plan	74	0	0	0	0	74
Cash dividends	-56,827	0	0	-56,827	0	0
Common stock options exercised	542	0	-852	0	0	1,394
Ending Balance at Dec. 31, 2011	968,844	127,169	238,761	692,043	-66,758	-22,371
Ending Balance, shares at Dec. 31, 2011	'	50,867,630	'	'	'	'
Net income	82,607	0	0	82,607	0	0
Other comprehensive income, net of tax	1,010	0	0	0	1,010	0
Comprehensive income, net of tax	83,617	'	'	'	'	'
Stock based compensation expense	1,908	0	1,908	0	0	0
Purchase of treasury stock	-13	0	0	0	0	-13
Distribution of treasury stock for deferred compensation plan	131	0	0	0	0	131
Cash dividends	-62,351	0	0	-62,351	0	0
Grant of restricted stock	0	0	-1,816	0	0	1,816
Forfeiture of restricted stock	0	0	29	0	0	-29
Common stock options exercised	115	0	-143	0	0	258
Ending Balance at Dec. 31, 2012	992,251	127,169	238,739	712,299	-65,748	-20,208
Ending Balance, shares at Dec. 31, 2012	'	50,867,630	'	'	'	'
Net income	85,628	0	0	85,628	0	0
Other comprehensive income, net of tax	22,701	0	0	0	22,701	0
Comprehensive income, net of tax	108,329	'	'	'	'	'
Stock based compensation expense	1,786	0	1,786	0	0	0
Purchase of treasury stock	-93	0	0	0	0	-93
Distribution of treasury stock for deferred compensation plan	77	0	0	0	0	77
Cash dividends	-62,982	0	0	-62,982	0	0
Grant of restricted stock	0	0	-1,819	0	0	1,819
Forfeiture of restricted stock	0	0	57	0	0	-57
Common stock options exercised	2,364	0	-1,089	0	0	3,453
Ending Balance at Dec. 31, 2013	$1,041,732	$127,169	$237,674	$734,945	($43,047)	($15,009)
Ending Balance, shares at Dec. 31, 2013	'	50,867,630	'	'	'	'

Consolidated_Statement_of_Chan1

Consolidated Statement of Changes in Shareholders' Equity (Parenthetical) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash dividends per share	$1.25	$1.24	$1.21
Common stock options exercised, shares	100,302	7,510	'
Common Stock [Member]	'	'	'
Grant of restricted stock, shares	52,825	52,700	'
Forfeiture of restricted stock, shares	1,664	840	'
Common stock options exercised, shares	100,302	7,510	4.0447
Treasury Stock [Member]	'	'	'
Purchase of treasury stock, shares	1,596	455	0.0676
Distribution of treasury stock for deferred compensation plan, shares	3,827	4,710	0.3069

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
OPERATING ACTIVITIES	'	'	'
Net income	$85,628	$82,607	$75,610
Adjustments to reconcile net income to net cash provided by operating activities:	'	'	'
Provision for loan losses	19,267	17,862	17,141
Depreciation, amortization and accretion	11,679	9,723	7,340
Loss on sales of bank premises, OREO and equipment	592	262	1,072
Loss on securities	5,809	6,930	18,838
Loans originated for sale	-135,260	-146,966	-66,990
Proceeds from sales of loans	151,357	135,577	72,971
Gain on sales of loans	-2,571	-2,471	-952
Stock-based compensation	1,786	1,908	1,133
Deferred income tax expense	2,990	337	10,907
Increase in cash surrender value of bank-owned life insurance policies	-6,043	-5,039	-5,195
Amortization of net periodic pension costs	4,094	3,567	912
Changes in:	'	'	'
Interest receivable	-364	159	-2,897
Other assets	9,721	17,264	3,329
Accrued expenses and other liabilities	-6,486	7,719	-14,652
NET CASH PROVIDED BY OPERATING ACTIVITIES	142,199	129,439	118,567
INVESTING ACTIVITIES	'	'	'
Proceeds from maturities and calls of held to maturity securities	2,479	15,973	7,635
Proceeds from sales of securities available for sale	14,352	5,381	24,763
Proceeds from maturities and calls of securities available for sale	683,913	1,991,166	1,462,173
Purchases of securities available for sale	-845,908	-1,926,898	-1,417,978
Redemption of bank-owned life insurance policies	2,573	0	822
Purchases of bank premises and equipment	-5,995	-5,207	-8,018
Proceeds from sales of bank premises and equipment	203	2,238	24
Acquisition of Centra Financial Holdings, Inc., net of cash acquired	0	0	49,085
Proceeds from sales and redemptions of other investment securities	27,648	13,345	10,819
Purchases of other investment securities	-40,237	-5,665	-338
Net change in loans	-212,137	-298,474	29,350
NET CASH (USED IN) PROVIDED BY INVESTING ACTIVITIES	-373,109	-208,141	158,337
FINANCING ACTIVITIES	'	'	'
Cash dividends paid	-62,434	-62,333	-54,344
Excess tax benefits from stock-based compensation arrangements	331	35	3,114
Acquisition of treasury stock	-93	-12	-18
Proceeds from exercise of stock options	2,364	115	542
Distribution of treasury stock for deferred compensation plan	77	130	74
Repayment of long-term Federal Home Loan Bank borrowings	-54,342	-55,398	-60,372
Proceeds of long-term Federal Home Loan Bank borrowings	345,000	0	0
Redemption of issued trust preferred securities	0	-5,155	0
Changes in:	'	'	'
Time deposits	-220,640	-299,803	-274,652
Other deposits	89,395	237,001	250,380
Federal funds purchased, securities sold under agreements to repurchase and other short-term borrowings	115,792	60,196	32,986
NET CASH PROVIDED BY (USED IN) FINANCING ACTIVITIES	215,450	-125,224	-102,290
(DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	-15,460	-203,926	174,614
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR	432,077	636,003	461,389
CASH AND CASH EQUIVALENTS AT END OF YEAR	$416,617	$432,077	$636,003

Summary_of_Significant_Account

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2013
Accounting Policies [Abstract]	'
Summary of Significant Accounting Policies	'
	NOTE A--SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
	Nature of Operations: United Bankshares, Inc. (United, the Company) is a multi-bank holding company headquartered in Charleston, West Virginia. United considers all of West Virginia to be included in its market area. This area includes the five largest West Virginia Metropolitan Statistical Areas (MSA): the Parkersburg MSA, the Charleston MSA, the Huntington MSA, the Morgantown MSA and the Wheeling MSA. United serves the Ohio counties of Lawrence, Belmont, Jefferson and Washington and Fayette county in Pennsylvania primarily because of their close proximity to the Ohio and Pennsylvania borders and United banking offices located in those counties or in nearby West Virginia. United’s Virginia markets include the Maryland, northern Virginia and Washington, D.C. MSA, the Winchester MSA, the Harrisonburg MSA, and the Charlottesville MSA. United considers all of the above locations to be the primary market area for the business of its banking subsidiaries.
	Operating Segments: United’s business activities are confined to one reportable segment which is community banking. As a community banking entity, United offers a full range of products and services through various delivery channels.
	Basis of Presentation: The consolidated financial statements and the notes to consolidated financial statements include the accounts of United Bankshares, Inc. and its wholly owned subsidiaries. All significant intercompany accounts and transactions have been eliminated in the consolidated financial statements.
	United determines whether it has a controlling financial interest in an entity by first evaluating whether the entity is a voting interest entity or a variable interest entity (VIE) under U.S. generally accepted accounting principles. Voting interest entities are entities in which the total equity investment at risk is sufficient to enable the entity to finance itself independently and provides the equity holders with the obligation to absorb losses, the right to receive residual returns and the right to make decisions about the entity’s activities. United consolidates voting interest entities in which it has all, or at least a majority of, the voting interest. As defined in applicable accounting standards, VIEs are entities that lack one or more of the characteristics of a voting interest entity. A controlling financial interest in a VIE is present when an enterprise has both the power to direct the activities of the VIE that most significantly impact the VIE’s economic performance and an obligation to absorb losses or the right to receive benefits that could potentially be significant to the VIE. The enterprise with a controlling financial interest, known as the primary beneficiary, consolidates the VIE. United’s wholly owned and indirect wholly owned statutory trust subsidiaries are VIEs for which United is not the primary beneficiary. Accordingly, its accounts are not included in United’s consolidated financial statements.
	The accounting and reporting policies of United conform with U.S. generally accepted accounting principles. In preparing the consolidated financial statements, management is required to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates. To conform to the 2013 presentation, certain reclassifications have been made to prior period amounts, which had no impact on net income, comprehensive income or shareholders’ equity. In the opinion of management, all adjustments necessary for a fair presentation of financial position and results of operations have been made. Such adjustments are of a normal and recurring nature.
	The Company has evaluated events and transactions subsequent to December 31, 2013 through the date these financial statements were issued. Based on definitions and requirements of generally accepted accounting principles for “Subsequent Events,” the Company has not identified any events that would require adjustments to, or disclosure in the financial statements other than the acquisition of Virginia Commerce Bancorp, Inc. after the close of business on January 31, 2014 (see Note B to these Notes to Consolidated Financial Statements). In addition, on February 20, 2014, United sold a former branch building for approximately $11.1 million and recognized a before-tax gain of approximately $8.9 million. A description of the significant accounting policies is presented below.
	Cash and Cash Equivalents: United considers cash and due from banks, interest-bearing deposits with other banks and federal funds sold as cash and cash equivalents.
	Securities: Management determines the appropriate classification of securities at the time of purchase. Debt securities that United has the positive intent and the ability to hold to maturity are carried at amortized cost. Securities to be held for indefinite periods of time and all marketable equity securities are classified as available for sale and carried at estimated fair value. Unrealized gains and losses on securities classified as available for sale are carried as a separate component of Accumulated Other Comprehensive Income (Loss), net of deferred income taxes.
	Gains or losses on sales of securities are recognized by the specific identification method and are reported in securities gains and losses within noninterest income of the Consolidated Statements of Income. United reviews available-for-sale and held-to-maturity securities on a quarterly basis for possible impairment. United determines whether a decline in fair value below the amortized cost basis of a security is other-than-temporary. This determination requires significant judgment. In making this judgment, United’s review includes an analysis of the facts and circumstances of each individual investment such as the severity of loss, the length of time the fair value has been below cost, the expectation for that security’s performance, the creditworthiness of the issuer, recent changes in external credit ratings, and the assessment of collection of the security’s contractual amounts from the issuer or issuers. If United intends to sell, or it is more likely than not that United will be required to sell an impaired debt security before recovery of its amortized cost basis less any current period credit loss, other-than-temporary impairment is recognized in earnings. The credit loss is defined as the difference between the present value of cash flows expected to be collected (discounted at the contractual rate) and the amortized cost basis. The amount recognized in earnings is equal to the entire difference between the security’s amortized cost basis and its fair value at the balance sheet date. If United does not intend to sell, and it is not more likely than not that United will be required to sell the impaired debt security prior to recovery of its amortized cost basis less any current-period credit loss, the other-than-temporary impairment is separated into the following: 1) the amount representing the credit loss, which is recognized within noninterest income of the Consolidated Statements of Income, and 2) the amount related to all other factors, which is recognized in other comprehensive income within shareholders’ equity of the Consolidated Balance Sheets.
	For equity securities, United evaluates the near-term prospects of the investment in relation to the severity and duration of any impairment and United’s ability and intent to hold these equity securities until a recovery of their fair value to at least the cost basis of the investment. Equity securities that are deemed to be other-than-temporarily impaired are written down to the fair value with the write-down recognized within noninterest income of the Consolidated Statements of Income.
	Certain security investments that do not have readily determinable fair values and for which United does not exercise significant influence are carried at cost and are classified as other investment securities on the balance sheet. These cost-method investments are reviewed for impairment at least annually or sooner if events or changes in circumstances indicate the carrying value may not be recoverable.
	Securities Purchased Under Resale Agreements and Securities Sold Under Agreements to Repurchase: Securities purchased under agreements to resell and securities sold under agreements to repurchase are accounted for as collateralized financing transactions. They are recorded at the amounts at which the securities were acquired or sold plus accrued interest. Securities, generally U.S. government and federal agency securities, pledged as collateral under these financing arrangements cannot be repledged or sold, unless replaced, by the secured party. The fair value of the collateral either received from or provided to a third party is continually monitored and additional collateral is obtained or is requested to be returned to United as deemed appropriate.
	Loans: Loans are reported at the principal amount outstanding, net of unearned income. Interest on loans is accrued and credited to operations using methods that produce a level yield on individual principal amounts outstanding. Loan origination and commitment fees and related direct loan origination costs are deferred and amortized as an adjustment of loan yield over the estimated life of the related loan. Loan fees accreted and included in interest income were $7,427,000, $10,765,000 and $6,264,000 for the years of 2013, 2012 and 2011, respectively. The accrual of interest income on commercial and most consumer loans generally is discontinued when a loan becomes 90 to 120 days past due as to principal or interest. When interest accruals are discontinued, unpaid interest recognized in income in the current year is reversed, and interest accrued in prior years is charged to the allowance for loan losses. Management may elect to continue the accrual of interest when the estimated net realizable value of collateral exceeds the principal balance and accrued interest, and the loan is in the process of collection.
	Loans are designated as impaired when, in the opinion of management, based on current information and events, the collection of principal and interest in accordance with the loan contract is doubtful. Consistent with United’s existing method of income recognition for loans, interest on impaired loans, except those classified as nonaccrual, is recognized as income using the accrual method. United’s method of income recognition for impaired loans that are classified as nonaccrual is to recognize interest income on the cash basis or apply the cash receipt to principal when the ultimate collectibility of principal is in doubt.
	A loan is categorized as restructured if a significant concession is granted to provide for a reduction of either interest or principal due to a deterioration in the financial condition of the borrower. A loan classified as restructured will generally retain such classification until the loan is paid in full. However, a restructured one-to-four-family residential mortgage loan that yields a market rate and demonstrates the ability to pay under the terms of the restructured note through a sustained period of repayment performance, which is generally one year, is removed from the restructured classification. Interest income on restructured loans is accrued at the reduced rate and the loan is returned to performing status once the borrower demonstrates the ability to pay under the terms of the restructured note through a sustained period of repayment performance, which is generally six months. The portfolio of restructured loans is monitored monthly.
	Loans Acquired Through Transfer: Loans acquired through the completion of a transfer, including loans acquired in a business combination, that have evidence of deterioration of credit quality since origination and for which it is probable, at acquisition, that United will be unable to collect all contractually required payment receivable are initially recorded at fair value (as determined by the present value of expected future cash flows) with no valuation allowance. The difference between the undiscounted cash flows expected at acquisition and the investment in the loan, or the “accretable yield,” is recognized as interest income on a level-yield method over the life of the loan. Contractually required payments for interest and principal that exceed the undiscounted cash flows expected at acquisition, or the “nonaccretable difference,” are not recognized as a yield adjustment or as a loss accrual or a valuation allowance. Increases in expected cash flows subsequent to the initial investment are recognized prospectively through adjustment of the yield on the loan over its remaining life. Decreases in expected cash flows are recognized as impairment. Valuation allowances on these impaired loans reflect only losses incurred after the acquisition (meaning the present value of all cash flows expected at acquisition that ultimately are not to be received).
	Loans Held for Sale: Loans held for sale consist of one-to-four family conforming residential real estate loans originated for sale in the secondary market and carried at the lower of cost or fair value determined on an aggregate basis. Generally, United’s current practice is to sell all fixed-rate, one-to-four family conforming residential real estate loans while holding adjustable–rate loans. However, United will sell certain adjustable-rate, one-to-four family conforming residential real estate loans based on prevailing interest rate conditions and interest rate risk management needs. Gains and losses on sales of loans held for sale are included in mortgage banking income.
	Allowance for Credit Losses: United maintains an allowance for loan losses and a reserve for lending-related commitments such as unfunded loan commitments and letters of credit. The combined allowance for loan losses and reserve for lending-related commitments are referred to as the allowance for credit losses.
	The allowance for loan losses is management’s estimate of the probable credit losses inherent in the loan portfolio. Management’s evaluation of the adequacy of the allowance for loan losses and the appropriate provision for credit losses is based upon a quarterly evaluation of the portfolio. This evaluation is inherently subjective and requires significant estimates, including the amounts and timing of estimated future cash flows, estimated losses on pools of loans based on historical loss experience, and consideration of current economic trends, all of which are susceptible to constant and significant change. The amounts allocated to specific credits and loan pools grouped by similar risk characteristics are reviewed on a quarterly basis and adjusted as necessary based upon subsequent changes in circumstances. In determining the components of the allowance for credit losses, management considers the risk arising in part from, but not limited to, charge-off and delinquency trends, current economic and business conditions, lending policies and procedures, the size and risk characteristics of the loan portfolio, concentrations of credit, and other various factors. Loans deemed to be uncollectible are charged against the allowance for loan losses, while recoveries of previously charged-off amounts are credited to the allowance for loan losses.
	In determining the adequacy of the allowance for loan losses, management makes allocations to specific commercial loans classified by management as to risk. Management determines the loan’s risk by considering the borrowers’ ability to repay, the collateral securing the credit and other borrower-specific factors that may impact collectibility. For impaired loans, specific allocations are based on the present value of expected future cash flows using the loan’s effective interest rate, or as a practical expedient, at the loan’s observable market price or the fair value of the collateral if the loan is collateral-dependent. Other commercial loans not specifically reviewed on an individual basis are evaluated based on loan pools, which are grouped by similar risk characteristics using management’s internal risk ratings. Allocations for these commercial loan pools are determined based upon historical loss experience adjusted for current environmental conditions and risk factors. Allocations for loans, other than commercial loans, are developed by applying historical loss experience adjusted for current environmental conditions and risk factors to loan pools grouped by similar risk characteristics. The environmental factors considered for each of the loan portfolios includes estimated probable inherent but undetected losses within the portfolio due to uncertainties in economic conditions, delays in obtaining information, including unfavorable information about a borrower’s financial condition, the difficulty in identifying triggering events that correlate perfectly to subsequent loss rates, and risk factors that have not yet fully manifested themselves in loss allocation factors. While allocations are made to specific loans and pools of loans, the allowance is available for all loan losses. In addition, a portion of the allowance accounts for the inherent imprecision in the allowance for credit losses analysis. Management believes that the allowance for credit losses is adequate to provide for probable losses on existing loans and loan-related commitments based on information currently available.
	Bank Premises and Equipment: Bank premises and equipment are stated at cost, less allowances for depreciation and amortization. The provision for depreciation is computed principally by the straight-line method over the estimated useful lives of the respective assets. Useful lives range primarily from three to 15 years for furniture, fixtures and equipment and five to 40 years for buildings and improvements. Leasehold improvements are generally amortized over the lesser of the term of the respective leases or the estimated useful lives of the improvements.
	Other Real Estate Owned: At December 31, 2013 and 2012, other real estate owned (OREO) included in other assets in the Consolidated Balance Sheets was $38,182,000 and $49,484,000, respectively. OREO consists of real estate acquired in foreclosure or other settlement of loans. Such assets are carried at the lower of the investment in the assets or the fair value of the assets less estimated selling costs. Any adjustment to the fair value at the date of transfer is charged against the allowance for loan losses. Any subsequent valuation adjustments as well as any costs relating to operating, holding or disposing of the property are recorded in other expense in the period incurred.
	Advertising Costs: Advertising costs are generally expensed as incurred and included in Other Expense on the Consolidated Statements of Income. Advertising expense was $3,777,000, $4,270,000 and $4,172,000 for the years of 2013, 2012, and 2011, respectively.
	Income Taxes: Income tax expense is the total of the current year income tax due or refundable and the change in deferred tax assets and liabilities (excluding deferred tax assets and liabilities related to business combinations or components of other comprehensive income). Deferred tax assets and liabilities are the expected future tax amounts for the temporary differences between carrying amounts and tax bases of assets and liabilities, computed using enacted tax rates. A valuation allowance, if needed, reduces deferred tax assets to the expected amount most likely to be realized. Realization of deferred tax assets is dependent upon the generation of a sufficient level of future taxable income and recoverable taxes paid in prior years. Although realization is not assured, management believes it is more likely than not that all of the deferred tax assets will be realized. Interest and/or penalties related to income taxes are reported as a component of income tax expense.
	For uncertain income tax positions, United records a liability based on a recognition threshold of more-likely-than-not, and a measurement attribute for all tax positions taken on a tax return, in order for those tax positions to be recognized in the financial statements.
	United files a consolidated income tax return with its subsidiaries. Federal income tax expense or benefit has been allocated to subsidiaries on a separate return basis.
	Intangible Assets: Intangible assets relating to the estimated fair value of the deposit base of the acquired institutions are being amortized on an accelerated basis over a one to seven year period. Management reviews intangible assets on an annual basis, or sooner if indicators of impairment exist, and evaluates changes in facts and circumstances that may indicate impairment in the carrying value. United incurred amortization expense of $1,969,000, $2,852,000 and $2,429,000 in 2013, 2012, and 2011, respectively, related to all intangible assets.
	Goodwill is not amortized, but is tested for impairment at least annually or sooner if indicators of impairment exist. Intangible assets with definite useful lives (such as core deposit intangibles) are amortized over their respective estimated useful lives to their estimated residual values, and reviewed for impairment at least annually. Based on the most recent goodwill impairment test, no impairment was noted. As of December 31, 2013 and 2012, total goodwill approximated $375,547,000 and $375,583,000, respectively.
	Derivative Financial Instruments: United accounts for its derivative financial instruments in accordance with the Derivatives and Hedging topic of the FASB Accounting Standards Codification. The Derivatives and Hedging topic requires all derivative instruments to be carried at fair value on the balance sheet. United has designated certain derivative instruments to manage interest rate risk as hedge relationships with certain assets, liabilities or cash flows being hedged. Certain derivatives used for interest rate risk management are not designated in a hedge relationship.
	Derivative instruments designated in a hedge relationship to mitigate exposure to changes in the fair value of an asset, liability, or firm commitment attributable to a particular risk, such as interest rate risk, are considered fair value hedges. Derivative instruments designated in a hedge relationship to mitigate exposure to variability in expected future cash flows, or other types of forecasted transactions, are considered cash flow hedges.
	For a fair value hedge, the fair value of the interest rate swap is recognized on the balance sheet as either a freestanding asset or liability with a corresponding adjustment to the hedged financial instrument. Subsequent adjustments due to changes in the fair value of a derivative that qualifies as a fair value hedge are offset in current period earnings. For a cash flow hedge, the fair value of the interest rate swap is recognized on the balance sheet as either a freestanding asset or liability with a corresponding adjustment to other comprehensive income within shareholders’ equity, net of tax. Subsequent adjustments due to changes in the fair value of a derivative that qualifies as a cash flow hedge are offset to other comprehensive income, net of tax. The portion of a hedge that is ineffective is recognized immediately in earnings.
	At inception of a hedge relationship, United formally documents the hedged item, the particular risk management objective, the nature of the risk being hedged, the derivative being used, how effectiveness of the hedge will be assessed and how the ineffectiveness of the hedge will be measured. United also assesses hedge effectiveness at inception and on an ongoing basis using regression analysis. Hedge ineffectiveness is measured by using the change in fair value method. The change in fair value method compares the change in the fair value of the hedging derivative to the change in the fair value of the hedged exposure, attributable to changes in the benchmark rate. Prior to January 1, 2006, United used the shortcut method for interest rate swaps that met the criteria as defined under the Derivatives and Hedging topic. Effective January 1, 2006, United adopted an internal policy accounting for all new derivative instruments entered thereafter whereby the shortcut method would no longer be used.
	For derivatives that are not designated in a hedge relationship, changes in the fair value of the derivatives are recognized in earnings in the same period as the change in the fair value.
	Stock-Based Compensation: Compensation expense related to stock options and restricted stock awards issued to participants is based upon the fair value of the award at the date of grant. The fair value of stock options is estimated at the date of grant using a binomial lattice option pricing model, while the fair value of restricted stock awards is based upon the stock price at the date of grant. Compensation expense is recognized on a straight line basis over the vesting period for options and the respective period for stock awards.
	Stock-based compensation expense was $1,786,000 in 2013, $1,908,000 in 2012 and $1,133,000 in 2011.
	Treasury Stock: United records common stock purchased for treasury at cost. At the date of subsequent reissuance, the treasury stock account is reduced by the cost of such stock using the weighted-average cost method.
	Trust Assets and Income: Assets held in a fiduciary or agency capacity for customers are not included in the balance sheets since such items are not assets of the company. Trust income is reported on an accrual basis.
	Earnings Per Common Share: Basic earnings per common share is calculated by dividing net income by the weighted-average number of shares of common stock outstanding, excluding participating securities, for the respective period. For diluted earnings per common share, the weighted-average number of shares of common stock outstanding, excluding participating securities, for the respective period is increased by the number of shares of common stock that would be issued assuming the exercise of common stock options which have an exercise price below market price. The dilutive effect of stock options approximated 72,626 shares in 2013, 32,399 shares in 2012 and 33,931 shares in 2011. There are no other common stock equivalents.
	Under the 2011 LTI Plan, United may award restricted common shares to key employees and non-employee directors. In the first quarter of 2013 and 2012, United granted 52,825 and 52,700 restricted shares, respectively, to participants with a four-year time-based vesting period. Recipients of restricted shares do not pay any consideration to United for the shares, have the right to vote all shares subject to such grant and receive all dividends with respect to such shares, whether or not the shares have vested. Presently, these nonvested participating securities have an immaterial impact on diluted earnings per share.
	The reconciliation of the numerator and denominator of basic earnings per share with that of diluted earnings per share is presented as follows:
		Year Ended December 31
	(Dollars in thousands, except per share)	2013			2012		2011
	Distributed earnings allocated to common stock	$	62,982		$	62,286	$	56,827
	Undistributed earnings allocated to common stock		22,512			20,245		18,783
	Net earnings allocated to common shareholders	$	85,494		$	82,531	$	75,610
	Average common shares outstanding		50,353,452			50,265,620		46,803,432
	Equivalents from stock options		72,626			32,399		33,931
	Average diluted shares outstanding		50,426,078			50,298,019		46,837,363
	Earnings per basic common share	$	1.7		$	1.64	$	1.62
	Earnings per diluted common share	$	1.7		$	1.64	$	1.61
	Fair Value Measurements: United determines the fair values of its financial instruments based on the fair value hierarchy established in ASC topic 820, which also clarifies that fair value of certain assets and liabilities is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants.
	The Fair Value Measurements and Disclosures topic specifies a hierarchy of valuation techniques based on whether the inputs to those valuation techniques are observable or unobservable. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect United’s market assumptions.
	The three levels of the fair value hierarchy based on these two types of inputs are as follows:
	Level 1	-		Valuation is based on quoted prices in active markets for identical assets and liabilities.
	Level 2	-		Valuation is based on observable inputs including quoted prices in active markets for similar assets and liabilities, quoted prices for identical or similar assets and liabilities in less active markets, and model-based valuation techniques for which significant assumptions can be derived primarily from or corroborated by observable data in the market.
	Level 3	-		Valuation is based on model-based techniques that use one or more significant inputs or assumptions that are unobservable in the market.
	When determining the fair value measurements for assets and liabilities, United looks to active and observable markets to price identical assets or liabilities whenever possible and classifies such items in Level 1. When identical assets and liabilities are not traded in active markets, United looks to market observable data for similar assets and liabilities and classifies such items as Level 2. Nevertheless, certain assets and liabilities are not actively traded in observable markets and United must use alternative valuation techniques using unobservable inputs to determine a fair value and classifies such items as Level 3. For assets and liabilities that are not actively traded, the fair value measurement is based primarily upon estimates that require significant judgment. Therefore, the results may not be realized in an actual sale or immediate settlement of the asset or liability. Additionally, there are inherent weaknesses in any calculation technique, and changes in the underlying assumptions used, including discount rates and estimates of future cash flows, could significantly affect the results of current or future values. The level within the fair value hierarchy is based on the lowest level of input that is significant in the fair value measurement.
	Recent Accounting Pronouncements: In February 2013, the FASB issued ASU 2013-02, “Reporting of Amounts Reclassified out of Accumulated Other Comprehensive Income.” ASU 2013-02 is intended to improve the reporting of reclassifications out of accumulated other comprehensive income of various components. ASU 2013-02 requires entities to disclose in a single location, either on the face of financial statement that reports net income or in the notes, the effects of reclassification out of accumulated other comprehensive income (AOCI). For items reclassified out of AOCI and into net income in their entirety, such as realized gains or losses on available-for-sale securities reclassified into net income on sale, entities must disclose the effect of the reclassification on each affected net income item. For AOCI reclassification items that are not reclassified in their entirety into net income, such as actuarial gains or losses amortized into pension cost that may be capitalized into inventory or other assets, entities must provide a cross reference to other required U.S. GAAP disclosures. ASU 2013-02 was effective for United on January 1, 2013 and did not have a significant impact on the Company’s financial condition or results of operation.
	In February 2013, the FASB issued ASU 2013-04, “Obligations Resulting from Joint and Several Liability Arrangements for which the Total Amount of the Obligation is Fixed at the Reporting Date.” ASU 2013-04 addresses the recognition, measurement and disclosure of certain obligations including debt arrangements, other contractual obligations, and settled litigation and judicial ruling. In particular, ASU 2013-04 requires entities to record an obligation resulting from joint and several liability arrangements that are fixed at the reporting date at the greater of the amount that the entity has agreed to pay or the amount the entity expects to pay. The guidance applies retrospectively for obligations that exist at the beginning of an entity’s fiscal year of adoption. ASU 2013-04 is effective for United beginning January 1, 2014 and is not expected to have a significant impact on the Company’s financial condition or results of operation.

Mergers_and_Acquisitions

Mergers and Acquisitions	12 Months Ended
	Dec. 31, 2013
Business Combinations [Abstract]	'
Mergers and Acquisitions	'
	NOTE B—MERGERS AND ACQUISITIONS
	At the close of business on January 31, 2014, United acquired 100% of the outstanding common stock of Virginia Commerce Bancorp, Inc. (Virginia Commerce), a Virginia corporation headquartered in Arlington, Virginia. The results of operations of Virginia Commerce will be included in the consolidated results of operations from the date of acquisition.
	At consummation, Virginia Commerce had assets of approximately $2.77 billion, loans of $2.10 billion and deposits of $2.02 billion. The transaction will be accounted for under the purchase acquisition method of accounting and accordingly, assets acquired, liabilities assumed and consideration exchanged will be recorded at estimated fair value on the acquisition date.
	In accordance of the merger agreement, each outstanding share of common stock of Virginia Commerce, par value $1.00 per share (other than shares held by United or its subsidiaries, in each case except for shares held by them in a fiduciary capacity or in satisfaction of a debt previously contracted) were converted into the right to receive 0.5442 shares of United common stock, par value $2.50 per share, plus cash in lieu of fractional shares. Shares of Virginia Commerce restricted stock that were outstanding immediately prior to the merger converted into the right to receive 0.5442 shares of United common stock, par value $2.50 per share, plus cash in lieu of fractional shares. Almost all of the shares of Virginia Commerce restricted stock fully vested upon the merger under the terms of the restricted stock agreements. Those shares of Virginia Commerce restricted stock that did not fully vest upon the merger were converted into restricted shares of United common stock in accordance with the exchange ratio. Also under the terms of the merger agreement, outstanding Virginia Commerce stock options, whether vested or not, converted into fully vested and exercisable stock options with respect to shares of United’s common stock, with appropriate adjustments to reflect the exchange ratio. As a result of the Merger, United issued approximately 18.3 million shares of its common stock for all of Virginia Commerce’s outstanding common stock and restricted stock, and issued options to purchase approximately 441 thousand shares of its common stock upon conversion of Virginia Commerce’s stock options. United paid approximately $8 thousand in cash to holders of Virginia Commerce common stock and restricted stock in lieu of fractional shares of United common stock. The cash was funded by cash on hand. Effective January 31, 2014, the warrant held by the U.S. Department of the Treasury (the Treasury) issued by Virginia Commerce in connection with the TARP Capital Purchase Program was purchased by United for $33.263 million. The repurchase price was based on the fair market value of the warrant as agreed upon by United and the Treasury. As a result of the repurchase by United, the warrant has been canceled.
	Because the merger occurred on January 31, 2014, the initial accounting for the business combination is incomplete at this time. United is in the process of determining the fair values which are subject to refinement for up to one year after the closing date of the acquisition. United is using an independent third party to help determine the fair values of the acquired assets and liabilities. The resulting goodwill will not be deductible for income tax purposes as the acquisition is accounted for as a tax-free exchange for tax purposes.

Investment_Securities

Investment Securities	12 Months Ended
	Dec. 31, 2013
Investments Debt And Equity Securities [Abstract]	'
Investment Securities	'
	NOTE C—INVESTMENT SECURITIES
	The following is a summary of the amortized cost and estimated fair values of securities available for sale.
			December 31, 2013
	(In thousands)		Amortized		Gross		Gross		Estimated				Cumulative
			Cost		Unrealized		Unrealized		Fair				OTTI in
					Gains		Losses		Value				AOCI (1)
	U.S. Treasury securities and obligations of U.S. Government corporations and agencies		$	172,324	$	178	$	748	$	171,754			$	0
	State and political subdivisions			60,861		1,874		26		62,709				0
	Residential mortgage-backed securities
	Agency			215,788		2,491		1,815		216,464				0
	Non-agency			16,369		163		0		16,532				458
	Commercial mortgage-backed securities
	Agency			241,947		225		8,740		233,432				0
	Asset-backed securities			9,257		1		31		9,227				0
	Trust preferred collateralized debt obligations			73,862		210		30,623		43,449				34,299
	Single issue trust preferred securities			14,346		305		2,019		12,632				0
	Other corporate securities			4,996		219		0		5,215				0
	Marketable equity securities			3,299		572		1		3,870				0
	Total		$	813,049	$	6,238	$	44,003	$	775,284			$	34,757
			December 31, 2012
	(In thousands)		Amortized		Gross		Gross		Estimated				Cumulative
			Cost		Unrealized		Unrealized		Fair				OTTI in
					Gains		Losses		Value				AOCI (1)
	U.S. Treasury securities and obligations of U.S.		$	336,747	$	827	$	52	$	337,522			$	0
	Government corporations and agencies
	State and political subdivisions			76,765		3,664		1		80,428				0
	Residential mortgage-backed securities
	Agency			101,769		4,741		0		106,510				0
	Non-agency			24,569		934		458		25,045				458
	Asset-backed securities			11,729		0		20		11,709				0
	Trust preferred collateralized debt obligations			94,794		5		54,186		40,613				46,522
	Single issue trust preferred securities			15,286		312		3,469		12,129				0
	Other corporate securities			4,996		287		0		5,283				0
	Marketable equity securities			6,660		257		531		6,386				0
	Total		$	673,315	$	11,027	$	58,717	$	625,625			$	46,980
		-1	Other-than-temporary impairment in accumulated other comprehensive income. Amounts are before-tax.
	The following is a summary of securities available for sale which were in an unrealized loss position at December 31, 2013 and 2012.
			Less than 12 months				12 months or longer
	(In thousands)		Fair		Unrealized		Fair		Unrealized
			Value		Losses		Value		Losses
	December 31, 2013
	U.S. Treasury securities and obligations of U.S. Government corporations and agencies		$	61,517	$	748	$	0	$	0
	State and political subdivisions			2,353		26		0		0
	Residential mortgage-backed securities
	Agency			160,835		1,815		0		0
	Commercial mortgage-backed securities
	Agency			208,979		8,740		0		0
	Asset-backed securities			7,976		31		0		0
	Trust preferred collateralized debt obligations			0		0		27,167		30,623
	Single issue trust preferred securities			502		2		8,210		2,017
	Marketable equity securities			0		0		25		1
	Total		$	442,162	$	11,362	$	35,402	$	32,641
	31-Dec-12
	U.S. Treasury securities and obligations of U.S. Government corporations and agencies		$	25,170	$	52	$	0	$	0
	State and political subdivisions			126		1		0		0
	Residential mortgage-backed securities
	Non-agency			0		0		10,879		458
	Asset-backed securities			7,993		20		0		0
	Trust preferred collateralized debt obligations			0		0		40,613		54,186
	Single issue trust preferred securities			0		0		7,221		3,469
	Marketable equity securities			603		507		313		24
	Total		$	33,892	$	580	$	59,026	$	58,137
	Marketable equity securities consist mainly of equity securities of financial institutions and mutual funds within a rabbi trust for the payment of benefits under a deferred compensation plan for certain key officers of United and its subsidiaries. The following table shows the proceeds from maturities, sales and calls of available for sale securities and the gross realized gains and losses on sales and calls of those securities that have been included in earnings as a result of any sales and calls. Gains or losses on sales and calls of available for sale securities were recognized by the specific identification method. The realized losses relate to sales of securities within a rabbi trust for the payment of benefits under a deferred compensation plan for certain key officers and its subsidiaries.
		Year Ended
(In thousands)		2013		2012		2011
Proceeds from maturities, sales and calls		$	698,264	$	1,996,547	$	1,486,936
Gross realized gains			1,259		157		1,729
Gross realized losses			43		141		311
At December 31, 2013, gross unrealized losses on available for sale securities were $44,003,000 on 89 securities of a total portfolio of 281 available for sale securities. Securities in an unrealized loss position at December 31, 2013 consisted primarily of pooled trust preferred collateralized debt obligations (Trup Cdos), single issue trust preferred securities and agency commercial mortgage-backed securities. The Trup Cdos and the single issue trust preferred securities relate mainly to securities of financial institutions. The agency commercial mortgage-backed securities relate to income-producing multifamily properties and provide a guaranty of full and timely payments of principal and interest by Fannie Mae. In determining whether or not a security is other-than-temporarily impaired (OTTI), management considered the severity and the duration of the loss in conjunction with United’s positive intent and the more likely than not ability to hold these securities to recovery of their cost basis or maturity.
Agency mortgage-backed securities
United’s agency mortgage-backed securities portfolio relates to securities issued by Fannie Mae, Freddie Mac, and Ginnie Mae. The total amortized cost of available for sale agency mortgage securities was $457.74 million at December 31, 2013. Of the $457.74 million, $241.95 million was related to agency commercial mortgage securities and $215.79 million was related to agency residential mortgage securities. Each of the agency mortgage securities provides a guarantee of full and timely payments of principal and interest by the issuing agency. Based upon management’s analysis and judgment, it was determined that none of the agency mortgage-backed securities were other-than-temporarily impaired at December 31, 2013.
Non-agency residential mortgage-backed securities
United’s non-agency residential mortgage-backed securities portfolio relates to securities of various private label issuers. The Company has no exposure to real estate investment trusts (REITS) in its investment portfolio. The total amortized cost of available for sale non-agency residential mortgage securities was $16.37 million at December 31, 2013. Of the $16.37 million, $6.31 million was rated above investment grade and $10.06 million was rated below investment grade. Approximately 47% of the portfolio includes collateral that was originated during the year of 2005 or before. The remaining 53% includes collateral that was originated in the years of 2006 and 2007. The entire portfolio of the non-agency residential mortgage securities are either the senior or super-senior tranches of their respective structure. In determining whether or not the non-agency mortgage-backed securities are other-than-temporarily impaired, management performs an in-depth analysis on each non-agency residential mortgage-backed security on a quarterly basis. The analysis includes a review of the following factors: weighted average loan to value, weighted average maturity, average FICO scores, historical collateral performance, geographic concentration, credit subordination, cross-collateralization, coverage ratios, origination year, full documentation percentage, event risk (repricing), and collateral type. Management completes a monthly stress test to determine the level of loss protection remaining in each individual security and compares the protection remaining to the future expected performance of the underlying collateral. Additionally, management utilizes a third-party cash flow model to perform a cash flow test for each bond below investment grade. The model produces a bond specific set of cash flows based upon assumptions input by management. The input assumptions that are incorporated include the projected constant default rate (CDR) of the underlying mortgages, the loss severity upon default, and the prepayment rate on the underlying mortgage collateral. CDR and loss severities are forecasted by management after full evaluation of the underlying collateral including recent performance statistics. Therefore, based upon management’s analysis and judgment, there was no additional credit-related or noncredit-related other-than-temporary impairment recognized on the non-agency residential mortgage-backed securities at December 31, 2013. There was no credit-related or noncredit-related other-than-temporary impairment recognized in earnings for the full year of 2013 on the non-agency residential mortgage-backed securities.
Single issue trust preferred securities
The majority of United’s single-issue trust preferred portfolio consists of obligations from large cap banks (i.e. banks with market capitalization in excess of $10 billion). Management reviews each issuer’s current and projected earnings trends, asset quality, capitalization levels, TARP participation status, and other key factors. Upon completing the review for the fourth quarter of 2013, it was determined that none of the single issue securities were other-than-temporarily impaired. With the exception of two securities, all single-issue trust preferred securities are currently receiving interest payments. The two securities that are deferring interest payments are from the same issuer with a total amortized cost of $632 thousand. The issuer has the contractual ability to defer interest payments for up to 5 years. The available for sale single issue trust preferred securities’ ratings ranged from a low of CCC to a high of BBB. The amortized cost of available for sale single issue trust preferred securities as of December 31, 2013 consisted of $2.98 million in split-rated bonds and $11.23 million in below investment grade bonds. Of the $11.23 million in below investment grade bonds, $10.23 million was in an unrealized loss position for twelve months or longer as of December 31, 2013.
Trust preferred collateralized debt obligations (Trup Cdos)
In analyzing the duration and severity of the losses on Trup Cdos, management considered the following: (1) the market for these securities was not active as evidenced by the lack of trades and the severe widening of the bid/ask spread; (2) the markets for Trup Cdos are dysfunctional with no significant transactions to report; (3) low market prices for certain bonds, in the overall debt markets, were evidence of credit stress in the general markets and not necessarily an indication of credit problems with a particular issuer; and (4) the general widening in overall risk premiums over the past four years in the broader markets was responsible for a significant amount of the price decline in the Trup Cdos portfolio.
In order to determine how and when the Company recognizes OTTI, the Company first assesses its intentions regarding any sale of securities as well as the likelihood that it would be required to sell prior to recovery of the amortized cost. As a result of Section 619 of the Dodd-Frank Wall Street Reform and Consumer Protection Act, commonly known as the Volcker Rule, the Company has determined that, as of December 31, 2013, it is more likely than not that the Company will be required to sell four of its Trup Cdos prior to recovery of the amortized cost. Therefore, the Company is required to mark these four securities to their respective fair values as of December 31, 2013. This resulted in credit-related other-than-temporary impairment of $2.33 million recognized in earnings on these four securities during the fourth quarter of 2013. The Company was also notified by the Trustee of one additional Trup Cdo during the fourth quarter of 2013 that it had been instructed to auction the underlying collateral of the security. With the proceeds from the auction insufficient to cover the amortized cost basis of the security, the Company was required to recognize credit-related other-than-temporary impairment of $4.03 million during the fourth quarter of 2013. Excluding these five Trup Cdos, the Company has determined that it does not intend to sell any other pooled trust preferred security and that it is not more likely than not that the Company will be required to sell such securities before recovery of their amortized cost.
To determine a net realizable value and assess whether other-than-temporary impairment existed on those securities which the Company is not more likely than not required to sell, management performed detailed cash flow analysis to determine whether, in management’s judgment, it was more likely that United would not recover the entire amortized cost basis of the security. The Company discounts the security-specific cash flow projection at the security-specific interest rate and compares the present value to the amortized cost. Management’s cash flow analysis was performed for each security and considered the current deferrals and defaults within the underlying collateral, the likelihood that current deferrals would cure or ultimately default, potential future deferrals and defaults, potential prepayments, cash reserves, excess interest spread, credit analysis of the underlying collateral and the priority of payments in the cash flow structure. The underlying collateral analysis for each issuer took into consideration multiple factors including TARP participation, capital adequacy, earnings trends and asset quality.
After completing its analysis of estimated cash flows, other than the five Trup Cdos mentioned above, management determined that none of the remaining Trup Cdos experienced an adverse change in cash flows during the fourth quarter of 2013, as the expected discounted cash flows from these securities were greater than or equal to the discounted cash flows originally expected at purchase or from the previous date of other-than-temporary impairment (cash flows are discounted at the contractual coupon rate for purposes of assessing OTTI).
The total credit-related other-than-temporary impairment recognized in earnings for the fourth quarter of 2013 related to the Trup Cdos was $6.36 million. The noncredit-related other-than-temporary impairment recognized in accumulated other comprehensive income (loss) in the fourth quarter on these securities resulted in a reduction of $5.22 million, or $3.39 million, net of taxes.
The credit-related other-than-temporary impairment recognized in earnings during 2013 related to these securities was $7.20 million, compared to $5.97 million in 2012. The noncredit-related other-than-temporary impairment recognized in accumulated other comprehensive income (loss) (OCI) during 2013 on these securities, which are not expected to be sold, resulted in a reduction of $12.22 million, or $7.94 million, net of taxes. At December 31, 2013, the balance of the noncredit-related other-than-temporary impairment recognized on United’s Trup Cdo portfolio was $34.30 million as compared to $46.52 million at December 31, 2012.
The amortized cost of available for sale Trup Cdos in an unrealized loss position for twelve months or longer as of December 31, 2013 consisted of $6.58 million in investment grade bonds, $5.00 million in split-rated bonds and $62.28 million in below investment grade bonds.
The following is a summary of the available for sale Trup Cdos and single issue trust preferred securities in an unrealized loss position twelve months or greater as of December 31, 2013.
										Amortized Cost
Class		Amortized		Fair		Unrealized				Investment				Split				Below
		Cost		Value		Loss				Grade				Rated				Investment
																		Grade
		(In thousands)
Senior – Bank		$	8,485	$	6,150	$	2,335			$	0			$	5,000			$	3,485
Senior – Insurance			6,577		6,577		0				6,577				0				0
Mezzanine —Bank (now in senior position)			13,741		8,929		4,812				0				0				13,741
Mezzanine – Bank			34,583		14,501		20,082				0				0				34,583
Mezzanine – Insurance			5,330		5,330		0				0				0				5,330
Mezzanine – Bank & Insurance (combination)			5,146		1,962		3,184				0				0				5,146
Totals		$	73,862	$	43,449	$	30,413			$	6,577			$	5,000			$	62,285
While a large difference remains between the fair value and amortized cost, the Company believes the remaining unrealized losses are related to the illiquid market for Trup Cdos rather than an adverse change in expected cash flows. The expected future cash flow substantiates the return of the remaining amortized cost of the security. The Company believes the following evidence supports the position that the remaining unrealized loss is related to the illiquid market for Trup Cdos:
	•		The market for new issuance of Trup Cdos was robust from 2000 to 2007 with an estimated $60 billion in new issuance. The new market issuances came to an abrupt halt in 2007.
	•		The secondary market for Trup Cdos ultimately became illiquid and is not reflective of orderly transactions between market participants. In making this determination, the Company holds discussions with institutional traders to identify trends in the number and type of transactions related to the Trup Cdos.
	•		The presence of a below-investment grade rating severely limits the pool of available buyers and contributes to the illiquidity of the market.
	•		Trup Cdos have a more complex structure than most debt instruments, making projections of tranche returns difficult for non-specialists in the product. Deferral features available to the underlying issuers within each pool are unique to these securities. Additionally, it can be difficult for market participants to predict whether deferrals will ultimately cure or ultimately default. Due to the lack of transparency, market participants will require a higher risk premium, thus resulting in higher required discount rates.
	•		The variability of cash flows at the time the securities were originated was expected to be very limited. Due to the financial crisis, Trup Cdos have experienced more substantive variability of cash flows compared to expectations, resulting in a higher risk premium when evaluating discount rates.
	•		The limited, yet relevant, observable inputs indicate that market yield requirements for Trup Cdos, on a credit-adjusted basis, remained very high relative to discount rates at purchase and compared to other similarly rated debt securities.
Overall, the Company believes the lack of new issuances, illiquid secondary market, limited pool of buyers, below investment grade ratings, complex structures and high market discount rates are the key drivers of the remaining unrealized losses in the Company’s Trup Cdos and the robust expected cash flow analysis substantiates the return of the remaining amortized cost under ASC 320.
Management also considered the ratings of the Company’s bonds in its portfolio and the extent of downgrades in United’s impairment analysis. However, due to historical discrepancies in ratings from the various rating agencies, management considered it imperative to independently perform its own credit analysis based on cash flows as described. The ratings of the investment grade Trup Cdos in the table above range from a low of BBB to a high of AA+. The ratings of the split-rated Trup Cdos range from a low of B+ to a high of Aa2, while the below investment grade Trup Cdos range from a low of D to a high of Ba1.
The Company has recognized cumulative credit-related other-than-temporary impairment of $43.11 million on certain Trup Cdos since the third quarter of 2009.
On the Trup Cdos that have not been deemed to be other-than-temporarily impaired, the collateralization ratios range from a low of 93.6% to a high of 209.2%, with a median of 133.4%, and a weighted average of 158.97%. The collateralization ratio is defined as the current performing collateral in a security, divided by the current balance of the specific tranche the Company owns, plus any debt which is senior or pari passu with the Company’s security’s priority level. Performing collateral excludes the balance of any issuer that has either defaulted or has deferred its interest payment. It is not uncommon for the collateralization of a security that is not other-than-temporarily impaired to be less than 100% due to the excess spread built into the securitization structure.
Except for the debt securities that have already been deemed to be other-than-temporarily impaired, management does not believe any other individual security with an unrealized loss as of December 31, 2013 is other-than-temporarily impaired. For these securities, United believes the decline in value resulted from changes in market interest rates, credit spreads and liquidity, not a change in the expected contractual cash flows. Based on a review of each of the securities in the investment portfolio, management concluded that it expected to recover the amortized cost basis of the investment in such securities.
Equity securities
The amortized cost of United’s equity securities was $3.30 million at December 31, 2013. For equity securities, management has evaluated the near-term prospects of the investment in relation to the severity and duration of any impairment and based on that evaluation, management determined that no equity securities were other-than-temporarily impaired at December 31, 2013. As of December 31, 2013, United has the ability and intent to hold these equity securities until a recovery of their fair value to at least the cost basis of the investment.
Other investment securities (cost method)
During the fourth quarter of 2013, United also evaluated all of its cost method investments to determine if certain events or changes in circumstances during the fourth quarter of 2013 had a significant adverse effect on the fair value of any of its cost method securities. United determined that there were no events or changes in circumstances during the fourth quarter which would have an adverse effect on the fair value of any of its cost method securities. Therefore, no impairment was recorded.
Below is a progression of the credit losses on securities which United has recorded other-than-temporary charges. These charges were recorded through earnings and other comprehensive income.
(In thousands)
Balance of cumulative credit losses at December 31, 2012		$	63,114
Additions for credit losses on securities for which OTTI was not previously recognized			1,267
Additions for additional credit losses on securities for which OTTI was previously recognized			6,065
Balance of cumulative credit losses at December 31, 2013		$	70,446
The amortized cost and estimated fair value of securities available for sale at December 31, 2013 by contractual maturity are shown below. Expected maturities may differ from contractual maturities because the issuers may have the right to call or prepay obligations without penalties.
Maturities of mortgage-backed securities with an amortized cost of $474,104,000 and an estimated fair value of $466,428,000 at December 31, 2013 are included below based upon contractual maturity.
				Estimated
(In thousands)		Amortized		Fair
		Cost		Value
Due in one year or less		$	28,837	$	28,960
Due after one year through five years			217,415		218,498
Due after five years through ten years			292,460		286,534
Due after ten years			271,038		237,422
Marketable equity securities			3,299		3,870
Total		$	813,049	$	775,284
The following is a summary of the amortized cost and estimated fair values of securities held to maturity.
		December 31, 2013
(In thousands)		Amortized		Gross		Gross		Estimated
		Cost		Unrealized		Unrealized		Fair
				Gains		Losses		Value
U.S. Treasury securities and obligations of U.S. Government corporations and agencies		$	10,762	$	1,689	$	0	$	12,451
State and political subdivisions			10,367		37		299		10,105
Residential mortgage-backed securities
Agency			50		9		0		59
Single issue trust preferred securities			19,766		0		4,108		15,658
Other corporate securities			20		0		0		20
Total		$	40,965	$	1,735	$	4,407	$	38,293
		December 31, 2012
(In thousands)		Amortized		Gross		Gross		Estimated
		Cost		Unrealized		Unrealized		Fair
				Gains		Losses		Value
U.S. Treasury securities and obligations of U.S. Government corporations and agencies		$	10,916	$	2,500	$	0	$	13,416
State and political subdivisions			12,515		108		0		12,623
Residential mortgage-backed securities
Agency			61		10		0		71
Single issue trust preferred securities			19,750		0		3,390		16,360
Other corporate securities			225		0		0		225
Total		$	43,467	$	2,618	$	3,390	$	42,695
Even though the market value of the held-to-maturity investment portfolio is less than its cost, the unrealized loss has no impact on the net worth or regulatory capital requirements of United. As of December 31, 2013, the Company’s two largest held-to-maturity single-issue trust preferred exposures were to Wells Fargo ($9.90 million) and SunTrust Bank ($7.39 million). The two held-to-maturity single-issue trust preferred exposures with at least one rating below investment grade included SunTrust Bank ($7.39 million) and Royal Bank of Scotland ($972 thousand). Other corporate securities consist mainly of bonds of corporations.
The following table shows the gross realized gains and losses on calls and sales of held to maturity securities that have been included in earnings as a result of those calls and sales. Gains or losses on calls of held to maturity securities are recognized by the specific identification method.
		Year Ended
(In thousands)		2013		2012		2011
Gross realized gains		$	114	$	352	$	1
Gross realized losses			0		0		0
The amortized cost and estimated fair value of debt securities held to maturity at December 31, 2013 by contractual maturity are shown below. Expected maturities may differ from contractual maturities because the issuers may have the right to call or prepay obligations with or without call or prepayment penalties.
Maturities of mortgage-backed securities with an amortized cost of $50,000 and an estimated fair value of $59,000 at December 31, 2013 are included below based upon contractual maturity.
				Estimated
(In thousands)		Amortized		Fair
		Cost		Value
Due in one year or less		$	555	$	556
Due after one year through five years			6,683		7,312
Due after five years through ten years			13,026		13,821
Due after ten years			20,701		16,604
Total		$	40,965	$	38,293
The carrying value of securities pledged to secure public deposits, securities sold under agreements to repurchase, and for other purposes as required or permitted by law, approximated $640,870,000 and $569,680,000 at December 31, 2013 and 2012, respectively.
The fair value of mortgage-backed securities is affected by changes in interest rates and prepayment speeds. When interest rates decline, prepayment speeds generally accelerate due to homeowners refinancing their mortgages at lower interest rates. This may result in the proceeds being reinvested at lower interest rates. Rising interest rates may decrease the assumed prepayment speed. Slower prepayment speeds may extend the maturity of the security beyond its estimated maturity. Therefore, investors may not be able to invest at current higher market rates due to the extended expected maturity of the security. United had a net unrealized loss of $7,667,000 at December 31, 2013 and a net unrealized gain of $5,227,000 at December 31, 2012 on all mortgage-backed securities.
The following table sets forth the maturities of all securities (based on amortized cost) at December 31, 2013, and the weighted-average yields of such securities (calculated on the basis of the cost and the effective yields weighted for the scheduled maturity of each security).
(Dollars in thousands)		Within 1 Year				After 1 But						After 5 But								After 10 Years
						Within 5 Years						Within 10 Years
		Amount		Yield		Amount		Yield				Amount				Yield				Amount		Yield
U.S. Treasury and other U.S. Government agencies and corporations		$	14,998		0.26%	$	117,261		1.06%			$	50,826				1.12%			$	0		0.00%
States and political subdivisions (1)			14,383		4.07%		28,895		5.66%				24,037				6.38%				3,912		6.78%
Residential mortgage-backed securities
Agency			12		6.00%		7,130		3.56%				45,918				3.73%				162,778		2.34%
Non-agency			0		0.00%		443		4.58%				6,872				5.02%				9,054		5.82%
Commercial mortgage-backed
Agency			0		0.00%		54,449		1.19%				179,499				2.21%				7,999		2.75%
Asset-backed securities			0		0.00%		8,008		0.69%				1,249				0.35%				0		0.00%
Trust preferred collateralized debt obligations			0		0.00%		0		0.00%				0				0.00%				73,862		4.58%
Single issue trust preferred securities			0		0.00%		0		0.00%				0				0.00%				34,112		2.40%
Marketable equity securities			0		0.00%		0		0.00%				0				0.00%				3,299		2.47%
Other Corporate securities			0		0.00%		4,996		2.73%				0				0.00%				20		0.00%
	-1	Tax-equivalent adjustments (using a 35% federal rate) have been made in calculating yields on obligations of states and political subdivisions.
There are no securities with a single issuer, other than the U.S. government and its agencies and corporations, the book value of which in the aggregate exceeds 10% of United’s total shareholders’ equity.

Loans

Loans	12 Months Ended
	Dec. 31, 2013
Receivables [Abstract]	'
Loans	'
	NOTE D—LOANS
	Major classes of loans are as follows:
		December 31
	(In thousands)	2013			2012
	Commercial, financial, and agricultural
	Owner-occupied	$	654,963		$	728,906
	Nonowner-occupied		1,917,785			1,740,420
	Other commercial		1,338,355			1,377,083
	Total commercial, financial & agricultural		3,911,103			3,846,409
	Residential real estate		1,821,378			1,838,252
	Construction & land development		670,364			550,677
	Consumer:
	Bankcard		11,023			11,236
	Other Consumer		299,731			271,206
	Less: Unearned interest		(9,016	)		(6,364	)
	Total Loans, net of unearned interest	$	6,704,583		$	6,511,416
	The table above does not include loans held for sale of $4,236,000 and $17,762,000 at December 31, 2013 and December 31, 2012, respectively. Loans held for sale consist of single-family residential real estate loans originated for sale in the secondary market.
	The outstanding balances in the table above include acquired impaired loans with a recorded investment of $31,099,000 and $33,206,000, or less than 1% of total gross loans, at December 31, 2013 and 2012, respectively. The contractual principal in these acquired impaired loans was $52,237,000 and $55,685,000 at December 31, 2013 and 2012, respectively. The balances above do not include future accretable net interest (i.e. the difference between the undiscounted expected cash flows and the recorded investment in the loan) on the acquired impaired loans.
	Activity for the accretable yield for the year of 2013 follows.
	(In thousands)
	Accretable yield at the beginning of the period	$	2,331
	Accretion (including cash recoveries)		(3,192	)
	Net reclassifications to accretable from non-accretable		3,373
	Disposals (including maturities, foreclosures, and charge-offs)		(261	)
	Accretable yield at the ending of the period	$	2,251
	At December 31, 2013 and 2012, loans-in-process of $43,158,000 and $68,255,000 and overdrafts from deposit accounts of $4,344,000 and $11,231,000, respectively, are included within the appropriate loan classifications above.
	United’s subsidiary banks have made loans, in the normal course of business, to the directors and officers of United and its subsidiaries, and to their associates. Such related party loans were made on substantially the same terms, including interest rates and collateral, as those prevailing at the time for comparable transactions with unrelated persons and did not involve more than normal risk of collectibility. The aggregate dollar amount of these loans was $150,798,000 and $150,638,000 at December 31, 2013 and 2012, respectively. During 2013, $208,970,000 of new loans were made and repayments totaled $208,810,000.

Credit_Quality

Credit Quality	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
Credit Quality	'
	NOTE E—CREDIT QUALITY
	Management monitors the credit quality of its loans on an ongoing basis. Measurement of delinquency and past due status are based on the contractual terms of each loan.
	For all loan classes, past due loans are reviewed on a monthly basis to identify loans for nonaccrual status. Generally, when collection in full of the principal and interest is jeopardized, the loan is placed on nonaccrual status. The accrual of interest income on commercial and most consumer loans generally is discontinued when a loan becomes 90 to 120 days past due as to principal or interest. However, regardless of delinquency status, if a loan is fully secured and in the process of collection and resolution of collection is expected in the near term (generally less than 90 days), then the loan will not be placed on nonaccrual status. When interest accruals are discontinued, unpaid interest recognized in income in the current year is reversed, and unpaid interest accrued in prior years is charged to the allowance for loan losses. United’s method of income recognition for loans that are classified as nonaccrual is to recognize interest income on a cash basis or apply the cash receipt to principal when the ultimate collectibility of principal is in doubt. Nonaccrual loans will not normally be returned to accrual status unless all past due principal and interest has been paid and the borrower has evidenced their ability to meet the contractual provisions of the note.
	A loan is categorized as a troubled debt restructuring (TDR) if a concession is granted and there is deterioration in the financial condition of the borrower. TDRs can take the form of a reduction of the stated interest rate, splitting a loan into separate loans with market terms on one loan and concessionary terms on the other loan, receipts of assets from a debtor in partial or full satisfaction of a loan, the extension of the maturity date or dates at a stated interest rate lower than the current market rate for new debt with similar risk, the reduction of the face amount or maturity amount of the debt as stated in the instrument or other agreement, the reduction of accrued interest or any other concessionary type of renegotiated debt. As of December 31, 2013, United had TDRs of $8,157,000 as compared to $3,175,000 as of December 31, 2012. Of the $8,157,000 aggregate balance of TDRs at December 31, 2013, $861,000 was on nonaccrual status and included in the “Loans on Nonaccrual Status” on the following page. Of the $3,175,000 aggregate balance of TDRs at December 31, 2012, $375,000 was on nonaccrual status and included in the “Loans on Nonaccrual Status” on the following page. As of December 31, 2013, there were no commitments to lend additional funds to debtors owing receivables whose terms have been modified in TDRs. At December 31, 2013, United had restructured loans in the amount of $4,267,000 that were modified by a reduction in the interest rate, $2,954,000 that were modified by a combination of a reduction in the interest rate and the principal and $936,000 that was modified by a change in terms.
	A loan acquired and accounted for under ASC topic 310-30 “Loans and Debt Securities Acquired with Deteriorated Credit Quality” is reported as an accruing loan and a performing asset.
	The following table sets forth United’s troubled debt restructurings that have been restructured during the year ended December 31, 2013 and 2012, segregated by class of loans:
	Troubled Debt Restructurings
	For the Year Ended December 31, 2013
	(In thousands)	Number of		Pre-Modification		Post-Modification
		Contracts		Outstanding		Outstanding
				Recorded Investment		Recorded  Investment
	Commercial real estate:
	Owner-occupied		4	$	5,143	$	4,561
	Nonowner-occupied		2		762		757
	Other commercial		0		0		0
	Residential real estate		1		105		104
	Construction & land development		0		0		0
	Consumer:
	Bankcard		0		0		0
	Other consumer		0		0		0
	Total		7	$	6,010	$	5,422
	Troubled Debt Restructurings
	For the Year Ended December 31, 2012
	(In thousands)	Number of		Pre-Modification		Post-Modification
		Contracts		Outstanding		Outstanding
				Recorded Investment		Recorded Investment
	Commercial real estate:
	Owner-occupied		0	$	0	$	0
	Nonowner-occupied		0		0		0
	Other commercial		0		0		0
	Residential real estate		1		640		651
	Construction & land development		1		731		375
	Consumer:
	Bankcard		0		0		0
	Other consumer		0		0		0
	Total		2	$	1,371	$	1,026
	During 2013, restructured loans of $2,954,000 were modified by a combination of a reduction in the interest rate and a change in terms. The remaining $2,166,000 and $302,000 of loans restructured during 2013 was modified by a reduction in the interest rate and a change in terms, respectively. During 2012, $375,000 of restructured loans was modified by a combination of a reduction in the interest rate and change in terms and the remaining $651,000 of restructured loans was modified by a change in terms. In some instances, the post-modification balance on a restructured loan is larger than the pre-modification balance due to the advancement of monies for items such as delinquent taxes on real estate property. The loans were evaluated individually for allocation within United’s allowance for loan losses. The modifications had an immaterial impact on the financial condition and results of operations for United.
	The following table presents troubled debt restructurings, by class of loan, that had charge-offs during the years ended December 31, 2013 and 2012. These loans were restructured during the last twelve months and subsequently defaulted, resulting in a principal charge-off during the respective time periods. Loans modified in a troubled debt restructuring that defaulted with a recorded investment of zero were fully paid down through the sale of foreclosed real estate property prior to period end.
		Year Ended				Year Ended
		December 31, 2013				December 31, 2012
	(In thousands)	Number of		Recorded		Number of		Recorded
		Contracts		Investment		Contracts		Investment
	Troubled Debt Restructurings
	Commercial real estate:		0	$	0		0	$	0
	Owner-occupied		0		0		0		0
	Nonowner-occupied		0		0		0		0
	Other commercial		0		0		0		0
	Residential real estate		0		0		0		0
	Construction & land development		1		375		1		375
	Consumer:		0		0		0		0
	Bankcard		0		0		0		0
	Other consumer		0		0		0		0
	Total		1	$	375		1	$	375
	The following table sets forth United’s age analysis of its past due loans, segregated by class of loans:
	Age Analysis of Past Due Loans
	As of December 31, 2013
	(In thousands)	30-89		90 Days		Total Past		Current		Total		Recorded
		Days Past		or more		Due				Financing		Investment
		Due		Past Due						Receivables		>90 Days
												& Accruing
	Commercial real estate:
	Owner-occupied	$	14,144	$	4,537	$	18,681	$	636,282	$	654,963	$	1,383
	Nonowner-occupied		30,836		11,725		42,561		1,875,224		1,917,785		186
Other commercial		54,319		11,794		66,113		1,272,242		1,338,355		896
Residential real estate		54,271		25,446		79,717		1,741,661		1,821,378		5,214
Construction & land development		9,921		18,491		28,412		641,952		670,364		1,611
Consumer:
Bankcard		229		128		357		10,666		11,023		128
Other consumer		9,466		1,712		11,178		288,553		299,731		1,626
Total	$	173,186	$	73,833	$	247,019	$	6,466,580	$	6,713,599	$	11,044
Age Analysis of Past Due Loans
As of December 31, 2012
(In thousands)	30-89		90 Days		Total Past		Current		Total		Recorded
	Days Past		or more		Due				Financing		Investment
	Due		Past Due						Receivables		>90 Days
											& Accruing
Commercial real estate:
Owner-occupied	$	11,122	$	16,691	$	27,813	$	701,093	$	728,906	$	4,038
Nonowner-occupied		12,793		11,643		24,436		1,715,984		1,740,420		2,549
Other commercial		8,379		20,808		29,187		1,347,896		1,377,083		1,687
Residential real estate		54,168		22,095		76,263		1,761,989		1,838,252		7,363
Construction & land development		14,046		16,918		30,964		519,713		550,677		654
Consumer:
Bankcard		394		164		558		10,678		11,236		164
Other consumer		8,738		1,683		10,421		260,785		271,206		1,613
Total	$	109,640	$	90,002	$	199,642	$	6,318,138	$	6,517,780	$	18,068
The following table sets forth United’s nonaccrual loans, segregated by class of loans:
Loans on Nonaccrual Status
(In thousands)	December 31,		December 31,
	2013		2012
Commercial real estate:
Owner-occupied	$	3,154	$	12,653
Nonowner-occupied		11,539		9,094
Other commercial		10,898		19,121
Residential real estate		20,232		14,732
Construction & land development		16,880		16,264
Consumer:
Bankcard		0		0
Other consumer		86		70
Total	$	62,789	$	71,934
United assigns credit quality indicators of pass, special mention, substandard and doubtful to its loans. For United’s loans with a corporate credit exposure, United internally assigns a grade based on the creditworthiness of the borrower. For loans with a consumer credit exposure, United internally assigns a grade based upon an individual loan’s delinquency status. United reviews and updates, as necessary, these grades on a quarterly basis.
Special mention loans, with a corporate credit exposure, have potential weaknesses that deserve management’s close attention. If left uncorrected, these potential weaknesses may result in deterioration of the repayment prospects for the loans or in the Company’s credit position at some future date. Borrowers may be experiencing adverse operating trends (declining revenues or margins) or an ill proportioned balance sheet (e.g., increasing inventory without an increase in sales, high leverage, tight liquidity). Adverse economic or market conditions, such as interest rate increases or the entry of a new competitor, may also support a special mention rating. Nonfinancial reasons for rating a credit exposure special mention include management problems, pending litigation, an ineffective loan agreement or other material structural weakness, and any other significant deviation from prudent lending practices. For loans with a consumer credit exposure, loans that are past due 30-89 days are considered special mention.
A substandard loan with a corporate credit exposure is inadequately protected by the current sound worth and paying capacity of the obligor or of the collateral pledged, if any. Loans so classified have a well-defined weakness, or weaknesses, that jeopardize the liquidation of the debt by the borrower. They are characterized by the distinct possibility that the Company will sustain some loss if the deficiencies are not corrected. They require more intensive supervision by management. Substandard loans are generally characterized by current or expected unprofitable operations, inadequate debt service coverage, inadequate liquidity, or marginal capitalization. Repayment may depend on collateral or other credit risk mitigants. For some substandard loans, the likelihood of full collection of interest and principal may be in doubt and thus, placed on nonaccrual. For loans with a consumer credit exposure, loans that are 90 days or more past due or that have been placed on nonaccrual are considered substandard.
A loan with corporate credit exposure is classified as doubtful if it has all the weaknesses inherent in one classified as substandard with the added characteristic that the weaknesses make collection in full, on the basis of currently existing facts, conditions, and values, highly questionable and improbable. A doubtful loan has a high probability of total or substantial loss, but because of specific pending events that may strengthen the loan, its classification as loss is deferred. Doubtful borrowers are usually in default, lack adequate liquidity or capital, and lack the resources necessary to remain an operating entity. Pending events can include mergers, acquisitions, liquidations, capital injections, the perfection of liens on additional collateral, the valuation of collateral, and refinancing. Generally, there are not any loans with a consumer credit exposure that are classified as doubtful. Usually, they are charged-off prior to such a classification. Loans classified as doubtful are also considered impaired.
The following tables set forth United’s credit quality indicators information, by class of loans:
Credit Quality Indicators
Corporate Credit Exposure
As of December 31, 2013
	Commercial Real Estate
(In thousands)	Owner-		Nonowner-		Other		Construction
	occupied		occupied		Commercial		& Land
							Development
Grade:
Pass	$	604,129	$	1,811,915	$	1,206,030	$	510,911
Special mention		27,576		45,617		60,668		63,375
Substandard		23,258		60,253		71,148		96,078
Doubtful		0		0		509		0
Total	$	654,963	$	1,917,785	$	1,338,355	$	670,364
Credit Quality Indicators
Corporate Credit Exposure
As of December 31, 2012
	Commercial Real Estate
(In thousands)	Owner-		Nonowner-		Other		Construction
	occupied		occupied		Commercial		& Land
							Development
Grade:
Pass	$	669,157	$	1,621,338	$	1,286,471	$	392,096
Special mention		25,487		54,399		31,293		92,667
Substandard		34,262		64,683		57,386		65,914
Doubtful		0		0		1,933		0
Total	$	728,906	$	1,740,420	$	1,377,083	$	550,677
Credit Quality Indicators
Consumer Credit Exposure
As of December 31, 2013
(In thousands)	Residential		Bankcard		Other
	Real Estate				Consumer
Grade:
Pass	$	1,773,244	$	10,666	$	288,401
Special mention		13,006		229		9,466
Substandard		35,128		128		1,712
Doubtful		0		0		152
Total	$	1,821,378	$	11,023	$	299,731
As of December 31, 2012
(In thousands)	Residential		Bankcard		Other
	Real Estate				Consumer
Grade:
Pass	$	1,800,377	$	10,678	$	271,054
Special mention		7,866		394		0
Substandard		30,009		164		152
Doubtful		0		0		0
Total	$	1,838,252	$	11,236	$	271,206
Loans are designated as impaired when, in the opinion of management, based on current information and events, the collection of principal and interest in accordance with the loan contract is doubtful. Typically, United does not consider loans for impairment unless a sustained period of delinquency (i.e. 90-plus days) is noted or there are subsequent events that impact repayment probability (i.e. negative financial trends, bankruptcy filings, eminent foreclosure proceedings, etc.). Impairment is evaluated in total for smaller-balance loans of a similar nature and on an individual loan basis for other loans. Consistent with United’s existing method of income recognition for loans, interest on impaired loans, except those classified as nonaccrual, is recognized as income using the accrual method. Impaired loans, or portions thereof, are charged off when deemed uncollectible.
The following table set forth United’s impaired loans information, by class of loans:
	Impaired Loans
	December 31, 2013						December 31, 2012
(In thousands)	Recorded		Unpaid		Related		Recorded		Unpaid		Related
	Investment		Principal		Allowance		Investment		Principal		Allowance
			Balance						Balance
With no related allowance recorded:
Commercial real estate:
Owner-occupied	$	4,672	$	4,672	$	0	$	15,591	$	16,279	$	0
Nonowner-occupied		5,938		6,651		0		10,907		14,601		0
Other commercial		10,292		17,753		0		3,036		5,501		0
Residential real estate		12,009		12,193		0		7,035		9,157		0
Construction & land development		13,866		14,662		0		7,682		10,089		0
Consumer:
Bankcard		0		0		0		0		0		0
Other consumer		0		0		0		152		152		0
With an allowance recorded:
Commercial real estate:
Owner-occupied	$	4,358	$	4,358	$	638	$	1,284	$	1,284	$	397
Nonowner-occupied		9,350		10,563		1,631		3,423		4,423		1,154
Other commercial		13,304		16,240		2,192		27,610		30,411		7,564
Residential real estate		7,669		8,191		4,112		5,635		7,028		1,427
Construction & land development		11,050		14,833		3,752		13,033		17,029		3,659
Consumer:
Bankcard		0		0		0		0		0		0
Other consumer		152		152		152		0		0		0
Total:
Commercial real estate:
Owner-occupied	$	9,030	$	9,030	$	638	$	16,875	$	17,563	$	397
Nonowner-occupied		15,288		17,214		1,631		14,330		19,024		1,154
Other commercial		23,596		33,993		2,192		30,646		35,912		7,564
Residential real estate		19,678		20,384		4,112		12,670		16,185		1,427
Construction & land development		24,916		29,495		3,752		20,715		27,118		3,659
Consumer:
Bankcard		0		0		0		0		0		0
Other consumer		152		152		152		152		152		0
	Impaired Loans
	For the Year Ended
	December 31, 2013				December 31, 2012
(In thousands)	Average		Interest		Average		Interest
	Recorded		Income		Recorded		Income
	Investment		Recognized		Investment		Recognized
With no related allowance recorded:
Commercial real estate:
Owner-occupied	$	11,379	$	242	$	12,160	$	770
Nonowner-occupied		10,168		194		23,393		431
Other commercial		11,550		1,828		5,208		178
Residential real estate		9,211		358		10,982		418
Construction & land development		9,305		373		18,104		285
Consumer:
Bankcard		0		0		0		0
Other consumer		114		0		165		0
With an allowance recorded:
Commercial real estate:
Owner-occupied	$	2,543	$	159	$	1,151	$	51
Nonowner-occupied		6,352		289		3,477		67
Other commercial		16,129		286		26,240		1,969
Residential real estate		6,009		283		8,989		380
Construction & land development		13,393		58		12,904		322
Consumer:
Bankcard		0		0		0		0
Other consumer		38		0		0		0
Total:
Commercial real estate:
Owner-occupied	$	13,922	$	401	$	13,311	$	821
Nonowner-occupied		16,520		483		26,870		498
Other commercial		27,679		2,114		31,448		2,147
Residential real estate		15,220		641		19,971		798
Construction & land development		22,698		431		31,008		607
Consumer:
Bankcard		0		0		0		0
Other consumer		152		0		165		0

Allowance_for_Credit_Losses

Allowance for Credit Losses	12 Months Ended
	Dec. 31, 2013
Receivables [Abstract]	'
Allowance for Credit Losses	'
	NOTE F—ALLOWANCE FOR CREDIT LOSSES
	The allowance for loan losses is management’s estimate of the probable credit losses inherent in the loan portfolio. For purposes of determining the general allowance, the loan portfolio is segregated by product type to recognize differing risk profiles among categories. It is further segregated by credit grade for risk-rated loan pools and delinquency for homogeneous loan pools. The outstanding principal balance within each pool is multiplied by historical loss data and certain qualitative factors to derive the general loss allocation per pool. Specific loss allocations are calculated for loans in excess of $500 thousand in accordance with ASC topic 310. Risk characteristics of owner-occupied commercial real estate loans and other commercial loans are similar in that they are normally dependent upon the borrower’s internal cash flow from operations to service debt. Nonowner-occupied commercial real estate loans differ in that cash flow to service debt is normally dependent on external income from third parties for use of the real estate such as rents, leases and room rates. Residential real estate loans are dependent upon individual borrowers who are affected by changes in general economic conditions, demand for housing and resulting residential real estate valuation. Construction and land development loans are impacted mainly by demand whether for new residential housing or for retail, industrial, office and other types of commercial construction within a given area. Consumer loan pool risk characteristics are influenced by general, regional and local economic conditions. During the year of 2013, there were no material changes to the accounting policy or methodology related to the allowance for loan losses.
	Loans deemed to be uncollectible are charged against the allowance for loan losses, while recoveries of previously charged-off amounts are credited to the allowance for loan losses. For commercial loans, when a loan or a portion of a loan is identified to contain a loss, a charge-off recommendation is directed to management to charge-off all or a portion of that loan. Generally, any unsecured commercial loan more than six months delinquent in payment of interest must be charged-off in full. If secured, the charge-off is generally made to reduce the loan balance to a level equal to the liquidation value of the collateral when payment of principal and interest is six months delinquent. Any commercial loan, secured or unsecured, on which a principal or interest payment has not been made within 90 days, is reviewed monthly for appropriate action.
	For consumer loans, closed-end retail loans that are past due 120 cumulative days delinquent from the contractual due date and open-end loans 180 cumulative days delinquent from the contractual due date are charged-off. Any consumer loan on which a principal or interest payment has not been made within 90 days is reviewed monthly for appropriate action. For a one-to-four family open-end or closed-end residential real estate loan, home equity loan, or high-loan-to-value loan that has reached 180 or more days past due, management evaluates the collateral position and charge-offs any amount that exceeds the value of the collateral. On retail credits for which the borrower is in bankruptcy, all amounts deemed unrecoverable are charged off within 60 days of the receipt of the notification. On retail credits effected by fraud, a loan is charged-off within 90 days of the discovery of the fraud. In the event of the borrower’s death and if repayment within the required timeframe is uncertain, the loan is generally charged-off as soon as the amount of the loss is determined.
	United maintains an allowance for loan losses and a reserve for lending-related commitments such as unfunded loan commitments and letters of credit. The reserve for lending-related commitments of $2,143,000 and $1,656,000 at December 31, 2013 and December 31, 2012, respectively, is separately classified on the balance sheet and is included in other liabilities. The combined allowance for loan losses and reserve for lending-related commitments are referred to as the allowance for credit losses.
	A progression of the allowance for credit losses, which includes the allowance for credit losses and the reserve for lending-related commitments, for the periods presented is summarized as follows:
		Year Ended December 31
	(In thousands)	2013		2012			2011
	Balance at beginning of period	$	75,557	$	75,727		$	75,039
	Provision for credit losses		19,754		17,665			16,988
			95,311		93,392			92,027
	Loans charged off		21,006		20,555			19,605
	Less recoveries		2,036		2,720			3,305
	Net charge-offs		18,970		17,835			16,300
	Balance at end of period	$	76,341	$	75,557		$	75,727
	A progression of the allowance for loan losses, by portfolio segment, for the year ended December 31, 2013 and 2012 is summarized as follows:
	Allowance for Loan Losses and Carrying Amount of Loans
	For the Year Ended December 31, 2013
	(In thousands)	Commercial Real Estate					Other		Residential		Construction		Consumer		Allowance			Total
							Commercial		Real Estate		& Land				for
											Development				Estimated
		Owner-		Nonowner-											Imprecision
		occupied		occupied
	Allowance for Loan Losses:
	Beginning balance	$	3,877	$	12,876		$	20,511	$	14,895	$	18,858	$	2,620	$	264		$	73,901
	Charge-offs		5,344		1,164			7,699		4,111		896		1,792		0			21,006
	Recoveries		150		56			641		698		73		418		0			2,036
	Provision		6,970		(2,776	)		7,464		5,212		918		1,699		(220	)		19,267
	Ending balance	$	5,653	$	8,992		$	20,917	$	16,694	$	18,953	$	2,945	$	44		$	74,198
	Ending Balance: individually evaluated for impairment	$	638	$	1,631		$	2,192	$	4,112	$	3,752	$	152	$	0		$	12,477
	Ending Balance: collectively evaluated for impairment	$	5,015	$	7,361		$	18,725	$	12,582	$	15,201	$	2,793	$	44		$	61,721
	Ending Balance: loans acquired with deteriorated credit quality	$	0	$	0		$	0	$	0	$	0	$	0	$	0		$	0
	Financing receivables:
	Ending balance	$	654,963	$	1,917,785		$	1,338,355	$	1,821,378	$	670,364	$	310,754	$	0		$	6,713,599
	Ending Balance: individually evaluated for impairment	$	7,157	$	13,913		$	22,327	$	16,160	$	21,593	$	152	$	0		$	81,302
	Ending Balance: collectively evaluated for impairment	$	646,548	$	1,894,421		$	1,314,543	$	1,802,686	$	632,407	$	310,593	$	0		$	6,601,198
	Ending Balance: loans acquired with deteriorated credit quality	$	1,258	$	9,451		$	1,485	$	2,532	$	16,364	$	9	$	0		$	31,099
	Allowance for Loan Losses and Carrying Amount of Loans
	For the Year Ended December 31, 2012
	(In thousands)	Commercial Real Estate					Other		Residential		Construction		Consumer		Allowance			Total
							Commercial		Real Estate		& Land				for
											Development				Estimated
		Owner-		Nonowner-											Imprecision
		occupied		occupied
	Allowance for Loan Losses:
	Beginning balance	$	3,670	$	11,647		$	20,803	$	13,880	$	19,151	$	2,151	$	2,572		$	73,874
	Charge-offs		801		2,608			3,619		8,882		3,099		1,546		0			20,555
	Recoveries		60		122			1,362		821		54		301		0			2,720
	Provision		948		3,715			1,965		9,076		2,752		1,714		(2,308	)		17,862
	Ending balance	$	3,877	$	12,876		$	20,511	$	14,895	$	18,858	$	2,620	$	264		$	73,901
	Ending Balance: individually evaluated for impairment	$	417	$	1,154		$	7,564	$	996	$	3,659	$	0	$	0		$	13,790
	Ending Balance: collectively evaluated for impairment	$	3,460	$	11,722		$	12,947	$	13,899	$	15,199	$	2,620	$	264		$	60,111
	Ending Balance: loans acquired with deteriorated credit quality	$	0	$	0		$	0	$	0	$	0	$	0	$	0		$	0
	Financing receivables:
	Ending balance	$	728,906	$	1,740,420		$	1,377,083	$	1,838,252	$	550,677	$	282,442	$	0		$	6,517,780
	Ending Balance: individually evaluated for impairment	$	14,474	$	12,101		$	28,997	$	8,541	$	17,827	$	0	$	0		$	81,940
	Ending Balance: collectively evaluated for impairment	$	712,776	$	1,718,913		$	1,346,600	$	1,826,196	$	515,718	$	282,431	$	0		$	6,402,634
	Ending Balance: loans acquired with deteriorated credit quality	$	1,656	$	9,406		$	1,486	$	3,515	$	17,132	$	11	$	0		$	33,206

Bank_Premises_and_Equipment_an

Bank Premises and Equipment and Leases	12 Months Ended
	Dec. 31, 2013
Property Plant And Equipment [Abstract]	'
Bank Premises and Equipment and Leases	'
	NOTE G—BANK PREMISES AND EQUIPMENT AND LEASES
	Bank premises and equipment are summarized as follows:
		December 31
	(In thousands)	2013		2012
	Land	$	23,018	$	23,166
	Buildings and improvements		83,144		80,997
	Leasehold improvements		22,092		20,906
	Furniture, fixtures and equipment		49,697		46,843
			177,951		171,912
	Less allowance for depreciation and amortization		108,054		99,742
	Net bank premises and equipment	$	69,897	$	72,170
	Depreciation expense was $7,912,000, $7,790,000, and $6,966,000 for years ending December 31, 2013, 2012 and 2011, respectively, while amortization expense was $103,000 in each of these respective periods.
	United and certain banking subsidiaries have entered into various noncancelable-operating leases. These noncancelable operating leases are subject to renewal options under various terms and some leases provide for periodic rate adjustments based on cost-of-living index changes. Rent expense for noncancelable operating leases approximated $8,969,000, $9,427,000 and $8,740,000 for the years ended December 31, 2013, 2012 and 2011, respectively. United Bank (WV) leases three of its offices from companies that are beneficially owned by two former United directors. Rent expense incurred on these facilities was $999,000, $1,755,000, and $1,044,000 for the years ended December 31, 2013, 2012, and 2011, respectively.
	Future minimum lease payments, by year and in the aggregate, under noncancelable operating leases with initial or remaining terms of one year or more, for years subsequent to December 31, 2013, consisted of the following:
	Year	Amount
	(In thousands)
	2014	$	8,181
	2015		6,903
	2016		6,030
	2017		5,606
	2018		5,644
	Thereafter		11,292
	Total minimum lease payments	$	43,656

Goodwill_and_Other_Intangibles

Goodwill and Other Intangibles	12 Months Ended
	Dec. 31, 2013
Goodwill And Intangible Assets Disclosure [Abstract]	'
Goodwill and Other Intangibles	'
	NOTE H—GOODWILL AND OTHER INTANGIBLES
	The following is a summary of intangible assets subject to amortization and those not subject to amortization:
		As of December 31, 2013
	(In thousands)	Gross Carrying		Accumulated			Net Carrying
		Amount		Amortization			Amount
	Amortized intangible assets:
	Core deposit intangible assets	$	43,434	$	(35,296	)	$	8,138
	Goodwill not subject to amortization						$	375,547
		As of December 31, 2012
		Gross Carrying		Accumulated			Net Carrying
		Amount		Amortization			Amount
	Amortized intangible assets:
	Core deposit intangible assets	$	43,434	$	(33,327	)	$	10,107
	Goodwill not subject to amortization						$	375,583
	The following table sets forth the anticipated amortization expense for intangible assets for the years subsequent to 2013:
	Year	Amount
	(In thousands)
	2014	$	1,478
	2015		1,149
	2016		1,089
	2017		1,047
	2018 and thereafter		3,375

Deposits

Deposits	12 Months Ended
	Dec. 31, 2013
Banking And Thrift [Abstract]	'
Deposits	'
	NOTE I—DEPOSITS
	The book value of deposits consisted of the following:
	(Dollars in thousands)	December 31
		2013		2012
	Demand deposits	$	1,874,520	$	1,824,411
	Interest-bearing checking		1,195,956		1,210,463
	Regular savings		556,183		523,336
	Money market accounts		1,224,116		1,203,341
	Time deposits under $100,000		887,516		1,035,815
	Time deposits over $100,000		883,280		955,620
	Total deposits	$	6,621,571	$	6,752,986
	Interest paid on deposits approximated $27,182,000, $33,133,000 and $39,853,000 in 2013, 2012 and 2011, respectively.
	United’s subsidiary banks have received deposits, in the normal course of business, from the directors and officers of United and its subsidiaries, and their associates. Such related party deposits were accepted on substantially the same terms, including interest rates and maturities, as those prevailing at the time for comparable transactions with unrelated persons. The aggregate dollar amount of these deposits was $137,428,000 and $77,167,000 at December 31, 2013 and 2012, respectively.

ShortTerm_Borrowings

Short-Term Borrowings	12 Months Ended
	Dec. 31, 2013
Debt Disclosure [Abstract]	'
Short-Term Borrowings	'
	NOTE J—SHORT-TERM BORROWINGS
	At December 31, 2013 and 2012, short-term borrowings and the related weighted-average interest rates were as follows:
		2013				2012
				Weighted-				Weighted-
	(Dollars in thousands)			Average				Average
		Amount		Rate		Amount		Rate
	Federal funds purchased	$	27,685		0.20%	$	5,446		0.20%
	Securities sold under agreements to repurchase		188,069		0.09%		209,516		0.09%
	Total	$	215,754			$	214,962
	Federal funds purchased and securities sold under agreements to repurchase have been a significant source of funds for the company. United has various unused lines of credit available from certain of its correspondent banks in the aggregate amount of $234,000,000. These lines of credit, which bear interest at prevailing market rates, permit United to borrow funds in the overnight market, and are renewable annually subject to certain conditions.
	The following table shows the distribution of United’s federal funds purchased and securities sold under agreements to repurchase and the weighted-average interest rates thereon at the end of each of the last three years. Also provided are the maximum amount of borrowings and the average amounts of borrowings as well as weighted-average interest rates for the last three years.
	(Dollars in thousands)	Federal		Securities Sold
		Funds		Under
		Purchased		Agreements
				To Repurchase
	At December 31:
	2013		$  27,685		$  188,069
	2012		5,446		209,516
	2011		7,120		247,646
	Weighted-average interest rate at year-end:
	2013		0.20%		0.09%
	2012		0.20%		0.09%
	2011		0.20%		0.07%
	Maximum amount outstanding at any month’s end:
	2013		$  27,685		$  220,155
	2012		23,100		273,041
	2011		20,440		274,546
	Average amount outstanding during the year:
	2013		$  12,595		$  199,823
	2012		16,314		261,558
	2011		13,377		242,371
	Weighted-average interest rate during the year:
	2013		0.20%		0.10%
	2012		0.20%		0.08%
	2011		0.21%		0.06%
	At December 31, 2013, all the repurchase agreements were in overnight accounts. The rates offered on these funds vary according to movements in the federal funds and short-term investment market rates.
	United has a $10,000,000 line of credit with an unrelated financial institution to provide for general liquidity needs. The line is an unsecured, revolving line of credit. The line is renewable on a 360 day basis and carries an indexed, floating-rate of interest. The line requires compliance with various financial and nonfinancial covenants. At December 31, 2013, United had no outstanding balance under this credit.
	Interest paid on short-term borrowings approximated $894,000, $304,000 and $464,000 in 2013, 2012 and 2011, respectively.

LongTerm_Borrowings

Long-Term Borrowings	12 Months Ended
	Dec. 31, 2013
Debt Disclosure [Abstract]	'
Long-Term Borrowings	'
	NOTE K—LONG-TERM BORROWINGS
	United’s subsidiary banks are members of the Federal Home Loan Bank (FHLB). Membership in the FHLB makes available short-term and long-term borrowings from collateralized advances. All FHLB borrowings are collateralized by a mix of single-family residential mortgage loans, commercial loans and investment securities. At December 31, 2013, the total carrying value of loans pledged as collateral for FHLB advances approximated $3,065,080,000. United had an unused borrowing amount as of December 31, 2013 of approximately $1,413,927,000 available subject to delivery of collateral after certain trigger points. Advances may be called by the FHLB or redeemed by United based on predefined factors and penalties.
	At December 31, 2013 and 2012, FHLB advances and the related weighted-average interest rates were as follows:
		2013										2012
	(Dollars in thousands)	Amount				Weighted-			Weighted-			Amount			Weighted-			Weighted-
						Average			Average						Average			Average
						Contractual			Effective						Contractual			Effective
						Rate			Rate						Rate			Rate
	FHLB advances	$	592,069				0.56	%		0.56	%	$	186,411			2.17	%		2.17	%
	Overnight funds of $215,000,000 were included in the $592,069,000 above at December 31, 2013. Overnight funds of $100,000,000 were included in the $186,411,000 above at December 31, 2012. The weighted-average effective rate considers the effect of any interest rate swaps designated as fair value hedges outstanding at year-end 2013 and 2012 to manage interest rate risk on its long-term debt. Additional information is provided in Note P, Notes to Consolidated Financial Statements.
	At December 31, 2013, United had a total of twelve statutory business trusts that were formed for the purpose of issuing or participating in pools of trust preferred capital securities (Capital Securities) with the proceeds invested in junior subordinated debt securities (Debentures) of United. The Debentures, which are subordinate and junior in right of payment to all present and future senior indebtedness and certain other financial obligations of United, are the sole assets of the trusts and United’s payment under the Debentures is the sole source of revenue for the trusts. At December 31, 2013 and 2012, the outstanding balance of the Debentures was $198,628,000 and $198,515,000, respectively, and was included in the category of long-term debt on the Consolidated Balance Sheets entitled “Other long-term borrowings.” The Capital Securities are not included as a component of shareholders’ equity in the Consolidated Balance Sheets. United fully and unconditionally guarantees each individual trust’s obligations under the Capital Securities.
	Under the provisions of the subordinated debt, United has the right to defer payment of interest on the subordinated debt at any time, or from time to time, for periods not exceeding five years. If interest payments on the subordinated debt are deferred, the dividends on the Capital Securities are also deferred. Interest on the subordinated debt is cumulative.
	The Trust Preferred Securities currently qualify as Tier 1 regulatory capital of United for regulatory purposes. In July of 2013, United’s primary federal regulator, the Federal Reserve, published final rules (the “Basel III Capital Rules”) establishing a new comprehensive capital framework for U.S. banking organizations. The Basel III Capital Rules grandfathers United’s Trust Preferred Securities as Tier 1 capital under the limitations for restricted capital elements in the general risk-based capital rules. As a result, beginning in 2015, United’s Trust Preferred Securities will be subject to a limit of 25 percent of Tier 1 capital elements excluding any non-qualifying capital instruments and after all regulatory capital deductions and adjustments applied to Tier 1 capital, which is substantially similar to the limit in the general risk-based capital rules. Trust preferred securities no longer included in United’s Tier 1 capital may be included as a component of Tier 2 capital on a permanent basis without phase-out.
	Information related to United’s statutory trusts is presented in the table below:
	(Dollars in thousands)	Issuance Date		Amount of				Interest Rate	Maturity Date
	Description			Capital
				Securities
				Issued
	Century Trust	23-Mar-00		$	8,800			10.875% Fixed		8-Mar-30
	Sequoia Trust I	March 28, 2001		$	2,000			10.18% Fixed		8-Jun-31
	United Statutory Trust III	17-Dec-03		$	20,000			3-month LIBOR + 2.85%		17-Dec-33
	United Statutory Trust IV	19-Dec-03		$	25,000			3-month LIBOR + 2.85%		23-Jan-34
	United Statutory Trust V	12-Jul-07		$	50,000			3-month LIBOR + 1.55%		1-Oct-37
	United Statutory Trust VI	20-Sep-07		$	30,000			3-month LIBOR + 1.30%		15-Dec-37
	Premier Statutory Trust II	September 25, 2003		$	6,000			3-month LIBOR + 3.10%		8-Oct-33
	Premier Statutory Trust III	16-May-05		$	8,000			3-month LIBOR + 1.74%		15-Jun-35
	Premier Statutory Trust IV	20-Jun-06		$	14,000			3-month LIBOR + 1.55%		September 23, 2036
	Premier Statutory Trust V	14-Dec-06		$	10,000			3-month LIBOR + 1.61%		1-Mar-37
	Centra Statutory Trust I	20-Sep-04		$	10,000			3-month LIBOR + 2.29%		20-Sep-34
	Centra Statutory Trust II	15-Jun-06		$	10,000			3-month LIBOR + 1.65%		7-Jul-36
	At December 31, 2013 and 2012, the Debentures and their related weighted-average interest rates were as follows:
		2013							2012
	(Dollars in thousands)	Amount				Weighted-			Amount			Weighted-
						Average						Average
						Rate						Rate
	Century Trust	$	8,800				10.88	%	$	8,800			10.88	%
	Sequoia Trust I		2,065				10.18	%		2,064			10.18	%
	United Statutory Trust III		20,619				3.1	%		20,619			3.16	%
	United Statutory Trust IV		25,774				3.09	%		25,774			3.16	%
	United Statutory Trust V		51,547				1.8	%		51,547			1.91	%
	United Statutory Trust VI		30,928				1.54	%		30,928			1.61	%
	Premier Statutory Trust II		6,186				3.34	%		6,186			3.44	%
	Premier Statutory Trust III		8,248				1.98	%		8,248			2.05	%
	Premier Statutory Trust IV		14,433				1.8	%		14,433			1.86	%
	Premier Statutory Trust V		10,310				1.85	%		10,310			1.92	%
	Centra Statutory Trust I		9,859				2.54	%		9,803			2.6	%
	Centra Statutory Trust II		9,859				1.89	%		9,803			1.99	%
	Total	$	198,628						$	198,515
	At December 31, 2013, the scheduled maturities of long-term borrowings were as follows:
	Year	Amount
	(In thousands)
	2014	$	321,388
	2015		4,395
	2016		622
	2017		383
	2018 and thereafter		248,909
	Total	$	575,697
	Interest paid on long-term borrowings approximated $8,846,000, $14,370,000 and $16,335,000 in 2013, 2012 and 2011, respectively.

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2013
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	NOTE L—INCOME TAXES
	The income tax provisions included in the consolidated statements of income are summarized as follows:
	(In thousands)	Year Ended December 31
		2013		2012		2011
	Current expense:
	Federal	$	32,378	$	37,623	$	23,341
	State		4,048		914		518
	Deferred expense:
	Federal and State		2,990		337		10,907
	Total income taxes	$	39,416	$	38,874	$	34,766
	The following is a reconciliation of income tax expense to the amount computed by applying the statutory federal income tax rate to income before income taxes.
		Year Ended December 31
	(Dollars in thousands)	2013				2012				2011
		Amount		%		Amount		%		Amount		%
	Tax on income before taxes	$	43,765		35.00%	$	42,519		35.00%	$	38,632		35.0%
	at statutory federal rate
	Plus: State income taxes		2,392		1.9		594		0.5		336		0.3
	net of federal tax benefits
			46,157		36.9		43,113		35.5		38,968		35.3
	Increase (decrease) resulting from:
	Tax-exempt interest income		-3,837		-3.1		-4,127		-3.4		-4,226		-3.8
	Other items-net		-2,904		-2.3		-112		-0.1		24		0
	Income taxes	$	39,416		31.5%	$	38,874		32.0%	$	34,766		31.5%
	For years ended 2013, 2012 and 2011, United incurred federal income tax expense applicable to the sales and calls of securities of $533,000, $156,000 and $552,000, respectively. Income taxes paid approximated $49,114,000, $27,057,000 and $34,531,000 in 2013, 2012 and 2011, respectively. Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. At December 31, 2013, United had no state net operating loss carryforwards.
	Taxes not on income, which consists mainly of business franchise taxes, were $4,816,000, $4,717,000 and $4,466,000 for the years ended December 31, 2013, 2012 and 2011, respectively. These amounts are recorded in other expense in the Consolidated Statements of Income.
	Significant components of United’s deferred tax assets and liabilities (included in other assets in the Consolidated Balance Sheets) at December 31, 2013 and 2012 are as follows:
	(In thousands)	2013		2012
	Deferred tax assets:
	Allowance for credit losses	$	28,108	$	41,853
	Other accrued liabilities		830		29
	Unrecognized components of net periodic pension costs		12,168		21,696
	Unrealized loss on securities available for sale		13,255		16,703
	Other real estate owned		4,288		0
	Purchase accounting intangibles		3,598		0
	Net operating loss		0		846
	Total deferred tax assets		62,247		81,127
	Deferred tax liabilities:
	Purchase accounting intangibles		0		6,436
	Deferred mortgage points		283		377
	Accrued benefits payable		7,806		10,961
	Premises and equipment		2,563		857
	Other		2,117		2,764
	Total deferred tax liabilities		12,769		21,395
	Net deferred tax assets	$	49,478	$	59,732
	In accordance with ASC topic 740, “Income Taxes,” United records a liability for uncertain income tax positions based on a recognition threshold of more-likely-than-not, and a measurement attribute for all tax positions taken on a tax return, in order for those tax positions to be recognized in the financial statements.
	Below is a reconciliation of the total amounts of unrecognized tax benefits:
		December 31
	(In thousands)	2013		2012
	Unrecognized tax benefits at beginning of year		$  2,106		$  2,028
	Decrease in unrecognized tax benefits as a result of tax positions settled during the current period		-213		0
	Increase in unrecognized tax benefits as a result of tax positions taken during the current period		661		226
	Decreases in the unrecognized tax benefits as a result of a		-42		(148)
	lapse of the applicable statute of limitations
	Unrecognized tax benefits at end of year		$  2,512		$  2,106
	The entire amount of unrecognized tax benefits, if recognized, would impact United’s effective tax rate. Over the next 12 months, the statute of limitations will close on certain income tax returns. However, at this time, United cannot reasonably estimate the amount of tax benefits it may recognize over the next 12 months.
	United is currently open to audit under the statute of limitations by the Internal Revenue Service for the years ended December 31, 2011 and 2012 and State Taxing authorities for the years ended December 31, 2009 through 2012.
	As of December 31, 2013 and 2012, the total amount of accrued interest related to uncertain tax positions was $455,000 and $1,138,000, respectively. United accounts for interest and penalties related to uncertain tax positions as part of its provision for federal and state income taxes. No interest or penalties were recognized in the results of operations for the years of 2013, 2012 and 2011.

Employee_Benefit_Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2013
Compensation And Retirement Disclosure [Abstract]	'
Employee Benefit Plans	'
	NOTE M--EMPLOYEE BENEFIT PLANS
	United has a defined benefit retirement plan covering a majority of all employees. Pension benefits are based on years of service and the average of the employee’s highest five consecutive plan years of basic compensation paid during the ten plan years preceding the date of determination. Contributions by United are intended to provide not only for benefits attributed to service to date, but also for those expected to be earned in the future.
	In September of 2007, after a recommendation by United’s Pension Committee and approval by United’s Board of Directors, the United Bankshares, Inc. Pension Plan (the Plan) was amended to change the participation rules. The decision to change the participation rules for the Plan followed current industry trends, as many large and medium size companies have taken similar steps. The amendment provided that employees hired on or after October 1, 2007, will not be eligible to participate in the Plan. However, new employees will continue to be eligible to participate in United’s Savings and Stock Investment 401(k) plan. This change had no impact on current employees hired prior to October 1, 2007 as they will continue to participate in the Plan, with no change in benefit provisions, and will continue to be eligible to participate in United’s Savings and Stock Investment 401(k) Plan.
	Included in accumulated other comprehensive income at December 31, 2013 are the following amounts that have not yet been recognized in net periodic pension cost: unrecognized prior service costs of $2,000 ($1,000 net of tax) and unrecognized actuarial losses of $31,151,000 ($20,248,000 net of tax). The amortization of these items expected to be recognized in net periodic pension cost during the fiscal year ended December 31, 2014 is $1,000 ($1,000 net of tax), and $4,821,000 ($3,134,000 net of tax), respectively.
	Net consolidated periodic pension cost included the following components:
	(Dollars in thousands)	Year Ended December 31,
		2013			2012			2011
	Service cost		$    2,672			$    2,517			$    2,272
	Interest cost		4,913			4,849			4,555
	Expected return on plan assets		-8,313			-7,999			-8,343
	Recognized net actuarial loss		4,821			4,199			2,427
	Amortization of prior service cost		1			1			1
	Net periodic pension cost		$    4,094			$    3,567			$      912
	Weighted-Average Assumptions:
	Discount rate		4.40%			5.15%			5.75%
	Expected return on assets		7.75%			8.00%			8.00%
	Rate of Compensation Increase (prior to age 45)		3.75%			3.75%			3.75%
	Rate of Compensation Increase (otherwise)		2.75%			2.75%			2.75%
	The reconciliation of the beginning and ending balances of the projected benefit obligation and the fair value of plan assets for the year ended December 31, 2013 and the accumulated benefit obligation at December 31, 2013 is as follows:
	(Dollars in thousands)	December 31,
	Change in Projected Benefit Obligation	2013			2012
	Projected Benefit Obligation at the Beginning of the Year	$	112,534		$	95,162
	Service Cost		2,672			2,517
	Interest Cost		4,913			4,849
	Actuarial (Gain) Loss		-11,646			13,000
	Benefits Paid		-3,287			-2,994
	Projected Benefit at the End of the Year	$	105,186		$	112,534
	Accumulated Benefit Obligation at the End of the Year	$	95,859		$	102,156
	Change in Plan Assets
	Fair Value of Plan Assets at the Beginning of the Year	$	108,859		$	101,383
	Actual Return on Plan Assets		17,616			10,470
	Benefits Paid		-3,287			-2,994
	Employer Contributions		0			0
	Fair value of plan assets at end of year	$	123,188		$	108,859
	Net Amount Recognized
	Funded Status	$	18,002		$	(3,675)
	Unrecognized Transition Asset		0			0
	Unrecognized Prior Service Cost		2			3
	Unrecognized Net Loss		31,151			56,921
	Net Amount Recognized	$	49,155		$	53,249
	Weighted-Average Assumptions at the End of the Year
	Discount Rate		5.20%			4.40%
	Rate of Compensation Increase (prior to age 45)		3.50%			3.75%
	Rate of Compensation Increase (otherwise)		3.00%			2.75%
	Asset allocation for the defined benefit pension plan as of the measurement date, by asset category, is as follows:
	Plan Assets	Target Allocation			Allowable			Percentage of
		2014			Allocation Range			Plan Assets at
								December 31,			December 31,
								2013			2012
	Equity Securities		62	%		50-70	%		66	%		63%
	Debt Securities		26	%		20-50	%		21	%		32%
	Other		12	%		15-Mar	%		13	%		5%
	Total								100	%		100%
	Equity securities include United common stock in the amounts of $3,328,000 (3%) at December 31, 2013 and $2,576,000 (2%) at December 31, 2012.
	The policy, as established by the Pension Committee, primarily consisting of United’s Executive Management, is to invest assets based upon the target allocations stated above. The assets are reallocated periodically to meet the above target allocations. The investment policy is reviewed at least annually, subject to the approval of the Pension Committee, to determine if the policy should be changed. Prohibited investments include, but are not limited to, futures contracts, private placements, uncovered options, real estate, the use of margin, short sales, derivatives for speculative purposes, and other investments that are speculative in nature. In order to achieve a prudent level of portfolio diversification, the securities of any one company are not to exceed 10% of the total plan assets, and no more than the 15% of total plan assets is to be invested in any one industry (other than securities of U.S. Government or Agencies). Additionally, no more than 15% of the plan assets is to be invested in foreign securities, both equity and fixed. The expected long-term rate of return for the plan’s total assets is based on the expected return of each of the above categories, weighted based on the median of the target allocation for each class.
	At December 31, 2013, the benefits expected to be paid in each of the next five fiscal years, and in the aggregate for the five years thereafter are as follows:
	Year	Amount
	(In thousands)
	2014		$  3,728
	2015		4,053
	2016		4,432
	2017		4,780
	2018		5,159
2019 through 2023		30,746
United did not contribute to the plan in 2013 and 2012 as no contributions were required by funding regulations or law. For 2014, no contributions to the plan are required by funding regulations or law. However, United may make a discretionary contribution in 2014, the amount of which cannot be reasonably estimated at this time.
In accordance with ASC topic 715 and using the guidance contained in ASC topic 820, the following is a description of the valuation methodologies used to measure the plan assets at fair value.
Cash and Cash Equivalents: These underlying assets are highly liquid U.S. government obligations. The fair value of cash and cash equivalents approximates cost (Level 1).
Debt Securities: Securities of the U.S. Government, municipalities, private issuers and corporations are valued at the closing price reported in the active market in which the individual security is traded, when available (Level 1). If quoted market prices are not available, fair values are measured utilizing independent valuation techniques of identical or similar securities for which significant assumptions are derived primarily from or corroborated by observable market data. Using a market approach valuation methodology, third party vendors compile prices from various sources and may determine the fair value of identical or similar securities by using pricing models that considers observable market data (Level 2).
Common and Preferred Stock: Theses securities are valued at the closing price on the respective stock exchange (Level 1).
Mutual Funds: Generally, these securities are valued at the closing price reported in the active market in which the individual mutual fund is traded (Level 1). However, certain funds are valued by the fund administrator using pricing models that considers observable market data (Level 2).
The following tables present the balances of the plan assets, by fair value hierarchy level, as of December 31, 2013 and 2012:
				Fair Value Measurements at December 31, 2013 Using
(In thousands)	Balance as of			Quoted Prices			Significant			Significant
	December 31,			in Active			Other			Unobservable
Description	2013			Markets for			Observable			Inputs
				Identical			Inputs			(Level 3)
				Assets			(Level 2)
				(Level 1)
Cash and Cash equivalents	$	2,985		$	2,985		$	0		$	0
Fixed Income Securities:
Mortgage backed securities		118			0			118			0
Collateralized mortgage obligations		245			0			245			0
Municipal obligations		1,112			0			1,112			0
Corporate bonds		2,363			0			2,363			0
Fixed Income Mutual Funds:
Strategic income		3,985			3,985			0			0
Taxable		3,970			3,970
Domestic		13,834			13,834			0			0
Alternative		6,131			6,131			0			0
Equity Securities:
Preferred stock		195			195			0			0
Common stock		20,089			20,089			0			0
Equity Mutual Funds:
Domestic equity large cap		23,042			23,042			0			0
Domestic equity mid cap		5,540			5,540			0			0
Domestic equity small cap		15,293			15,293			0			0
International emerging equity		6,076			6,076			0			0
International equity developed		11,817			11,817			0			0
Alternative equity		5,692			5,692			0			0
Other Assets:
Partnerships		701			0			701			0
Total	$	123,188		$	118,649		$	4,539		$	0
				Fair Value Measurements at December 31, 2012 Using
(In thousands)	Balance as of			Quoted Prices			Significant			Significant
	December 31,			in Active			Other			Unobservable
Description	2012			Markets for			Observable			Inputs
				Identical			Inputs			(Level 3)
				Assets			(Level 2)
				(Level 1)
Cash and Cash equivalents		$     4,396			$     4,396			$          0			$    0
Fixed Income Securities:
Mortgage backed securities		207			0			207			0
Collateralized mortgage obligations		208			0			208			0
Municipal obligations		910			0			910			0
Corporate bonds		2,588			2,226			362			0
Fixed Income Mutual Funds:
Fixed income—general		12,463			12,463			0			0
Domestic		12,600			12,600			0			0
Alternative		6,116			6,116			0			0
Equity Securities:
Preferred stock		209			209			0			0
Common stock		14,712			14,712			0			0
Equity Mutual Funds:
Global equity		5,186			5,186			0			0
Domestic equity large cap		19,172			19,172			0			0
Domestic equity mid cap		2,552			2,552			0			0
Domestic equity small cap		10,688			10,688			0			0
International emerging equity		5,241			5,241			0			0
International equity developed		4,158			4,158			0			0
Alternative equity		6,727			6,727			0			0
Other Assets:
Partnerships		726			0			726			0
Total		$ 108,859			$ 106,446			$    2,413			$    0
Preferred stock investments are in financial institutions. Common stock investments are diversified amongst various industries with no industry representing more than 5% of the total plan assets.
The United Bankshares, Inc. Savings and Stock Investment Plan (the Plan) is a defined contribution plan under Section 401(k) of the Internal Revenue Code. Each employee of United, who completes ninety (90) days of qualified service, is eligible to participate in the Plan. Each participant may contribute from 1% to 100% of compensation to his/her account, subject to Internal Revenue Service maximum deferral limits. Prior to December 31, 2008, after one year of eligible service, United matched 100% of the first 2% of salary deferred and 25% of the second 2% of salary deferred with United stock. Beginning January 1, 2009, United matched 100% of the first 3% of salary deferred and 25% of the next 1% of salary deferred with United stock. Vesting is 100% for employee deferrals and the company match at the time the employee makes his/her deferral. United’s expense relating to the Plan approximated $1,411,000, $1,330,000 and $1,332,000 in 2013, 2012 and 2011, respectively.
The assets of United’s defined benefit plan and 401(k) Plan each include investments in United common stock. At December 31, 2013 and 2012, the combined plan assets included 912,713 and 932,125 shares, respectively, of United common stock with an approximate fair value of $28,705,000 and $22,671,000, respectively. Dividends paid on United common stock held by the plans approximated $1,171,631, $1,112,000 and $1,022,000 for the years ended December 31, 2013, 2012, and 2011, respectively.
United has certain other supplemental deferred compensation plans covering various key employees. Periodic charges are made to operations so that the liability due each employee is fully recorded as of the date of their retirement. Amounts charged to expense have not been significant in any year.

Stock_Based_Compensation

Stock Based Compensation	12 Months Ended
	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Stock Based Compensation	'
	NOTE N—STOCK BASED COMPENSATION
	On May 16, 2011, United’s shareholders approved the 2011 Long-Term Incentive Plan (2011 LTI Plan). The 2011 LTI Plan became effective as of July 1, 2011. An award granted under the 2011 LTI Plan may consist of any non-qualified stock options or incentive stock options, stock appreciation rights, restricted stock, or restricted stock units. These awards all relate to the common stock of United. The maximum number of shares of United common stock which may be issued under the 2011 LTI Plan is 1,500,000. Any and all shares may be issued in respect of any of the types of awards, provided that (1) the aggregate number of shares that may be issued in respect of restricted stock awards, and restricted stock units awards which are settled in shares is 350,000, and (2) the aggregate number of shares that may be issued pursuant to stock options is 1,150,000. The shares to be offered under the 2011 LTI Plan may be authorized and unissued shares or treasury shares. With respect to awards that are intended to satisfy the requirements for performance-based compensation under Code Section 162(m), the maximum number of options and stock appreciation rights, in the aggregate, which may be awarded pursuant to the 2011 LTI Plan to any individual participant during any calendar year is 100,000, and the maximum number of shares of restricted stock and/or shares subject to a restricted stock units award that may be granted pursuant to the 2011 LTI Plan to any individual participant during any calendar year is 50,000 shares. A participant may be any key employee of United or its affiliates or a non-employee member of United’s Board of Directors. Subject to certain change in control provisions, stock options, SARs, restricted stock and restricted stock units will vest in 25% increments over the first four anniversaries of the awards unless the Committee specifies otherwise in the award agreement. No award will vest sooner than 1/3 per year over the first three anniversaries of the award. A Form S-8 was filed on September 2, 2011 with the Securities and Exchange Commission to register all the shares which were available for the 2011 LTI Plan. During the year of 2013, a total of 194,225 non-qualified stock options and 52,825 shares of restricted stock were granted under the 2011 LTI Plan.
	Compensation expense of $1,786,000 and $1,908,000 related to the nonvested awards under the 2011 LTI Plan and the 2006 Stock Option Plan was incurred for the years 2013 and 2012, respectively. Compensation expense was included in employee compensation in the Consolidated Statements of Income.
	Stock Options
	United currently has options outstanding from various option plans other than the 2006 Stock Option Plan (the Prior Plans); however, no common shares of United stock are available for grants under the Prior Plans as these plans have expired. Awards outstanding under the Prior Plans will remain in effect in accordance with their respective terms. The maximum term for options granted under the plans is ten (10) years.
	The fair value of the options for 2013 was estimated at the date of grant using a binomial lattice option pricing model with the following weighted-average assumptions: risk-free interest rates of 1.42%; dividend yield of 3.00%; volatility factors of the expected market price of United’s common stock of 0.316; and a weighted-average expected option life of 7.18 years, respectively. The estimated fair value of the options at the date of grant was $5.74 for the options granted during 2013. ASC topic 718, “Compensation – Stock Compensation” defines a lattice model as a model that produces an estimated fair value based on the assumed changes in prices of a financial instrument over successive periods of time. A binomial lattice model assumes at least two price movements are possible in each period of time.
	A summary of activity under the United’s stock option plans as of December 31, 2013, and the changes during the year of 2013 are presented below:
		Year ended December 31, 2013
						Weighted Average
	(Dollars in thousands, except per share data)	Shares		Aggregate		Remaining		Exercise
				Intrinsic		Contractual		Price
				Value		Term (Yrs.)
	Outstanding at January 1, 2013		1,629,237					$	29.64
	Granted		194,225						26.24
	Exercised		100,302						23.56
	Forfeited or expired		275,163						31.1
	Outstanding at December 31, 2013		1,447,997	$	5,145		5.4	$	29.33
	Exercisable at December 31, 2013		858,800	$	3,148		3.6	$	30.2
	The following table summarizes the status of United’s nonvested awards for the year ended December 31, 2013:
		Shares		Weighted-Average
				Grant Date Fair Value
				Per Share
	Nonvested at January 1, 2013		770,750	$	7.04
	Granted		194,225		5.74
	Vested		348,339		6.33
	Forfeited or expired		27,439		7.53
	Nonvested at December 31, 2013		589,197	$	7.01
	As of December 31, 2013, the total unrecognized compensation cost related to nonvested option awards was $1,290,000 with a weighted-average expense recognition period of 0.9 years. The total fair value of awards vested during the year ended December 31, 2013, was $2,204,000.
	Cash received from options exercised under the Plans for the years ended December 31, 2013, 2012 and 2011 was $2,364,000, $115,000, and $542,000, respectively. During 2013 and 2012, 100,302 and 7,510 shares, respectively, were issued in connection with stock option exercises. All shares issued in connection with stock option exercises were issued from available treasury stock for 2013 and 2012. The weighted-average grant-date fair value of options granted in the year of 2013, 2012, and 2011 was $5.74, $6.86, and $7.91, respectively. The total intrinsic value of options exercised under the Plans during the years ended December 31, 2013, 2012, and 2011 was $507,000, $98,000, and $518,000, respectively.
	The Statement of Cash Flows topic of the FASB Accounting Standards Codification requires the benefits of tax deductions in excess of recognized compensation cost to be reported as a financing cash flow, rather than as an operating cash flow as required under previous standards. This requirement reduces net operating cash flows and increase net financing cash flows in periods after adoption. While the company cannot estimate what those amounts will be in the future (because they depend on, among other things, the date employees exercise stock options), United recognized cash flows from financing activities of $331,000, $35,000 and $3,114,000 from excess tax benefits related to share-based compensation for the year of 2013, 2012 and 2011, respectively.
	Restricted Stock
	Under the 2011 LTI Plan, United may award restricted common shares to key employees and non-employee directors. In the first quarters of 2013 and 2012, United granted restricted shares to participants with a four-year time-based vesting period. Recipients of restricted shares do not pay any consideration to United for the shares, have the right to vote all shares subject to such grant and receive all dividends with respect to such shares, whether or not the shares have vested. Presently, these nonvested participating securities have an immaterial impact on diluted earnings per share. As of December 31, 2013, the total unrecognized compensation cost related to nonvested stock awards was $1,441,000 with a weighted-average expense recognition period of 1.5 years.
	The following summarizes the changes to United’s restricted common shares for the year ended December 31, 2013:
		Number of		Weighted-Average
		Shares		Grant Date Fair Value
				Per Share
	Outstanding at January 1, 2013		51,125	$	29.4
	Granted		52,825		26.19
	Vested		16,789		28.96
	Forfeited		1,664		27.91
	Outstanding at December 31, 2013		85,497	$	27.53

Commitments_and_Contingent_Lia

Commitments and Contingent Liabilities	12 Months Ended
	Dec. 31, 2013
Commitments And Contingencies Disclosure [Abstract]	'
Commitments and Contingent Liabilities	'
	NOTE O--COMMITMENTS AND CONTINGENT LIABILITIES
	United is a party to financial instruments with off-balance-sheet risk in the normal course of business to meet the financing needs of its customers and to alter its own exposure to fluctuations in interest rates. These financial instruments include loan commitments, standby letters of credit, and interest rate swap agreements. The instruments involve, to varying degrees, elements of credit and interest rate risk in excess of the amount recognized in the financial statements.
	United’s maximum exposure to credit loss in the event of nonperformance by the counterparty to the financial instrument for the loan commitments and standby letters of credit is the contractual or notional amount of those instruments. United uses the same policies in making commitments and conditional obligations as it does for on-balance sheet instruments. Collateral may be obtained, if deemed necessary, based on management’s credit evaluation of the counterparty.
	Commitments to extend credit are agreements to lend to a customer as long as there is no violation of any condition established in the commitment contract. Commitments generally have fixed expiration dates or other termination clauses and may require the payment of a fee. Since many of the commitments are expected to expire without being drawn upon, the total commitment amounts do not necessarily, and historically do not, represent future cash requirements. The amount of collateral obtained, if deemed necessary upon the extension of credit, is based on management’s credit evaluation of the counterparty. United had approximately $2,504,093,000 and $2,173,377,000 of loan commitments outstanding as of December 31, 2013 and 2012, respectively, substantially all of which contractually expire within one year.
	Commercial and standby letters of credit are agreements used by United’s customers as a means of improving their credit standing in their dealings with others. Under these agreements, United guarantees certain financial commitments of its customers. A commercial letter of credit is issued specifically to facilitate trade or commerce. Typically, under the terms of a commercial letter of credit, a commitment is drawn upon when the underlying transaction is consummated as intended between the customer and a third party. As of December 31, 2013, United had no outstanding commercial letters of credit and $250,000 as of December 31, 2012. A standby letter of credit is generally contingent upon the failure of a customer to perform according to the terms of an underlying contract with a third party. United has issued standby letters of credit of $114,664,000 and $96,856,000 as of December 31, 2013 and 2012, respectively. In accordance with the Contingencies Topic of the FASB Accounting Standards Codification, United has determined that substantially all of its letters of credit are renewed on an annual basis and the fees associated with these letters of credit are immaterial.
	United and its subsidiaries are currently involved in various legal proceedings in the normal course of business. Management is vigorously pursuing all its legal and factual defenses and, after consultation with legal counsel, believes that all such litigation will be resolved with no material effect on United’s financial position.

Derivative_Financial_Instrumen

Derivative Financial Instruments	12 Months Ended
	Dec. 31, 2013
Derivative Instruments And Hedging Activities Disclosure [Abstract]	'
Derivative Financial Instruments	'
	NOTE P—DERIVATIVE FINANCIAL INSTRUMENTS
	United uses derivative instruments to help aid against adverse prices or interest rate movements on the value of certain assets or liabilities and on future cash flows. These derivatives may consist of interest rate swaps, caps, floors, collars, futures, forward contracts, written and purchased options. United also executes derivative instruments with its commercial banking customers to facilitate its risk management strategies.
	Derivative instruments designated in a hedge relationship to mitigate exposure to changes in the fair value of an asset, liability, or firm commitment attributable to a particular risk, such as interest rate risk, are considered fair value hedges. Derivative instruments designated in a hedge relationship to mitigate exposure to variability in expected future cash flows, or other types of forecasted transactions, are considered cash flow hedges. As of December 31, 2013, United has only fair value hedges.
	For the years ended December 31, 2013 and 2012, the derivative portfolio also included derivative financial instruments not included in hedge relationships. These derivatives consist of interest rate swaps used for interest rate management purposes and derivatives executed with commercial banking customers to facilitate their interest rate management strategies. Gains and losses on other derivative financial instruments are included in noninterest income and noninterest expense, respectively.
	The following table sets forth certain information regarding interest rate derivatives portfolio used for interest-rate risk management purposes and designated as accounting hedges at December 31, 2013 and 2012.
			Derivative Hedging Instruments
			December 31, 2013								December 31, 2012
	(Dollars in thousands)		Notional				Average				Notional				Average
			Amount				Pay				Amount				Pay
							Rate								Rate
	Fair Value Hedges:
	Pay Fixed Swap (Hedging Commercial Loans)		$	41,868				5.07	%		$	52,558				5.14	%
	Total Derivatives Used in Fair Value Hedges		$	41,868							$	52,558
	Total Derivatives Used for Interest Rate Risk Management and Designated as Hedges		$	41,868							$	52,558
	The following tables summarize the fair value of United’s derivative financial instruments:
			Asset Derivatives
			December 31, 2013						December 31, 2012
	(In thousands)		Balance		Fair				Balance		Fair
			Sheet		Value				Sheet		Value
			Location						Location
	Derivatives designated as hedging instruments
	Interest rate contracts		Other assets		$	2,179			Other assets		$	0
	Total derivatives designated as hedging instruments				$	2,179					$	0
	Derivatives not designated as hedging instruments
	Interest rate contracts		Other assets		$	1,045			Other assets		$	2,367
	Total derivatives not designated as hedging instruments				$	1,045					$	2,367
	Total asset derivatives				$	3,224					$	2,367
			Liability Derivatives
			December 31, 2013						December 31, 2012
	(In thousands)		Balance		Fair				Balance		Fair
			Sheet		Value				Sheet		Value
			Location						Location
	Derivatives designated as hedging instruments
	Interest rate contracts		Other liabilities		$	149			Other liabilities		$	1,914
	Total derivatives designated as hedging instruments				$	149					$	1,914
	Derivatives not designated as hedging instruments
	Interest rate contracts		Other liabilities		$	1,045			Other liabilities		$	2,367
	Total derivatives not designated as hedging instruments				$	1,045					$	2,367
	Total liability derivatives				$	1,194					$	4,281
	Derivative contracts involve the risk of dealing with both bank customers and institutional derivative counterparties and their ability to meet contractual terms. Credit risk arises from the possible inability of counterparties to meet the terms of their contracts. United’s exposure is limited to the replacement value of the contracts rather than the notional amount of the contract. The Company’s agreements generally contain provisions that limit the unsecured exposure up to an agreed upon threshold. Additionally, the Company attempts to minimize credit risk through certain approval processes established by management.
	The effect of United’s derivative financial instruments on its Consolidated Statements of Income for the years ended December 31, 2013, 2012 and 2011 is presented as follows:
					Year Ended
	(In thousands)		Income Statement		December 31,				December 31,				December 31,
			Location		2013				2012				2011
	Derivatives in fair value hedging relationships
	Interest rate contracts		Interest income/ (expense)		$	(522	)		$	(298	)		$	81
	Total derivatives in fair value hedging relationships				$	(522	)		$	(298	)		$	81
	Derivatives not designated as hedging instruments
	Interest rate contracts (1)		Other income		$	1,322			$	1,450			$	1,782
	Interest rate contracts (2)		Other expense		$	(1,322	)		$	(1,450	)		$	(1,782	)
	Total derivatives not designated as hedging instruments				$	0			$	0			$	0
	Total derivatives				$	(522	)		$	(298	)		$	81
	-1	Represents net gains from derivative assets not designated as hedging instruments.
	-2	Represents net losses from derivative liabilities not designated as hedging instruments.
	For the years ended December 31, 2013, 2012 and 2011, changes in the fair value of any interest rate swaps attributed to hedge ineffectiveness were not significant to United’s Consolidated Statements of Income.

Comprehensive_Income

Comprehensive Income	12 Months Ended
	Dec. 31, 2013
Equity [Abstract]	'
Comprehensive Income	'
	NOTE Q—COMPREHENSIVE INCOME
	The changes in accumulated other comprehensive income are as follows:
			For the Years Ended December 31
	(In thousands)		2013			2012			2011
	Net Income		$	85,628		$	82,607		$	75,610
	Available for sale (“AFS”) securities:
	AFS securities with OTTI charges during the period			(7,534	)		(10,840	)		(33,580	)
	Related income tax effect			2,637			3,794			11,753
	Less : OTTI charges recognized in net income			7,332			7,376			20,414
	Related income tax effect			(2,566	)		(2,582	)		(7,145	)
	Reclassification of previous noncredit OTTI to credit OTTI			12,425			5,887			12,622
	Related income tax effect			(4,349	)		(2,061	)		(4,418	)
	Net unrealized gains (losses) on AFS securities with OTTI			7,945			1,574			(354	)
	Net change in unrealized (losses) gains on AFS securities arising during the period			(1,082	)		5,471			10,917
	Related income tax effect			379			(1,915	)		(3,821	)
	Net reclassification adjustment for gains included in net income			(1,216	)		(16	)		(1,418	)
	Related income tax effect			426			6			496
				(1,493	)		3,546			6,174
	Net effect of AFS securities on other comprehensive income			6,452			5,120			5,820
	Held to maturity (“HTM”) securities:
	Unrealized loss related to the call of HTM securities transferred from AFS to the HTM portfolio			0			0			0
	Related income tax effect			0			0			0
	Accretion on the unrealized loss for securities transferred from AFS to the HTM investment portfolio prior to call or maturity			8			7			8
	Related income tax effect			(3	)		(3	)		(3	)
	Net effect of HTM securities on other comprehensive income			5			4			5
	Defined benefit pension plan:
	Net actuarial loss during the period			20,305			(10,206	)		(20,591	)
	Related income tax effect			(7,107	)		3,572			7,206
	Amortization of transition asset recognized in net income			0			0			0
	Related income tax effect			0			0			0
	Amortization of prior service cost recognized in net income			1			1			1
	Related income tax effect			0			0			0
	Amortization of net actuarial loss recognized in net income			4,821			4,199			2,427
	Related income tax effect			(1,776	)		(1,680	)		(970	)
	Net effect of change in defined benefit pension plan on other comprehensive income			16,244			(4,114	)		(11,927	)
	Total change in other comprehensive income, net of tax			22,701			1,010			(6,102	)
	Total Comprehensive Income		$	108,329		$	83,617		$	69,508
	The components of accumulated other comprehensive income for the year ended December 31, 2013 are as follows:
	Changes in Accumulated Other Comprehensive Income (AOCI) by Component (a)
	For the Year Ended December 31, 2013
	(Dollars in thousands)		Unrealized			Accretion on			Defined			Total
			Gains/Losses			the unrealized			Benefit
			on AFS			loss for			Pension
			Securities			securities			Items
						transferred
						from AFS  to
						the HTM
	Balance at January 1, 2013		($	29,687	)	($	72	)	($	35,989	)	($	65,748	)
	Other comprehensive income before reclassification			(834	)		5			0			(829	)
	Amounts reclassified from accumulated other comprehensive income			7,286			0			16,244			23,530
	Net current-period other comprehensive income, net of tax			6,452			5			16,244			22,701
	Balance at December 31, 2013		($	23,235	)	($	67	)	($	19,745	)	($	43,047	)
	(a)	All amounts are net-of-tax.
	Reclassifications out of Accumulated Other Comprehensive Income (AOCI)
	For the Year Ended December 31, 2013
	(Dollars in thousands)		Amount			Affected Line Item in the Statement Where
			Reclassified			Net Income is Presented
	Details about AOCI Components		from AOCI
	Available for sale (“AFS”) securities:
	Reclassification of previous noncredit OTTI to credit OTTI		$	12,425		Total other-than-temporary impairment losses
	Net reclassification adjustment for losses (gains) included in net income			(1,216	)	Net gains on sales/calls of investment securities
				11,209		Total before tax
	Related income tax effect			(3,923	)	Tax expense
			7,286		Net of tax
Pension plan:
Change in pension asset			20,305	(a)
Amortization of transition asset			1	(b)
Recognized net actuarial loss			4,821	(b)
			25,127		Total before tax
Related income tax effect			(8,883	)	Tax expense
			16,244		Net of tax
Total reclassifications for the period		$	23,530
(a)	This AOCI component is included in the computation of changes in plan assets (see Note M, Employee Benefit Plans)
(b)	This AOCI component is included in the computation of net periodic pension cost (see Note M, Employee Benefit Plans)

United_Bankshares_Inc_Parent_C

United Bankshares, Inc. (Parent Company Only) Financial Information	12 Months Ended
	Dec. 31, 2013
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]	'
United Bankshares, Inc. (Parent Company Only) Financial Information	'
	NOTE R—UNITED BANKSHARES, INC. (PARENT COMPANY ONLY) FINANCIAL INFORMATION
	Condensed Balance Sheets
		December 31
	(In thousands)	2013			2012
	Assets
	Cash and due from banks	$	43,613		$	30,585
	Securities available for sale		1,925			3,271
	Securities held to maturity		20			225
	Other investment securities		125			162
	Investment in subsidiaries:
	Bank subsidiaries		1,139,786			1,100,880
	Nonbank subsidiaries		6,396			6,355
	Other assets		11,751			10,069
	Total Assets	$	1,203,616		$	1,151,547
	Liabilities and Shareholders’ Equity
	Junior subordinated debentures of subsidiary trusts	$	128,868		$	128,868
	Accrued expenses and other liabilities		33,016			30,428
	Shareholders’ equity (including other accumulated comprehensive loss of $43,047 and $65,748 at December 31, 2013 and 2012, respectively)		1,041,732			992,251
	Total Liabilities and Shareholders’ Equity	$	1,203,616		$	1,151,547
	Condensed Statements of Income
		Year Ended December 31
	(In thousands)	2013			2012			2011
	Income
	Dividends from banking subsidiaries	$	69,500		$	67,600		$	68,323
	Net interest income		74			119			417
	Management fees:
	Bank subsidiaries		17,665			15,854			13,000
	Nonbank subsidiaries		27			27			27
	Other income		555			105			414
	Total Income		87,821			83,705			82,181
	Expenses
	Operating expenses		20,595			20,879			20,431
	Income Before Income Taxes and Equity in Undistributed Net Income of Subsidiaries		67,226			62,826			61,750
	Applicable income tax benefit		(709	)		(1,487	)		(2,025	)
	Income Before Equity in Undistributed Net Income of Subsidiaries		67,935			64,313			63,775
	Equity in undistributed net income of subsidiaries:
	Bank subsidiaries		17,652			18,186			11,710
	Nonbank subsidiaries		41			108			125
	Net Income	$	85,628		$	82,607		$	75,610
	Condensed Statements of Cash Flows
		Year Ended December 31
	(In thousands)	2013			2012			2011
	Operating Activities
	Net income	$	85,628		$	82,607		$	75,610
	Adjustments to reconcile net income to net cash provided by operating activities:
	Equity in undistributed net income of subsidiaries		(17,693	)		(18,294	)		(11,835	)
	Amortization of net periodic pension costs		373			117			76
	Stock-based compensation		1,786			1,908			1,133
	Net (gain) loss on securities transactions		(556	)		(55	)		(12	)
	Net change in other assets and liabilities		867			(1,553	)		(6,895	)
	Net Cash Provided by Operating Activities		70,405			64,730			58,077
	Investing Activities
	Net proceeds from (purchases of) sales of securities		2,341			1,541			4,854
	Net cash paid in acquisition of subsidiary		0			0			(8,576	)
	Change in other investment securities		37			38			1,376
	Net Cash Provided by (Used in) Investing Activities		2,378			1,579			(2,346	)
	Financing Activities
	Cash dividends paid		(62,434	)		(62,333	)		(54,344	)
	Net (repayment) liquidation of subsidiary trusts		0			(5,155	)		0
	Acquisition of treasury stock		(93	)		(12	)		(18	)
	Proceeds from sale of treasury stock from deferred compensation plan		77			130			74
	Excess tax benefits from stock-based compensation arrangements		331			35			3,114
	Proceeds from exercise of stock options		2,364			115			542
Net Cash Used in Financing Activities		(59,755	)		(67,220	)		(50,632	)
Increase (Decrease) in Cash and Cash Equivalents		13,028			(911	)		5,099
Cash and Cash Equivalents at Beginning of Year		30,585			31,496			26,397
Cash and Cash Equivalents at End of Year	$	43,613		$	30,585		$	31,496

Regulatory_Matters

Regulatory Matters

12 Months Ended

Dec. 31, 2013

Banking And Thrift [Abstract]

'

Regulatory Matters

'

NOTE S--REGULATORY MATTERS

The subsidiary banks are required to maintain average reserve balances with their respective Federal Reserve Bank. The average amount of those reserve balances maintained and required for the year ended December 31, 2013, were approximately $245,566,000 and $239,755,000, respectively. The average amount of those reserve balances maintained and required for the year ended December 31, 2012, was approximately $438,761,000 and $89,439,000, respectively.

The primary source of funds for the dividends paid by United Bankshares, Inc. to its shareholders is dividends received from its subsidiary banks. Dividends paid by United’s subsidiary banks are subject to certain regulatory limitations. Generally, the most restrictive provision requires regulatory approval if dividends declared in any year exceed that year’s net income, as defined, plus the retained net profits of the two preceding years.

During 2014, the retained net profits available for distribution to United Bankshares, Inc. by its banking subsidiaries as dividends without regulatory approval, are approximately $35,547,000, plus net income for the interim period through the date of declaration.

Under Federal Reserve regulation, the banking subsidiaries are also limited as to the amount they may loan to affiliates, including the parent company. Loans from the banking subsidiaries to the parent company are limited to 10% of the banking subsidiaries’ capital and surplus, as defined, or $77,648,000 at December 31, 2013, and must be secured by qualifying collateral.

United’s subsidiary banks are subject to various regulatory capital requirements administered by federal banking agencies. Pursuant to capital adequacy guidelines, United’s subsidiary banks must meet specific capital guidelines that involve various quantitative measures of the banks’ assets, liabilities, and certain off-balance-sheet items as calculated under regulatory accounting practices. United’s subsidiary banks’ capital amounts and classifications are also subject to qualitative judgments by the regulators about components, risk weightings, and other factors.

Quantitative measures established by regulation to ensure capital adequacy require United to maintain minimum amounts and ratios of total and Tier I capital, as defined in the regulations, to risk-weighted assets, as defined, and of Tier I capital, as defined, to average assets, as defined. Failure to meet minimum capital requirements can initiate certain mandatory and possibly additional discretionary actions by regulators that, if undertaken, could have a direct material effect on United’s financial statements. As of December 31, 2013, United exceeds all capital adequacy requirements to which it is subject.

At December 31, 2013, the most recent notification from its regulators, United and its subsidiary banks were categorized as well-capitalized. To be categorized as well-capitalized, United must maintain minimum total risk-based, Tier I risk-based, and Tier I leverage ratios as set forth in the following table. There are no conditions or events since that notification that management believes would impact United’s well-capitalized status.

United’s and its subsidiary banks’, United Bank (WV) and United Bank (VA), capital amounts (in thousands of dollars) and ratios are presented in the following table.

(Dollars in thousands)

Actual

For Capital

To Be  Well-

Adequacy  Purposes

Capitalized

Amount

Ratio

Amount

Ratio

Amount

Ratio

As of December 31, 2013:

Total Capital (to Risk-Weighted Assets):

United Bankshares

$ 971,401

13.70%

$ 566,836

³8.0%

$ 708,545

³10.0%

United Bank (WV)

525,517

12.50%

336,100

³8.0%

420,125

³10.0%

United Bank (VA)

412,120

14.40%

229,656

³8.0%

287,070

³10.0%

Tier I Capital (to Risk-Weighted Assets):

United Bankshares

886,094

12.50%

283,418

³4.0%

425,127

³6.0%

United Bank (WV)

485,038

11.60%

168,050

³4.0%

252,075

³6.0%

United Bank (VA)

376,255

13.10%

114,828

³4.0%

172,242

³6.0%

Tier I Capital (to Average Assets):

United Bankshares

886,094

10.70%

330,614

³4.0%

413,267

³5.0%

United Bank (WV)

485,038

9.70%

199,209

³4.0%

249,012

³5.0%

United Bank (VA)

376,255

11.20%

134,613

³4.0%

168,266

³5.0%

(Dollars in thousands)

Actual

For Capital

To Be  Well-

Adequacy  Purposes

Capitalized

Amount

Ratio

Amount

Ratio

Amount

Ratio

As of December 31, 2012:

Total Capital (to Risk-Weighted Assets):

United Bankshares

$  941,448

13.70%

$ 551,114

³8.0%

$ 688,892

³10.0%

United Bank (WV)

511,451

12.70%

321,957

³8.0%

402,446

³10.0%

United Bank (VA)

404,405

14.10%

229,769

³8.0%

287,211

³10.0%

(Dollars in thousands)

Actual

For Capital

To Be  Well-

Adequacy  Purposes

Capitalized

Amount

Ratio

Amount

Ratio

Amount

Ratio

Tier I Capital (to Risk-Weighted Assets):

United Bankshares

857,091

12.40%

275,557

³4.0%

413,335

³6.0%

United Bank (WV)

473,044

11.80%

160,978

³4.0%

241,468

³6.0%

United Bank (VA)

368,488

12.80%

114,884

³4.0%

172,327

³6.0%

Tier I Capital (to Average Assets):

United Bankshares

857,091

10.60%

322,941

³4.0%

403,676

³5.0%

United Bank (WV)

473,044

9.80%

193,775

³4.0%

242,218

³5.0%

United Bank (VA)

368,488

11.20%

132,158

³4.0%

165,197

³5.0%

Fair_Values_of_Financial_Instr

Fair Values of Financial Instruments	12 Months Ended
	Dec. 31, 2013
Fair Value Disclosures [Abstract]	'
Fair Values of Financial Instruments	'
	NOTE T--FAIR VALUES OF FINANCIAL INSTRUMENTS
	In accordance with ASC topic 820, the following describes the valuation techniques used by United to measure certain financial assets and liabilities recorded at fair value on a recurring basis in the financial statements.
	Securities available for sale: Securities available for sale are recorded at fair value on a recurring basis. Fair value measurement is based upon quoted market prices, when available (Level 1). If quoted market prices are not available, fair values are measured utilizing independent valuation techniques of identical or similar securities for which significant assumptions are derived primarily from or corroborated by observable market data. Using a market approach valuation methodology, third party vendors compile prices from various sources and may determine the fair value of identical or similar securities by using pricing models that considers observable market data (Level 2). Management internally reviews the fair values provided by third party vendors on a monthly basis. Management’s review consists of comparing fair values assigned by third party vendors to trades and offerings observed by management. The review requires some degree of judgment as to the number or percentage of securities to review on the part of management which could fluctuate based on results of past reviews and in comparison to current expectations. Exceptions that are deemed to be material are reviewed by management. Additionally, to assess the reliability of the information received from third party vendors, management obtains documentation from third party vendors related to the sources, methodologies, and inputs utilized in valuing securities classified as Level 2. Management analyzes this information to ensure the underlying assumptions appear reasonable. Management also obtains an independent service auditor’s report from third party vendors to provide reasonable assurance that appropriate controls are in place over the valuation process. Upon completing its review of the pricing from third party vendors at December 31, 2013, management determined that the prices provided by its third party pricing source were reasonable and in line with management’s expectations for the market values of these securities. Therefore, prices obtained from third party vendors that did not reflect forced liquidation or distressed sales were not adjusted by management at December 31, 2013. Management utilizes a number of factors to determine if a market is inactive, all of which may require a significant level of judgment. Factors that management considers include: a significant widening of the bid-ask spread, a considerable decline in the volume and level of trading activity in the instrument, a significant variance in prices among market participants, and a significant reduction in the level of observable inputs. Any securities available for sale not valued based upon quoted market prices or third party pricing models that consider observable market data are considered Level 3. Currently, United considers its valuation of available-for-sale Trup Cdos as Level 3. The Fair Value Measurements and Disclosures topic assumes that fair values of financial assets are determined in an orderly transaction and not a forced liquidation or distressed sale at the measurement date. Based on financial market conditions, United feels that the fair values obtained from its third party vendor reflect forced liquidation or distressed sales for these Trup Cdos due to decreased volume and trading activity. Additionally, management held discussions with institutional traders to identify trends in the number and type of transactions related to the Trup Cdos sector. Based upon management’s review of the market conditions for Trup Cdos, it was determined that an income approach valuation technique (present value technique) that maximizes the use of relevant observable inputs and minimizes the use of unobservable inputs is more representative of fair value than the valuation technique used by United’s third party vendor. The present value technique discounts expected future cash flows of a security to arrive at a present value. Management considers the following items when calculating the appropriate discount rate: the implied rate of return when the market
	was last active, changes in the implied rate of return as markets moved from very active to inactive, recent changes in credit ratings, and recent activity showing that the market has built in increased liquidity and credit premiums. Management’s internal credit review of each security was also factored in to determine the appropriate discount rate. The credit review considered each security’s collateral, subordination, excess spread, priority of claims, principal and interest. Discount margins used in the valuation at December 31, 2013 ranged from LIBOR plus 3.75% to LIBOR plus 19.00%. Management completed a sensitivity analysis on the fair value of its Trup Cdos. Given a comprehensive 200 basis point increase in the discount rates, the total fair value of these securities would decline by approximately 17%.
	Derivatives: United utilizes interest rate swaps to hedge exposure to interest rate risk and variability of cash flows associated to changes in the underlying interest rate of the hedged item. These hedging interest rate swaps are classified as either a fair value hedge or a cash flow hedge. United’s derivative portfolio also includes derivative financial instruments not included in hedge relationships. These derivatives consist of interest rate swaps used for interest rate management purposes and derivatives executed with commercial banking customers to facilitate their interest rate management strategies. United utilizes third-party vendors for derivative valuation purposes. These vendors determine the appropriate fair value based on a net present value calculation of the cash flows related to the interest rate swaps using primarily observable market inputs such as interest rate yield curves (Level 2). Valuation adjustments to derivative fair values for liquidity and credit risk are also taken into consideration, as well as the likelihood of default by United and derivative counterparties, the net counterparty exposure and the remaining maturities of the positions. Values obtained from third party vendors are typically not adjusted by management. Management internally reviews the derivative values provided by third party vendors on a quarterly basis. All derivative values are tested for reasonableness by management utilizing a net present value calculation.
	For a fair value hedge, the fair value of the interest rate swap is recognized on the balance sheet as either a freestanding asset or liability with a corresponding adjustment to the hedged financial instrument. Subsequent adjustments due to changes in the fair value of a derivative that qualifies as a fair value hedge are offset in current period earnings either in interest income or interest expense depending on the nature of the hedged financial instrument. For a cash flow hedge, the fair value of the interest rate swap is recognized on the balance sheet as either a freestanding asset or liability with a corresponding adjustment to other comprehensive income within shareholders’ equity, net of tax. Subsequent adjustments due to changes in the fair value of a derivative that qualifies as a cash flow hedge are offset to other comprehensive income, net of tax. The portion of a hedge that is ineffective is recognized immediately in earnings.
	For derivatives that are not designated in a hedge relationship, changes in the fair value of the derivatives are recognized in earnings in the same period as the change in the fair value. Unrealized gains and losses due to changes in the fair value of other derivative financial instruments not in hedge relationship are included in noninterest income and noninterest expense, respectively.
	The following table presents the balances of financial assets and liabilities measured at fair value on a recurring basis as of December 31, 2013 and 2012, segregated by the level of the valuation inputs within the fair value hierarchy:
			Balance as of			Fair Value at December 31, 2013 Using
			December 31,
	Description		2013			Quoted Prices			Significant		Significant
						in Active			Other		Unobservable
						Markets for			Observable		Inputs
						Identical			Inputs		(Level 3)
						Assets			(Level 2)
						(Level 1)
	Assets
	Available for sale debt securities:
	U.S. Treasury securities and obligations of U.S. Government corporations and agencies			$    171,754			$            0			$    171,754		$              0
	State and political subdivisions			62,709			0			62,709		0
	Residential mortgage-backed securities
	Agency			216,464			0			216,464		0
	Non-agency			16,532			0			16,532		0
	Asset-backed securities			9,227			0			9,227		0
	Commercial mortgage-backed securities Agency			233,432			0			233,432		0
	Trust preferred collateralized debt obligations			43,449			0			0		43,449
	Single issue trust preferred securities			12,632			502			12,130		0
	Other corporate securities			5,215			0			5,215		0
	Total available for sale debt securities			771,414			502			727,463		43,449
	Available for sale equity securities:
	Financial services industry			2,292			716			1,576		0
	Equity mutual funds (1)			434			434			0		0
	Other equity securities			1,144			1,144			0		0
	Total available for sale equity securities			3,870			2,294			1,576		0
	Total available for sale securities			775,284			2,796			729,039		43,449
	Derivative financial assets:
	Interest rate contracts			3,224			0			3,224		0
	Liabilities
	Derivative financial liabilities:
	Interest rate contracts			1,194			0			1,194		0
	-1	The equity mutual funds are within a rabbi trust for the payment of benefits under a deferred compensation plan for certain key officers of United and its subsidiaries.
						Fair Value at December 31, 2012 Using
	Description		Balance as of			Quoted Prices			Significant		Significant
			December 31,			in Active			Other		Unobservable
			2012			Markets for			Observable		Inputs
						Identical			Inputs		(Level 3)
						Assets			(Level 2)
						(Level 1)
	Assets
	Available for sale debt securities:
	U.S. Treasury securities and obligations of U.S. Government corporations and agencies			$    337,522			$            0			$    337,522		$            0
	State and political subdivisions			80,428			0			80,428		0
	Residential mortgage-backed securities
	Agency			106,510			0			106,510		0
	Non-agency			25,045			0			25,045		0
	Asset-backed securities			11,709			0			11,709		0
	Trust preferred collateralized debt obligations			40,613			0			0		40,613
	Single issue trust preferred securities			12,129			499			11,630		0
	Other corporate securities			5,283			0			5,283		0
	Total available for sale debt securities			619,239			499			578,127		40,613
	Available for sale equity securities:
	Financial services industry			5,382			2,304			3,078		0
	Equity mutual funds (1)			55			55			0		0
Other equity securities			949			949			0		0
Total available for sale equity securities			6,386			3,308			3,078		0
Total available for sale securities			625,625			3,807			581,205		40,613
Derivative financial assets:
Interest rate contracts			2,367			0			2,367		0
Liabilities
Derivative financial liabilities:
Interest rate contracts			4,281			0			4,281		0
-1	The equity mutual funds are within a rabbi trust for the payment of benefits under a deferred compensation plan for certain key officers of United and its subsidiaries.
The following table presents additional information about financial assets and liabilities measured at fair value at December 31, 2013 and 2012 on a recurring basis and for which United has utilized Level 3 inputs to determine fair value:
		Available-for-sale
		Securities
(In thousands)		Trust preferred
		collateralized debt obligations
		2013			2012
Balance, beginning of year			$    40,613			$    42,369
Total gains or losses (realized/unrealized):
Included in earnings (or changes in net assets)			(6,456	)		(5,970	)
Included in other comprehensive income			14,520			4,214
Purchases, issuances, and settlements			(5,228	)		0
Transfers in and/or out of Level 3			0			0
Balance, ending of year			$ 43,449			$ 40,613
The amount of total gains or losses for the period included in earnings (or changes in net assets) attributable to the change in unrealized gains or losses relating to assets still held at reporting date			0			0
Certain financial assets are measured at fair value on a nonrecurring basis in accordance with GAAP. Adjustments to the fair value of these assets usually result from the application of lower-of-cost-or-market accounting or write-downs of individual assets.
The following describes the valuation techniques used by United to measure certain financial assets recorded at fair value on a nonrecurring basis in the financial statements.
Loans held for sale: Loans held for sale are carried at the lower of cost or market value. These loans currently consist of one-to-four family residential loans originated for sale in the secondary market. Fair value is based on the price secondary markets are currently offering for similar loans using observable market data which is not materially different than cost due to the short duration between origination and sale (Level 2). As such, United records any fair value adjustments on a nonrecurring basis. No nonrecurring fair value adjustments were recorded on loans held for sale during the year ended December 31, 2013. Gains and losses on sale of loans are recorded within income from mortgage banking on the Consolidated Statements of Income.
Impaired Loans: Loans are designated as impaired when, in the judgment of management based on current information and events, it is probable that all amounts due according to the contractual terms of the loan agreement will not be collected. Impairment is measured based upon the present value of expected future cash flows from the loan discounted at the loan’s effective rate and the loan’s observable market price or the fair value of collateral, if the loan is collateral dependent. Fair value is measured using a market approach based on the value of the collateral securing the loans. Collateral may be in the form of real estate or business assets including equipment, inventory, and accounts receivable. The vast majority of the collateral is real estate. The value of real estate collateral is determined utilizing an appraisal conducted by an independent, licensed appraiser outside of the Company using comparable property sales (Level 2). However, if the collateral is a house or building in the process of construction or if an appraisal of the real estate property is over two years old, then the fair value is considered Level 3. The value of business equipment is based upon an outside appraisal if deemed significant, or the net book value on the applicable business’ financial statements if not considered significant using observable market data. Likewise, values for inventory and accounts receivables collateral are based on financial statement balances or aging reports (Level 3). Impaired loans allocated to the Allowance for Loan Losses are measured at fair value on a nonrecurring basis. Any fair value adjustments are recorded in the period incurred as provision for credit losses expense on the Consolidated Statements of Income.
OREO: OREO consists of real estate acquired in foreclosure or other settlement of loans. Such assets are carried on the balance sheet at the lower of the investment in the assets or the fair value of the assets less estimated selling costs. Fair value is determined by one of two market approach methods depending on whether the property has been vacated and an appraisal can be conducted. If the property has yet to be vacated and thus an appraisal cannot be performed, a Brokers Price Opinion (i.e. BPO), is obtained. A BPO represents a best estimate valuation performed by a realtor based on knowledge of current property values and a visual examination of the exterior condition of the property. Once the property is subsequently vacated, a formal appraisal is obtained and the recorded asset value appropriately adjusted. On the other hand, if the OREO property has been vacated and an appraisal can be conducted, the fair value of the property is determined based upon the appraisal using a market approach. An authorized independent appraiser conducts appraisals for United. Appraisals for property other than ongoing construction are based on consideration of comparable property sales (Level 2). In contrast, valuation of ongoing construction assets requires some degree of professional judgment. In conducting an appraisal for ongoing construction property, the appraiser develops two appraised amounts: an “as is” appraised value and a “completed” value. Based on professional judgment and their knowledge of the particular situation, management determines the appropriate fair value to be utilized for such property (Level 3). As a matter of policy, valuations are reviewed at least annually and appraisals are generally updated on a bi-annual basis with values lowered as necessary.
Intangible Assets: For United, intangible assets consist of goodwill and core deposit intangibles. Goodwill is tested for impairment at least annually or sooner if indicators of impairment exist. Goodwill impairment would be defined as the difference between the recorded value of goodwill (i.e. book value) and the implied fair value of goodwill. In determining the implied fair value of goodwill for purposes of evaluating goodwill impairment, United determines the fair value of the reporting unit using a market approach and compares the fair value to its carrying value. If the carrying value exceeds the fair value, a step two test is performed whereby the implied fair value is computed by deducting the fair value of all tangible and intangible net assets from the fair value of the reporting unit. Core deposit intangibles relate to the estimated value of the deposit base of acquired institutions. Management reviews core deposit intangible assets on an annual basis, or sooner if indicators of impairment exist, and evaluates changes in facts and circumstances that may indicate impairment in the carrying value. Other than those intangible assets recorded in the acquisition of Centra, no fair value measurement of intangible assets was made during the year of 2013 and 2012.
The following table summarizes United’s financial assets that were measured at fair value on a nonrecurring basis as of December 31, 2013 and 2012:
(In thousands)		Balance as of			Fair Value at December 31, 2013 Using							YTD
		December 31,										Losses
Description		2013			Quoted Prices			Significant		Significant
					in Active			Other		Unobservable
					Markets for			Observable		Inputs
					Identical			Inputs		(Level 3)
					Assets			(Level 2)
					(Level 1)
Assets
Impaired Loans		$	45,883		$	0		$	13,081	$	32,802	$	1,886
OREO			38,182			0			38,107		75		2,548
(In thousands)		Balance as of			Fair Value at December 31, 2012 Using							YTD
		December 31,										Losses
Description		2012			Quoted Prices			Significant		Significant
					in Active			Other		Unobservable
					Markets for			Observable		Inputs
					Identical			Inputs		(Level 3)
					Assets			(Level 2)
					(Level 1)
Assets
Impaired Loans		$	50,985		$	0		$	28,947	$	22,038	$	3,238
OREO			49,484			0			45,588		3,896		3,677
The following methods and assumptions were used by United in estimating its fair value disclosures for other financial instruments:
Cash and Cash Equivalents: The carrying amounts reported in the balance sheet for cash and cash equivalents approximate those assets’ fair values.
Securities held to maturity and other securities: The estimated fair values of held to maturity are based on quoted market prices, where available. If quoted market prices are not available, fair values are measured utilizing independent valuation techniques of identical or similar securities for which significant assumptions are derived primarily from or corroborated by observable market data. Third party vendors compile prices from various sources and may determine the fair value of identical or similar securities by using pricing models that considers observable market data. Any securities held to maturity not valued based upon the methods above are valued based on a discounted cash flow methodology using appropriately adjusted discount rates reflecting nonperformance and liquidity risks. Other securities consist mainly of shares of Federal Home Loan Bank and Federal Reserve Bank stock that do not have readily determinable fair values and are carried at cost.
Loans: The fair values of certain mortgage loans (e.g., one-to-four family residential), credit card loans, and other consumer loans are based on quoted market prices of similar loans sold in conjunction with securitization transactions, adjusted for differences in loan characteristics. The fair values of other loans (e.g., commercial real estate and rental property mortgage loans, commercial and industrial loans, financial institution loans and agricultural loans) are estimated using discounted cash flow analyses, using market interest rates currently being offered for loans with similar terms to borrowers of similar creditworthiness, which include adjustments for liquidity concerns.
Deposits: The fair values of demand deposits (e.g., interest and noninterest checking, regular savings and certain types of money market accounts) are, by definition, equal to the amount payable on demand at the reporting date (i.e., their carrying amounts). The carrying amounts of variable-rate, fixed-term money market accounts and certificates of deposit approximate their fair values at the reporting date. Fair values of fixed-rate certificates of deposit are estimated using a discounted cash flow calculation that applies interest rates currently being offered on certificates to a schedule of aggregated expected monthly maturities on time deposits.
Short-term Borrowings: The carrying amounts of federal funds purchased, borrowings under repurchase agreements and other short-term borrowings approximate their fair values.
Long-term Borrowings: The fair values of United’s Federal Home Loan Bank borrowings and trust preferred securities are estimated using discounted cash flow analyses, based on United’s current incremental borrowing rates for similar types of borrowing arrangements.
The estimated fair values of United’s financial instruments are summarized below:
								Fair Value Measurements
		Carrying			Fair			Quoted Prices		Significant		Significant
		Amount			Value			in Active		Other		Unobservable
								Markets for		Observable		Inputs
								Identical		Inputs		(Level 3)
								Assets		(Level 2)
								(Level 1)
December 31, 2013
Cash and cash equivalents		$	416,617		$	416,617		$	0	$	416,617	$	0
Securities available for sale			775,284			775,284			2,796		729,039		43,449
Securities held to maturity			40,965			38,293			0		35,773		2,520
Other securities			73,093			70,072			0		0		70,072
Loans held for sale			4,236			4,236			0		4,236		0
Loans			6,630,385			6,657,376			0		0		6,657,376
Derivative financial assets			3,224			3,224			0		3,224		0
Deposits			6,621,571			6,641,070			0		6,641,070		0
Short-term borrowings			430,754			430,754			0		430,754		0
Long-term borrowings			575,697			553,796			0		553,796		0
Derivative financial liabilities			1,194			1,194			0		1,194		0
December 31, 2012
Cash and cash equivalents		$	432,077		$	432,077		$	0	$	432,077	$	0
Securities available for sale			625,625			625,625			3,807		581,205		40,613
Securities held to maturity			43,467			42,696			0		36,999		5,697
Other securities			60,310			57,643			0		0		57,643
Loans held for sale			17,762			17,762			0		17,762		0
Loans			6,437,515			6,473,974			0		0		6,473,974
Derivative financial assets			2,367			2,367			0		2,367		0
Deposits			6,752,986			6,776,012			0		6,776,012		0
Short-term borrowings			314,962			314,962			0		314,962		0
Long-term borrowings			284,926			277,899			0		277,899		0
Derivative financial liabilities			4,281			4,281			0		4,281		0

Variable_Interest_Entities

Variable Interest Entities

12 Months Ended

Dec. 31, 2013

Text Block [Abstract]

'

Variable Interest Entities

'

NOTE U--VARIABLE INTEREST ENTITIES

Variable interest entities (VIEs) are entities that either have a total equity investment that is insufficient to permit the entity to finance its activities without additional subordinated financial support or whose equity investors lack the characteristics of a controlling financial interest (i.e., ability to make significant decisions, through voting rights, right to receive the expected residual returns of the entity, and obligation to absorb the expected losses of the entity). VIEs can be structured as corporations, trusts, partnerships, or other legal entities. United’s business practices include relationships with certain VIEs. For United, the business purpose of these relationships primarily consists of funding activities in the form of issuing trust preferred securities.

United currently sponsors ten statutory business trusts that were created for the purpose of raising funds that qualify for Tier I regulatory capital. These trusts, of which several were acquired through bank acquisitions, issued or participated in pools of trust preferred capital securities to third-party investors with the proceeds invested in junior subordinated debt securities of United. The Company, through a small capital contribution, owns 100% of the voting equity shares of each trust. The assets, liabilities, operations, and cash flows of each trust are solely related to the issuance, administration, and repayment of the preferred equity securities held by third-party investors. United fully and unconditionally guarantees the obligations of each trust and is obligated to redeem the junior subordinated debentures upon maturity.

The trusts utilized in these transactions are variable interest entities (VIEs) as the third-party equity holders lack a controlling financial interest in the trusts through their inability to make decisions that have a significant effect on the operations and success of the entities. United does not consolidate these trusts as it is not the primary beneficiary of these entities because United’s equity interest does not absorb the majority of the trusts’ expected losses or receive a majority of their expected residual returns. Information related to United’s statutory trusts is presented in Note K, Notes to Consolidated Financial Statements.

The following table summarizes quantitative information about United’s significant involvement in unconsolidated VIEs:

As of December 31, 2013

As of December 31, 2012

(In thousands)

Aggregate

Aggregate

Risk Of

Aggregate

Aggregate

Risk Of

Assets

Liabilities

Loss (1)

Assets

Liabilities

Loss (1)

Trust preferred securities

$201,186

$194,453

$6,733

$201,297

$194,636

$6,661

(1)  Represents investment in VIEs.

United, through its banking subsidiaries, also makes limited partner equity investments in various low income housing and community development partnerships sponsored by independent third-parties. United invests in these partnerships to either realize tax credits on its consolidated federal income tax return or for purposes of earning a return on its investment. These partnerships are considered VIEs as the limited partners lack a controlling financial interest in the entities through their inability to make decisions that have a significant effect on the operations and success of the partnerships. United’s limited partner interests in these entities is immaterial; however, these partnerships are not consolidated as United is not deemed to be the primary beneficiary.

On July 11, 2012, a wholly-owned subsidiary of United submitted a redemption notice to the trustee of Sequoia Trust I, to redeem $5.0 million of the trust preferred securities outstanding. The Federal Reserve Board did not object to the partial redemption of the securities. The redemption was made by a cash payment on August 20, 2012 (the “Redemption Date”) equal to the redemption price of 104.581% of $5.0 million of the principal amount of the Securities (total of $5.23 million) plus any accrued and unpaid interest up to the Redemption Date. The partial redemption was funded with excess cash currently available to United.

Quarterly_Financial_Data

Quarterly Financial Data	12 Months Ended
	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]	'
Quarterly Financial Data	'
	NOTE V--QUARTERLY FINANCIAL DATA (UNAUDITED)
	Quarterly financial data for 2013 and 2012 is summarized below (dollars in thousands, except for per share data):
			1st Quarter		2nd Quarter		3rd Quarter		4th Quarter
	2013
	Interest income			$76,325		$75,485		$76,705		$77,639
	Interest expense			9,503		9,282		9,075		8,453
	Net interest income			66,822		66,203		67,630		69,186
	Provision for credit losses			5,187		4,960		4,777		4,343
	Mortgage banking income			965		739		605		262
	Securities (losses) gains, net			-694		211		101		-5,427
	Other noninterest income			18,077		18,149		17,629		17,211
	Noninterest expense			48,249		48,547		48,585		47,977
	Income taxes			10,155		9,576		10,433		9,252
	Net income (1)			21,579		22,219		22,170		19,660
	Per share data:
	Average shares outstanding (000s):
	Basic			50,302		50,346		50,379		50,417
	Diluted			50,332		50,402		50,473		50,564
	Net income per share:
	Basic			$0.43		$0.44		$0.44		$0.39
	Diluted			$0.43		$0.44		$0.44		$0.39
	Dividends per share			$0.31		$0.31		$0.31		$0.32
			1st Quarter		2nd Quarter		3rd Quarter		4th Quarter
	2012
	Interest income			$81,788		$81,105		$81,336		$79,668
	Interest expense			12,822		12,050		11,322		9,996
	Net interest income			68,966		69,055		70,014		69,672
	Provision for credit losses			4,133		3,436		4,346		5,947
	Mortgage banking income			318		483		819		851
	Securities losses, net			-1,459		-1,543		-2,188		-1,740
	Other noninterest income			17,467		17,647		18,003		17,634
	Noninterest expense			50,262		51,252		53,869		49,273
	Income taxes			9,887		9,905		9,099		9,983
	Net income (1)			21,010		21,049		19,334		21,214
	Per share data:
	Average shares outstanding (000s):
	Basic			50,235		50,275		50,276		50,276
	Diluted			50,301		50,308		50,295		50,295
	Net income per share:
	Basic			$0.42		$0.42		$0.38		$0.42
	Diluted			$0.42		$0.42		$0.38		$0.42
	Dividends per share			$0.31		$0.31		$0.31		$0.31
	(1)	For further information, see the related discussion “Quarterly Results” included in Management’s Discussion and Analysis.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2013
Accounting Policies [Abstract]	'
Nature of Operations	'
	Nature of Operations: United Bankshares, Inc. (United, the Company) is a multi-bank holding company headquartered in Charleston, West Virginia. United considers all of West Virginia to be included in its market area. This area includes the five largest West Virginia Metropolitan Statistical Areas (MSA): the Parkersburg MSA, the Charleston MSA, the Huntington MSA, the Morgantown MSA and the Wheeling MSA. United serves the Ohio counties of Lawrence, Belmont, Jefferson and Washington and Fayette county in Pennsylvania primarily because of their close proximity to the Ohio and Pennsylvania borders and United banking offices located in those counties or in nearby West Virginia. United’s Virginia markets include the Maryland, northern Virginia and Washington, D.C. MSA, the Winchester MSA, the Harrisonburg MSA, and the Charlottesville MSA. United considers all of the above locations to be the primary market area for the business of its banking subsidiaries.
Operating Segments	'
	Operating Segments: United’s business activities are confined to one reportable segment which is community banking. As a community banking entity, United offers a full range of products and services through various delivery channels.
Basis of Presentation	'
	Basis of Presentation: The consolidated financial statements and the notes to consolidated financial statements include the accounts of United Bankshares, Inc. and its wholly owned subsidiaries. All significant intercompany accounts and transactions have been eliminated in the consolidated financial statements.
	United determines whether it has a controlling financial interest in an entity by first evaluating whether the entity is a voting interest entity or a variable interest entity (VIE) under U.S. generally accepted accounting principles. Voting interest entities are entities in which the total equity investment at risk is sufficient to enable the entity to finance itself independently and provides the equity holders with the obligation to absorb losses, the right to receive residual returns and the right to make decisions about the entity’s activities. United consolidates voting interest entities in which it has all, or at least a majority of, the voting interest. As defined in applicable accounting standards, VIEs are entities that lack one or more of the characteristics of a voting interest entity. A controlling financial interest in a VIE is present when an enterprise has both the power to direct the activities of the VIE that most significantly impact the VIE’s economic performance and an obligation to absorb losses or the right to receive benefits that could potentially be significant to the VIE. The enterprise with a controlling financial interest, known as the primary beneficiary, consolidates the VIE. United’s wholly owned and indirect wholly owned statutory trust subsidiaries are VIEs for which United is not the primary beneficiary. Accordingly, its accounts are not included in United’s consolidated financial statements.
	The accounting and reporting policies of United conform with U.S. generally accepted accounting principles. In preparing the consolidated financial statements, management is required to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates. To conform to the 2013 presentation, certain reclassifications have been made to prior period amounts, which had no impact on net income, comprehensive income or shareholders’ equity. In the opinion of management, all adjustments necessary for a fair presentation of financial position and results of operations have been made. Such adjustments are of a normal and recurring nature.
	The Company has evaluated events and transactions subsequent to December 31, 2013 through the date these financial statements were issued. Based on definitions and requirements of generally accepted accounting principles for “Subsequent Events,” the Company has not identified any events that would require adjustments to, or disclosure in the financial statements other than the acquisition of Virginia Commerce Bancorp, Inc. after the close of business on January 31, 2014 (see Note B to these Notes to Consolidated Financial Statements). In addition, on February 20, 2014, United sold a former branch building for approximately $11.1 million and recognized a before-tax gain of approximately $8.9 million. A description of the significant accounting policies is presented below.
Cash and Cash Equivalents	'
	Cash and Cash Equivalents: United considers cash and due from banks, interest-bearing deposits with other banks and federal funds sold as cash and cash equivalents.
Securities	'
	Securities: Management determines the appropriate classification of securities at the time of purchase. Debt securities that United has the positive intent and the ability to hold to maturity are carried at amortized cost. Securities to be held for indefinite periods of time and all marketable equity securities are classified as available for sale and carried at estimated fair value. Unrealized gains and losses on securities classified as available for sale are carried as a separate component of Accumulated Other Comprehensive Income (Loss), net of deferred income taxes.
	Gains or losses on sales of securities are recognized by the specific identification method and are reported in securities gains and losses within noninterest income of the Consolidated Statements of Income. United reviews available-for-sale and held-to-maturity securities on a quarterly basis for possible impairment. United determines whether a decline in fair value below the amortized cost basis of a security is other-than-temporary. This determination requires significant judgment. In making this judgment, United’s review includes an analysis of the facts and circumstances of each individual investment such as the severity of loss, the length of time the fair value has been below cost, the expectation for that security’s performance, the creditworthiness of the issuer, recent changes in external credit ratings, and the assessment of collection of the security’s contractual amounts from the issuer or issuers. If United intends to sell, or it is more likely than not that United will be required to sell an impaired debt security before recovery of its amortized cost basis less any current period credit loss, other-than-temporary impairment is recognized in earnings. The credit loss is defined as the difference between the present value of cash flows expected to be collected (discounted at the contractual rate) and the amortized cost basis. The amount recognized in earnings is equal to the entire difference between the security’s amortized cost basis and its fair value at the balance sheet date. If United does not intend to sell, and it is not more likely than not that United will be required to sell the impaired debt security prior to recovery of its amortized cost basis less any current-period credit loss, the other-than-temporary impairment is separated into the following: 1) the amount representing the credit loss, which is recognized within noninterest income of the Consolidated Statements of Income, and 2) the amount related to all other factors, which is recognized in other comprehensive income within shareholders’ equity of the Consolidated Balance Sheets.
	For equity securities, United evaluates the near-term prospects of the investment in relation to the severity and duration of any impairment and United’s ability and intent to hold these equity securities until a recovery of their fair value to at least the cost basis of the investment. Equity securities that are deemed to be other-than-temporarily impaired are written down to the fair value with the write-down recognized within noninterest income of the Consolidated Statements of Income.
	Certain security investments that do not have readily determinable fair values and for which United does not exercise significant influence are carried at cost and are classified as other investment securities on the balance sheet. These cost-method investments are reviewed for impairment at least annually or sooner if events or changes in circumstances indicate the carrying value may not be recoverable.
Securities Purchased Under Resale Agreements and Securities Sold Under Agreements to Repurchase	'
	Securities Purchased Under Resale Agreements and Securities Sold Under Agreements to Repurchase: Securities purchased under agreements to resell and securities sold under agreements to repurchase are accounted for as collateralized financing transactions. They are recorded at the amounts at which the securities were acquired or sold plus accrued interest. Securities, generally U.S. government and federal agency securities, pledged as collateral under these financing arrangements cannot be repledged or sold, unless replaced, by the secured party. The fair value of the collateral either received from or provided to a third party is continually monitored and additional collateral is obtained or is requested to be returned to United as deemed appropriate.
Loans	'
	Loans: Loans are reported at the principal amount outstanding, net of unearned income. Interest on loans is accrued and credited to operations using methods that produce a level yield on individual principal amounts outstanding. Loan origination and commitment fees and related direct loan origination costs are deferred and amortized as an adjustment of loan yield over the estimated life of the related loan. Loan fees accreted and included in interest income were $7,427,000, $10,765,000 and $6,264,000 for the years of 2013, 2012 and 2011, respectively. The accrual of interest income on commercial and most consumer loans generally is discontinued when a loan becomes 90 to 120 days past due as to principal or interest. When interest accruals are discontinued, unpaid interest recognized in income in the current year is reversed, and interest accrued in prior years is charged to the allowance for loan losses. Management may elect to continue the accrual of interest when the estimated net realizable value of collateral exceeds the principal balance and accrued interest, and the loan is in the process of collection.
	Loans are designated as impaired when, in the opinion of management, based on current information and events, the collection of principal and interest in accordance with the loan contract is doubtful. Consistent with United’s existing method of income recognition for loans, interest on impaired loans, except those classified as nonaccrual, is recognized as income using the accrual method. United’s method of income recognition for impaired loans that are classified as nonaccrual is to recognize interest income on the cash basis or apply the cash receipt to principal when the ultimate collectibility of principal is in doubt.
	A loan is categorized as restructured if a significant concession is granted to provide for a reduction of either interest or principal due to a deterioration in the financial condition of the borrower. A loan classified as restructured will generally retain such classification until the loan is paid in full. However, a restructured one-to-four-family residential mortgage loan that yields a market rate and demonstrates the ability to pay under the terms of the restructured note through a sustained period of repayment performance, which is generally one year, is removed from the restructured classification. Interest income on restructured loans is accrued at the reduced rate and the loan is returned to performing status once the borrower demonstrates the ability to pay under the terms of the restructured note through a sustained period of repayment performance, which is generally six months. The portfolio of restructured loans is monitored monthly.
Loans Acquired Through Transfer	'
	Loans Acquired Through Transfer: Loans acquired through the completion of a transfer, including loans acquired in a business combination, that have evidence of deterioration of credit quality since origination and for which it is probable, at acquisition, that United will be unable to collect all contractually required payment receivable are initially recorded at fair value (as determined by the present value of expected future cash flows) with no valuation allowance. The difference between the undiscounted cash flows expected at acquisition and the investment in the loan, or the “accretable yield,” is recognized as interest income on a level-yield method over the life of the loan. Contractually required payments for interest and principal that exceed the undiscounted cash flows expected at acquisition, or the “nonaccretable difference,” are not recognized as a yield adjustment or as a loss accrual or a valuation allowance. Increases in expected cash flows subsequent to the initial investment are recognized prospectively through adjustment of the yield on the loan over its remaining life. Decreases in expected cash flows are recognized as impairment. Valuation allowances on these impaired loans reflect only losses incurred after the acquisition (meaning the present value of all cash flows expected at acquisition that ultimately are not to be received).
Loans Held for Sale	'
	Loans Held for Sale: Loans held for sale consist of one-to-four family conforming residential real estate loans originated for sale in the secondary market and carried at the lower of cost or fair value determined on an aggregate basis. Generally, United’s current practice is to sell all fixed-rate, one-to-four family conforming residential real estate loans while holding adjustable–rate loans. However, United will sell certain adjustable-rate, one-to-four family conforming residential real estate loans based on prevailing interest rate conditions and interest rate risk management needs. Gains and losses on sales of loans held for sale are included in mortgage banking income.
Allowance for Credit Losses	'
	Allowance for Credit Losses: United maintains an allowance for loan losses and a reserve for lending-related commitments such as unfunded loan commitments and letters of credit. The combined allowance for loan losses and reserve for lending-related commitments are referred to as the allowance for credit losses.
	The allowance for loan losses is management’s estimate of the probable credit losses inherent in the loan portfolio. Management’s evaluation of the adequacy of the allowance for loan losses and the appropriate provision for credit losses is based upon a quarterly evaluation of the portfolio. This evaluation is inherently subjective and requires significant estimates, including the amounts and timing of estimated future cash flows, estimated losses on pools of loans based on historical loss experience, and consideration of current economic trends, all of which are susceptible to constant and significant change. The amounts allocated to specific credits and loan pools grouped by similar risk characteristics are reviewed on a quarterly basis and adjusted as necessary based upon subsequent changes in circumstances. In determining the components of the allowance for credit losses, management considers the risk arising in part from, but not limited to, charge-off and delinquency trends, current economic and business conditions, lending policies and procedures, the size and risk characteristics of the loan portfolio, concentrations of credit, and other various factors. Loans deemed to be uncollectible are charged against the allowance for loan losses, while recoveries of previously charged-off amounts are credited to the allowance for loan losses.
	In determining the adequacy of the allowance for loan losses, management makes allocations to specific commercial loans classified by management as to risk. Management determines the loan’s risk by considering the borrowers’ ability to repay, the collateral securing the credit and other borrower-specific factors that may impact collectibility. For impaired loans, specific allocations are based on the present value of expected future cash flows using the loan’s effective interest rate, or as a practical expedient, at the loan’s observable market price or the fair value of the collateral if the loan is collateral-dependent. Other commercial loans not specifically reviewed on an individual basis are evaluated based on loan pools, which are grouped by similar risk characteristics using management’s internal risk ratings. Allocations for these commercial loan pools are determined based upon historical loss experience adjusted for current environmental conditions and risk factors. Allocations for loans, other than commercial loans, are developed by applying historical loss experience adjusted for current environmental conditions and risk factors to loan pools grouped by similar risk characteristics. The environmental factors considered for each of the loan portfolios includes estimated probable inherent but undetected losses within the portfolio due to uncertainties in economic conditions, delays in obtaining information, including unfavorable information about a borrower’s financial condition, the difficulty in identifying triggering events that correlate perfectly to subsequent loss rates, and risk factors that have not yet fully manifested themselves in loss allocation factors. While allocations are made to specific loans and pools of loans, the allowance is available for all loan losses. In addition, a portion of the allowance accounts for the inherent imprecision in the allowance for credit losses analysis. Management believes that the allowance for credit losses is adequate to provide for probable losses on existing loans and loan-related commitments based on information currently available.
Bank Premises and Equipment	'
	Bank Premises and Equipment: Bank premises and equipment are stated at cost, less allowances for depreciation and amortization. The provision for depreciation is computed principally by the straight-line method over the estimated useful lives of the respective assets. Useful lives range primarily from three to 15 years for furniture, fixtures and equipment and five to 40 years for buildings and improvements. Leasehold improvements are generally amortized over the lesser of the term of the respective leases or the estimated useful lives of the improvements.
Other Real Estate Owned	'
	Other Real Estate Owned: At December 31, 2013 and 2012, other real estate owned (OREO) included in other assets in the Consolidated Balance Sheets was $38,182,000 and $49,484,000, respectively. OREO consists of real estate acquired in foreclosure or other settlement of loans. Such assets are carried at the lower of the investment in the assets or the fair value of the assets less estimated selling costs. Any adjustment to the fair value at the date of transfer is charged against the allowance for loan losses. Any subsequent valuation adjustments as well as any costs relating to operating, holding or disposing of the property are recorded in other expense in the period incurred.
Advertising Costs	'
	Advertising Costs: Advertising costs are generally expensed as incurred and included in Other Expense on the Consolidated Statements of Income. Advertising expense was $3,777,000, $4,270,000 and $4,172,000 for the years of 2013, 2012, and 2011, respectively.
Income Taxes	'
	Income Taxes: Income tax expense is the total of the current year income tax due or refundable and the change in deferred tax assets and liabilities (excluding deferred tax assets and liabilities related to business combinations or components of other comprehensive income). Deferred tax assets and liabilities are the expected future tax amounts for the temporary differences between carrying amounts and tax bases of assets and liabilities, computed using enacted tax rates. A valuation allowance, if needed, reduces deferred tax assets to the expected amount most likely to be realized. Realization of deferred tax assets is dependent upon the generation of a sufficient level of future taxable income and recoverable taxes paid in prior years. Although realization is not assured, management believes it is more likely than not that all of the deferred tax assets will be realized. Interest and/or penalties related to income taxes are reported as a component of income tax expense.
	For uncertain income tax positions, United records a liability based on a recognition threshold of more-likely-than-not, and a measurement attribute for all tax positions taken on a tax return, in order for those tax positions to be recognized in the financial statements.
	United files a consolidated income tax return with its subsidiaries. Federal income tax expense or benefit has been allocated to subsidiaries on a separate return basis.
Intangible Assets	'
	Intangible Assets: Intangible assets relating to the estimated fair value of the deposit base of the acquired institutions are being amortized on an accelerated basis over a one to seven year period. Management reviews intangible assets on an annual basis, or sooner if indicators of impairment exist, and evaluates changes in facts and circumstances that may indicate impairment in the carrying value. United incurred amortization expense of $1,969,000, $2,852,000 and $2,429,000 in 2013, 2012, and 2011, respectively, related to all intangible assets.
	Goodwill is not amortized, but is tested for impairment at least annually or sooner if indicators of impairment exist. Intangible assets with definite useful lives (such as core deposit intangibles) are amortized over their respective estimated useful lives to their estimated residual values, and reviewed for impairment at least annually. Based on the most recent goodwill impairment test, no impairment was noted. As of December 31, 2013 and 2012, total goodwill approximated $375,547,000 and $375,583,000, respectively.
Derivative Financial Instruments	'
	Derivative Financial Instruments: United accounts for its derivative financial instruments in accordance with the Derivatives and Hedging topic of the FASB Accounting Standards Codification. The Derivatives and Hedging topic requires all derivative instruments to be carried at fair value on the balance sheet. United has designated certain derivative instruments to manage interest rate risk as hedge relationships with certain assets, liabilities or cash flows being hedged. Certain derivatives used for interest rate risk management are not designated in a hedge relationship.
	Derivative instruments designated in a hedge relationship to mitigate exposure to changes in the fair value of an asset, liability, or firm commitment attributable to a particular risk, such as interest rate risk, are considered fair value hedges. Derivative instruments designated in a hedge relationship to mitigate exposure to variability in expected future cash flows, or other types of forecasted transactions, are considered cash flow hedges.
	For a fair value hedge, the fair value of the interest rate swap is recognized on the balance sheet as either a freestanding asset or liability with a corresponding adjustment to the hedged financial instrument. Subsequent adjustments due to changes in the fair value of a derivative that qualifies as a fair value hedge are offset in current period earnings. For a cash flow hedge, the fair value of the interest rate swap is recognized on the balance sheet as either a freestanding asset or liability with a corresponding adjustment to other comprehensive income within shareholders’ equity, net of tax. Subsequent adjustments due to changes in the fair value of a derivative that qualifies as a cash flow hedge are offset to other comprehensive income, net of tax. The portion of a hedge that is ineffective is recognized immediately in earnings.
	At inception of a hedge relationship, United formally documents the hedged item, the particular risk management objective, the nature of the risk being hedged, the derivative being used, how effectiveness of the hedge will be assessed and how the ineffectiveness of the hedge will be measured. United also assesses hedge effectiveness at inception and on an ongoing basis using regression analysis. Hedge ineffectiveness is measured by using the change in fair value method. The change in fair value method compares the change in the fair value of the hedging derivative to the change in the fair value of the hedged exposure, attributable to changes in the benchmark rate. Prior to January 1, 2006, United used the shortcut method for interest rate swaps that met the criteria as defined under the Derivatives and Hedging topic. Effective January 1, 2006, United adopted an internal policy accounting for all new derivative instruments entered thereafter whereby the shortcut method would no longer be used.
	For derivatives that are not designated in a hedge relationship, changes in the fair value of the derivatives are recognized in earnings in the same period as the change in the fair value.
Stock-Based Compensation	'
	Stock-Based Compensation: Compensation expense related to stock options and restricted stock awards issued to participants is based upon the fair value of the award at the date of grant. The fair value of stock options is estimated at the date of grant using a binomial lattice option pricing model, while the fair value of restricted stock awards is based upon the stock price at the date of grant. Compensation expense is recognized on a straight line basis over the vesting period for options and the respective period for stock awards.
	Stock-based compensation expense was $1,786,000 in 2013, $1,908,000 in 2012 and $1,133,000 in 2011.
Treasury Stock	'
	Treasury Stock: United records common stock purchased for treasury at cost. At the date of subsequent reissuance, the treasury stock account is reduced by the cost of such stock using the weighted-average cost method.
Trust Assets and Income	'
	Trust Assets and Income: Assets held in a fiduciary or agency capacity for customers are not included in the balance sheets since such items are not assets of the company. Trust income is reported on an accrual basis.
Earnings Per Common Share	'
	Earnings Per Common Share: Basic earnings per common share is calculated by dividing net income by the weighted-average number of shares of common stock outstanding, excluding participating securities, for the respective period. For diluted earnings per common share, the weighted-average number of shares of common stock outstanding, excluding participating securities, for the respective period is increased by the number of shares of common stock that would be issued assuming the exercise of common stock options which have an exercise price below market price. The dilutive effect of stock options approximated 72,626 shares in 2013, 32,399 shares in 2012 and 33,931 shares in 2011. There are no other common stock equivalents.
	Under the 2011 LTI Plan, United may award restricted common shares to key employees and non-employee directors. In the first quarter of 2013 and 2012, United granted 52,825 and 52,700 restricted shares, respectively, to participants with a four-year time-based vesting period. Recipients of restricted shares do not pay any consideration to United for the shares, have the right to vote all shares subject to such grant and receive all dividends with respect to such shares, whether or not the shares have vested. Presently, these nonvested participating securities have an immaterial impact on diluted earnings per share.
	The reconciliation of the numerator and denominator of basic earnings per share with that of diluted earnings per share is presented as follows:
		Year Ended December 31
	(Dollars in thousands, except per share)	2013			2012		2011
	Distributed earnings allocated to common stock	$	62,982		$	62,286	$	56,827
	Undistributed earnings allocated to common stock		22,512			20,245		18,783
	Net earnings allocated to common shareholders	$	85,494		$	82,531	$	75,610
	Average common shares outstanding		50,353,452			50,265,620		46,803,432
	Equivalents from stock options		72,626			32,399		33,931
	Average diluted shares outstanding		50,426,078			50,298,019		46,837,363
	Earnings per basic common share	$	1.7		$	1.64	$	1.62
	Earnings per diluted common share	$	1.7		$	1.64	$	1.61
Fair Value Measurements	'
	Fair Value Measurements: United determines the fair values of its financial instruments based on the fair value hierarchy established in ASC topic 820, which also clarifies that fair value of certain assets and liabilities is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants.
	The Fair Value Measurements and Disclosures topic specifies a hierarchy of valuation techniques based on whether the inputs to those valuation techniques are observable or unobservable. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect United’s market assumptions.
	The three levels of the fair value hierarchy based on these two types of inputs are as follows:
	Level 1	-		Valuation is based on quoted prices in active markets for identical assets and liabilities.
	Level 2	-		Valuation is based on observable inputs including quoted prices in active markets for similar assets and liabilities, quoted prices for identical or similar assets and liabilities in less active markets, and model-based valuation techniques for which significant assumptions can be derived primarily from or corroborated by observable data in the market.
	Level 3	-		Valuation is based on model-based techniques that use one or more significant inputs or assumptions that are unobservable in the market.
	When determining the fair value measurements for assets and liabilities, United looks to active and observable markets to price identical assets or liabilities whenever possible and classifies such items in Level 1. When identical assets and liabilities are not traded in active markets, United looks to market observable data for similar assets and liabilities and classifies such items as Level 2. Nevertheless, certain assets and liabilities are not actively traded in observable markets and United must use alternative valuation techniques using unobservable inputs to determine a fair value and classifies such items as Level 3. For assets and liabilities that are not actively traded, the fair value measurement is based primarily upon estimates that require significant judgment. Therefore, the results may not be realized in an actual sale or immediate settlement of the asset or liability. Additionally, there are inherent weaknesses in any calculation technique, and changes in the underlying assumptions used, including discount rates and estimates of future cash flows, could significantly affect the results of current or future values. The level within the fair value hierarchy is based on the lowest level of input that is significant in the fair value measurement.
Recent Accounting Pronouncements	'
	Recent Accounting Pronouncements: In February 2013, the FASB issued ASU 2013-02, “Reporting of Amounts Reclassified out of Accumulated Other Comprehensive Income.” ASU 2013-02 is intended to improve the reporting of reclassifications out of accumulated other comprehensive income of various components. ASU 2013-02 requires entities to disclose in a single location, either on the face of financial statement that reports net income or in the notes, the effects of reclassification out of accumulated other comprehensive income (AOCI). For items reclassified out of AOCI and into net income in their entirety, such as realized gains or losses on available-for-sale securities reclassified into net income on sale, entities must disclose the effect of the reclassification on each affected net income item. For AOCI reclassification items that are not reclassified in their entirety into net income, such as actuarial gains or losses amortized into pension cost that may be capitalized into inventory or other assets, entities must provide a cross reference to other required U.S. GAAP disclosures. ASU 2013-02 was effective for United on January 1, 2013 and did not have a significant impact on the Company’s financial condition or results of operation.
	In February 2013, the FASB issued ASU 2013-04, “Obligations Resulting from Joint and Several Liability Arrangements for which the Total Amount of the Obligation is Fixed at the Reporting Date.” ASU 2013-04 addresses the recognition, measurement and disclosure of certain obligations including debt arrangements, other contractual obligations, and settled litigation and judicial ruling. In particular, ASU 2013-04 requires entities to record an obligation resulting from joint and several liability arrangements that are fixed at the reporting date at the greater of the amount that the entity has agreed to pay or the amount the entity expects to pay. The guidance applies retrospectively for obligations that exist at the beginning of an entity’s fiscal year of adoption. ASU 2013-04 is effective for United beginning January 1, 2014 and is not expected to have a significant impact on the Company’s financial condition or results of operation.

Summary_of_Significant_Account2

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2013
Accounting Policies [Abstract]	'
Reconciliation of Numerator and Denominator of Basic Earnings Per Share with that of Diluted Earnings Per Share	'
	The reconciliation of the numerator and denominator of basic earnings per share with that of diluted earnings per share is presented as follows:
		Year Ended December 31
	(Dollars in thousands, except per share)	2013		2012		2011
	Distributed earnings allocated to common stock	$	62,982	$	62,286	$	56,827
	Undistributed earnings allocated to common stock		22,512		20,245		18,783
	Net earnings allocated to common shareholders	$	85,494	$	82,531	$	75,610
	Average common shares outstanding		50,353,452		50,265,620		46,803,432
	Equivalents from stock options		72,626		32,399		33,931
	Average diluted shares outstanding		50,426,078		50,298,019		46,837,363
	Earnings per basic common share	$	1.7	$	1.64	$	1.62
	Earnings per diluted common share	$	1.7	$	1.64	$	1.61

Investment_Securities_Tables

Investment Securities (Tables)	12 Months Ended
	Dec. 31, 2013
Investments Debt And Equity Securities [Abstract]	'
Summary of Amortized Cost and Estimated Fair Values of Available for Sale Securities	'
	The following is a summary of the amortized cost and estimated fair values of securities available for sale.
			December 31, 2013
	(In thousands)				Gross			Gross		Estimated			Cumulative
			Amortized		Unrealized			Unrealized		Fair			OTTI in
			Cost		Gains			Losses		Value			AOCI (1)
	U.S. Treasury securities and obligations of U.S. Government corporations and agencies		$	172,324	$	178		$	748	$	171,754		$	0
	State and political subdivisions			60,861		1,874			26		62,709			0
	Residential mortgage-backed securities
	Agency			215,788		2,491			1,815		216,464			0
	Non-agency			16,369		163			0		16,532			458
	Commercial mortgage-backed securities
	Agency			241,947		225			8,740		233,432			0
	Asset-backed securities			9,257		1			31		9,227			0
	Trust preferred collateralized debt obligations			73,862		210			30,623		43,449			34,299
	Single issue trust preferred securities			14,346		305			2,019		12,632			0
	Other corporate securities			4,996		219			0		5,215			0
	Marketable equity securities			3,299		572			1		3,870			0
	Total		$	813,049	$	6,238		$	44,003	$	775,284		$	34,757
			December 31, 2012
	(In thousands)				Gross			Gross		Estimated			Cumulative
			Amortized		Unrealized			Unrealized		Fair			OTTI in
			Cost		Gains			Losses		Value			AOCI (1)
	U.S. Treasury securities and obligations of U.S. Government corporations and agencies		$	336,747	$	827		$	52	$	337,522		$	0
	State and political subdivisions			76,765		3,664			1		80,428			0
	Residential mortgage-backed securities
	Agency			101,769		4,741			0		106,510			0
	Non-agency			24,569		934			458		25,045			458
	Asset-backed securities			11,729		0			20		11,709			0
	Trust preferred collateralized debt obligations			94,794		5			54,186		40,613			46,522
	Single issue trust preferred securities			15,286		312			3,469		12,129			0
	Other corporate securities			4,996		287			0		5,283			0
	Marketable equity securities			6,660		257			531		6,386			0
	Total		$	673,315	$	11,027		$	58,717	$	625,625		$	46,980
	-1	Other-than-temporary impairment in accumulated other comprehensive income. Amounts are before-tax.
Summary of Securities Available for Sale in an Unrealized Loss Position	'
	The following is a summary of securities available for sale which were in an unrealized loss position at December 31, 2013 and 2012.
			Less than 12 months					12 months or longer
	(In thousands)		Fair		Unrealized			Fair		Unrealized
			Value		Losses			Value		Losses
	December 31, 2013
	U.S. Treasury securities and obligations of U.S. Government corporations and agencies		$	61,517	$	748		$	0	$	0
	State and political subdivisions			2,353		26			0		0
	Residential mortgage-backed securities
	Agency			160,835		1,815			0		0
	Commercial mortgage-backed securities
	Agency			208,979		8,740			0		0
	Asset-backed securities			7,976		31			0		0
	Trust preferred collateralized debt obligations			0		0			27,167		30,623
	Single issue trust preferred securities			502		2			8,210		2,017
	Marketable equity securities			0		0			25		1
	Total		$	442,162	$	11,362		$	35,402	$	32,641
	December 31, 2012
	U.S. Treasury securities and obligations of U.S. Government corporations and agencies		$	25,170	$	52		$	0	$	0
	State and political subdivisions			126		1			0		0
	Residential mortgage-backed securities
	Non-agency			0		0			10,879		458
	Asset-backed securities			7,993		20			0		0
	Trust preferred collateralized debt obligations			0		0			40,613		54,186
	Single issue trust preferred securities			0		0			7,221		3,469
	Marketable equity securities			603		507			313		24
	Total		$	33,892	$	580		$	59,026	$	58,137
Summary of Gains or Losses on Proceeds from Maturities, Sales and Calls of Available for Sale Securities by Specific Identification Method	'
	The realized losses relate to sales of securities within a rabbi trust for the payment of benefits under a deferred compensation plan for certain key officers and its subsidiaries.
			Year Ended
	(In thousands)		2013		2012			2011
	Proceeds from maturities, sales and calls		$	698,264	$	1,996,547		$	1,486,936
	Gross realized gains			1,259		157			1,729
	Gross realized losses			43		141			311
Summary of Unrealized Loss Positions of Available for Sale TRUP CDOs and Single Issue Trust Preferred Securities	'
	The following is a summary of the available for sale Trup Cdos and single issue trust preferred securities in an unrealized loss position twelve months or greater as of December 31, 2013.
										Amortized Cost
	Class		Amortized		Fair			Unrealized		Investment			Split		Below
			Cost		Value			Loss		Grade			Rated		Investment
															Grade
			(In thousands)
	Senior – Bank		$	8,485	$	6,150		$	2,335	$	0		$	5,000	$	3,485
	Senior – Insurance			6,577		6,577			0		6,577			0		0
	Mezzanine – Bank (now in senior position)			13,741		8,929			4,812		0			0		13,741
	Mezzanine – Bank			34,583		14,501			20,082		0			0		34,583
	Mezzanine – Insurance			5,330		5,330			0		0			0		5,330
	Mezzanine – Bank & Insurance (combination)			5,146		1,962			3,184		0			0		5,146
	Totals		$	73,862	$	43,449		$	30,413	$	6,577		$	5,000	$	62,285
Roll Forward of Credit Losses on Securities	'
	Below is a progression of the credit losses on securities which United has recorded other-than-temporary charges. These charges were recorded through earnings and other comprehensive income.
	(In thousands)
	Balance of cumulative credit losses at December 31, 2012		$	63,114
	Additions for credit losses on securities for which OTTI was not previously recognized			1,267
	Additions for additional credit losses on securities for which OTTI was previously recognized			6,065
	Balance of cumulative credit losses at December 31, 2013		$	70,446
Summary of Maturities of Securities Available for Sale by Amortized Cost and Estimated Fair Value	'
	The amortized cost and estimated fair value of securities available for sale at December 31, 2013 by contractual maturity are shown below. Expected maturities may differ from contractual maturities because the issuers may have the right to call or prepay obligations without penalties.
	Maturities of mortgage-backed securities with an amortized cost of $474,104,000 and an estimated fair value of $466,428,000 at December 31, 2013 are included below based upon contractual maturity.
					Estimated
	(In thousands)		Amortized		Fair
			Cost		Value
	Due in one year or less		$	28,837	$	28,960
	Due after one year through five years			217,415		218,498
	Due after five years through ten years			292,460		286,534
	Due after ten years			271,038		237,422
	Marketable equity securities			3,299		3,870
	Total		$	813,049	$	775,284
Summary of Amortized Cost and Estimated Fair Values of Securities Held to Maturity	'
	The following is a summary of the amortized cost and estimated fair values of securities held to maturity.
			December 31, 2013
	(In thousands)				Gross			Gross		Estimated
			Amortized		Unrealized			Unrealized		Fair
			Cost		Gains			Losses		Value
	U.S. Treasury securities and obligations of U.S. Government corporations and agencies		$	10,762	$	1,689		$	0	$	12,451
	State and political subdivisions			10,367		37			299		10,105
	Residential mortgage-backed securities
	Agency			50		9			0		59
	Single issue trust preferred securities			19,766		0			4,108		15,658
	Other corporate securities			20		0			0		20
	Total		$	40,965	$	1,735		$	4,407	$	38,293
			December 31, 2012
	(In thousands)				Gross			Gross		Estimated
			Amortized		Unrealized			Unrealized		Fair
			Cost		Gains			Losses		Value
	U.S. Treasury securities and obligations of U.S. Government corporations and agencies		$	10,916	$	2,500		$	0	$	13,416
	State and political subdivisions			12,515		108			0		12,623
	Residential mortgage-backed securities
	Agency			61		10			0		71
	Single issue trust preferred securities			19,750		0			3,390		16,360
	Other corporate securities			225		0			0		225
	Total		$	43,467	$	2,618		$	3,390	$	42,695
Summary of Gross Realized Gains and Losses on Calls and Sales of Held to Maturity Securities Included in Earnings	'
	The following table shows the gross realized gains and losses on calls and sales of held to maturity securities that have been included in earnings as a result of those calls and sales. Gains or losses on calls of held to maturity securities are recognized by the specific identification method.
			Year Ended
	(In thousands)		2013		2012			2011
	Gross realized gains		$	114	$	352		$	1
	Gross realized losses			0		0			0
Summary of Maturities of Debt Securities Held to Maturity by Amortized Cost and Estimated Fair Value	'
	The amortized cost and estimated fair value of debt securities held to maturity at December 31, 2013 by contractual maturity are shown below. Expected maturities may differ from contractual maturities because the issuers may have the right to call or prepay obligations with or without call or prepayment penalties.
	Maturities of mortgage-backed securities with an amortized cost of $50,000 and an estimated fair value of $59,000 at December 31, 2013 are included below based upon contractual maturity.
					Estimated
	(In thousands)		Amortized		Fair
			Cost		Value
	Due in one year or less		$	555	$	556
	Due after one year through five years			6,683		7,312
	Due after five years through ten years			13,026		13,821
	Due after ten years			20,701		16,604
	Total		$	40,965	$	38,293
Maturities and Weighted-Average Yields of Securities	'
	The following table sets forth the maturities of all securities (based on amortized cost) at December 31, 2013, and the weighted-average yields of such securities (calculated on the basis of the cost and the effective yields weighted for the scheduled maturity of each security).
								After 1 But					After 5 But
	(Dollars in thousands)		Within 1 Year					Within 5 Years					Within 10 Years					After 10 Years
			Amount		Yield			Amount		Yield			Amount		Yield			Amount		Yield
	U.S. Treasury and other U.S. Government agencies and corporations		$	14,998		0.26	%	$	117,261		1.06	%	$	50,826		1.12	%	$	0		0	%
	States and political subdivisions (1)			14,383		4.07	%		28,895		5.66	%		24,037		6.38	%		3,912		6.78	%
	Residential mortgage-backed securities
	Agency			12		6	%		7,130		3.56	%		45,918		3.73	%		162,778		2.34	%
	Non-agency			0		0	%		443		4.58	%		6,872		5.02	%		9,054		5.82	%
	Commercial mortgage-backed
	Agency			0		0	%		54,449		1.19	%		179,499		2.21	%		7,999		2.75	%
	Asset-backed securities			0		0	%		8,008		0.69	%		1,249		0.35	%		0		0	%
	Trust preferred collateralized debt obligations			0		0	%		0		0	%		0		0	%		73,862		4.58	%
	Single issue trust preferred securities			0		0	%		0		0	%		0		0	%		34,112		2.4	%
	Marketable equity securities			0		0	%		0		0	%		0		0	%		3,299		2.47	%
	Other Corporate securities			0		0	%		4,996		2.73	%		0		0	%		20		0	%
	-1	Tax-equivalent adjustments (using a 35% federal rate) have been made in calculating yields on obligations of states and political subdivisions.

Loans_Tables

Loans (Tables)	12 Months Ended
	Dec. 31, 2013
Receivables [Abstract]	'
Classes of Loans	'
	Major classes of loans are as follows:
		December 31
	(In thousands)	2013			2012
	Commercial, financial, and agricultural
	Owner-occupied	$	654,963		$	728,906
	Nonowner-occupied		1,917,785			1,740,420
	Other commercial		1,338,355			1,377,083
	Total commercial, financial & agricultural		3,911,103			3,846,409
	Residential real estate		1,821,378			1,838,252
	Construction & land development		670,364			550,677
	Consumer:
	Bankcard		11,023			11,236
	Other Consumer		299,731			271,206
	Less: Unearned interest		(9,016	)		(6,364	)
	Total Loans, net of unearned interest	$	6,704,583		$	6,511,416
Activity for Accretable Yield	'
	Activity for the accretable yield for the year of 2013 follows.
	(In thousands)
	Accretable yield at the beginning of the period	$	2,331
	Accretion (including cash recoveries)		(3,192	)
	Net reclassifications to accretable from non-accretable		3,373
	Disposals (including maturities, foreclosures, and charge-offs)		(261	)
	Accretable yield at the ending of the period	$	2,251

Credit_Quality_Tables

Credit Quality (Tables)	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
Schedule of Troubled Debt Restructurings, Segregated by Class of Loans	'
	The following table sets forth United’s troubled debt restructurings that have been restructured during the year ended December 31, 2013 and 2012, segregated by class of loans:
	Troubled Debt Restructurings
	For the Year Ended December 31, 2013
	(In thousands)	Number of		Pre-Modification		Post-Modification
		Contracts		Outstanding		Outstanding
				Recorded Investment		Recorded Investment
	Commercial real estate:
	Owner-occupied		4	$	5,143	$	4,561
	Nonowner-occupied		2		762		757
	Other commercial		0		0		0
	Residential real estate		1		105		104
	Construction & land development		0		0		0
	Consumer:
	Bankcard		0		0		0
	Other consumer		0		0		0
	Total		7	$	6,010	$	5,422
	Troubled Debt Restructurings
	For the Year Ended December 31, 2012
	(In thousands)	Number of		Pre-Modification		Post-Modification
		Contracts		Outstanding		Outstanding
				Recorded Investment		Recorded Investment
	Commercial real estate:
	Owner-occupied		0	$	0	$	0
	Nonowner-occupied		0		0		0
	Other commercial		0		0		0
	Residential real estate		1		640		651
	Construction & land development		1		731		375
	Consumer:
	Bankcard		0		0		0
	Other consumer		0		0		0
	Total		2	$	1,371	$	1,026
Schedule of Charged-off Troubled Debt Restructurings on Financing Receivables	'
	The following table presents troubled debt restructurings, by class of loan, that had charge-offs during the years ended December 31, 2013 and 2012.
		Year Ended				Year Ended
		December 31, 2013				December 31, 2012
	(In thousands)	Number of		Recorded		Number of		Recorded
		Contracts		Investment		Contracts		Investment
	Troubled Debt Restructurings
	Commercial real estate:		0	$	0		0	$	0
	Owner-occupied		0		0		0		0
	Nonowner-occupied		0		0		0		0
	Other commercial		0		0		0		0
	Residential real estate		0		0		0		0
	Construction & land development		1		375		1		375
	Consumer:		0		0		0		0
	Bankcard		0		0		0		0
	Other consumer		0		0		0		0
	Total		1	$	375		1	$	375
Schedule of Age Analysis of its Past Due Loans, Segregated by Class of Loans	'
	The following table sets forth United’s age analysis of its past due loans, segregated by class of loans:
	Age Analysis of Past Due Loans
	As of December 31, 2013
	(In thousands)	30-89		90 Days		Total Past		Current		Total		Recorded
		Days Past		or more		Due				Financing		Investment
		Due		Past Due						Receivables		>90 Days
												& Accruing
	Commercial real estate:
	Owner-occupied	$	14,144	$	4,537	$	18,681	$	636,282	$	654,963	$	1,383
	Nonowner-occupied		30,836		11,725		42,561		1,875,224		1,917,785		186
	Other commercial		54,319		11,794		66,113		1,272,242		1,338,355		896
	Residential real estate		54,271		25,446		79,717		1,741,661		1,821,378		5,214
	Construction & land development		9,921		18,491		28,412		641,952		670,364		1,611
	Consumer:
	Bankcard		229		128		357		10,666		11,023		128
	Other consumer		9,466		1,712		11,178		288,553		299,731		1,626
	Total	$	173,186	$	73,833	$	247,019	$	6,466,580	$	6,713,599	$	11,044
	Age Analysis of Past Due Loans
	As of December 31, 2012
	(In thousands)	30-89		90 Days		Total Past		Current		Total		Recorded
		Days Past		or more		Due				Financing		Investment
		Due		Past Due						Receivables		>90 Days
												& Accruing
	Commercial real estate:
	Owner-occupied	$	11,122	$	16,691	$	27,813	$	701,093	$	728,906	$	4,038
	Nonowner-occupied		12,793		11,643		24,436		1,715,984		1,740,420		2,549
	Other commercial		8,379		20,808		29,187		1,347,896		1,377,083		1,687
	Residential real estate		54,168		22,095		76,263		1,761,989		1,838,252		7,363
	Construction & land development		14,046		16,918		30,964		519,713		550,677		654
	Consumer:
	Bankcard		394		164		558		10,678		11,236		164
	Other consumer		8,738		1,683		10,421		260,785		271,206		1,613
	Total	$	109,640	$	90,002	$	199,642	$	6,318,138	$	6,517,780	$	18,068
Schedule of Nonaccrual Loans, Segregated by Class of Loans	'
	The following table sets forth United’s nonaccrual loans, segregated by class of loans:
	Loans on Nonaccrual Status
	(In thousands)	December 31,		December 31,
		2013		2012
	Commercial real estate:
	Owner-occupied	$	3,154	$	12,653
	Nonowner-occupied		11,539		9,094
	Other commercial		10,898		19,121
	Residential real estate		20,232		14,732
	Construction & land development		16,880		16,264
	Consumer:
	Bankcard		0		0
	Other consumer		86		70
	Total	$	62,789	$	71,934
Schedule of Credit Quality Indicators Information, by Class of Loans	'
	The following tables set forth United’s credit quality indicators information, by class of loans:
	Credit Quality Indicators
	Corporate Credit Exposure
	As of December 31, 2013
		Commercial Real Estate
	(In thousands)	Owner-		Nonowner-		Other		Construction
		occupied		occupied		Commercial		& Land
								Development
	Grade:
	Pass	$	604,129	$	1,811,915	$	1,206,030	$	510,911
	Special mention		27,576		45,617		60,668		63,375
	Substandard		23,258		60,253		71,148		96,078
	Doubtful		0		0		509		0
	Total	$	654,963	$	1,917,785	$	1,338,355	$	670,364
	Credit Quality Indicators
	Corporate Credit Exposure
	As of December 31, 2012
		Commercial Real Estate
	(In thousands)	Owner-		Nonowner-		Other		Construction
		occupied		occupied		Commercial		& Land
								Development
	Grade:
	Pass	$	669,157	$	1,621,338	$	1,286,471	$	392,096
	Special mention		25,487		54,399		31,293		92,667
	Substandard		34,262		64,683		57,386		65,914
	Doubtful		0		0		1,933		0
	Total	$	728,906	$	1,740,420	$	1,377,083	$	550,677
	Credit Quality Indicators
	Consumer Credit Exposure
	As of December 31, 2013
	(In thousands)	Residential		Bankcard		Other
		Real Estate				Consumer
	Grade:
	Pass	$	1,773,244	$	10,666	$	288,401
	Special mention		13,006		229		9,466
	Substandard		35,128		128		1,712
	Doubtful		0		0		152
	Total	$	1,821,378	$	11,023	$	299,731
	As of December 31, 2012
	(In thousands)	Residential		Bankcard		Other
		Real Estate				Consumer
	Grade:
	Pass	$	1,800,377	$	10,678	$	271,054
	Special mention		7,866		394		0
	Substandard		30,009		164		152
	Doubtful		0		0		0
	Total	$	1,838,252	$	11,236	$	271,206
Schedule of Impaired Loans Information by Class of Loans	'
	The following table set forth United’s impaired loans information, by class of loans:
		Impaired Loans
		December 31, 2013						December 31, 2012
	(In thousands)	Recorded		Unpaid		Related		Recorded		Unpaid		Related
		Investment		Principal		Allowance		Investment		Principal		Allowance
				Balance						Balance
	With no related allowance recorded:
	Commercial real estate:
	Owner-occupied	$	4,672	$	4,672	$	0	$	15,591	$	16,279	$	0
	Nonowner-occupied		5,938		6,651		0		10,907		14,601		0
	Other commercial		10,292		17,753		0		3,036		5,501		0
	Residential real estate		12,009		12,193		0		7,035		9,157		0
	Construction & land development		13,866		14,662		0		7,682		10,089		0
	Consumer:
	Bankcard		0		0		0		0		0		0
	Other consumer		0		0		0		152		152		0
	With an allowance recorded:
	Commercial real estate:
	Owner-occupied	$	4,358	$	4,358	$	638	$	1,284	$	1,284	$	397
	Nonowner-occupied		9,350		10,563		1,631		3,423		4,423		1,154
	Other commercial		13,304		16,240		2,192		27,610		30,411		7,564
	Residential real estate		7,669		8,191		4,112		5,635		7,028		1,427
	Construction & land development		11,050		14,833		3,752		13,033		17,029		3,659
	Consumer:
	Bankcard		0		0		0		0		0		0
	Other consumer		152		152		152		0		0		0
	Total:
	Commercial real estate:
	Owner-occupied	$	9,030	$	9,030	$	638	$	16,875	$	17,563	$	397
	Nonowner-occupied		15,288		17,214		1,631		14,330		19,024		1,154
	Other commercial		23,596		33,993		2,192		30,646		35,912		7,564
	Residential real estate		19,678		20,384		4,112		12,670		16,185		1,427
	Construction & land development		24,916		29,495		3,752		20,715		27,118		3,659
	Consumer:
	Bankcard		0		0		0		0		0		0
	Other consumer		152		152		152		152		152		0
		Impaired Loans
		For the Year Ended
		December 31, 2013				December 31, 2012
	(In thousands)	Average		Interest		Average		Interest
		Recorded		Income		Recorded		Income
		Investment		Recognized		Investment		Recognized
	With no related allowance recorded:
	Commercial real estate:
	Owner-occupied	$	11,379	$	242	$	12,160	$	770
	Nonowner-occupied		10,168		194		23,393		431
	Other commercial		11,550		1,828		5,208		178
	Residential real estate		9,211		358		10,982		418
	Construction & land development		9,305		373		18,104		285
	Consumer:
	Bankcard		0		0		0		0
	Other consumer		114		0		165		0
	With an allowance recorded:
	Commercial real estate:
	Owner-occupied	$	2,543	$	159	$	1,151	$	51
	Nonowner-occupied		6,352		289		3,477		67
	Other commercial		16,129		286		26,240		1,969
	Residential real estate		6,009		283		8,989		380
	Construction & land development		13,393		58		12,904		322
	Consumer:
	Bankcard		0		0		0		0
	Other consumer		38		0		0		0
	Total:
Commercial real estate:
Owner-occupied	$	13,922	$	401	$	13,311	$	821
Nonowner-occupied		16,520		483		26,870		498
Other commercial		27,679		2,114		31,448		2,147
Residential real estate		15,220		641		19,971		798
Construction & land development		22,698		431		31,008		607
Consumer:
Bankcard		0		0		0		0
Other consumer		152		0		165		0

Allowance_for_Credit_Losses_Ta

Allowance for Credit Losses (Tables)	12 Months Ended
	Dec. 31, 2013
Receivables [Abstract]	'
Progression of Allowance for Credit Losses Including Allowance for Credit Losses and Reserve for Lending-Related Commitments	'
	A progression of the allowance for credit losses, which includes the allowance for credit losses and the reserve for lending-related commitments, for the periods presented is summarized as follows:
		Year Ended December 31
	(In thousands)	2013		2012			2011
	Balance at beginning of period	$	75,557	$	75,727		$	75,039
	Provision for credit losses		19,754		17,665			16,988
			95,311		93,392			92,027
	Loans charged off		21,006		20,555			19,605
	Less recoveries		2,036		2,720			3,305
	Net charge-offs		18,970		17,835			16,300
	Balance at end of period	$	76,341	$	75,557		$	75,727
Schedule of Allowance for Loan Losses and Carrying Amount of Loans	'
	A progression of the allowance for loan losses, by portfolio segment, for the year ended December 31, 2013 and 2012 is summarized as follows:
	Allowance for Loan Losses and Carrying Amount of Loans
	For the Year Ended December 31, 2013
	(In thousands)	Commercial Real Estate					Other		Residential		Construction		Consumer		Allowance			Total
							Commercial		Real Estate		& Land				for
											Development				Estimated
		Owner-		Nonowner-											Imprecision
		occupied		occupied
	Allowance for Loan Losses:
	Beginning balance	$	3,877	$	12,876		$	20,511	$	14,895	$	18,858	$	2,620	$	264		$	73,901
	Charge-offs		5,344		1,164			7,699		4,111		896		1,792		0			21,006
	Recoveries		150		56			641		698		73		418		0			2,036
	Provision		6,970		(2,776	)		7,464		5,212		918		1,699		(220	)		19,267
	Ending balance	$	5,653	$	8,992		$	20,917	$	16,694	$	18,953	$	2,945	$	44		$	74,198
	Ending Balance: individually evaluated for impairment	$	638	$	1,631		$	2,192	$	4,112	$	3,752	$	152	$	0		$	12,477
	Ending Balance: collectively evaluated for impairment	$	5,015	$	7,361		$	18,725	$	12,582	$	15,201	$	2,793	$	44		$	61,721
	Ending Balance: loans acquired with deteriorated credit quality	$	0	$	0		$	0	$	0	$	0	$	0	$	0		$	0
	Financing receivables:
	Ending balance	$	654,963	$	1,917,785		$	1,338,355	$	1,821,378	$	670,364	$	310,754	$	0		$	6,713,599
	Ending Balance: individually evaluated for impairment	$	7,157	$	13,913		$	22,327	$	16,160	$	21,593	$	152	$	0		$	81,302
	Ending Balance: collectively evaluated for impairment	$	646,548	$	1,894,421		$	1,314,543	$	1,802,686	$	632,407	$	310,593	$	0		$	6,601,198
	Ending Balance: loans acquired with deteriorated credit quality	$	1,258	$	9,451		$	1,485	$	2,532	$	16,364	$	9	$	0		$	31,099
	Allowance for Loan Losses and Carrying Amount of Loans
	For the Year Ended December 31, 2012
	(In thousands)	Commercial Real Estate					Other		Residential		Construction		Consumer		Allowance			Total
							Commercial		Real Estate		& Land				for
											Development				Estimated
		Owner-		Nonowner-											Imprecision
		occupied		occupied
	Allowance for Loan Losses:
	Beginning balance	$	3,670	$	11,647		$	20,803	$	13,880	$	19,151	$	2,151	$	2,572		$	73,874
	Charge-offs		801		2,608			3,619		8,882		3,099		1,546		0			20,555
	Recoveries		60		122			1,362		821		54		301		0			2,720
	Provision		948		3,715			1,965		9,076		2,752		1,714		(2,308	)		17,862
	Ending balance	$	3,877	$	12,876		$	20,511	$	14,895	$	18,858	$	2,620	$	264		$	73,901
	Ending Balance: individually evaluated for impairment	$	417	$	1,154		$	7,564	$	996	$	3,659	$	0	$	0		$	13,790
	Ending Balance: collectively evaluated for impairment	$	3,460	$	11,722		$	12,947	$	13,899	$	15,199	$	2,620	$	264		$	60,111
	Ending Balance: loans acquired with deteriorated credit quality	$	0	$	0		$	0	$	0	$	0	$	0	$	0		$	0
	Financing receivables:
	Ending balance	$	728,906	$	1,740,420		$	1,377,083	$	1,838,252	$	550,677	$	282,442	$	0		$	6,517,780
	Ending Balance: individually evaluated for impairment	$	14,474	$	12,101		$	28,997	$	8,541	$	17,827	$	0	$	0		$	81,940
	Ending Balance: collectively evaluated for impairment	$	712,776	$	1,718,913		$	1,346,600	$	1,826,196	$	515,718	$	282,431	$	0		$	6,402,634
	Ending Balance: loans acquired with deteriorated credit quality	$	1,656	$	9,406		$	1,486	$	3,515	$	17,132	$	11	$	0		$	33,206

Bank_Premises_and_Equipment_an1

Bank Premises and Equipment and Leases (Tables)	12 Months Ended
	Dec. 31, 2013
Property Plant And Equipment [Abstract]	'
Bank Premises and Equipment	'
	Bank premises and equipment are summarized as follows:
		December 31
	(In thousands)	2013		2012
	Land	$	23,018	$	23,166
	Buildings and improvements		83,144		80,997
	Leasehold improvements		22,092		20,906
	Furniture, fixtures and equipment		49,697		46,843
			177,951		171,912
	Less allowance for depreciation and amortization		108,054		99,742
	Net bank premises and equipment	$	69,897	$	72,170
Future Minimum Lease Payments	'
	Future minimum lease payments, by year and in the aggregate, under noncancelable operating leases with initial or remaining terms of one year or more, for years subsequent to December 31, 2013, consisted of the following:
	Year	Amount
	(In thousands)
	2014	$	8,181
	2015		6,903
	2016		6,030
	2017		5,606
	2018		5,644
	Thereafter		11,292
	Total minimum lease payments	$	43,656

Goodwill_and_Other_Intangibles1

Goodwill and Other Intangibles (Tables)	12 Months Ended
	Dec. 31, 2013
Goodwill And Intangible Assets Disclosure [Abstract]	'
Summary of Intangible Assets	'
	The following is a summary of intangible assets subject to amortization and those not subject to amortization:
		As of December 31, 2013
	(In thousands)	Gross Carrying		Accumulated			Net Carrying
		Amount		Amortization			Amount
	Amortized intangible assets:
	Core deposit intangible assets	$	43,434	$	(35,296	)	$	8,138
	Goodwill not subject to amortization						$	375,547
		As of December 31, 2012
		Gross Carrying		Accumulated			Net Carrying
		Amount		Amortization			Amount
	Amortized intangible assets:
	Core deposit intangible assets	$	43,434	$	(33,327	)	$	10,107
	Goodwill not subject to amortization						$	375,583
Schedule of Anticipated Amortization Expense	'
	The following table sets forth the anticipated amortization expense for intangible assets for the years subsequent to 2013:
	Year	Amount
	(In thousands)
	2014	$	1,478
	2015		1,149
	2016		1,089
	2017		1,047
	2018 and thereafter		3,375

Deposits_Tables

Deposits (Tables)	12 Months Ended
	Dec. 31, 2013
Banking And Thrift [Abstract]	'
Book Value of Deposits	'
	The book value of deposits consisted of the following:
	(Dollars in thousands)	December 31
		2013		2012
	Demand deposits	$	1,874,520	$	1,824,411
	Interest-bearing checking		1,195,956		1,210,463
	Regular savings		556,183		523,336
	Money market accounts		1,224,116		1,203,341
	Time deposits under $100,000		887,516		1,035,815
	Time deposits over $100,000		883,280		955,620
	Total deposits	$	6,621,571	$	6,752,986

ShortTerm_Borrowings_Tables

Short-Term Borrowings (Tables)	12 Months Ended
	Dec. 31, 2013
Funds Purchased and Securities Sold Under Agreements to Repurchase and Weighted-Average Interest Rates	'
	At December 31, 2013 and 2012, short-term borrowings and the related weighted-average interest rates were as follows:
		2013					2012
	(Dollars in thousands)	Amount		Weighted-			Amount		Weighted-
				Average					Average
				Rate					Rate
	Federal funds purchased	$	27,685		0.2	%	$	5,446		0.2	%
	Securities sold under agreements to repurchase		188,069		0.09	%		209,516		0.09	%
	Total	$	215,754				$	214,962
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Member]	'
Funds Purchased and Securities Sold Under Agreements to Repurchase and Weighted-Average Interest Rates	'
	The following table shows the distribution of United’s federal funds purchased and securities sold under agreements to repurchase and the weighted-average interest rates thereon at the end of each of the last three years. Also provided are the maximum amount of borrowings and the average amounts of borrowings as well as weighted-average interest rates for the last three years.
	(Dollars in thousands)	Federal		Securities Sold
		Funds		Under
		Purchased		Agreements
				To Repurchase
	At December 31:
	2013		$  27,685		$  188,069
	2012		5,446		209,516
	2011		7,120		247,646
	Weighted-average interest rate at year-end:
	2013		0.20%		0.09%
	2012		0.20%		0.09%
	2011		0.20%		0.07%
	Maximum amount outstanding at any month’s end:
	2013		$  27,685		$  220,155
	2012		23,100		273,041
	2011		20,440		274,546
	Average amount outstanding during the year:
	2013		$  12,595		$  199,823
	2012		16,314		261,558
	2011		13,377		242,371
	Weighted-average interest rate during the year:
	2013		0.20%		0.10%
	2012		0.20%		0.08%
	2011		0.21%		0.06%

LongTerm_Borrowings_Tables

Long-Term Borrowings (Tables)	12 Months Ended
	Dec. 31, 2013
Debt Disclosure [Abstract]	'
FHLB Advances and Related Weighted Average Interest Rates	'
	At December 31, 2013 and 2012, FHLB advances and the related weighted-average interest rates were as follows:
		2013										2012
	(Dollars in thousands)	Amount				Weighted-			Weighted-			Amount			Weighted-			Weighted-
						Average			Average						Average			Average
						Contractual			Effective						Contractual			Effective
						Rate			Rate						Rate			Rate
	FHLB advances	$	592,069				0.56	%		0.56	%	$	186,411			2.17	%		2.17	%
Tier One Regulatory Capital	'
	Information related to United’s statutory trusts is presented in the table below:
	(Dollars in thousands)	Issuance Date		Amount of				Interest Rate	Maturity Date
	Description			Capital
				Securities
				Issued
	Century Trust	23-Mar-00		$	8,800			10.875% Fixed		8-Mar-30
	Sequoia Trust I	March 28, 2001		$	2,000			10.18% Fixed		8-Jun-31
	United Statutory Trust III	17-Dec-03		$	20,000			3-month LIBOR + 2.85%		17-Dec-33
	United Statutory Trust IV	19-Dec-03		$	25,000			3-month LIBOR + 2.85%		23-Jan-34
	United Statutory Trust V	12-Jul-07		$	50,000			3-month LIBOR + 1.55%		1-Oct-37
	United Statutory Trust VI	20-Sep-07		$	30,000			3-month LIBOR + 1.30%		15-Dec-37
	Premier Statutory Trust II	September 25, 2003		$	6,000			3-month LIBOR + 3.10%		8-Oct-33
	Premier Statutory Trust III	16-May-05		$	8,000			3-month LIBOR + 1.74%		15-Jun-35
	Premier Statutory Trust IV	20-Jun-06		$	14,000			3-month LIBOR + 1.55%		September 23, 2036
	Premier Statutory Trust V	14-Dec-06		$	10,000			3-month LIBOR + 1.61%		1-Mar-37
	Centra Statutory Trust I	20-Sep-04		$	10,000			3-month LIBOR + 2.29%		20-Sep-34
	Centra Statutory Trust II	15-Jun-06		$	10,000			3-month LIBOR + 1.65%		7-Jul-36
Debentures and Related Weighted Average Interest Rates	'
	At December 31, 2013 and 2012, the Debentures and their related weighted-average interest rates were as follows:
		2013							2012
	(Dollars in thousands)	Amount				Weighted-			Amount			Weighted-
						Average						Average
						Rate						Rate
	Century Trust	$	8,800				10.88	%	$	8,800			10.88	%
	Sequoia Trust I		2,065				10.18	%		2,064			10.18	%
	United Statutory Trust III		20,619				3.1	%		20,619			3.16	%
	United Statutory Trust IV		25,774				3.09	%		25,774			3.16	%
	United Statutory Trust V		51,547				1.8	%		51,547			1.91	%
	United Statutory Trust VI		30,928				1.54	%		30,928			1.61	%
	Premier Statutory Trust II		6,186				3.34	%		6,186			3.44	%
	Premier Statutory Trust III		8,248				1.98	%		8,248			2.05	%
	Premier Statutory Trust IV		14,433				1.8	%		14,433			1.86	%
	Premier Statutory Trust V		10,310				1.85	%		10,310			1.92	%
	Centra Statutory Trust I		9,859				2.54	%		9,803			2.6	%
	Centra Statutory Trust II		9,859				1.89	%		9,803			1.99	%
	Total	$	198,628						$	198,515
Schedule of Maturities of FHLB Borrowings	'
	At December 31, 2013, the scheduled maturities of long-term borrowings were as follows:
	Year	Amount
	(In thousands)
	2014	$	321,388
	2015		4,395
	2016		622
	2017		383
	2018 and thereafter		248,909
	Total	$	575,697

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2013
Income Tax Disclosure [Abstract]	'
Income Tax Provisions Included in the Consolidated Statements of Income	'
	The income tax provisions included in the consolidated statements of income are summarized as follows:
	(In thousands)	Year Ended December 31
		2013		2012		2011
	Current expense:
	Federal	$	32,378	$	37,623	$	23,341
	State		4,048		914		518
	Deferred expense:
	Federal and State		2,990		337		10,907
	Total income taxes	$	39,416	$	38,874	$	34,766
Reconciliation of Income Tax Expense to the Amount Computed by Applying the Statutory Federal Income Tax Rate	'
	The following is a reconciliation of income tax expense to the amount computed by applying the statutory federal income tax rate to income before income taxes.
		Year Ended December 31
	(Dollars in thousands)	2013				2012				2011
		Amount		%		Amount		%		Amount		%
	Tax on income before taxes	$	43,765		35.00%	$	42,519		35.00%	$	38,632		35.0%
	at statutory federal rate
	Plus: State income taxes		2,392		1.9		594		0.5		336		0.3
	net of federal tax benefits
			46,157		36.9		43,113		35.5		38,968		35.3
	Increase (decrease) resulting from:
	Tax-exempt interest income		-3,837		-3.1		-4,127		-3.4		-4,226		-3.8
	Other items-net		-2,904		-2.3		-112		-0.1		24		0
	Income taxes	$	39,416		31.5%	$	38,874		32.0%	$	34,766		31.5%
Components of United's Deferred Tax Assets and Liabilities	'
	Significant components of United’s deferred tax assets and liabilities (included in other assets in the Consolidated Balance Sheets) at December 31, 2013 and 2012 are as follows:
	(In thousands)	2013		2012
	Deferred tax assets:
	Allowance for credit losses	$	28,108	$	41,853
	Other accrued liabilities		830		29
	Unrecognized components of net periodic pension costs		12,168		21,696
	Unrealized loss on securities available for sale		13,255		16,703
	Other real estate owned		4,288		0
	Purchase accounting intangibles		3,598		0
	Net operating loss		0		846
	Total deferred tax assets		62,247		81,127
	Deferred tax liabilities:
	Purchase accounting intangibles		0		6,436
	Deferred mortgage points		283		377
	Accrued benefits payable		7,806		10,961
	Premises and equipment		2,563		857
	Other		2,117		2,764
	Total deferred tax liabilities		12,769		21,395
	Net deferred tax assets	$	49,478	$	59,732
Reconciliation of the Total Amounts of Unrecognized Tax Benefits	'
	Below is a reconciliation of the total amounts of unrecognized tax benefits:
		December 31
	(In thousands)	2013		2012
	Unrecognized tax benefits at beginning of year		$  2,106		$  2,028
	Decrease in unrecognized tax benefits as a result of tax positions settled during the current period		-213		0
	Increase in unrecognized tax benefits as a result of tax positions taken during the current period		661		226
	Decreases in the unrecognized tax benefits as a result of a		-42		(148)
	lapse of the applicable statute of limitations
	Unrecognized tax benefits at end of year		$  2,512		$  2,106

Employee_Benefit_Plans_Tables

Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2013
Compensation And Retirement Disclosure [Abstract]	'
Net Periodic Pension Cost	'
	Net consolidated periodic pension cost included the following components:
	(Dollars in thousands)	Year Ended December 31,
		2013			2012				2011
	Service cost		$    2,672			$    2,517				$    2,272
	Interest cost		4,913			4,849				4,555
	Expected return on plan assets		-8,313			-7,999				-8,343
	Recognized net actuarial loss		4,821			4,199				2,427
	Amortization of prior service cost		1			1				1
	Net periodic pension cost		$    4,094			$    3,567				$      912
	Weighted-Average Assumptions:
	Discount rate		4.40%			5.15%				5.75%
	Expected return on assets		7.75%			8.00%				8.00%
	Rate of Compensation Increase (prior to age 45)		3.75%			3.75%				3.75%
	Rate of Compensation Increase (otherwise)		2.75%			2.75%				2.75%
Reconciliation of the Beginning and Ending Balances of the Projected Benefit Obligation and the Fair Value of Plan Assets and the Accumulated Benefit Obligation	'
	The reconciliation of the beginning and ending balances of the projected benefit obligation and the fair value of plan assets for the year ended December 31, 2013 and the accumulated benefit obligation at December 31, 2013 is as follows:
	(Dollars in thousands)	December 31,
	Change in Projected Benefit Obligation	2013			2012
	Projected Benefit Obligation at the Beginning of the Year	$	112,534		$	95,162
	Service Cost		2,672			2,517
	Interest Cost		4,913			4,849
	Actuarial (Gain) Loss		-11,646			13,000
	Benefits Paid		-3,287			-2,994
	Projected Benefit at the End of the Year	$	105,186		$	112,534
	Accumulated Benefit Obligation at the End of the Year	$	95,859		$	102,156
	Change in Plan Assets
	Fair Value of Plan Assets at the Beginning of the Year	$	108,859		$	101,383
	Actual Return on Plan Assets		17,616			10,470
	Benefits Paid		-3,287			-2,994
	Employer Contributions		0			0
	Fair value of plan assets at end of year	$	123,188		$	108,859
	Net Amount Recognized
	Funded Status	$	18,002		$	(3,675)
	Unrecognized Transition Asset		0			0
	Unrecognized Prior Service Cost		2			3
	Unrecognized Net Loss		31,151			56,921
	Net Amount Recognized	$	49,155		$	53,249
	Weighted-Average Assumptions at the End of the Year
	Discount Rate		5.20%			4.40%
	Rate of Compensation Increase (prior to age 45)		3.50%			3.75%
	Rate of Compensation Increase (otherwise)		3.00%			2.75%
Asset Allocation for the Defined Benefit Pension Plan as of the Measurement Date, by Asset Category	'
	Asset allocation for the defined benefit pension plan as of the measurement date, by asset category, is as follows:
	Plan Assets	Target Allocation			Allowable		Percentage of
		2014			Allocation Range		Plan Assets at
							December 31,				December 31,
							2013				2012
	Equity Securities		62	%	50-70%			66	%			63	%
	Debt Securities		26	%	20-50%			21	%			32	%
	Other		12	%	3-15%			13	%			5	%
	Total							100	%			100	%
Expected Benefit Payments	'
	At December 31, 2013, the benefits expected to be paid in each of the next five fiscal years, and in the aggregate for the five years thereafter are as follows:
	Year	Amount
	(In thousands)
	2014	$	3,728
	2015		4,053
	2016		4,432
	2017		4,780
	2018		5,159
	2019 through 2023		30,746
Balances of the Plan Assets, by Fair Value Hierarchy Level	'
	The following tables present the balances of the plan assets, by fair value hierarchy level, as of December 31, 2013 and 2012:
					Fair Value Measurements at December 31, 2013 Using
	(In thousands)	Balance as of			Quoted Prices				Significant				Significant
	Description	December 31,			in Active				Other				Unobservable
		2013			Markets for				Observable				Inputs
					Identical				Inputs				(Level 3)
					Assets				(Level 2)
					(Level 1)
	Cash and Cash equivalents	$	2,985		$	2,985			$	0			$	0
	Fixed Income Securities:
	Mortgage backed securities		118			0				118				0
	Collateralized mortgage obligations		245			0				245				0
	Municipal obligations		1,112			0				1,112				0
	Corporate bonds		2,363			0				2,363				0
	Fixed Income Mutual Funds:
	Strategic income		3,985			3,985				0				0
	Taxable		3,970			3,970
	Domestic		13,834			13,834				0				0
	Alternative		6,131			6,131				0				0
	Equity Securities:
	Preferred stock		195			195				0				0
	Common stock		20,089			20,089				0				0
	Equity Mutual Funds:
	Domestic equity large cap		23,042			23,042				0				0
	Domestic equity mid cap		5,540			5,540				0				0
	Domestic equity small cap		15,293			15,293				0				0
	International emerging equity		6,076			6,076				0				0
	International equity developed		11,817			11,817				0				0
	Alternative equity		5,692			5,692				0				0
	Other Assets:
	Partnerships		701			0				701				0
	Total	$	123,188		$	118,649			$	4,539			$	0
					Fair Value Measurements at December 31, 2012 Using
	(In thousands)	Balance as of			Quoted Prices				Significant				Significant
	Description	December 31,			in Active				Other				Unobservable
		2012			Markets for				Observable				Inputs
					Identical				Inputs				(Level 3)
					Assets				(Level 2)
					(Level 1)
	Cash and Cash equivalents	$	4,396		$	4,396			$	0			$	0
	Fixed Income Securities:
	Mortgage backed securities		207			0				207				0
	Collateralized mortgage obligations		208			0				208				0
	Municipal obligations		910			0				910				0
	Corporate bonds		2,588			2,226				362				0
	Fixed Income Mutual Funds:
	Fixed income - general		12,463			12,463				0				0
	Domestic		12,600			12,600				0				0
	Alternative		6,116			6,116				0				0
	Equity Securities:
	Preferred stock		209			209				0				0
	Common stock		14,712			14,712				0				0
	Equity Mutual Funds:
	Global equity		5,186			5,186				0				0
	Domestic equity large cap		19,172			19,172				0				0
	Domestic equity mid cap		2,552			2,552				0				0
	Domestic equity small cap		10,688			10,688				0				0
	International emerging equity		5,241			5,241				0				0
	International equity developed		4,158			4,158				0				0
	Alternative equity		6,727			6,727				0				0
	Other Assets:
	Partnerships		726			0				726				0
	Total	$	108,859		$	106,446			$	2,413			$	0

Stock_Based_Compensation_Table

Stock Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Summary of Stock Option Plans	'
	A summary of activity under the United’s stock option plans as of December 31, 2013, and the changes during the year of 2013 are presented below:
		Year ended December 31, 2013
						Weighted Average
	(Dollars in thousands, except per share data)	Shares		Aggregate		Remaining		Exercise
				Intrinsic		Contractual		Price
				Value		Term (Yrs.)
	Outstanding at January 1, 2013		1,629,237					$	29.64
	Granted		194,225						26.24
	Exercised		100,302						23.56
	Forfeited or expired		275,163						31.1
	Outstanding at December 31, 2013		1,447,997	$	5,145		5.4	$	29.33
	Exercisable at December 31, 2013		858,800	$	3,148		3.6	$	30.2
Status of United's Nonvested Stock Option Awards	'
	The following table summarizes the status of United’s nonvested awards for the year ended December 31, 2013:
		Shares		Weighted-Average
				Grant Date Fair Value
				Per Share
	Nonvested at January 1, 2013		770,750	$	7.04
	Granted		194,225		5.74
	Vested		348,339		6.33
	Forfeited or expired		27,439		7.53
	Nonvested at December 31, 2013		589,197	$	7.01
Changes to United's Restricted Common Shares	'
	The following summarizes the changes to United’s restricted common shares for the year ended December 31, 2013:
		Number of		Weighted-Average
		Shares		Grant Date Fair Value
				Per Share
	Outstanding at January 1, 2013		51,125	$	29.4
	Granted		52,825		26.19
	Vested		16,789		28.96
	Forfeited		1,664		27.91
	Outstanding at December 31, 2013		85,497	$	27.53

Derivative_Financial_Instrumen1

Derivative Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2013
Derivative Instruments And Hedging Activities Disclosure [Abstract]	'
Schedule of Derivative Instruments	'
	The following table sets forth certain information regarding interest rate derivatives portfolio used for interest-rate risk management purposes and designated as accounting hedges at December 31, 2013 and 2012.
			Derivative Hedging Instruments
			December 31, 2013								December 31, 2012
	(Dollars in thousands)		Notional				Average				Notional				Average
			Amount				Pay				Amount				Pay
							Rate								Rate
	Fair Value Hedges:
	Pay Fixed Swap (Hedging Commercial Loans)		$	41,868				5.07	%		$	52,558				5.14	%
	Total Derivatives Used in Fair Value Hedges		$	41,868							$	52,558
	Total Derivatives Used for Interest Rate Risk Management and Designated as Hedges		$	41,868							$	52,558
Schedule of Fair Value Derivative Financial Instruments	'
	The following tables summarize the fair value of United’s derivative financial instruments:
			Asset Derivatives
			December 31, 2013						December 31, 2012
	(In thousands)		Balance		Fair				Balance		Fair
			Sheet		Value				Sheet		Value
			Location						Location
	Derivatives designated as hedging instruments
	Interest rate contracts		Other assets		$	2,179			Other assets		$	0
	Total derivatives designated as hedging instruments				$	2,179					$	0
	Derivatives not designated as hedging instruments
	Interest rate contracts		Other assets		$	1,045			Other assets		$	2,367
	Total derivatives not designated as hedging instruments				$	1,045					$	2,367
	Total asset derivatives				$	3,224					$	2,367
			Liability Derivatives
			December 31, 2013						December 31, 2012
	(In thousands)		Balance		Fair				Balance		Fair
			Sheet		Value				Sheet		Value
			Location						Location
	Derivatives designated as hedging instruments
	Interest rate contracts		Other liabilities		$	149			Other liabilities		$	1,914
	Total derivatives designated as hedging instruments				$	149					$	1,914
	Derivatives not designated as hedging instruments
	Interest rate contracts		Other liabilities		$	1,045			Other liabilities		$	2,367
	Total derivatives not designated as hedging instruments				$	1,045					$	2,367
	Total liability derivatives				$	1,194					$	4,281
Schedule of Derivative Financial Instruments on Statement of Income	'
	The effect of United’s derivative financial instruments on its Consolidated Statements of Income for the years ended December 31, 2013, 2012 and 2011 is presented as follows:
					Year Ended
	(In thousands)		Income Statement		December 31,				December 31,				December 31,
			Location		2013				2012				2011
	Derivatives in fair value hedging relationships
	Interest rate contracts		Interest income/ (expense)		$	(522	)		$	(298	)		$	81
	Total derivatives in fair value hedging relationships				$	(522	)		$	(298	)		$	81
	Derivatives not designated as hedging instruments
	Interest rate contracts (1)		Other income		$	1,322			$	1,450			$	1,782
	Interest rate contracts (2)		Other expense		$	(1,322	)		$	(1,450	)		$	(1,782	)
	Total derivatives not designated as hedging instruments				$	0			$	0			$	0
	Total derivatives				$	(522	)		$	(298	)		$	81
	-1	Represents net gains from derivative assets not designated as hedging instruments.
	-2	Represents net losses from derivative liabilities not designated as hedging instruments.

Comprehensive_Income_Tables

Comprehensive Income (Tables)	12 Months Ended
	Dec. 31, 2013
Equity [Abstract]	'
Components of Total Comprehensive Income	'
	The changes in accumulated other comprehensive income are as follows:
			For the Years Ended December 31
	(In thousands)		2013			2012			2011
	Net Income		$	85,628		$	82,607		$	75,610
	Available for sale (“AFS”) securities:
	AFS securities with OTTI charges during the period			(7,534	)		(10,840	)		(33,580	)
	Related income tax effect			2,637			3,794			11,753
	Less : OTTI charges recognized in net income			7,332			7,376			20,414
	Related income tax effect			(2,566	)		(2,582	)		(7,145	)
	Reclassification of previous noncredit OTTI to credit OTTI			12,425			5,887			12,622
	Related income tax effect			(4,349	)		(2,061	)		(4,418	)
	Net unrealized gains (losses) on AFS securities with OTTI			7,945			1,574			(354	)
	Net change in unrealized (losses) gains on AFS securities arising during the period			(1,082	)		5,471			10,917
	Related income tax effect			379			(1,915	)		(3,821	)
	Net reclassification adjustment for gains included in net income			(1,216	)		(16	)		(1,418	)
	Related income tax effect			426			6			496
				(1,493	)		3,546			6,174
	Net effect of AFS securities on other comprehensive income			6,452			5,120			5,820
	Held to maturity (“HTM”) securities:
	Unrealized loss related to the call of HTM securities transferred from AFS to the HTM portfolio			0			0			0
	Related income tax effect			0			0			0
	Accretion on the unrealized loss for securities transferred from AFS to the HTM investment portfolio prior to call or maturity			8			7			8
	Related income tax effect			(3	)		(3	)		(3	)
	Net effect of HTM securities on other comprehensive income			5			4			5
	Defined benefit pension plan:
	Net actuarial loss during the period			20,305			(10,206	)		(20,591	)
	Related income tax effect			(7,107	)		3,572			7,206
	Amortization of transition asset recognized in net income			0			0			0
	Related income tax effect			0			0			0
	Amortization of prior service cost recognized in net income			1			1			1
	Related income tax effect			0			0			0
	Amortization of net actuarial loss recognized in net income			4,821			4,199			2,427
	Related income tax effect			(1,776	)		(1,680	)		(970	)
	Net effect of change in defined benefit pension plan on other comprehensive income			16,244			(4,114	)		(11,927	)
	Total change in other comprehensive income, net of tax			22,701			1,010			(6,102	)
	Total Comprehensive Income		$	108,329		$	83,617		$	69,508
Components of Accumulated Other Comprehensive Income	'
	The components of accumulated other comprehensive income for the year ended December 31, 2013 are as follows:
	Changes in Accumulated Other Comprehensive Income (AOCI) by Component (a)
	For the Year Ended December 31, 2013
	(Dollars in thousands)		Unrealized			Accretion on			Defined			Total
			Gains/Losses			the unrealized			Benefit
			on AFS			loss for			Pension
			Securities			securities			Items
						transferred
						from AFS  to
						the HTM
	Balance at January 1, 2013		($	29,687	)	($	72	)	($	35,989	)	($	65,748	)
	Other comprehensive income before reclassification			(834	)		5			0			(829	)
	Amounts reclassified from accumulated other comprehensive income			7,286			0			16,244			23,530
	Net current-period other comprehensive income, net of tax			6,452			5			16,244			22,701
	Balance at December 31, 2013		($	23,235	)	($	67	)	($	19,745	)	($	43,047	)
	(a)	All amounts are net-of-tax.
Reclassifications Out of Accumulated Other Comprehensive Income	'
	Reclassifications out of Accumulated Other Comprehensive Income (AOCI)
	For the Year Ended December 31, 2013
	(Dollars in thousands)		Amount			Affected Line Item in the Statement Where
			Reclassified			Net Income is Presented
	Details about AOCI Components		from AOCI
	Available for sale (“AFS”) securities:
	Reclassification of previous noncredit OTTI to credit OTTI		$	12,425		Total other-than-temporary impairment losses
	Net reclassification adjustment for losses (gains) included in net income			(1,216	)	Net gains on sales/calls of investment securities
				11,209		Total before tax
	Related income tax effect			(3,923	)	Tax expense
				7,286		Net of tax
	Pension plan:
	Change in pension asset			20,305	(a)
	Amortization of transition asset			1	(b)
	Recognized net actuarial loss			4,821	(b)
				25,127		Total before tax
	Related income tax effect			(8,883	)	Tax expense
				16,244		Net of tax
	Total reclassifications for the period		$	23,530
	(a)	This AOCI component is included in the computation of changes in plan assets (see Note M, Employee Benefit Plans)
	(b)	This AOCI component is included in the computation of net periodic pension cost (see Note M, Employee Benefit Plans)

United_Bankshares_Inc_Parent_C1

United Bankshares, Inc. (Parent Company Only) Financial Information (Tables)	12 Months Ended
	Dec. 31, 2013
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]	'
Condensed Balance Sheets	'
	Condensed Balance Sheets
		December 31
	(In thousands)	2013			2012
	Assets
	Cash and due from banks	$	43,613		$	30,585
	Securities available for sale		1,925			3,271
	Securities held to maturity		20			225
	Other investment securities		125			162
	Investment in subsidiaries:
	Bank subsidiaries		1,139,786			1,100,880
	Nonbank subsidiaries		6,396			6,355
	Other assets		11,751			10,069
	Total Assets	$	1,203,616		$	1,151,547
	Liabilities and Shareholders’ Equity
	Junior subordinated debentures of subsidiary trusts	$	128,868		$	128,868
	Accrued expenses and other liabilities		33,016			30,428
	Shareholders’ equity (including other accumulated comprehensive loss of $43,047 and $65,748 at December 31, 2013 and 2012, respectively)		1,041,732			992,251
	Total Liabilities and Shareholders’ Equity	$	1,203,616		$	1,151,547
Condensed Statements of Income	'
	Condensed Statements of Income
		Year Ended December 31
	(In thousands)	2013			2012			2011
	Income
	Dividends from banking subsidiaries	$	69,500		$	67,600		$	68,323
	Net interest income		74			119			417
	Management fees:
	Bank subsidiaries		17,665			15,854			13,000
	Nonbank subsidiaries		27			27			27
	Other income		555			105			414
	Total Income		87,821			83,705			82,181
	Expenses
	Operating expenses		20,595			20,879			20,431
	Income Before Income Taxes and Equity in Undistributed Net Income of Subsidiaries		67,226			62,826			61,750
	Applicable income tax benefit		(709	)		(1,487	)		(2,025	)
	Income Before Equity in Undistributed Net Income of Subsidiaries		67,935			64,313			63,775
	Equity in undistributed net income of subsidiaries:
	Bank subsidiaries		17,652			18,186			11,710
	Nonbank subsidiaries		41			108			125
	Net Income	$	85,628		$	82,607		$	75,610
Condensed Statements of Cash Flows	'
	Condensed Statements of Cash Flows
		Year Ended December 31
	(In thousands)	2013			2012			2011
	Operating Activities
	Net income	$	85,628		$	82,607		$	75,610
	Adjustments to reconcile net income to net cash provided by operating activities:
	Equity in undistributed net income of subsidiaries		(17,693	)		(18,294	)		(11,835	)
	Amortization of net periodic pension costs		373			117			76
	Stock-based compensation		1,786			1,908			1,133
	Net (gain) loss on securities transactions		(556	)		(55	)		(12	)
	Net change in other assets and liabilities		867			(1,553	)		(6,895	)
	Net Cash Provided by Operating Activities		70,405			64,730			58,077
	Investing Activities
	Net proceeds from (purchases of) sales of securities		2,341			1,541			4,854
	Net cash paid in acquisition of subsidiary		0			0			(8,576	)
	Change in other investment securities		37			38			1,376
	Net Cash Provided by (Used in) Investing Activities		2,378			1,579			(2,346	)
	Financing Activities
	Cash dividends paid		(62,434	)		(62,333	)		(54,344	)
	Net (repayment) liquidation of subsidiary trusts		0			(5,155	)		0
	Acquisition of treasury stock		(93	)		(12	)		(18	)
	Proceeds from sale of treasury stock from deferred compensation plan		77			130			74
	Excess tax benefits from stock-based compensation arrangements		331			35			3,114
	Proceeds from exercise of stock options		2,364			115			542
	Net Cash Used in Financing Activities		(59,755	)		(67,220	)		(50,632	)
	Increase (Decrease) in Cash and Cash Equivalents		13,028			(911	)		5,099
	Cash and Cash Equivalents at Beginning of Year		30,585			31,496			26,397
	Cash and Cash Equivalents at End of Year	$	43,613		$	30,585		$	31,496

Regulatory_Matters_Tables

Regulatory Matters (Tables)	12 Months Ended
	Dec. 31, 2013
Banking And Thrift [Abstract]	'
Capital Amounts and Ratios	'
	United’s and its subsidiary banks’, United Bank (WV) and United Bank (VA), capital amounts (in thousands of dollars) and ratios are presented in the following table.
	(Dollars in thousands)	Actual				For Capital						To Be  Well-
						Adequacy  Purposes						Capitalized
		Amount		Ratio		Amount		Ratio				Amount			Ratio
	As of December 31, 2013:
	Total Capital (to Risk-Weighted Assets):
	United Bankshares		$ 971,401		13.70%		$ 566,836		³8.0%				$ 708,545			³10.0%
	United Bank (WV)		525,517		12.50%		336,100		³8.0%				420,125			³10.0%
	United Bank (VA)		412,120		14.40%		229,656		³8.0%				287,070			³10.0%
	Tier I Capital (to Risk-Weighted Assets):
	United Bankshares		886,094		12.50%		283,418		³4.0%				425,127			³6.0%
	United Bank (WV)		485,038		11.60%		168,050		³4.0%				252,075			³6.0%
	United Bank (VA)		376,255		13.10%		114,828		³4.0%				172,242			³6.0%
	Tier I Capital (to Average Assets):
	United Bankshares		886,094		10.70%		330,614		³4.0%				413,267			³5.0%
	United Bank (WV)		485,038		9.70%		199,209		³4.0%				249,012			³5.0%
	United Bank (VA)		376,255		11.20%		134,613		³4.0%				168,266			³5.0%
	(Dollars in thousands)	Actual				For Capital						To Be  Well-
						Adequacy  Purposes						Capitalized
		Amount		Ratio		Amount		Ratio				Amount			Ratio
	As of December 31, 2012:
	Total Capital (to Risk-Weighted Assets):
	United Bankshares		$  941,448		13.70%		$ 551,114		³8.0%				$ 688,892			³10.0%
	United Bank (WV)		511,451		12.70%		321,957		³8.0%				402,446			³10.0%
	United Bank (VA)		404,405		14.10%		229,769		³8.0%				287,211			³10.0%
	(Dollars in thousands)	Actual				For Capital				To Be  Well-
						Adequacy  Purposes				Capitalized
		Amount		Ratio		Amount		Ratio		Amount				Ratio
	Tier I Capital (to Risk-Weighted Assets):
	United Bankshares		857,091		12.40%		275,557	³4.0%			413,335			³6.0%
	United Bank (WV)		473,044		11.80%		160,978	³4.0%			241,468			³6.0%
	United Bank (VA)		368,488		12.80%		114,884	³4.0%			172,327			³6.0%
	Tier I Capital (to Average Assets):
	United Bankshares		857,091		10.60%		322,941	³4.0%			403,676			³5.0%
	United Bank (WV)		473,044		9.80%		193,775	³4.0%			242,218			³5.0%
	United Bank (VA)		368,488		11.20%		132,158	³4.0%			165,197			³5.0%

Fair_Values_of_Financial_Instr1

Fair Values of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2013
Fair Value Disclosures [Abstract]	'
Schedule of Financial Assets and Liabilities Measured at Fair Value	'
	The following table presents the balances of financial assets and liabilities measured at fair value on a recurring basis as of December 31, 2013 and 2012, segregated by the level of the valuation inputs within the fair value hierarchy:
			Balance as of			Fair Value at December 31, 2013 Using
			December 31,
	Description		2013			Quoted Prices			Significant		Significant
						in Active			Other		Unobservable
						Markets for			Observable		Inputs
						Identical			Inputs		(Level 3)
						Assets			(Level 2)
						(Level 1)
	Assets
	Available for sale debt securities:
	U.S. Treasury securities and obligations of U.S. Government corporations and agencies			$    171,754			$            0			$    171,754		$              0
	State and political subdivisions			62,709			0			62,709		0
	Residential mortgage-backed securities
	Agency			216,464			0			216,464		0
	Non-agency			16,532			0			16,532		0
	Asset-backed securities			9,227			0			9,227		0
	Commercial mortgage-backed securities Agency			233,432			0			233,432		0
	Trust preferred collateralized debt obligations			43,449			0			0		43,449
	Single issue trust preferred securities			12,632			502			12,130		0
	Other corporate securities			5,215			0			5,215		0
	Total available for sale debt securities			771,414			502			727,463		43,449
	Available for sale equity securities:
	Financial services industry			2,292			716			1,576		0
	Equity mutual funds (1)			434			434			0		0
	Other equity securities			1,144			1,144			0		0
	Total available for sale equity securities			3,870			2,294			1,576		0
	Total available for sale securities			775,284			2,796			729,039		43,449
	Derivative financial assets:
	Interest rate contracts			3,224			0			3,224		0
	Liabilities
	Derivative financial liabilities:
	Interest rate contracts			1,194			0			1,194		0
	-1	The equity mutual funds are within a rabbi trust for the payment of benefits under a deferred compensation plan for certain key officers of United and its subsidiaries.
						Fair Value at December 31, 2012 Using
	Description		Balance as of			Quoted Prices			Significant		Significant
			December 31,			in Active			Other		Unobservable
			2012			Markets for			Observable		Inputs
						Identical			Inputs		(Level 3)
						Assets			(Level 2)
						(Level 1)
	Assets
	Available for sale debt securities:
	U.S. Treasury securities and obligations of U.S. Government corporations and agencies			$    337,522			$            0			$    337,522		$            0
	State and political subdivisions			80,428			0			80,428		0
	Residential mortgage-backed securities
	Agency			106,510			0			106,510		0
	Non-agency			25,045			0			25,045		0
	Asset-backed securities			11,709			0			11,709		0
	Trust preferred collateralized debt obligations			40,613			0			0		40,613
	Single issue trust preferred securities			12,129			499			11,630		0
	Other corporate securities			5,283			0			5,283		0
	Total available for sale debt securities			619,239			499			578,127		40,613
	Available for sale equity securities:
	Financial services industry			5,382			2,304			3,078		0
	Equity mutual funds (1)			55			55			0		0
	Other equity securities			949			949			0		0
	Total available for sale equity securities			6,386			3,308			3,078		0
	Total available for sale securities			625,625			3,807			581,205		40,613
	Derivative financial assets:
	Interest rate contracts			2,367			0			2,367		0
	Liabilities
	Derivative financial liabilities:
Interest rate contracts			4,281			0			4,281		0
-1	The equity mutual funds are within a rabbi trust for the payment of benefits under a deferred compensation plan for certain key officers of United and its subsidiaries.
Schedule of Additional Information about Financial Assets and Liabilities Measured at Fair Value Utilized Level 3	'
	The following table presents additional information about financial assets and liabilities measured at fair value at December 31, 2013 and 2012 on a recurring basis and for which United has utilized Level 3 inputs to determine fair value:
			Available-for-sale
			Securities
	(In thousands)		Trust preferred
			collateralized debt obligations
			2013			2012
	Balance, beginning of year		$	40,613		$	42,369
	Total gains or losses (realized/unrealized):
	Included in earnings (or changes in net assets)			(6,456	)		(5,970	)
	Included in other comprehensive income			14,520			4,214
	Purchases, issuances, and settlements			(5,228	)		0
	Transfers in and/or out of Level 3			0			0
	Balance, ending of year		$	43,449		$	40,613
	The amount of total gains or losses for the period included in earnings (or changes in net assets) attributable to the change in unrealized gains or losses relating to assets still held at reporting date			0			0
Summary of Financial Assets Measured at Fair Value on Nonrecurring Basis	'
	The following table summarizes United’s financial assets that were measured at fair value on a nonrecurring basis as of December 31, 2013 and 2012:
						Fair Value at December 31, 2013 Using
	(In thousands)		Balance as of			Quoted Prices			Significant		Significant		YTD
			December 31,			in Active			Other		Unobservable		Losses
	Description		2013			Markets for			Observable		Inputs
						Identical			Inputs		(Level 3)
						Assets			(Level 2)
						(Level 1)
	Assets
	Impaired Loans		$	45,883		$	0		$	13,081	$	32,802	$	1,886
	OREO			38,182			0			38,107		75		2,548
						Fair Value at December 31, 2012 Using
	(In thousands)		Balance as of			Quoted Prices			Significant		Significant		YTD
			December 31,			in Active			Other		Unobservable		Losses
	Description		2012			Markets for			Observable		Inputs
						Identical			Inputs		(Level 3)
						Assets			(Level 2)
						(Level 1)
	Assets
	Impaired Loans		$	50,985		$	0		$	28,947	$	22,038	$	3,238
	OREO			49,484			0			45,588		3,896		3,677
Summary of Estimated Fair Values of Financial Instruments	'
	The estimated fair values of United’s financial instruments are summarized below:
									Fair Value Measurements
			Carrying			Fair			Quoted Prices		Significant		Significant
			Amount			Value			in Active		Other		Unobservable
									Markets for		Observable		Inputs
									Identical		Inputs		(Level 3)
									Assets		(Level 2)
									(Level 1)
	December 31, 2013
	Cash and cash equivalents		$	416,617		$	416,617		$	0	$	416,617	$	0
	Securities available for sale			775,284			775,284			2,796		729,039		43,449
	Securities held to maturity			40,965			38,293			0		35,773		2,520
	Other securities			73,093			70,072			0		0		70,072
	Loans held for sale			4,236			4,236			0		4,236		0
	Loans			6,630,385			6,657,376			0		0		6,657,376
	Derivative financial assets			3,224			3,224			0		3,224		0
	Deposits			6,621,571			6,641,070			0		6,641,070		0
	Short-term borrowings			430,754			430,754			0		430,754		0
	Long-term borrowings			575,697			553,796			0		553,796		0
	Derivative financial liabilities			1,194			1,194			0		1,194		0
	December 31, 2012
	Cash and cash equivalents		$	432,077		$	432,077		$	0	$	432,077	$	0
	Securities available for sale			625,625			625,625			3,807		581,205		40,613
	Securities held to maturity			43,467			42,696			0		36,999		5,697
	Other securities			60,310			57,643			0		0		57,643
	Loans held for sale			17,762			17,762			0		17,762		0
	Loans			6,437,515			6,473,974			0		0		6,473,974
	Derivative financial assets			2,367			2,367			0		2,367		0
	Deposits			6,752,986			6,776,012			0		6,776,012		0
	Short-term borrowings			314,962			314,962			0		314,962		0
	Long-term borrowings			284,926			277,899			0		277,899		0
	Derivative financial liabilities			4,281			4,281			0		4,281		0

Variable_Interest_Entities_Tab

Variable Interest Entities (Tables)

12 Months Ended

Dec. 31, 2013

Text Block [Abstract]

'

Summary of Quantitative Information Related to Significant Involvement in Unconsolidated Variable Interest Entities

'

The following table summarizes quantitative information about United’s significant involvement in unconsolidated VIEs:

As of December 31, 2013

As of December 31, 2012

(In thousands)

Aggregate

Aggregate

Risk Of

Aggregate

Aggregate

Risk Of

Assets

Liabilities

Loss (1)

Assets

Liabilities

Loss (1)

Trust preferred securities

$201,186

$194,453

$6,733

$201,297

$194,636

$6,661

(1)  Represents investment in VIEs.

Quarterly_Financial_Data_Table

Quarterly Financial Data (Tables)	12 Months Ended
	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]	'
Quarterly Financial Data	'
	Quarterly financial data for 2013 and 2012 is summarized below (dollars in thousands, except for per share data):
			1st Quarter			2nd Quarter			3rd Quarter			4th Quarter
	2013
	Interest income		$	76,325		$	75,485		$	76,705		$	77,639
	Interest expense			9,503			9,282			9,075			8,453
	Net interest income			66,822			66,203			67,630			69,186
	Provision for credit losses			5,187			4,960			4,777			4,343
	Mortgage banking income			965			739			605			262
	Securities (losses) gains, net			(694	)		211			101			(5,427	)
	Other noninterest income			18,077			18,149			17,629			17,211
	Noninterest expense			48,249			48,547			48,585			47,977
	Income taxes			10,155			9,576			10,433			9,252
	Net income (1)			21,579			22,219			22,170			19,660
	Per share data:
	Average shares outstanding (000s):
	Basic			50,302			50,346			50,379			50,417
	Diluted			50,332			50,402			50,473			50,564
	Net income per share:
	Basic		$	0.43		$	0.44		$	0.44		$	0.39
	Diluted		$	0.43		$	0.44		$	0.44		$	0.39
	Dividends per share		$	0.31		$	0.31		$	0.31		$	0.32
			1st Quarter			2nd Quarter			3rd Quarter			4th Quarter
	2012
	Interest income		$	81,788		$	81,105		$	81,336		$	79,668
	Interest expense			12,822			12,050			11,322			9,996
	Net interest income			68,966			69,055			70,014			69,672
	Provision for credit losses			4,133			3,436			4,346			5,947
	Mortgage banking income			318			483			819			851
	Securities losses, net			(1,459	)		(1,543	)		(2,188	)		(1,740	)
	Other noninterest income			17,467			17,647			18,003			17,634
	Noninterest expense			50,262			51,252			53,869			49,273
	Income taxes			9,887			9,905			9,099			9,983
	Net income (1)			21,010			21,049			19,334			21,214
	Per share data:
	Average shares outstanding (000s):
	Basic			50,235			50,275			50,276			50,276
	Diluted			50,301			50,308			50,295			50,295
	Net income per share:
	Basic		$	0.42		$	0.42		$	0.38		$	0.42
	Diluted		$	0.42		$	0.42		$	0.38		$	0.42
	Dividends per share		$	0.31		$	0.31		$	0.31		$	0.31
	(1)	For further information, see the related discussion “Quarterly Results” included in Management’s Discussion and Analysis.

Summary_of_Significant_Account3

Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)

3 Months Ended

12 Months Ended

0 Months Ended

12 Months Ended

Mar. 31, 2013

Mar. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Feb. 20, 2014

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Region

Subsequent Event [Member]

Minimum [Member]

Maximum [Member]

Furniture Fixtures and Equipment [Member]

Furniture Fixtures and Equipment [Member]

Buildings and Improvements [Member]

Buildings and Improvements [Member]

Core Deposit Intangible Assets [Member]

Core Deposit Intangible Assets [Member]

Minimum [Member]

Maximum [Member]

Minimum [Member]

Maximum [Member]

Summary Of Significant Accounting Policies [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

Number of Metropolitan Statistical Areas

'

'

5

'

'

'

'

'

'

'

'

'

Sale of former branch building

'

'

'

'

'

$11,100,000

'

'

'

'

'

'

Recognized before-tax gain

'

'

-592,000

-262,000

-1,072,000

8,900,000

'

'

'

'

'

'

Loan fees amortized and included in interest income

'

'

7,427,000

10,765,000

6,264,000

'

'

'

'

'

'

'

Minimum days, related to accrual of interest on discontinued commercial and consumer loans

'

'

'90 days

'

'

'

'

'

'

'

'

'

Maximum days, related to accrual of interest on discontinued commercial and consumer loans

'

'

'120 days

'

'

'

'

'

'

'

'

'

Sustained period of repayment performance in restructured loans

'

'

'6 months

'

'

'

'

'

'

'

'

'

Bank premises and equipment, useful life

'

'

'

'

'

'

'

'

'3 years

'15 years

'5 years

'40 years

Real estate acquired in foreclosure or other settlement of loans

'

'

38,182,000

49,484,000

'

'

'

'

'

'

'

'

Advertising expense

'

'

3,777,000

4,270,000

4,172,000

'

'

'

'

'

'

'

Amortization expense on intangible assets

'

'

1,969,000

2,852,000

2,429,000

'

'

'

'

'

'

'

Intangible assets amortization period

'

'

'

'

'

'

'1 year

'7 years

'

'

'

'

Total goodwill

'

'

375,547,000

375,583,000

'

'

'

'

'

'

'

'

Stock based compensation expense

'

'

$1,786,000

$1,908,000

$1,133,000

'

'

'

'

'

'

'

Equivalents from stock options

'

'

72,626

32,399

33,931

'

'

'

'

'

'

'

Restricted shares, granted

52,825

52,700

'

'

'

'

'

'

'

'

'

'

Restricted shares, vesting period

'Four-year

'Four-year

'

'

'

'

'

'

'

'

'

'

Summary_of_Significant_Account4

Summary of Significant Accounting Policies - Reconciliation of Numerator and Denominator of Basic Earnings Per Share with that of Diluted Earnings Per Share (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Regulatory Assets [Abstract]	'	'	'	'	'	'	'	'	'	'	'
Distributed earnings allocated to common stock	'	'	'	'	'	'	'	'	$62,982	$62,286	$56,827
Undistributed earnings allocated to common stock	'	'	'	'	'	'	'	'	22,512	20,245	18,783
Net earnings allocated to common shareholders	'	'	'	'	'	'	'	'	$85,494	$82,531	$75,610
Average common shares outstanding	50,417,000	50,379,000	50,346,000	50,302,000	50,276,000	50,276,000	50,275,000	50,235,000	50,353,452	50,265,620	46,803,432
Equivalents from stock options	'	'	'	'	'	'	'	'	72,626	32,399	33,931
Average diluted shares outstanding	50,564,000	50,473,000	50,402,000	50,332,000	50,295,000	50,295,000	50,308,000	50,301,000	50,426,078	50,298,019	46,837,363
Earnings per basic common share	$0.39	$0.44	$0.44	$0.43	$0.42	$0.38	$0.42	$0.42	$1.70	$1.64	$1.62
Earnings per diluted common share	$0.39	$0.44	$0.44	$0.43	$0.42	$0.38	$0.42	$0.42	$1.70	$1.64	$1.61

Mergers_and_Acquisition_Additi

Mergers and Acquisition - Additional Information (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Jan. 31, 2014	Dec. 31, 2013
			Virginia Commerce Bancorp, Inc. [Member]	Subsequent [Member]	Centra Financial Holdings Inc [Member]
Outstanding common stock acquired	'	'	'	100.00%	'
Total assets at consummation	$8,735,324,000	$8,420,013,000	'	'	$2,770,000,000
Loans at consummation	6,713,599,000	6,517,780,000	'	'	2,100,000,000
Deposits at consummation	6,621,571,000	6,752,986,000	'	'	2,020,000,000
Common stock, par value	$2.50	$2.50	$1	'	'
Outstanding share of common stock	'	'	0.5442	'	'
Issue of common stock	'	'	18,300,000	'	'
Issue of options to purchase upon conversion of Commerce's stock options	'	'	441,000	'	'
Common stock paid in cash	'	'	8,000	'	'
Warrant held and purchased by TARP Capital Purchase Program	'	'	$33,263,000	'	'

Investment_Securities_Summary_

Investment Securities - Summary of Amortized Cost and Estimated Fair Values of Available for Sale Securities (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Schedule of Investments [Line Items]	'	'
Amortized Cost	$813,049	$673,315
Gross Unrealized Gains	6,238	11,027
Gross Unrealized Losses	44,003	58,717
Estimated Fair Value	775,284	625,625
Cumulative OTTI in AOCI	34,757	46,980
U.S. Treasury Securities and Obligations of U.S. Government Corporations and Agencies [Member]	'	'
Schedule of Investments [Line Items]	'	'
Amortized Cost	172,324	336,747
Gross Unrealized Gains	178	827
Gross Unrealized Losses	748	52
Estimated Fair Value	171,754	337,522
Cumulative OTTI in AOCI	0	0
State and Political Subdivisions [Member]	'	'
Schedule of Investments [Line Items]	'	'
Amortized Cost	60,861	76,765
Gross Unrealized Gains	1,874	3,664
Gross Unrealized Losses	26	1
Estimated Fair Value	62,709	80,428
Cumulative OTTI in AOCI	0	0
Residential Mortgage-Backed Securities, Agency [Member]	'	'
Schedule of Investments [Line Items]	'	'
Amortized Cost	215,788	101,769
Gross Unrealized Gains	2,491	4,741
Gross Unrealized Losses	1,815	0
Estimated Fair Value	216,464	106,510
Cumulative OTTI in AOCI	0	0
Residential Mortgage-Backed Securities, Non-agency [Member]	'	'
Schedule of Investments [Line Items]	'	'
Amortized Cost	16,369	24,569
Gross Unrealized Gains	163	934
Gross Unrealized Losses	0	458
Estimated Fair Value	16,532	25,045
Cumulative OTTI in AOCI	458	458
Commercial Mortgage-Backed Securities Agency [Member]	'	'
Schedule of Investments [Line Items]	'	'
Amortized Cost	241,947	'
Gross Unrealized Gains	225	'
Gross Unrealized Losses	8,740	'
Estimated Fair Value	233,432	'
Cumulative OTTI in AOCI	0	'
Asset-Backed Securities [Member]	'	'
Schedule of Investments [Line Items]	'	'
Amortized Cost	9,257	11,729
Gross Unrealized Gains	1	0
Gross Unrealized Losses	31	20
Estimated Fair Value	9,227	11,709
Cumulative OTTI in AOCI	0	0
Trust Preferred Collateralized Debt Obligations [Member]	'	'
Schedule of Investments [Line Items]	'	'
Amortized Cost	73,862	94,794
Gross Unrealized Gains	210	5
Gross Unrealized Losses	30,623	54,186
Estimated Fair Value	43,449	40,613
Cumulative OTTI in AOCI	34,299	46,522
Single Issue Trust Preferred Securities [Member]	'	'
Schedule of Investments [Line Items]	'	'
Amortized Cost	14,346	15,286
Gross Unrealized Gains	305	312
Gross Unrealized Losses	2,019	3,469
Estimated Fair Value	12,632	12,129
Cumulative OTTI in AOCI	0	0
Other Corporate Securities [Member]	'	'
Schedule of Investments [Line Items]	'	'
Amortized Cost	4,996	4,996
Gross Unrealized Gains	219	287
Gross Unrealized Losses	0	0
Estimated Fair Value	5,215	5,283
Cumulative OTTI in AOCI	0	0
Marketable Equity Securities [Member]	'	'
Schedule of Investments [Line Items]	'	'
Amortized Cost	3,299	6,660
Gross Unrealized Gains	572	257
Gross Unrealized Losses	1	531
Estimated Fair Value	3,870	6,386
Cumulative OTTI in AOCI	$0	$0

Investment_Securities_Summary_1

Investment Securities - Summary of Securities Available for Sale in an Unrealized Loss Position (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Schedule of Investments [Line Items]	'	'
Less than 12 months, Fair Value	$442,162	$33,892
Less than 12 months, Unrealized Losses	11,362	580
12 months or longer, Fair Value	35,402	59,026
12 months or longer, Unrealized Losses	32,641	58,137
U.S. Treasury Securities and Obligations of U.S. Government Corporations and Agencies [Member]	'	'
Schedule of Investments [Line Items]	'	'
Less than 12 months, Fair Value	61,517	25,170
Less than 12 months, Unrealized Losses	748	52
12 months or longer, Fair Value	0	0
12 months or longer, Unrealized Losses	0	0
State and Political Subdivisions [Member]	'	'
Schedule of Investments [Line Items]	'	'
Less than 12 months, Fair Value	2,353	126
Less than 12 months, Unrealized Losses	26	1
12 months or longer, Fair Value	0	0
12 months or longer, Unrealized Losses	0	0
Residential Mortgage-Backed Securities, Agency [Member]	'	'
Schedule of Investments [Line Items]	'	'
Less than 12 months, Fair Value	160,835	'
Less than 12 months, Unrealized Losses	1,815	'
12 months or longer, Fair Value	0	'
12 months or longer, Unrealized Losses	0	'
Commercial Mortgage-Backed Securities Agency [Member]	'	'
Schedule of Investments [Line Items]	'	'
Less than 12 months, Fair Value	208,979	'
Less than 12 months, Unrealized Losses	8,740	'
12 months or longer, Fair Value	0	'
12 months or longer, Unrealized Losses	0	'
Residential Mortgage-Backed Securities, Non-agency [Member]	'	'
Schedule of Investments [Line Items]	'	'
Less than 12 months, Fair Value	'	0
Less than 12 months, Unrealized Losses	'	0
12 months or longer, Fair Value	'	10,879
12 months or longer, Unrealized Losses	'	458
Asset-Backed Securities [Member]	'	'
Schedule of Investments [Line Items]	'	'
Less than 12 months, Fair Value	7,976	7,993
Less than 12 months, Unrealized Losses	31	20
12 months or longer, Fair Value	0	0
12 months or longer, Unrealized Losses	0	0
Trust Preferred Collateralized Debt Obligations [Member]	'	'
Schedule of Investments [Line Items]	'	'
Less than 12 months, Fair Value	0	0
Less than 12 months, Unrealized Losses	0	0
12 months or longer, Fair Value	27,167	40,613
12 months or longer, Unrealized Losses	30,623	54,186
Single Issue Trust Preferred Securities [Member]	'	'
Schedule of Investments [Line Items]	'	'
Less than 12 months, Fair Value	502	0
Less than 12 months, Unrealized Losses	2	0
12 months or longer, Fair Value	8,210	7,221
12 months or longer, Unrealized Losses	2,017	3,469
Marketable Equity Securities [Member]	'	'
Schedule of Investments [Line Items]	'	'
Less than 12 months, Fair Value	0	603
Less than 12 months, Unrealized Losses	0	507
12 months or longer, Fair Value	25	313
12 months or longer, Unrealized Losses	$1	$24

Investment_Securities_Summary_2

Investment Securities - Summary of Gains or Losses on Proceeds from Maturities, Sales and Calls of Available for Sale Securities by Specific Identification Method (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Investments Debt And Equity Securities [Abstract]	'	'	'
Proceeds from maturities, sales and calls	$698,264	$1,996,547	$1,486,936
Gross realized gains	1,259	157	1,729
Gross realized losses	$43	$141	$311

Investment_Securities_Addition

Investment Securities - Additional Information (Detail) (USD $)

12 Months Ended

12 Months Ended

12 Months Ended

12 Months Ended

3 Months Ended

12 Months Ended

12 Months Ended

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2012

Securities

Wells Fargo [Member]

SunTrust Bank [Member]

Royal Bank of Scotland [Member]

Split Rated [Member]

Below Investment Grade [Member]

Marketable Equity Securities [Member]

Marketable Equity Securities [Member]

Residential Mortgage-Backed Securities, Non-agency [Member]

Residential Mortgage-Backed Securities, Non-agency [Member]

Single Issue Trust Preferred [Member]

U.S. Treasury Securities and Obligations of U.S. Government Corporations and Agencies [Member]

U.S. Treasury Securities and Obligations of U.S. Government Corporations and Agencies [Member]

Commercial Mortgage-Backed Securities Agency [Member]

Residential Mortgage-Backed Securities, Agency [Member]

Residential Mortgage-Backed Securities, Agency [Member]

Originated Prior to 2005 [Member]

Originated in 2006 and 2007 [Member]

TRUP CDOs [Member]

TRUP CDOs [Member]

TRUP CDOs [Member]

TRUP CDOs [Member]

TRUP CDOs [Member]

TRUP CDOs [Member]

TRUP CDOs [Member]

Mortgage Backed Securities [Member]

Mortgage Backed Securities [Member]

Securities

Below Investment Grade [Member]

Securities

Likely Sold Four Securities [Member]

Split Rated [Member]

Below Investment Grade [Member]

Investment Grade [Member]

Schedule of Investments [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Gross unrealized losses on available for sale securities

$44,003,000

$58,717,000

'

'

'

'

'

'

$1,000

$531,000

$0

$458,000

'

$748,000

$52,000

$8,740,000

$1,815,000

$0

'

'

'

'

'

'

'

'

'

'

'

Available for sale securities in unrealized loss position

89

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Available for sale securities in portfolio, number

281

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Amortized cost agency residential mortgage securities

813,049,000

673,315,000

'

'

'

'

'

'

3,299,000

6,660,000

16,369,000

24,569,000

'

172,324,000

336,747,000

241,947,000

215,788,000

101,769,000

'

'

'

'

'

'

'

'

'

'

'

Amortized cost

'

'

'

'

'

'

'

'

3,300,000

'

16,370,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Amortized cost above investment grade

'

'

'

'

'

'

'

'

'

'

6,310,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Amortized cost below investment grade

'

'

'

'

'

'

'

'

'

'

10,060,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Percentage of portfolio of non-agency mortgage backed securities with collateral

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

47.00%

53.00%

'

'

'

'

'

'

'

'

'

Credit-related other-than-temporary impairment recognized in earnings

'

'

'

'

'

'

'

'

'

'

0

'

'

'

'

'

'

'

'

'

6,360,000

7,200,000

5,970,000

'

'

'

'

'

'

Noncredit-related other-than-temporary impairment recognized in accumulated other comprehensive income (loss)

'

'

'

'

'

'

'

'

'

'

0

'

'

'

'

'

'

'

'

'

5,220,000

12,220,000

7,940,000

'

'

'

'

'

'

Capitalization of banks, equal to or greater than, in the single-issue trust preferred portfolio

10,000,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of trust preferred securities deferring interest payments

2

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Amortized cost of trust preferred securities

632,000

'

'

9,900,000

7,390,000

972,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Defer interest payments, maximum period

'5 years

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Amortized cost of available for sale single issue trust preferred securities

'

'

'

'

'

'

2,980,000

11,230,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Amortized cost of available for sale TRUP CDOs and single issue trust preferred securities in an unrealized loss position 12 months or longer

'

'

'

'

'

'

'

'

'

'

'

'

10,230,000

'

'

'

'

'

'

'

'

'

'

'

5,000,000

'

'

'

'

Period of general widening in overall risk premiums

'4 years

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Credit-related other-than-temporary impairment

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4,030,000

'

2,330,000

'

'

'

'

'

Issue of Trup Cdos securities

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4

'

'

'

'

'

'

'

Issue of Additional Trup Cdos securities

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1

'

'

'

'

'

'

'

Excluded Trup Cdos securities

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

5

'

'

'

'

'

'

'

Noncredit related other-than-temporary impairment, net of deferred taxes

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

3,390,000

'

'

'

'

'

'

'

'

Noncredit-related other-than-temporary impairment recognized

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

34,300,000

34,300,000

46,520,000

'

'

'

'

'

'

Amortized cost of available for sale TRUP CDOs and single issue trust preferred securities in an unrealized loss position 12 months or longer

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

62,280,000

6,580,000

'

'

New issuance of Preferred Stock estimated

60,000,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Recognized cumulative credit-related other-than-temporary impairment

860,000

4,955,000

20,958,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Other-than-temporarily impaired, the collateralization ratios low

93.60%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Other-than-temporarily impaired, the collateralization ratios high

209.20%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Other-than-temporarily impaired, the collateralization ratios median

133.40%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Other-than-temporarily impaired, the collateralization ratios weighted average

158.97%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Security other-than-temporarily impaired

100.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of equity securities other-than-temporarily impaired

'

'

'

'

'

'

'

'

0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Available-for-sale securities amortized cost

813,049,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

474,104,000

'

Available-for-sale securities estimated fair value

775,284,000

625,625,000

'

'

'

'

'

'

3,870,000

6,386,000

16,532,000

25,045,000

'

171,754,000

337,522,000

233,432,000

216,464,000

106,510,000

'

'

'

'

'

'

'

'

'

466,428,000

'

Held-to-maturity securities amortized cost

40,965,000

43,467,000

'

'

'

'

'

'

'

'

'

'

'

10,762,000

10,916,000

'

50,000

61,000

'

'

'

'

'

'

'

'

'

50,000

'

Held-to-maturity securities estimated fair value

38,293,000

42,695,000

'

'

'

'

'

'

'

'

'

'

'

12,451,000

13,416,000

'

59,000

71,000

'

'

'

'

'

'

'

'

'

59,000

'

Carrying value of securities pledged

640,870,000

569,680,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Mortgage backed securities net unrealized gains

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$7,667,000

$5,227,000

Aggregate book value percentage of securities to shareholders' equity

'

'

'

'

'

'

'

'

'

'

'

'

'

10.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Investment_Securities_Summary_3

Investment Securities - Summary of Unrealized Loss Positions of Available for Sale TRUP CDOs and Single Issue Trust Preferred Securities (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Assumptions Utilized In Other Than Temporary Impairment Analysis Of Securities [Line Items]	'	'
Fair Value	$35,402	$59,026
Unrealized Loss	32,641	58,137
Trup CDOs and Single Issue Trust Preferred Securities [Member]	'	'
Assumptions Utilized In Other Than Temporary Impairment Analysis Of Securities [Line Items]	'	'
Amortized Cost	73,862	'
Fair Value	43,449	'
Unrealized Loss	30,413	'
Investment Grade [Member] | Trup CDOs and Single Issue Trust Preferred Securities [Member]	'	'
Assumptions Utilized In Other Than Temporary Impairment Analysis Of Securities [Line Items]	'	'
Amortized Cost	6,577	'
Split Rated [Member] | Trup CDOs and Single Issue Trust Preferred Securities [Member]	'	'
Assumptions Utilized In Other Than Temporary Impairment Analysis Of Securities [Line Items]	'	'
Amortized Cost	5,000	'
Below Investment Grade [Member] | Trup CDOs and Single Issue Trust Preferred Securities [Member]	'	'
Assumptions Utilized In Other Than Temporary Impairment Analysis Of Securities [Line Items]	'	'
Amortized Cost	62,285	'
Senior - Bank [Member] | Trup CDOs and Single Issue Trust Preferred Securities [Member]	'	'
Assumptions Utilized In Other Than Temporary Impairment Analysis Of Securities [Line Items]	'	'
Amortized Cost	8,485	'
Fair Value	6,150	'
Unrealized Loss	2,335	'
Senior - Bank [Member] | Investment Grade [Member] | Trup CDOs and Single Issue Trust Preferred Securities [Member]	'	'
Assumptions Utilized In Other Than Temporary Impairment Analysis Of Securities [Line Items]	'	'
Amortized Cost	0	'
Senior - Bank [Member] | Split Rated [Member] | Trup CDOs and Single Issue Trust Preferred Securities [Member]	'	'
Assumptions Utilized In Other Than Temporary Impairment Analysis Of Securities [Line Items]	'	'
Amortized Cost	5,000	'
Senior - Bank [Member] | Below Investment Grade [Member] | Trup CDOs and Single Issue Trust Preferred Securities [Member]	'	'
Assumptions Utilized In Other Than Temporary Impairment Analysis Of Securities [Line Items]	'	'
Amortized Cost	3,485	'
Senior - Insurance [Member] | Trup CDOs and Single Issue Trust Preferred Securities [Member]	'	'
Assumptions Utilized In Other Than Temporary Impairment Analysis Of Securities [Line Items]	'	'
Amortized Cost	6,577	'
Fair Value	6,577	'
Unrealized Loss	0	'
Senior - Insurance [Member] | Investment Grade [Member] | Trup CDOs and Single Issue Trust Preferred Securities [Member]	'	'
Assumptions Utilized In Other Than Temporary Impairment Analysis Of Securities [Line Items]	'	'
Amortized Cost	6,577	'
Senior - Insurance [Member] | Split Rated [Member] | Trup CDOs and Single Issue Trust Preferred Securities [Member]	'	'
Assumptions Utilized In Other Than Temporary Impairment Analysis Of Securities [Line Items]	'	'
Amortized Cost	0	'
Senior - Insurance [Member] | Below Investment Grade [Member] | Trup CDOs and Single Issue Trust Preferred Securities [Member]	'	'
Assumptions Utilized In Other Than Temporary Impairment Analysis Of Securities [Line Items]	'	'
Amortized Cost	0	'
Mezzanine - Bank (now in senior position) [Member] | Trup CDOs and Single Issue Trust Preferred Securities [Member]	'	'
Assumptions Utilized In Other Than Temporary Impairment Analysis Of Securities [Line Items]	'	'
Amortized Cost	13,741	'
Fair Value	8,929	'
Unrealized Loss	4,812	'
Mezzanine - Bank (now in senior position) [Member] | Investment Grade [Member] | Trup CDOs and Single Issue Trust Preferred Securities [Member]	'	'
Assumptions Utilized In Other Than Temporary Impairment Analysis Of Securities [Line Items]	'	'
Amortized Cost	0	'
Mezzanine - Bank (now in senior position) [Member] | Split Rated [Member] | Trup CDOs and Single Issue Trust Preferred Securities [Member]	'	'
Assumptions Utilized In Other Than Temporary Impairment Analysis Of Securities [Line Items]	'	'
Amortized Cost	0	'
Mezzanine - Bank (now in senior position) [Member] | Below Investment Grade [Member] | Trup CDOs and Single Issue Trust Preferred Securities [Member]	'	'
Assumptions Utilized In Other Than Temporary Impairment Analysis Of Securities [Line Items]	'	'
Amortized Cost	13,741	'
Mezzanine - Bank [Member] | Trup CDOs and Single Issue Trust Preferred Securities [Member]	'	'
Assumptions Utilized In Other Than Temporary Impairment Analysis Of Securities [Line Items]	'	'
Amortized Cost	34,583	'
Fair Value	14,501	'
Unrealized Loss	20,082	'
Mezzanine - Bank [Member] | Investment Grade [Member] | Trup CDOs and Single Issue Trust Preferred Securities [Member]	'	'
Assumptions Utilized In Other Than Temporary Impairment Analysis Of Securities [Line Items]	'	'
Amortized Cost	0	'
Mezzanine - Bank [Member] | Split Rated [Member] | Trup CDOs and Single Issue Trust Preferred Securities [Member]	'	'
Assumptions Utilized In Other Than Temporary Impairment Analysis Of Securities [Line Items]	'	'
Amortized Cost	0	'
Mezzanine - Bank [Member] | Below Investment Grade [Member] | Trup CDOs and Single Issue Trust Preferred Securities [Member]	'	'
Assumptions Utilized In Other Than Temporary Impairment Analysis Of Securities [Line Items]	'	'
Amortized Cost	34,583	'
Mezzanine - Insurance [Member] | Trup CDOs and Single Issue Trust Preferred Securities [Member]	'	'
Assumptions Utilized In Other Than Temporary Impairment Analysis Of Securities [Line Items]	'	'
Amortized Cost	5,330	'
Fair Value	5,330	'
Unrealized Loss	0	'
Mezzanine - Insurance [Member] | Investment Grade [Member] | Trup CDOs and Single Issue Trust Preferred Securities [Member]	'	'
Assumptions Utilized In Other Than Temporary Impairment Analysis Of Securities [Line Items]	'	'
Amortized Cost	0	'
Mezzanine - Insurance [Member] | Split Rated [Member] | Trup CDOs and Single Issue Trust Preferred Securities [Member]	'	'
Assumptions Utilized In Other Than Temporary Impairment Analysis Of Securities [Line Items]	'	'
Amortized Cost	0	'
Mezzanine - Insurance [Member] | Below Investment Grade [Member] | Trup CDOs and Single Issue Trust Preferred Securities [Member]	'	'
Assumptions Utilized In Other Than Temporary Impairment Analysis Of Securities [Line Items]	'	'
Amortized Cost	5,330	'
Mezzanine - Bank & Insurance (combination) [Member] | Trup CDOs and Single Issue Trust Preferred Securities [Member]	'	'
Assumptions Utilized In Other Than Temporary Impairment Analysis Of Securities [Line Items]	'	'
Amortized Cost	5,146	'
Fair Value	1,962	'
Unrealized Loss	3,184	'
Mezzanine - Bank & Insurance (combination) [Member] | Investment Grade [Member] | Trup CDOs and Single Issue Trust Preferred Securities [Member]	'	'
Assumptions Utilized In Other Than Temporary Impairment Analysis Of Securities [Line Items]	'	'
Amortized Cost	0	'
Mezzanine - Bank & Insurance (combination) [Member] | Split Rated [Member] | Trup CDOs and Single Issue Trust Preferred Securities [Member]	'	'
Assumptions Utilized In Other Than Temporary Impairment Analysis Of Securities [Line Items]	'	'
Amortized Cost	0	'
Mezzanine - Bank & Insurance (combination) [Member] | Below Investment Grade [Member] | Trup CDOs and Single Issue Trust Preferred Securities [Member]	'	'
Assumptions Utilized In Other Than Temporary Impairment Analysis Of Securities [Line Items]	'	'
Amortized Cost	$5,146	'

Investment_Securities_Roll_For

Investment Securities - Roll Forward of Credit Losses on Securities (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013
Investments Debt And Equity Securities [Abstract]	'
Cumulative credit losses, Beginning Balance	$63,114
Additions for credit losses on securities for which OTTI was not previously recognized	1,267
Additions for additional credit losses on securities for which OTTI was previously recognized	6,065
Cumulative credit losses, Ending Balance	$70,446

Investment_Securities_Summary_4

Investment Securities - Summary of Maturities of Securities Available for Sale by Amortized Cost and Estimated Fair Value (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Investments Debt And Equity Securities [Abstract]	'	'
Due in one year or less, Amortized Cost	$28,837	'
Due after one year through five years, Amortized Cost	217,415	'
Due after five years through ten years, Amortized Cost	292,460	'
Due after ten years, Amortized Cost	271,038	'
Marketable equity securities, Amortized Cost	3,299	'
Amortized Cost, Total	813,049	'
Due in one year or less, Estimated Fair Value	28,960	'
Due after one year through five years, Estimated Fair Value	218,498	'
Due after five years through ten years, Estimated Fair Value	286,534	'
Due after ten years, Estimated Fair Value	237,422	'
Marketable equity securities, Estimated Fair Value	3,870	'
Total available for sale securities	$775,284	$625,625

Investment_Securities_Summary_5

Investment Securities - Summary of Amortized Cost and Estimated Fair Values of Securities Held to Maturity (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Schedule of Investments [Line Items]	'	'
Amortized Cost	$40,965,000	$43,467,000
Gross Unrealized Gains	1,735,000	2,618,000
Gross Unrealized Losses	4,407,000	3,390,000
Estimated Fair Value	38,293,000	42,695,000
U.S. Treasury Securities and Obligations of U.S. Government Corporations and Agencies [Member]	'	'
Schedule of Investments [Line Items]	'	'
Amortized Cost	10,762,000	10,916,000
Gross Unrealized Gains	1,689,000	2,500,000
Gross Unrealized Losses	0	0
Estimated Fair Value	12,451,000	13,416,000
State and Political Subdivisions [Member]	'	'
Schedule of Investments [Line Items]	'	'
Amortized Cost	10,367,000	12,515,000
Gross Unrealized Gains	37,000	108,000
Gross Unrealized Losses	299,000	0
Estimated Fair Value	10,105,000	12,623,000
Residential Mortgage-Backed Securities, Agency [Member]	'	'
Schedule of Investments [Line Items]	'	'
Amortized Cost	50,000	61,000
Gross Unrealized Gains	9,000	10,000
Gross Unrealized Losses	0	0
Estimated Fair Value	59,000	71,000
Single Issue Trust Preferred Securities [Member]	'	'
Schedule of Investments [Line Items]	'	'
Amortized Cost	19,766,000	19,750,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	4,108,000	3,390,000
Estimated Fair Value	15,658,000	16,360,000
Other Corporate Securities [Member]	'	'
Schedule of Investments [Line Items]	'	'
Amortized Cost	20,000	225,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	$20,000	$225,000

Investment_Securities_Summary_6

Investment Securities - Summary of Gross Realized Gains and Losses on Calls and Sales of Held to Maturity Securities Included in Earnings (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Amortized Cost And Fair Value Debt Securities [Abstract]	'	'	'
Gross realized gains	$114	$352	$1
Gross realized losses	$0	$0	$0

Investment_Securities_Summary_7

Investment Securities - Summary of Maturities of Debt Securities Held to Maturity by Amortized Cost and Estimated Fair Value (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Investments Debt And Equity Securities [Abstract]	'	'
Due in one year or less, Amortized Cost	$555	'
Due after one year through five years, Amortized Cost	6,683	'
Due after five years through ten years, Amortized Cost	13,026	'
Due after ten years, Amortized Cost	20,701	'
Amortized Cost, Total	40,965	43,467
Due in one year or less, Estimated Fair Value	556	'
Due after one year through five years, Estimated Fair Value	7,312	'
Due after five years through ten years, Estimated Fair Value	13,821	'
Due after ten years, Estimated Fair Value	16,604	'
Estimated Fair Value, Total	$38,293	$42,695

Investment_Securities_Maturiti

Investment Securities - Maturities and Weighted-Average Yields of Securities (Detail) (USD $)	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Held-to-maturity Securities [Line Items]	'
Securities matured Within 1 Year, Amount	$555
Securities matured After 1 But Within 5 Years, Amount	6,683
Securities matured After 5 But Within 10 Years, Amount	13,026
Securities matured After 10 Years, Amount	20,701
U.S. Treasury Securities and Obligations of U.S. Government Corporations and Agencies [Member]	'
Schedule of Held-to-maturity Securities [Line Items]	'
Securities matured Within 1 Year, Amount	14,998
Weighted-average Within 1 Year, Yield	0.26%
Securities matured After 1 But Within 5 Years, Amount	117,261
Weighted-average After 1 But Within 5 Years, Yield	1.06%
Securities matured After 5 But Within 10 Years, Amount	50,826
Weighted-average After 5 But Within 10 Years, Yield	1.12%
Securities matured After 10 Years, Amount	0
Weighted-average After 10 Years, Yield	0.00%
State and Political Subdivisions [Member]	'
Schedule of Held-to-maturity Securities [Line Items]	'
Securities matured Within 1 Year, Amount	14,383
Weighted-average Within 1 Year, Yield	4.07%
Securities matured After 1 But Within 5 Years, Amount	28,895
Weighted-average After 1 But Within 5 Years, Yield	5.66%
Securities matured After 5 But Within 10 Years, Amount	24,037
Weighted-average After 5 But Within 10 Years, Yield	6.38%
Securities matured After 10 Years, Amount	3,912
Weighted-average After 10 Years, Yield	6.78%
Residential Mortgage-Backed Securities, Agency [Member]	'
Schedule of Held-to-maturity Securities [Line Items]	'
Securities matured Within 1 Year, Amount	12
Weighted-average Within 1 Year, Yield	6.00%
Securities matured After 1 But Within 5 Years, Amount	7,130
Weighted-average After 1 But Within 5 Years, Yield	3.56%
Securities matured After 5 But Within 10 Years, Amount	45,918
Weighted-average After 5 But Within 10 Years, Yield	3.73%
Securities matured After 10 Years, Amount	162,778
Weighted-average After 10 Years, Yield	2.34%
Residential Mortgage-Backed Securities, Non-agency [Member]	'
Schedule of Held-to-maturity Securities [Line Items]	'
Securities matured Within 1 Year, Amount	0
Weighted-average Within 1 Year, Yield	0.00%
Securities matured After 1 But Within 5 Years, Amount	443
Weighted-average After 1 But Within 5 Years, Yield	4.58%
Securities matured After 5 But Within 10 Years, Amount	6,872
Weighted-average After 5 But Within 10 Years, Yield	5.02%
Securities matured After 10 Years, Amount	9,054
Weighted-average After 10 Years, Yield	5.82%
Commercial Mortgage-backed Agency [Member]	'
Schedule of Held-to-maturity Securities [Line Items]	'
Securities matured Within 1 Year, Amount	0
Weighted-average Within 1 Year, Yield	0.00%
Securities matured After 1 But Within 5 Years, Amount	54,449
Weighted-average After 1 But Within 5 Years, Yield	1.19%
Securities matured After 5 But Within 10 Years, Amount	179,499
Weighted-average After 5 But Within 10 Years, Yield	2.21%
Securities matured After 10 Years, Amount	7,999
Weighted-average After 10 Years, Yield	2.75%
Asset-Backed Securities [Member]	'
Schedule of Held-to-maturity Securities [Line Items]	'
Securities matured Within 1 Year, Amount	0
Weighted-average Within 1 Year, Yield	0.00%
Securities matured After 1 But Within 5 Years, Amount	8,008
Weighted-average After 1 But Within 5 Years, Yield	0.69%
Securities matured After 5 But Within 10 Years, Amount	1,249
Weighted-average After 5 But Within 10 Years, Yield	0.35%
Securities matured After 10 Years, Amount	0
Weighted-average After 10 Years, Yield	0.00%
Trust Preferred Collateralized Debt Obligations [Member]	'
Schedule of Held-to-maturity Securities [Line Items]	'
Securities matured Within 1 Year, Amount	0
Weighted-average Within 1 Year, Yield	0.00%
Securities matured After 1 But Within 5 Years, Amount	0
Weighted-average After 1 But Within 5 Years, Yield	0.00%
Securities matured After 5 But Within 10 Years, Amount	0
Weighted-average After 5 But Within 10 Years, Yield	0.00%
Securities matured After 10 Years, Amount	73,862
Weighted-average After 10 Years, Yield	4.58%
Single Issue Trust Preferred Securities [Member]	'
Schedule of Held-to-maturity Securities [Line Items]	'
Securities matured Within 1 Year, Amount	0
Weighted-average Within 1 Year, Yield	0.00%
Securities matured After 1 But Within 5 Years, Amount	0
Weighted-average After 1 But Within 5 Years, Yield	0.00%
Securities matured After 5 But Within 10 Years, Amount	0
Weighted-average After 5 But Within 10 Years, Yield	0.00%
Securities matured After 10 Years, Amount	34,112
Weighted-average After 10 Years, Yield	2.40%
Marketable Equity Securities [Member]	'
Schedule of Held-to-maturity Securities [Line Items]	'
Securities matured Within 1 Year, Amount	0
Weighted-average Within 1 Year, Yield	0.00%
Securities matured After 1 But Within 5 Years, Amount	0
Weighted-average After 1 But Within 5 Years, Yield	0.00%
Securities matured After 5 But Within 10 Years, Amount	0
Weighted-average After 5 But Within 10 Years, Yield	0.00%
Securities matured After 10 Years, Amount	3,299
Weighted-average After 10 Years, Yield	2.47%
Other Corporate Securities [Member]	'
Schedule of Held-to-maturity Securities [Line Items]	'
Securities matured Within 1 Year, Amount	0
Weighted-average Within 1 Year, Yield	0.00%
Securities matured After 1 But Within 5 Years, Amount	4,996
Weighted-average After 1 But Within 5 Years, Yield	2.73%
Securities matured After 5 But Within 10 Years, Amount	0
Weighted-average After 5 But Within 10 Years, Yield	0.00%
Securities matured After 10 Years, Amount	$20
Weighted-average After 10 Years, Yield	0.00%

Investment_Securities_Maturiti1

Investment Securities - Maturities and Weighted-Average Yields of Securities (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Amortized Cost And Fair Value Debt Securities [Abstract]	'	'	'
Tax on income before taxes at statutory federal rate, rate	35.00%	35.00%	35.00%

Loans_Classes_of_Loans_Detail

Loans - Classes of Loans (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'
Total commercial, financial & agricultural	$3,911,103	$3,846,409
Residential real estate	1,821,378	1,838,252
Construction & land development	670,364	550,677
Bankcard	11,023	11,236
Other Consumer	299,731	271,206
Less: Unearned interest	-9,016	-6,364
Loans net of unearned income	6,704,583	6,511,416
Owner-Occupied [Member]	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'
Commercial real estate	654,963	728,906
Nonowner-Occupied [Member]	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'
Commercial real estate	1,917,785	1,740,420
Other Commercial [Member]	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'
Commercial real estate	$1,338,355	$1,377,083

Loans_Additional_Information_D

Loans - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Loans [Abstract]	'	'
Loans held for sale	$4,236,000	$17,762,000
Acquired impaired loans from merger	31,099,000	33,206,000
Percentage of acquired impaired loans from merger on total gross loans	1.00%	1.00%
Recorded investment in acquired impaired loans	52,237,000	55,685,000
Loans-in-process	43,158,000	68,255,000
Overdrafts from deposit accounts	4,344,000	11,231,000
Related party loans	150,798,000	150,638,000
Additional amount of loan	208,970,000	'
Repayment of Loan	$208,810,000	'

Loans_Activity_for_Accretable_

Loans - Activity for Accretable Yield (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013
Loans [Abstract]	'
Accretable yield at the beginning of the period	$2,331
Accretion (including cash recoveries)	-3,192
Net reclassifications to accretable from non-accretable	3,373
Disposals (including maturities, foreclosures, and charge-offs)	-261
Accretable yield at the ending of the period	$2,251

Credit_Quality_Additional_Info

Credit Quality - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Minimum days for discontinue of accrual interest on commercial and consumer loan	'90 days	'
Maximum days for discontinue of accrual interest on commercial and consumer loan	'120 days	'
Troubled debt restructuring	$8,157,000	$3,175,000
Loans on nonaccrual status	861,000	375,000
Restructured loans modified by reduction in interest	4,267,000	'
Restructured Loan and Interest	2,954,000	'
Restructured loans modified by reduction in interest	936,000	651,000
Restructured loans and interest	$2,166,000	$375,000
Number of days required for substandard	'90 days	'
Minimum [Member]	'	'
Number of days required for special mention	'30 days	'
Maximum [Member]	'	'
Number of days required for special mention	'89 days	'

Credit_Quality_Schedule_of_Tro

Credit Quality - Schedule of Troubled Debt Restructurings, Segregated by Class of Loans (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
	Contract	Contract
Financing Receivable, Modifications [Line Items]	'	'
Number of Contracts	7	2
Pre-Modification Outstanding Recorded Investment	$6,010	$1,371
Post-Modification Outstanding Recorded Investment	5,422	1,026
Owner-Occupied [Member]	'	'
Financing Receivable, Modifications [Line Items]	'	'
Number of Contracts	4	0
Pre-Modification Outstanding Recorded Investment	5,143	0
Post-Modification Outstanding Recorded Investment	4,561	0
Nonowner-Occupied [Member]	'	'
Financing Receivable, Modifications [Line Items]	'	'
Number of Contracts	2	0
Pre-Modification Outstanding Recorded Investment	762	0
Post-Modification Outstanding Recorded Investment	757	0
Other Commercial [Member]	'	'
Financing Receivable, Modifications [Line Items]	'	'
Number of Contracts	0	0
Pre-Modification Outstanding Recorded Investment	0	0
Post-Modification Outstanding Recorded Investment	0	0
Residential Real Estate [Member]	'	'
Financing Receivable, Modifications [Line Items]	'	'
Number of Contracts	1	1
Pre-Modification Outstanding Recorded Investment	105	640
Post-Modification Outstanding Recorded Investment	104	651
Construction & Land Development [Member]	'	'
Financing Receivable, Modifications [Line Items]	'	'
Number of Contracts	0	1
Pre-Modification Outstanding Recorded Investment	0	731
Post-Modification Outstanding Recorded Investment	0	375
Bankcard [Member]	'	'
Financing Receivable, Modifications [Line Items]	'	'
Number of Contracts	0	0
Pre-Modification Outstanding Recorded Investment	0	0
Post-Modification Outstanding Recorded Investment	0	0
Other Consumer [Member]	'	'
Financing Receivable, Modifications [Line Items]	'	'
Number of Contracts	0	0
Pre-Modification Outstanding Recorded Investment	0	0
Post-Modification Outstanding Recorded Investment	$0	$0

Credit_Quality_Schedule_of_Cha

Credit Quality - Schedule of Charged-off Troubled Debt Restructurings on Financing Receivables (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
	Contract	Contract
Financing Receivable Modifications Number Of Contracts [Line Items]	'	'
Number of Contracts	1	1
Recorded Investment	$375	$375
Owner-Occupied [Member]	'	'
Financing Receivable Modifications Number Of Contracts [Line Items]	'	'
Number of Contracts	0	0
Recorded Investment	0	0
Nonowner-Occupied [Member]	'	'
Financing Receivable Modifications Number Of Contracts [Line Items]	'	'
Number of Contracts	0	0
Recorded Investment	0	0
Other Commercial [Member]	'	'
Financing Receivable Modifications Number Of Contracts [Line Items]	'	'
Number of Contracts	0	0
Recorded Investment	0	0
Residential Real Estate [Member]	'	'
Financing Receivable Modifications Number Of Contracts [Line Items]	'	'
Number of Contracts	0	0
Recorded Investment	0	0
Construction & Land Development [Member]	'	'
Financing Receivable Modifications Number Of Contracts [Line Items]	'	'
Number of Contracts	1	1
Recorded Investment	375	375
Bankcard [Member]	'	'
Financing Receivable Modifications Number Of Contracts [Line Items]	'	'
Number of Contracts	0	0
Recorded Investment	0	0
Other Consumer [Member]	'	'
Financing Receivable Modifications Number Of Contracts [Line Items]	'	'
Number of Contracts	0	0
Recorded Investment	$0	$0

Credit_Quality_Schedule_of_Age

Credit Quality - Schedule of Age Analysis of its Past Due Loans, Segregated by Class of Loans (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Financing Receivable, Recorded Investment, Past Due [Line Items]	'	'
Loans, 30-89 Days Past Due	$173,186	$109,640
Loans, 90 Days or more Past Due	73,833	90,002
Loans, Total Past Due	247,019	199,642
Loans, Current	6,466,580	6,318,138
Total gross loans	6,713,599	6,517,780
Loans, Recorded Investment >90 Days & Accruing	11,044	18,068
Owner-Occupied [Member]	'	'
Financing Receivable, Recorded Investment, Past Due [Line Items]	'	'
Loans, 30-89 Days Past Due	14,144	11,122
Loans, 90 Days or more Past Due	4,537	16,691
Loans, Total Past Due	18,681	27,813
Loans, Current	636,282	701,093
Total gross loans	654,963	728,906
Loans, Recorded Investment >90 Days & Accruing	1,383	4,038
Nonowner-Occupied [Member]	'	'
Financing Receivable, Recorded Investment, Past Due [Line Items]	'	'
Loans, 30-89 Days Past Due	30,836	12,793
Loans, 90 Days or more Past Due	11,725	11,643
Loans, Total Past Due	42,561	24,436
Loans, Current	1,875,224	1,715,984
Total gross loans	1,917,785	1,740,420
Loans, Recorded Investment >90 Days & Accruing	186	2,549
Other Commercial [Member]	'	'
Financing Receivable, Recorded Investment, Past Due [Line Items]	'	'
Loans, 30-89 Days Past Due	54,319	8,379
Loans, 90 Days or more Past Due	11,794	20,808
Loans, Total Past Due	66,113	29,187
Loans, Current	1,272,242	1,347,896
Total gross loans	1,338,355	1,377,083
Loans, Recorded Investment >90 Days & Accruing	896	1,687
Residential Real Estate [Member]	'	'
Financing Receivable, Recorded Investment, Past Due [Line Items]	'	'
Loans, 30-89 Days Past Due	54,271	54,168
Loans, 90 Days or more Past Due	25,446	22,095
Loans, Total Past Due	79,717	76,263
Loans, Current	1,741,661	1,761,989
Total gross loans	1,821,378	1,838,252
Loans, Recorded Investment >90 Days & Accruing	5,214	7,363
Construction & Land Development [Member]	'	'
Financing Receivable, Recorded Investment, Past Due [Line Items]	'	'
Loans, 30-89 Days Past Due	9,921	14,046
Loans, 90 Days or more Past Due	18,491	16,918
Loans, Total Past Due	28,412	30,964
Loans, Current	641,952	519,713
Total gross loans	670,364	550,677
Loans, Recorded Investment >90 Days & Accruing	1,611	654
Bankcard [Member]	'	'
Financing Receivable, Recorded Investment, Past Due [Line Items]	'	'
Loans, 30-89 Days Past Due	229	394
Loans, 90 Days or more Past Due	128	164
Loans, Total Past Due	357	558
Loans, Current	10,666	10,678
Total gross loans	11,023	11,236
Loans, Recorded Investment >90 Days & Accruing	128	164
Other Consumer [Member]	'	'
Financing Receivable, Recorded Investment, Past Due [Line Items]	'	'
Loans, 30-89 Days Past Due	9,466	8,738
Loans, 90 Days or more Past Due	1,712	1,683
Loans, Total Past Due	11,178	10,421
Loans, Current	288,553	260,785
Total gross loans	299,731	271,206
Loans, Recorded Investment >90 Days & Accruing	$1,626	$1,613

Credit_Quality_Schedule_of_Non

Credit Quality - Schedule of Nonaccrual Loans, Segregated by Class of Loans (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Non Accrual Loans Segregated By Class Of Loans [Line Items]	'	'
Loans on Nonaccrual Status	$62,789	$71,934
Owner-Occupied [Member]	'	'
Non Accrual Loans Segregated By Class Of Loans [Line Items]	'	'
Loans on Nonaccrual Status	3,154	12,653
Nonowner-Occupied [Member]	'	'
Non Accrual Loans Segregated By Class Of Loans [Line Items]	'	'
Loans on Nonaccrual Status	11,539	9,094
Other Commercial [Member]	'	'
Non Accrual Loans Segregated By Class Of Loans [Line Items]	'	'
Loans on Nonaccrual Status	10,898	19,121
Residential Real Estate [Member]	'	'
Non Accrual Loans Segregated By Class Of Loans [Line Items]	'	'
Loans on Nonaccrual Status	20,232	14,732
Construction & Land Development [Member]	'	'
Non Accrual Loans Segregated By Class Of Loans [Line Items]	'	'
Loans on Nonaccrual Status	16,880	16,264
Bankcard [Member]	'	'
Non Accrual Loans Segregated By Class Of Loans [Line Items]	'	'
Loans on Nonaccrual Status	0	0
Other Consumer [Member]	'	'
Non Accrual Loans Segregated By Class Of Loans [Line Items]	'	'
Loans on Nonaccrual Status	$86	$70

Credit_Quality_Schedule_of_Cre

Credit Quality - Schedule of Credit Quality Indicators Information, by Class of Loans (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	$6,713,599	$6,517,780
Owner-Occupied [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	654,963	728,906
Owner-Occupied [Member] | Pass [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	604,129	669,157
Owner-Occupied [Member] | Special Mention [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	27,576	25,487
Owner-Occupied [Member] | Substandard [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	23,258	34,262
Owner-Occupied [Member] | Doubtful [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	0	0
Nonowner-Occupied [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	1,917,785	1,740,420
Nonowner-Occupied [Member] | Pass [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	1,811,915	1,621,338
Nonowner-Occupied [Member] | Special Mention [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	45,617	54,399
Nonowner-Occupied [Member] | Substandard [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	60,253	64,683
Nonowner-Occupied [Member] | Doubtful [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	0	0
Other Commercial [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	1,338,355	1,377,083
Other Commercial [Member] | Pass [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	1,206,030	1,286,471
Other Commercial [Member] | Special Mention [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	60,668	31,293
Other Commercial [Member] | Substandard [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	71,148	57,386
Other Commercial [Member] | Doubtful [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	509	1,933
Construction & Land Development [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	670,364	550,677
Construction & Land Development [Member] | Pass [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	510,911	392,096
Construction & Land Development [Member] | Special Mention [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	63,375	92,667
Construction & Land Development [Member] | Substandard [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	96,078	65,914
Construction & Land Development [Member] | Doubtful [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	0	0
Residential Real Estate [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	1,821,378	1,838,252
Residential Real Estate [Member] | Pass [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	1,773,244	1,800,377
Residential Real Estate [Member] | Special Mention [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	13,006	7,866
Residential Real Estate [Member] | Substandard [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	35,128	30,009
Residential Real Estate [Member] | Doubtful [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	0	0
Bankcard [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	11,023	11,236
Bankcard [Member] | Pass [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	10,666	10,678
Bankcard [Member] | Special Mention [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	229	394
Bankcard [Member] | Substandard [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	128	164
Bankcard [Member] | Doubtful [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	0	0
Other Consumer [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	299,731	271,206
Other Consumer [Member] | Pass [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	288,401	271,054
Other Consumer [Member] | Special Mention [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	9,466	0
Other Consumer [Member] | Substandard [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	1,712	152
Other Consumer [Member] | Doubtful [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Financing receivable, credit quality indicators information	$152	$0

Credit_Quality_Schedule_of_Imp

Credit Quality - Schedule of Impaired Loans Information by Class of Loans (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Owner-Occupied [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Impaired Loans, Recorded Investment	$9,030	$16,875
Impaired Loans, Unpaid Principal Balance	9,030	17,563
Impaired Loans, Related Allowance	638	397
Impaired Loans, Average Recorded Investment	13,922	13,311
Impaired Loans, Interest Income Recognized	401	821
Nonowner-Occupied [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Impaired Loans, Recorded Investment	15,288	14,330
Impaired Loans, Unpaid Principal Balance	17,214	19,024
Impaired Loans, Related Allowance	1,631	1,154
Impaired Loans, Average Recorded Investment	16,520	26,870
Impaired Loans, Interest Income Recognized	483	498
Other Commercial [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Impaired Loans, Recorded Investment	23,596	30,646
Impaired Loans, Unpaid Principal Balance	33,993	35,912
Impaired Loans, Related Allowance	2,192	7,564
Impaired Loans, Average Recorded Investment	27,679	31,448
Impaired Loans, Interest Income Recognized	2,114	2,147
Residential Real Estate [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Impaired Loans, Recorded Investment	19,678	12,670
Impaired Loans, Unpaid Principal Balance	20,384	16,185
Impaired Loans, Related Allowance	4,112	1,427
Impaired Loans, Average Recorded Investment	15,220	19,971
Impaired Loans, Interest Income Recognized	641	798
Construction & Land Development [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Impaired Loans, Recorded Investment	24,916	20,715
Impaired Loans, Unpaid Principal Balance	29,495	27,118
Impaired Loans, Related Allowance	3,752	3,659
Impaired Loans, Average Recorded Investment	22,698	31,008
Impaired Loans, Interest Income Recognized	431	607
Bankcard [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Impaired Loans, Recorded Investment	0	0
Impaired Loans, Unpaid Principal Balance	0	0
Impaired Loans, Related Allowance	0	0
Impaired Loans, Average Recorded Investment	0	0
Impaired Loans, Interest Income Recognized	0	0
Other Consumer [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Impaired Loans, Recorded Investment	152	152
Impaired Loans, Unpaid Principal Balance	152	152
Impaired Loans, Related Allowance	152	0
Impaired Loans, Average Recorded Investment	152	165
Impaired Loans, Interest Income Recognized	0	0
Impaired Loans with no Related Allowance Recorded [Member] | Owner-Occupied [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Impaired Loans, Recorded Investment	4,672	15,591
Impaired Loans, Unpaid Principal Balance	4,672	16,279
Impaired Loans, Related Allowance	0	0
Impaired Loans, Average Recorded Investment	11,379	12,160
Impaired Loans, Interest Income Recognized	242	770
Impaired Loans with no Related Allowance Recorded [Member] | Nonowner-Occupied [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Impaired Loans, Recorded Investment	5,938	10,907
Impaired Loans, Unpaid Principal Balance	6,651	14,601
Impaired Loans, Related Allowance	0	0
Impaired Loans, Average Recorded Investment	10,168	23,393
Impaired Loans, Interest Income Recognized	194	431
Impaired Loans with no Related Allowance Recorded [Member] | Other Commercial [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Impaired Loans, Recorded Investment	10,292	3,036
Impaired Loans, Unpaid Principal Balance	17,753	5,501
Impaired Loans, Related Allowance	0	0
Impaired Loans, Average Recorded Investment	11,550	5,208
Impaired Loans, Interest Income Recognized	1,828	178
Impaired Loans with no Related Allowance Recorded [Member] | Residential Real Estate [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Impaired Loans, Recorded Investment	12,009	7,035
Impaired Loans, Unpaid Principal Balance	12,193	9,157
Impaired Loans, Related Allowance	0	0
Impaired Loans, Average Recorded Investment	9,211	10,982
Impaired Loans, Interest Income Recognized	358	418
Impaired Loans with no Related Allowance Recorded [Member] | Construction & Land Development [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Impaired Loans, Recorded Investment	13,866	7,682
Impaired Loans, Unpaid Principal Balance	14,662	10,089
Impaired Loans, Related Allowance	0	0
Impaired Loans, Average Recorded Investment	9,305	18,104
Impaired Loans, Interest Income Recognized	373	285
Impaired Loans with no Related Allowance Recorded [Member] | Bankcard [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Impaired Loans, Recorded Investment	0	0
Impaired Loans, Unpaid Principal Balance	0	0
Impaired Loans, Related Allowance	0	0
Impaired Loans, Average Recorded Investment	0	0
Impaired Loans, Interest Income Recognized	0	0
Impaired Loans with no Related Allowance Recorded [Member] | Other Consumer [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Impaired Loans, Recorded Investment	0	152
Impaired Loans, Unpaid Principal Balance	0	152
Impaired Loans, Related Allowance	0	0
Impaired Loans, Average Recorded Investment	114	165
Impaired Loans, Interest Income Recognized	0	0
Impaired Loans with an Allowance Recorded [Member] | Owner-Occupied [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Impaired Loans, Recorded Investment	4,358	1,284
Impaired Loans, Unpaid Principal Balance	4,358	1,284
Impaired Loans, Related Allowance	638	397
Impaired Loans, Average Recorded Investment	2,543	1,151
Impaired Loans, Interest Income Recognized	159	51
Impaired Loans with an Allowance Recorded [Member] | Nonowner-Occupied [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Impaired Loans, Recorded Investment	9,350	3,423
Impaired Loans, Unpaid Principal Balance	10,563	4,423
Impaired Loans, Related Allowance	1,631	1,154
Impaired Loans, Average Recorded Investment	6,352	3,477
Impaired Loans, Interest Income Recognized	289	67
Impaired Loans with an Allowance Recorded [Member] | Other Commercial [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Impaired Loans, Recorded Investment	13,304	27,610
Impaired Loans, Unpaid Principal Balance	16,240	30,411
Impaired Loans, Related Allowance	2,192	7,564
Impaired Loans, Average Recorded Investment	16,129	26,240
Impaired Loans, Interest Income Recognized	286	1,969
Impaired Loans with an Allowance Recorded [Member] | Residential Real Estate [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Impaired Loans, Recorded Investment	7,669	5,635
Impaired Loans, Unpaid Principal Balance	8,191	7,028
Impaired Loans, Related Allowance	4,112	1,427
Impaired Loans, Average Recorded Investment	6,009	8,989
Impaired Loans, Interest Income Recognized	283	380
Impaired Loans with an Allowance Recorded [Member] | Construction & Land Development [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Impaired Loans, Recorded Investment	11,050	13,033
Impaired Loans, Unpaid Principal Balance	14,833	17,029
Impaired Loans, Related Allowance	3,752	3,659
Impaired Loans, Average Recorded Investment	13,393	12,904
Impaired Loans, Interest Income Recognized	58	322
Impaired Loans with an Allowance Recorded [Member] | Bankcard [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Impaired Loans, Recorded Investment	0	0
Impaired Loans, Unpaid Principal Balance	0	0
Impaired Loans, Related Allowance	0	0
Impaired Loans, Average Recorded Investment	0	0
Impaired Loans, Interest Income Recognized	0	0
Impaired Loans with an Allowance Recorded [Member] | Other Consumer [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Impaired Loans, Recorded Investment	152	0
Impaired Loans, Unpaid Principal Balance	152	0
Impaired Loans, Related Allowance	152	0
Impaired Loans, Average Recorded Investment	38	0
Impaired Loans, Interest Income Recognized	$0	$0

Allowance_for_Credit_Losses_Ad

Allowance for Credit Losses - Additional Information (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'
Specific loss allocations are calculated for loans in excess	$500	'
Number of days for collecting principal or interest on consumer loans	'90 days	'
Minimum collection period for home equity loan or high loan to value loan	'180 days	'
Retail credits amount deemed unrecoverable charged-off period	'60 days	'
Retail credits charged off period after discovery of the fraud	'90 days	'
Reserve for lending-related commitments	$2,143	$1,656
Closed-End Retail Loans [Member]	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'
Number of days delinquent from contractual due date	'120 days	'
Open-End Loans [Member]	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'
Number of days delinquent from contractual due date	'180 days	'

Allowance_for_Credit_Losses_Pr

Allowance for Credit Losses - Progression of Allowance for Credit Losses Including Allowance for Credit Losses and Reserve for Lending-Related Commitments (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Receivables [Abstract]	'	'	'
Balance at beginning of period	$75,557	$75,727	$75,039
Provision for credit losses	19,754	17,665	16,988
Financing receivable allowance and provisions for credit losses	95,311	93,392	92,027
Loans charged off	21,006	20,555	19,605
Less recoveries	2,036	2,720	3,305
Net charge-offs	18,970	17,835	16,300
Balance at end of period	$76,341	$75,557	$75,727

Allowance_for_Credit_Losses_Sc

Allowance for Credit Losses - Schedule of Allowance for Loan Losses and Carrying Amount of Loans (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Allowance for Loan Losses:	'	'	'	'	'	'	'	'	'	'	'
Beginning balance	'	'	'	$73,901	'	'	'	$73,874	$73,901	$73,874	'
Charge-offs	'	'	'	'	'	'	'	'	21,006	20,555	'
Recoveries	'	'	'	'	'	'	'	'	2,036	2,720	'
Provision	4,343	4,777	4,960	5,187	5,947	4,346	3,436	4,133	19,267	17,862	17,141
Ending balance	74,198	'	'	'	73,901	'	'	'	74,198	73,901	73,874
Ending Balance: individually evaluated for impairment	12,477	'	'	'	13,790	'	'	'	12,477	13,790	'
Ending Balance: collectively evaluated for impairment	61,721	'	'	'	60,111	'	'	'	61,721	60,111	'
Ending Balance: loans acquired with deteriorated credit quality	0	'	'	'	0	'	'	'	0	0	'
Financing receivables:	'	'	'	'	'	'	'	'	'	'	'
Ending balance	6,713,599	'	'	'	6,517,780	'	'	'	6,713,599	6,517,780	'
Ending Balance: individually evaluated for impairment	81,302	'	'	'	81,940	'	'	'	81,302	81,940	'
Ending Balance: collectively evaluated for impairment	6,601,198	'	'	'	6,402,634	'	'	'	6,601,198	6,402,634	'
Ending Balance: loans acquired with deteriorated credit quality	31,099	'	'	'	33,206	'	'	'	31,099	33,206	'
Owner-Occupied [Member]	'	'	'	'	'	'	'	'	'	'	'
Allowance for Loan Losses:	'	'	'	'	'	'	'	'	'	'	'
Beginning balance	'	'	'	3,877	'	'	'	3,670	3,877	3,670	'
Charge-offs	'	'	'	'	'	'	'	'	5,344	801	'
Recoveries	'	'	'	'	'	'	'	'	150	60	'
Provision	'	'	'	'	'	'	'	'	6,970	948	'
Ending balance	5,653	'	'	'	3,877	'	'	'	5,653	3,877	'
Ending Balance: individually evaluated for impairment	638	'	'	'	417	'	'	'	638	417	'
Ending Balance: collectively evaluated for impairment	5,015	'	'	'	3,460	'	'	'	5,015	3,460	'
Ending Balance: loans acquired with deteriorated credit quality	0	'	'	'	0	'	'	'	0	0	'
Financing receivables:	'	'	'	'	'	'	'	'	'	'	'
Ending balance	654,963	'	'	'	728,906	'	'	'	654,963	728,906	'
Ending Balance: individually evaluated for impairment	7,157	'	'	'	14,474	'	'	'	7,157	14,474	'
Ending Balance: collectively evaluated for impairment	646,548	'	'	'	712,776	'	'	'	646,548	712,776	'
Ending Balance: loans acquired with deteriorated credit quality	1,258	'	'	'	1,656	'	'	'	1,258	1,656	'
Nonowner-Occupied [Member]	'	'	'	'	'	'	'	'	'	'	'
Allowance for Loan Losses:	'	'	'	'	'	'	'	'	'	'	'
Beginning balance	'	'	'	12,876	'	'	'	11,647	12,876	11,647	'
Charge-offs	'	'	'	'	'	'	'	'	1,164	2,608	'
Recoveries	'	'	'	'	'	'	'	'	56	122	'
Provision	'	'	'	'	'	'	'	'	-2,776	3,715	'
Ending balance	8,992	'	'	'	12,876	'	'	'	8,992	12,876	'
Ending Balance: individually evaluated for impairment	1,631	'	'	'	1,154	'	'	'	1,631	1,154	'
Ending Balance: collectively evaluated for impairment	7,361	'	'	'	11,722	'	'	'	7,361	11,722	'
Ending Balance: loans acquired with deteriorated credit quality	0	'	'	'	0	'	'	'	0	0	'
Financing receivables:	'	'	'	'	'	'	'	'	'	'	'
Ending balance	1,917,785	'	'	'	1,740,420	'	'	'	1,917,785	1,740,420	'
Ending Balance: individually evaluated for impairment	13,913	'	'	'	12,101	'	'	'	13,913	12,101	'
Ending Balance: collectively evaluated for impairment	1,894,421	'	'	'	1,718,913	'	'	'	1,894,421	1,718,913	'
Ending Balance: loans acquired with deteriorated credit quality	9,451	'	'	'	9,406	'	'	'	9,451	9,406	'
Other Commercial [Member]	'	'	'	'	'	'	'	'	'	'	'
Allowance for Loan Losses:	'	'	'	'	'	'	'	'	'	'	'
Beginning balance	'	'	'	20,511	'	'	'	20,803	20,511	20,803	'
Charge-offs	'	'	'	'	'	'	'	'	7,699	3,619	'
Recoveries	'	'	'	'	'	'	'	'	641	1,362	'
Provision	'	'	'	'	'	'	'	'	7,464	1,965	'
Ending balance	20,917	'	'	'	20,511	'	'	'	20,917	20,511	'
Ending Balance: individually evaluated for impairment	2,192	'	'	'	7,564	'	'	'	2,192	7,564	'
Ending Balance: collectively evaluated for impairment	18,725	'	'	'	12,947	'	'	'	18,725	12,947	'
Ending Balance: loans acquired with deteriorated credit quality	0	'	'	'	0	'	'	'	0	0	'
Financing receivables:	'	'	'	'	'	'	'	'	'	'	'
Ending balance	1,338,355	'	'	'	1,377,083	'	'	'	1,338,355	1,377,083	'
Ending Balance: individually evaluated for impairment	22,327	'	'	'	28,997	'	'	'	22,327	28,997	'
Ending Balance: collectively evaluated for impairment	1,314,543	'	'	'	1,346,600	'	'	'	1,314,543	1,346,600	'
Ending Balance: loans acquired with deteriorated credit quality	1,485	'	'	'	1,486	'	'	'	1,485	1,486	'
Residential Real Estate [Member]	'	'	'	'	'	'	'	'	'	'	'
Allowance for Loan Losses:	'	'	'	'	'	'	'	'	'	'	'
Beginning balance	'	'	'	14,895	'	'	'	13,880	14,895	13,880	'
Charge-offs	'	'	'	'	'	'	'	'	4,111	8,882	'
Recoveries	'	'	'	'	'	'	'	'	698	821	'
Provision	'	'	'	'	'	'	'	'	5,212	9,076	'
Ending balance	16,694	'	'	'	14,895	'	'	'	16,694	14,895	'
Ending Balance: individually evaluated for impairment	4,112	'	'	'	996	'	'	'	4,112	996	'
Ending Balance: collectively evaluated for impairment	12,582	'	'	'	13,899	'	'	'	12,582	13,899	'
Ending Balance: loans acquired with deteriorated credit quality	0	'	'	'	0	'	'	'	0	0	'
Financing receivables:	'	'	'	'	'	'	'	'	'	'	'
Ending balance	1,821,378	'	'	'	1,838,252	'	'	'	1,821,378	1,838,252	'
Ending Balance: individually evaluated for impairment	16,160	'	'	'	8,541	'	'	'	16,160	8,541	'
Ending Balance: collectively evaluated for impairment	1,802,686	'	'	'	1,826,196	'	'	'	1,802,686	1,826,196	'
Ending Balance: loans acquired with deteriorated credit quality	2,532	'	'	'	3,515	'	'	'	2,532	3,515	'
Construction & Land Development [Member]	'	'	'	'	'	'	'	'	'	'	'
Allowance for Loan Losses:	'	'	'	'	'	'	'	'	'	'	'
Beginning balance	'	'	'	18,858	'	'	'	19,151	18,858	19,151	'
Charge-offs	'	'	'	'	'	'	'	'	896	3,099	'
Recoveries	'	'	'	'	'	'	'	'	73	54	'
Provision	'	'	'	'	'	'	'	'	918	2,752	'
Ending balance	18,953	'	'	'	18,858	'	'	'	18,953	18,858	'
Ending Balance: individually evaluated for impairment	3,752	'	'	'	3,659	'	'	'	3,752	3,659	'
Ending Balance: collectively evaluated for impairment	15,201	'	'	'	15,199	'	'	'	15,201	15,199	'
Ending Balance: loans acquired with deteriorated credit quality	0	'	'	'	0	'	'	'	0	0	'
Financing receivables:	'	'	'	'	'	'	'	'	'	'	'
Ending balance	670,364	'	'	'	550,677	'	'	'	670,364	550,677	'
Ending Balance: individually evaluated for impairment	21,593	'	'	'	17,827	'	'	'	21,593	17,827	'
Ending Balance: collectively evaluated for impairment	632,407	'	'	'	515,718	'	'	'	632,407	515,718	'
Ending Balance: loans acquired with deteriorated credit quality	16,364	'	'	'	17,132	'	'	'	16,364	17,132	'
Consumer [Member]	'	'	'	'	'	'	'	'	'	'	'
Allowance for Loan Losses:	'	'	'	'	'	'	'	'	'	'	'
Beginning balance	'	'	'	2,620	'	'	'	2,151	2,620	2,151	'
Charge-offs	'	'	'	'	'	'	'	'	1,792	1,546	'
Recoveries	'	'	'	'	'	'	'	'	418	301	'
Provision	'	'	'	'	'	'	'	'	1,699	1,714	'
Ending balance	2,945	'	'	'	2,620	'	'	'	2,945	2,620	'
Ending Balance: individually evaluated for impairment	152	'	'	'	0	'	'	'	152	0	'
Ending Balance: collectively evaluated for impairment	2,793	'	'	'	2,620	'	'	'	2,793	2,620	'
Ending Balance: loans acquired with deteriorated credit quality	0	'	'	'	0	'	'	'	0	0	'
Financing receivables:	'	'	'	'	'	'	'	'	'	'	'
Ending balance	310,754	'	'	'	282,442	'	'	'	310,754	282,442	'
Ending Balance: individually evaluated for impairment	152	'	'	'	0	'	'	'	152	0	'
Ending Balance: collectively evaluated for impairment	310,593	'	'	'	282,431	'	'	'	310,593	282,431	'
Ending Balance: loans acquired with deteriorated credit quality	9	'	'	'	11	'	'	'	9	11	'
Allowance for Estimated Imprecision [Member]	'	'	'	'	'	'	'	'	'	'	'
Allowance for Loan Losses:	'	'	'	'	'	'	'	'	'	'	'
Beginning balance	'	'	'	264	'	'	'	2,572	264	2,572	'
Charge-offs	'	'	'	'	'	'	'	'	0	0	'
Recoveries	'	'	'	'	'	'	'	'	0	0	'
Provision	'	'	'	'	'	'	'	'	-220	-2,308	'
Ending balance	44	'	'	'	264	'	'	'	44	264	'
Ending Balance: individually evaluated for impairment	0	'	'	'	0	'	'	'	0	0	'
Ending Balance: collectively evaluated for impairment	44	'	'	'	264	'	'	'	44	264	'
Ending Balance: loans acquired with deteriorated credit quality	0	'	'	'	0	'	'	'	0	0	'
Financing receivables:	'	'	'	'	'	'	'	'	'	'	'
Ending balance	0	'	'	'	0	'	'	'	0	0	'
Ending Balance: individually evaluated for impairment	0	'	'	'	0	'	'	'	0	0	'
Ending Balance: collectively evaluated for impairment	0	'	'	'	0	'	'	'	0	0	'
Ending Balance: loans acquired with deteriorated credit quality	$0	'	'	'	$0	'	'	'	$0	$0	'

Bank_Premises_and_Equipment_an2

Bank Premises and Equipment and Leases - Bank Premises and Equipment (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Property, Plant and Equipment [Line Items]	'	'
Bank premises and equipment, Gross	$177,951	$171,912
Less allowance for depreciation and amortization	108,054	99,742
Bank premises and equipment, Net	69,897	72,170
Land [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Bank premises and equipment, Gross	23,018	23,166
Building and Improvements [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Bank premises and equipment, Gross	83,144	80,997
Leasehold Improvements [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Bank premises and equipment, Gross	22,092	20,906
Furniture, Fixtures and Equipment [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Bank premises and equipment, Gross	$49,697	$46,843

Bank_Premises_and_Equipment_an3

Bank Premises and Equipment and Leases - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
	Office
	Directors
Property, Plant and Equipment [Line Items]	'	'	'
Depreciation expense	$7,912,000	$7,790,000	$6,966,000
Amortization expense	103,000	103,000	103,000
Rent expense related to properties owned by related parties	8,969,000	9,427,000	8,740,000
Number of offices on lease from related parties	3	'	'
Number of former directors	2	'	'
Two Former Founder Directors [Member]	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'
Rent expense related to properties owned by related parties	$999,000	$1,755,000	$1,044,000

Bank_Premises_and_Equipment_an4

Bank Premises and Equipment and Leases - Future Minimum Lease Payments (Detail) (USD $)	Dec. 31, 2013
In Thousands, unless otherwise specified
Property Plant And Equipment Useful Life And Values [Abstract]	'
2014	$8,181
2015	6,903
2016	6,030
2017	5,606
2018	5,644
Thereafter	11,292
Total minimum lease payments	$43,656

Goodwill_and_Other_Intangibles2

Goodwill and Other Intangibles - Summary of Intangible Assets (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Core Deposit Intangible Assets [Member]	'	'
Finite-Lived Intangible Assets [Line Items]	'	'
Gross Carrying Amount	$43,434	$43,434
Accumulated Amortization	-35,296	-33,327
Net Carrying Amount	8,138	10,107
Goodwill Not Subject to Amortization [Member]	'	'
Finite-Lived Intangible Assets [Line Items]	'	'
Net Carrying Amount	$375,547	$375,583

Goodwill_and_Other_Intangibles3

Goodwill and Other Intangibles - Schedule of Anticipated Amortization Expense (Detail) (USD $)	Dec. 31, 2013
In Thousands, unless otherwise specified
Goodwill And Intangible Assets Disclosure [Abstract]	'
2014	$1,478
2015	1,149
2016	1,089
2017	1,047
2018 and thereafter	$3,375

Deposits_Book_Value_of_Deposit

Deposits - Book Value of Deposits (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Deposits [Abstract]	'	'
Demand deposits	$1,874,520	$1,824,411
Interest-bearing checking	1,195,956	1,210,463
Regular savings	556,183	523,336
Money market accounts	1,224,116	1,203,341
Time deposits under $100,000	887,516	1,035,815
Time deposits over $100,000	883,280	955,620
Total deposits	$6,621,571	$6,752,986

Deposits_Additional_Informatio

Deposits - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Deposits [Line Items]	'	'	'
Deposits	$6,621,571,000	$6,752,986,000	'
Subsidiaries [Member]	'	'	'
Deposits [Line Items]	'	'	'
Deposits	137,428,000	77,167,000	'
Deposits [Member]	'	'	'
Deposits [Line Items]	'	'	'
Interest paid	$27,182,000	$33,133,000	$39,853,000

ShortTerm_Borrowings_ShortTerm

Short-Term Borrowings -Short-Term Borrowings and the Related Weighted-Average Interest Rates (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
In Thousands, unless otherwise specified
Short-term Debt [Line Items]	'	'	'
Short-term borrowings	$215,754	$214,962	'
Federal Funds Purchased [Member]	'	'	'
Short-term Debt [Line Items]	'	'	'
Weighted-Average Rate	0.20%	0.20%	0.20%
Short-term borrowings	27,685	5,446	7,120
Securities Sold Under Agreements to Repurchase [Member]	'	'	'
Short-term Debt [Line Items]	'	'	'
Weighted-Average Rate	0.09%	0.09%	0.07%
Short-term borrowings	$188,069	$209,516	$247,646

ShortTerm_Borrowings_Additiona

Short-Term Borrowings - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Short-term Debt [Line Items]	'	'	'
Unused lines of credit	$234,000,000	'	'
Short-Term Borrowings [Member]	'	'	'
Short-term Debt [Line Items]	'	'	'
Interest paid	894,000	304,000	464,000
Unrelated Financial Institution [Member]	'	'	'
Short-term Debt [Line Items]	'	'	'
Unused lines of credit	10,000,000	'	'
Renewal period of line of credit	'360 days	'	'
Amount of outstanding balance under line of credit	$0	'	'

ShortTerm_Borrowings_Funds_Pur

Short-Term Borrowings - Funds Purchased and Securities Sold Under Agreements to Repurchase and Weighted-Average Interest Rates (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Short-term Debt [Line Items]	'	'	'
Short-term borrowings	$215,754	$214,962	'
Federal Funds Purchased [Member]	'	'	'
Short-term Debt [Line Items]	'	'	'
Short-term borrowings	27,685	5,446	7,120
Weighted-average interest rate at year-end	0.20%	0.20%	0.20%
Maximum amount outstanding at any month's end	27,685	23,100	20,440
Average amount outstanding during the year	12,595	16,314	13,377
Weighted-average interest rate during the year	0.20%	0.20%	0.21%
Securities Sold Under Agreements to Repurchase [Member]	'	'	'
Short-term Debt [Line Items]	'	'	'
Short-term borrowings	188,069	209,516	247,646
Weighted-average interest rate at year-end	0.09%	0.09%	0.07%
Maximum amount outstanding at any month's end	220,155	273,041	274,546
Average amount outstanding during the year	$199,823	$261,558	$242,371
Weighted-average interest rate during the year	0.10%	0.08%	0.06%

LongTerm_Borrowings_Additional

Long-Term Borrowings - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Debt Instrument [Line Items]	'	'	'
Overnight funds	$215,000,000	$100,000,000	'
FHLB advances	592,069,000	186,411,000	'
Number of statutory business trusts	12	'	'
Outstanding balances of debentures	198,628,000	198,515,000	'
Maximum time to defer payment of interest on subordinate debt	'5 years	'	'
Trust Preferred Securities limit percentage	25.00%	'	'
Federal Home Loan Bank Borrowings [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Carrying value of loans pledged as collateral for FHLB advances	3,065,080,000	'	'
Unused borrowing amount	1,413,927,000	'	'
Long-Term Borrowings [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Interest paid	$8,846,000	$14,370,000	$16,335,000

LongTerm_Borrowings_FHLB_Advan

Long-Term Borrowings - FHLB Advances and Related Weighted Average Interest Rates (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Debt Disclosure [Abstract]	'	'
FHLB advances, Amount	$592,069	$186,411
FHLB advances, Weighted-Average Contractual Rate	0.56%	2.17%
FHLB advances, Weighted-Average Effective Rate	0.56%	2.17%

LongTerm_Borrowings_Tier_One_R

Long-Term Borrowings - Tier One Regulatory capital (Detail) (USD $)

1 Months Ended

12 Months Ended

In Thousands, unless otherwise specified

Aug. 20, 2012

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Century Trust [Member]

Sequoia Trust I [Member]

United Statutory Trust III [Member]

United Statutory Trust IV [Member]

United Statutory Trust V [Member]

United Statutory Trust VI [Member]

Premier Statutory Trust II [Member]

Premier Statutory Trust III [Member]

Premier Statutory Trust IV [Member]

Premier Statutory Trust V [Member]

Centra Statutory Trust I [Member]

Centra Statutory Trust II [Member]

Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

Issuance Date

'

23-Mar-00

28-Mar-01

17-Dec-03

19-Dec-03

12-Jul-07

20-Sep-07

25-Sep-03

16-May-05

20-Jun-06

14-Dec-06

20-Sep-04

15-Jun-06

Amount of Capital Securities Issued

'

$8,800

$2,000

$20,000

$25,000

$50,000

$30,000

$6,000

$8,000

$14,000

$10,000

$10,000

$10,000

Interest Rate

'

'10.875% Fixed

'10.18% Fixed

'3-month LIBOR + 2.85%

'3-month LIBOR + 2.85%

'3-month LIBOR + 1.55%

'3-month LIBOR + 1.30%

'3-month LIBOR + 3.10%

'3-month LIBOR + 1.74%

'3-month LIBOR + 1.55%

'3-month LIBOR + 1.61%

'3-month LIBOR + 2.29%

'3-month LIBOR + 1.65%

Maturity Date

20-Aug-12

8-Mar-30

8-Jun-31

17-Dec-33

23-Jan-34

1-Oct-37

15-Dec-37

8-Oct-33

15-Jun-35

23-Sep-36

1-Mar-37

20-Sep-34

7-Jul-36

Long_Term_Borrowings_Debenture

Long -Term Borrowings - Debentures and Related Weighted Average Interest Rates (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Debt Instrument [Line Items]	'	'
Amount	$198,628	$198,515
Century Trust [Member]	'	'
Debt Instrument [Line Items]	'	'
Amount	8,800	8,800
Weighted-Average Rate	10.88%	10.88%
Sequoia Trust I [Member]	'	'
Debt Instrument [Line Items]	'	'
Amount	2,065	2,064
Weighted-Average Rate	10.18%	10.18%
United Statutory Trust III [Member]	'	'
Debt Instrument [Line Items]	'	'
Amount	20,619	20,619
Weighted-Average Rate	3.10%	3.16%
United Statutory Trust IV [Member]	'	'
Debt Instrument [Line Items]	'	'
Amount	25,774	25,774
Weighted-Average Rate	3.09%	3.16%
United Statutory Trust V [Member]	'	'
Debt Instrument [Line Items]	'	'
Amount	51,547	51,547
Weighted-Average Rate	1.80%	1.91%
United Statutory Trust VI [Member]	'	'
Debt Instrument [Line Items]	'	'
Amount	30,928	30,928
Weighted-Average Rate	1.54%	1.61%
Premier Statutory Trust II [Member]	'	'
Debt Instrument [Line Items]	'	'
Amount	6,186	6,186
Weighted-Average Rate	3.34%	3.44%
Premier Statutory Trust III [Member]	'	'
Debt Instrument [Line Items]	'	'
Amount	8,248	8,248
Weighted-Average Rate	1.98%	2.05%
Premier Statutory Trust IV [Member]	'	'
Debt Instrument [Line Items]	'	'
Amount	14,433	14,433
Weighted-Average Rate	1.80%	1.86%
Premier Statutory Trust V [Member]	'	'
Debt Instrument [Line Items]	'	'
Amount	10,310	10,310
Weighted-Average Rate	1.85%	1.92%
Centra Statutory Trust I [Member]	'	'
Debt Instrument [Line Items]	'	'
Amount	9,859	9,803
Weighted-Average Rate	2.54%	2.60%
Centra Statutory Trust II [Member]	'	'
Debt Instrument [Line Items]	'	'
Amount	$9,859	$9,803
Weighted-Average Rate	1.89%	1.99%

LongTerm_Borrowings_Schedule_o

Long-Term Borrowings - Schedule of Maturities of FHLB Borrowings (Detail) (USD $)	Dec. 31, 2013
In Thousands, unless otherwise specified
Debt Disclosure [Abstract]	'
2014	$321,388
2015	4,395
2016	622
2017	383
2018 and thereafter	248,909
Total	$575,697

Income_Taxes_Income_Tax_Provis

Income Taxes - Income Tax Provisions Included in the Consolidated Statements of Income (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Current expense:	'	'	'	'	'	'	'	'	'	'	'
Federal	'	'	'	'	'	'	'	'	$32,378	$37,623	$23,341
State	'	'	'	'	'	'	'	'	4,048	914	518
Deferred expense:	'	'	'	'	'	'	'	'	'	'	'
Federal and State	'	'	'	'	'	'	'	'	2,990	337	10,907
Total income taxes	$9,252	$10,433	$9,576	$10,155	$9,983	$9,099	$9,905	$9,887	$39,416	$38,874	$34,766

Income_Taxes_Reconciliation_of

Income Taxes - Reconciliation of Income Tax Expense to the Amount Computed by Applying the Statutory Federal Income Tax Rate (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]	'	'	'	'	'	'	'	'	'	'	'
Tax on income before taxes at statutory federal rate	'	'	'	'	'	'	'	'	$43,765	$42,519	$38,632
Plus: State income taxes net of federal tax benefits	'	'	'	'	'	'	'	'	2,392	594	336
Income tax before adjustments	'	'	'	'	'	'	'	'	46,157	43,113	38,968
Tax-exempt interest income	'	'	'	'	'	'	'	'	-3,837	-4,127	-4,226
Other items-net	'	'	'	'	'	'	'	'	-2,904	-112	24
Total income taxes	$9,252	$10,433	$9,576	$10,155	$9,983	$9,099	$9,905	$9,887	$39,416	$38,874	$34,766
Tax on income before taxes at statutory federal rate, rate	'	'	'	'	'	'	'	'	35.00%	35.00%	35.00%
Plus: State income taxes net of federal tax benefits, rate	'	'	'	'	'	'	'	'	1.90%	0.50%	0.30%
Income tax before adjustments, rate	'	'	'	'	'	'	'	'	36.90%	35.50%	35.30%
Increase (decrease) resulting from:	'	'	'	'	'	'	'	'	'	'	'
Tax-exempt interest income, rate	'	'	'	'	'	'	'	'	-3.10%	-3.40%	-3.80%
Other items-net, rate	'	'	'	'	'	'	'	'	-2.30%	-0.10%	0.00%
Income taxes, rate	'	'	'	'	'	'	'	'	31.50%	32.00%	31.50%

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]	'	'	'
Federal income tax expense applicable to sales and calls of securities	$533,000	$156,000	$552,000
Income taxes paid	49,114,000	27,057,000	34,531,000
State net operating loss carryforwards	0	'	'
Business franchise taxes	4,816,000	4,717,000	4,466,000
Estimate of unrecognized tax benefits, reasonable possible	'United cannot reasonably estimate the amount of tax benefits it may recognize over the next 12 months	'	'
Accrued interest related to uncertain tax positions	455,000	1,138,000	'
Interest or penalties were recognized	$0	$0	'

Income_Taxes_Components_of_Uni

Income Taxes - Components of United's Deferred Tax Assets and Liabilities (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Deferred tax assets:	'	'
Allowance for credit losses	$28,108	$41,853
Other accrued liabilities	830	29
Unrecognized components of net periodic pension costs	12,168	21,696
Unrealized loss on securities available for sale	13,255	16,703
Other real estate owned	4,288	0
Purchase accounting intangibles	3,598	0
Net operating loss	0	846
Total deferred tax assets	62,247	81,127
Deferred tax liabilities:	'	'
Purchase accounting intangibles	0	6,436
Deferred mortgage points	283	377
Accrued benefits payable	7,806	10,961
Premises and equipment	2,563	857
Other	2,117	2,764
Total deferred tax liabilities	12,769	21,395
Net deferred tax assets	$49,478	$59,732

Income_Taxes_Reconciliation_of1

Income Taxes - Reconciliation of the Total Amounts of Unrecognized Tax Benefits (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]	'	'
Unrecognized tax benefits at beginning of year	$2,106	$2,028
Decreases in unrecognized tax benefits as a result of tax positions settled during the current period	-213	0
Increase in unrecognized tax benefits as a result of tax positions taken during the current period	661	226
Decreases in the unrecognized tax benefits as a result of a lapse of the applicable statute of limitations	-42	-148
Unrecognized tax benefits at end of year	$2,512	$2,106

Employee_Benefit_Plans_Additio

Employee Benefit Plans - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2008	Dec. 31, 2007
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'	'
Unrecognized prior service costs, before tax	$2,000	'	'	'	'
Unrecognized prior service costs, net of tax	1,000	'	'	'	'
Unrecognized actuarial losses, before tax	31,151,000	'	'	'	'
Unrecognized actuarial losses, net of tax	20,248,000	'	'	'	'
Amortization of transition asset, before tax, expected for fiscal year ended December 31, 2013	1,000	'	'	'	'
Amortization of transition asset, net of tax, expected for fiscal year ended December 31, 2013	1,000	'	'	'	'
Amortization of actuarial losses, before tax, expected for fiscal year ended December 31, 2013	4,821,000	'	'	'	'
Amortization of actuarial losses, net of tax, expected for fiscal year ended December 31, 2013	3,134,000	'	'	'	'
Amount of United common stock held in the pension plan	123,188,000	108,859,000	101,383,000	'	'
Percentage of equity securities include united common stock	100.00%	100.00%	'	'	'
Minimum number of days required to be eligible for the participation in the plan	'90 days	'	'	'	'
Percentage of salary deferred under condition one of contribution by company	'	'	'	100.00%	100.00%
First percentage of salary deferred under condition one of contribution by company	'	'	'	3.00%	2.00%
Percentage of salary deferred under condition two of contribution by company	'	'	'	25.00%	25.00%
Second percentage of salary deferred under condition two of contribution by company	'	'	'	1.00%	2.00%
Vesting percentage of employee deferrals	'	'	'	100.00%	'
Cost related to savings and stock investment plan	1,411,000	1,330,000	1,332,000	'	'
Employer contribution in shares of common stock	912,713	932,125	'	'	'
Dividends paid on United common stock	1,171,631	1,112,000	1,022,000	'	'
Minimum [Member]	'	'	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'	'
Maximum percentage allowed as of contribution to respective accounts by participants	1.00%	'	'	'	'
Maximum [Member]	'	'	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'	'
Maximum percentage allowed as of contribution to respective accounts by participants	100.00%	'	'	'	'
Company [Member]	'	'	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'	'
Maximum percentage limit of common stock to invest in portfolio for any industry	10.00%	'	'	'	'
Industry [Member]	'	'	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'	'
Maximum percentage limit of common stock to invest in portfolio for any industry	15.00%	'	'	'	'
Securities of U.S. Government or Agencies [Member]	'	'	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'	'
Maximum percentage limit of common stock to invest in portfolio for any industry	15.00%	'	'	'	'
Common Stock [Member]	'	'	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'	'
Amount of United common stock held in the pension plan	20,089,000	14,712,000	'	'	'
Percentage of equity securities include united common stock	3.00%	2.00%	'	'	'
Maximum percentage limit of common stock to invest in portfolio for any industry	5.00%	'	'	'	'
Marketable Equity Securities [Member]	'	'	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'	'
Amount of United common stock held in the pension plan	$3,328,000	$2,576,000	'	'	'
Percentage of equity securities include united common stock	66.00%	63.00%	'	'	'
Maximum percentage limit of common stock to invest in portfolio for any industry	-70.00%	'	'	'	'

Employee_Benefit_Plans_Net_Per

Employee Benefit Plans - Net Periodic Pension Cost (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Service Cost	$2,672	$2,517	$2,272
Interest cost	4,913	4,849	4,555
Expected return on plan assets	-8,313	-7,999	-8,343
Recognized net actuarial loss	4,821	4,199	2,427
Amortization of prior service cost	1	1	1
Net periodic pension cost	$4,094	$3,567	$912
Weighted-Average Assumptions:	'	'	'
Discount rate	4.40%	5.15%	5.75%
Expected return on assets	7.75%	8.00%	8.00%
Rate of Compensation Increase	2.75%	2.75%	2.75%
Prior to Age 45 [Member]	'	'	'
Weighted-Average Assumptions:	'	'	'
Rate of Compensation Increase	3.75%	3.75%	3.75%

Employee_Benefit_Plans_Reconci

Employee Benefit Plans - Reconciliation of the Beginning and Ending Balances of the Projected Benefit Obligation and the Fair Value of Plan Assets and the Accumulated Benefit Obligation (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Change in Projected Benefit Obligation	'	'	'
Projected Benefit Obligation at the Beginning of the Year	$112,534,000	$95,162,000	'
Service Cost	2,672,000	2,517,000	2,272,000
Interest cost	4,913,000	4,849,000	4,555,000
Actuarial (Gain) Loss	-11,646,000	13,000,000	'
Benefits Paid	-3,287,000	-2,994,000	'
Projected Benefit at the End of the Year	105,186,000	112,534,000	95,162,000
Accumulated Benefit Obligation at the End of the Year	95,859,000	102,156,000	'
Change in Plan Assets	'	'	'
Fair Value of Plan Assets at the Beginning of the Year	108,859,000	101,383,000	'
Actual Return on Plan Assets	17,616,000	10,470,000	'
Benefits Paid	-3,287,000	-2,994,000	'
Employer Contributions	0	0	'
Fair value of plan assets at end of year	123,188,000	108,859,000	101,383,000
Net Amount Recognized	'	'	'
Funded Status	18,002,000	-3,675,000	'
Unrecognized Transition Asset	0	0	'
Unrecognized Prior Service Cost	2,000	3,000	'
Unrecognized Net Loss	31,151,000	56,921,000	'
Net Amount Recognized	$49,155,000	$53,249,000	'
Weighted-Average Assumptions at the End of the Year	'	'	'
Discount Rate	5.20%	4.40%	'
Rate of Compensation Increase	2.75%	2.75%	2.75%
Prior to Age 45 [Member]	'	'	'
Weighted-Average Assumptions at the End of the Year	'	'	'
Rate of Compensation Increase	3.75%	3.75%	3.75%

Employee_Benefit_Plans_Asset_A

Employee Benefit Plans - Asset Allocation for the Defined Benefit Pension Plan as of the Measurement Date, by Asset Category (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Pension Plans, Postretirement and Other Employee Benefits [Line Items]	'	'
Percentage of Plan Assets	100.00%	100.00%
Marketable Equity Securities [Member]	'	'
Pension Plans, Postretirement and Other Employee Benefits [Line Items]	'	'
Target Allocation 2014	62.00%	'
Allowable Allocation Range, Minimum	50.00%	'
Allowable Allocation Range, Maximum	-70.00%	'
Percentage of Plan Assets	66.00%	63.00%
Debt Securities [Member]	'	'
Pension Plans, Postretirement and Other Employee Benefits [Line Items]	'	'
Target Allocation 2014	26.00%	'
Allowable Allocation Range, Minimum	20.00%	'
Allowable Allocation Range, Maximum	-50.00%	'
Percentage of Plan Assets	21.00%	32.00%
Other [Member]	'	'
Pension Plans, Postretirement and Other Employee Benefits [Line Items]	'	'
Target Allocation 2014	12.00%	'
Allowable Allocation Range, Minimum	-3.00%	'
Allowable Allocation Range, Maximum	15.00%	'
Percentage of Plan Assets	13.00%	5.00%

Employee_Benefit_Plans_Expecte

Employee Benefit Plans - Expected Benefit Payments (Detail) (USD $)	Dec. 31, 2013
In Thousands, unless otherwise specified
Compensation And Retirement Disclosure [Abstract]	'
2014	$3,728
2015	4,053
2016	4,432
2017	4,780
2018	5,159
2019 through 2023	$30,746

Employee_Benefit_Plans_Balance

Employee Benefit Plans - Balances of the Plan Assets, by Fair Value Hierarchy Level (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	$123,188,000	$108,859,000	$101,383,000
Cash and Cash Equivalents [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	2,985,000	4,396,000	'
Mortgage Backed Securities [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	118,000	207,000	'
Collateralized Mortgage Obligations [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	245,000	208,000	'
Municipal Obligations [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	1,112,000	910,000	'
Corporate Bonds [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	2,363,000	2,588,000	'
Strategic Income Fund [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	3,985,000	'	'
Taxable Income [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	3,970,000	'	'
Fixed Income Funds Domestic [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	13,834,000	12,600,000	'
Fixed Income Funds Alternative [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	6,131,000	6,116,000	'
Preferred Stock [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	195,000	209,000	'
Common Stock [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	20,089,000	14,712,000	'
Equity Mutual Funds Domestic Equity Large Cap [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	23,042,000	19,172,000	'
Equity Mutual Funds Domestic Equity Mid Cap [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	5,540,000	2,552,000	'
Equity Mutual Funds Domestic Equity Small Cap [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	15,293,000	10,688,000	'
Equity Mutual Funds International Emerging Equity [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	6,076,000	5,241,000	'
Equity Mutual Funds International Equity Developed [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	11,817,000	4,158,000	'
Equity Mutual Funds Alternative Equity [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	5,692,000	6,727,000	'
Partnerships [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	701,000	726,000	'
Fixed Income Funds General [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	'	12,463,000	'
Equity Mutual Funds Global Equity [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	'	5,186,000	'
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	118,649,000	106,446,000	'
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Cash and Cash Equivalents [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	2,985,000	4,396,000	'
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Mortgage Backed Securities [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	0	'
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Collateralized Mortgage Obligations [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	0	'
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Municipal Obligations [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	0	'
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Corporate Bonds [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	2,226,000	'
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Strategic Income Fund [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	3,985,000	'	'
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Taxable Income [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	3,970,000	'	'
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fixed Income Funds Domestic [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	13,834,000	12,600,000	'
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fixed Income Funds Alternative [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	6,131,000	6,116,000	'
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Preferred Stock [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	195,000	209,000	'
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Common Stock [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	20,089,000	14,712,000	'
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Equity Mutual Funds Domestic Equity Large Cap [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	23,042,000	19,172,000	'
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Equity Mutual Funds Domestic Equity Mid Cap [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	5,540,000	2,552,000	'
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Equity Mutual Funds Domestic Equity Small Cap [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	15,293,000	10,688,000	'
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Equity Mutual Funds International Emerging Equity [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	6,076,000	5,241,000	'
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Equity Mutual Funds International Equity Developed [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	11,817,000	4,158,000	'
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Equity Mutual Funds Alternative Equity [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	5,692,000	6,727,000	'
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Partnerships [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	0	'
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fixed Income Funds General [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	'	12,463,000	'
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Equity Mutual Funds Global Equity [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	'	5,186,000	'
Significant Other Observable Inputs (Level 2) [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	4,539,000	2,413,000	'
Significant Other Observable Inputs (Level 2) [Member] | Cash and Cash Equivalents [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	0	'
Significant Other Observable Inputs (Level 2) [Member] | Mortgage Backed Securities [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	118,000	207,000	'
Significant Other Observable Inputs (Level 2) [Member] | Collateralized Mortgage Obligations [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	245,000	208,000	'
Significant Other Observable Inputs (Level 2) [Member] | Municipal Obligations [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	1,112,000	910,000	'
Significant Other Observable Inputs (Level 2) [Member] | Corporate Bonds [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	2,363,000	362,000	'
Significant Other Observable Inputs (Level 2) [Member] | Strategic Income Fund [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	'	'
Significant Other Observable Inputs (Level 2) [Member] | Fixed Income Funds Domestic [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	0	'
Significant Other Observable Inputs (Level 2) [Member] | Fixed Income Funds Alternative [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	0	'
Significant Other Observable Inputs (Level 2) [Member] | Preferred Stock [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	0	'
Significant Other Observable Inputs (Level 2) [Member] | Common Stock [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	0	'
Significant Other Observable Inputs (Level 2) [Member] | Equity Mutual Funds Domestic Equity Large Cap [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	0	'
Significant Other Observable Inputs (Level 2) [Member] | Equity Mutual Funds Domestic Equity Mid Cap [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	0	'
Significant Other Observable Inputs (Level 2) [Member] | Equity Mutual Funds Domestic Equity Small Cap [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	0	'
Significant Other Observable Inputs (Level 2) [Member] | Equity Mutual Funds International Emerging Equity [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	0	'
Significant Other Observable Inputs (Level 2) [Member] | Equity Mutual Funds International Equity Developed [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	0	'
Significant Other Observable Inputs (Level 2) [Member] | Equity Mutual Funds Alternative Equity [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	0	'
Significant Other Observable Inputs (Level 2) [Member] | Partnerships [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	701,000	726,000	'
Significant Other Observable Inputs (Level 2) [Member] | Fixed Income Funds General [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	'	0	'
Significant Other Observable Inputs (Level 2) [Member] | Equity Mutual Funds Global Equity [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	'	0	'
Significant Unobservable Inputs (Level 3) [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	0	'
Significant Unobservable Inputs (Level 3) [Member] | Cash and Cash Equivalents [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	0	'
Significant Unobservable Inputs (Level 3) [Member] | Mortgage Backed Securities [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	0	'
Significant Unobservable Inputs (Level 3) [Member] | Collateralized Mortgage Obligations [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	0	'
Significant Unobservable Inputs (Level 3) [Member] | Municipal Obligations [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	0	'
Significant Unobservable Inputs (Level 3) [Member] | Corporate Bonds [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	0	'
Significant Unobservable Inputs (Level 3) [Member] | Strategic Income Fund [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	'	'
Significant Unobservable Inputs (Level 3) [Member] | Fixed Income Funds Domestic [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	0	'
Significant Unobservable Inputs (Level 3) [Member] | Fixed Income Funds Alternative [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	0	'
Significant Unobservable Inputs (Level 3) [Member] | Preferred Stock [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	0	'
Significant Unobservable Inputs (Level 3) [Member] | Common Stock [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	0	'
Significant Unobservable Inputs (Level 3) [Member] | Equity Mutual Funds Domestic Equity Large Cap [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	0	'
Significant Unobservable Inputs (Level 3) [Member] | Equity Mutual Funds Domestic Equity Mid Cap [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	0	'
Significant Unobservable Inputs (Level 3) [Member] | Equity Mutual Funds Domestic Equity Small Cap [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	0	'
Significant Unobservable Inputs (Level 3) [Member] | Equity Mutual Funds International Emerging Equity [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	0	'
Significant Unobservable Inputs (Level 3) [Member] | Equity Mutual Funds International Equity Developed [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	0	'
Significant Unobservable Inputs (Level 3) [Member] | Equity Mutual Funds Alternative Equity [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	0	'
Significant Unobservable Inputs (Level 3) [Member] | Partnerships [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	0	0	'
Significant Unobservable Inputs (Level 3) [Member] | Fixed Income Funds General [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	'	0	'
Significant Unobservable Inputs (Level 3) [Member] | Equity Mutual Funds Global Equity [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Asset at fair value	'	$0	'

Stock_Based_Compensation_Addit

Stock Based Compensation - Additional Information (Detail) (USD $)	0 Months Ended	12 Months Ended
	16-May-11	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Authorized shares of stock, option plan, maximum	1,500,000	'	'	'
Aggregate number of shares issued in respect of restricted stock awards	350,000	'	'	'
Options available for award each plan year	1,150,000	'	'	'
Maximum number of shares of restricted stock or shares subject to a restricted stock units award granted	'	50,000	'	'
Maximum number of options and stock appreciation rights	'	100,000	'	'
Percentage of restricted stock and restricted stock units vest	'	25.00%	'	'
Vesting period of awards	'	'1/3 per year over the first three anniversaries of the award	'	'
Recognition of compensation expense	'	$1,786,000	$1,908,000	'
Maximum term for awards granted (years)	'	'10 years	'	'
Weighted average risk free interest rate	'	1.42%	'	'
Weighted average dividend yield	'	3.00%	'	'
Weighted average volatility factors of the expected market price of United's common stock	'	0.32%	'	'
Weighted-average expected option life	'	'7 years 2 months 5 days	'	'
Estimated fair value of the options at the date of grant	'	$5.74	'	'
Total unrecognized compensation cost related to nonvested option awards	'	1,290,000	'	'
Weighted-average expense recognition period	'	'10 months 24 days	'	'
Total fair value of awards vested	'	2,204,000	'	'
Cash received from options exercised under the plans	'	2,364,000	115,000	542,000
Shares issued related stock option exercises	'	100,302	7,510	'
Weighted-average grant-date fair value of options granted	'	$5.74	$6.86	$7.91
Total intrinsic value of options exercised	'	507,000	98,000	518,000
Excess tax benefits related to share-based compensation	'	331,000	35,000	3,114,000
Nonvested Stock Awards [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Total unrecognized compensation cost related to nonvested option awards	'	$1,441,000	'	'
Weighted-average expense recognition period	'	'1 year 6 months	'	'
Restricted Stock [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Shares, Granted	'	52,825	'	'
Weighted-average grant-date fair value of options granted	'	$26.19	'	'
Vesting period	'	'4 years	'4 years	'
Non-qualified Stock Options [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Shares, Granted	'	194,225	'	'

Stock_Based_Compensation_Summa

Stock Based Compensation - Summary of Stock Option Plans (Detail) (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'	'
Shares, Outstanding, Beginning balance	1,629,237	'
Shares, Granted	194,225	'
Shares, Exercised	100,302	7,510
Shares, Forfeited or expired	275,163	'
Shares, Outstanding, Ending balance	1,447,997	1,629,237
Shares, Exercisable at December 31, 2013	858,800	'
Aggregate Intrinsic Value, Outstanding at December 31, 2013	$5,145	'
Aggregate Intrinsic Value, Exercisable at December 31, 2013	$3,148	'
Weighted Average Remaining Contractual Term, Outstanding at December 31, 2013	'5 years 4 months 24 days	'
Weighted Average Remaining Contractual Term, Exercisable at December 31, 2013	'3 years 7 months 6 days	'
Weighted Average Exercise Price, Outstanding, Beginning balance	$29.64	'
Weighted Average Exercise Price, Granted	$26.24	'
Weighted Average Exercise Price, Exercised	$23.56	'
Weighted Average Exercise Price, Forfeited or expired	$31.10	'
Weighted Average Exercise Price, Outstanding, Ending balance	$29.33	$29.64
Weighted Average Exercise Price, Exercisable at September December 31, 2013	$30.20	'

Stock_Based_Compensation_Statu

Stock Based Compensation - Status of United's Nonvested Stock Option Awards (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Shares, Nonvested, Beginning balance	770,750
Shares, Granted	194,225
Shares, Vested	348,339
Shares, Forfeited or expired	27,439
Shares, Nonvested, Ending balance	589,197
Weighted-Average Grant Date Fair Value Per Share, Nonvested beginning Balance	$7.04
Weighted-Average Grant Date Fair Value Per Share, Granted	$5.74
Weighted-Average Grant Date Fair Value Per Share, Vested	$6.33
Weighted-Average Grant Date Fair Value Per Share, Forfeited or expired	$7.53
Weighted-Average Grant Date Fair Value Per Share, Nonvested Ending balance	$7.01

Stock_Based_Compensation_Chang

Stock Based Compensation - Changes to United's Restricted Common Shares (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Weighted-Average Grant Date Fair Value Per Share, Granted	$5.74	$6.86	$7.91
Restricted Stock [Member]	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Number of Shares, Outstanding, Beginning balance	51,125	'	'
Shares, Granted	52,825	'	'
Shares, Vested	16,789	'	'
Shares, Forfeited	1,664	'	'
Number of Shares, Outstanding, Ending balance	85,497	'	'
Weighted-Average Grant Date Fair Value Per Share, Outstanding, Beginning Balance	$29.40	'	'
Weighted-Average Grant Date Fair Value Per Share, Granted	$26.19	'	'
Weighted-Average Grant Date Fair Value Per Share, Vested	$28.96	'	'
Weighted-Average Grant Date Fair Value Per Share, Forfeited	$27.91	'	'
Weighted-Average Grant Date Fair Value Per Share, Outstanding, Ending Balance	$27.53	'	'

Commitments_and_Contingent_Lia1

Commitments and Contingent Liabilities - Additional Information (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Loss Contingencies [Line Items]	'	'
Loan commitments outstanding	$2,504,093,000	$2,173,377,000
Commercial Letters of Credit [Member]	'	'
Loss Contingencies [Line Items]	'	'
Letters of credit issued	0	250,000
Standby Letters of Credit [Member]	'	'
Loss Contingencies [Line Items]	'	'
Letters of credit issued	$114,664,000	$96,856,000

Derivative_Financial_Instrumen2

Derivative Financial Instruments - Schedule of Derivative Instruments (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Derivative Instruments, Gain (Loss) [Line Items]	'	'
Total Derivatives Used for Interest Rate Risk Management and Designated as Hedges	$41,868	$52,558
Average Pay Rate	5.07%	5.14%
Fair Value Hedging [Member] | Interest Rate Contracts [Member]	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'
Notional Amount, Pay Fixed Swap (Hedging Commercial Loans)	41,868	52,558
Cash Flow Hedging [Member] | Interest Rate Contracts [Member]	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'
Notional Amount, Pay Fixed Swap (Hedging Commercial Loans)	$41,868	$52,558

Derivative_Financial_Instrumen3

Derivative Financial Instruments - Schedule of Fair Value Derivative Financial Instruments (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Derivative [Line Items]	'	'
Derivatives designated as hedging instruments	$2,179	$0
Derivatives not designated as hedging instruments	1,045	2,367
Total asset derivatives	3,224	2,367
Derivatives designated as hedging instruments	149	1,914
Derivatives not designated as hedging instruments	1,045	2,367
Total liability derivatives	1,194	4,281
Interest Rate Contracts [Member] | Other Assets [Member]	'	'
Derivative [Line Items]	'	'
Derivatives designated as hedging instruments	2,179	0
Derivatives not designated as hedging instruments	1,045	2,367
Interest Rate Contracts [Member] | Other Liabilities [Member]	'	'
Derivative [Line Items]	'	'
Derivatives designated as hedging instruments	149	1,914
Derivatives not designated as hedging instruments	$1,045	$2,367

Derivative_Financial_Instrumen4

Derivative Financial Instruments - Schedule of Derivative Financial Instruments on Statement of Income (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Interest Rate Contracts [Member]	'	'	'
Derivative [Line Items]	'	'	'
Derivatives in fair value hedging relationships	($522)	($298)	$81
Interest Income/(Expense) [Member]	'	'	'
Derivative [Line Items]	'	'	'
Derivatives in fair value hedging relationships	-522	-298	81
Interest Income/(Expense) [Member] | Interest Rate Contracts [Member]	'	'	'
Derivative [Line Items]	'	'	'
Derivatives in fair value hedging relationships	-522	-298	81
Other Income [Member] | Interest Rate Contracts [Member]	'	'	'
Derivative [Line Items]	'	'	'
Derivative instruments not designated as hedging instruments, gain	1,322	1,450	1,782
Other Expense [Member] | Interest Rate Contracts [Member]	'	'	'
Derivative [Line Items]	'	'	'
Derivative instruments not designated as hedging instruments, loss	-1,322	-1,450	-1,782
Other Income/ (Expense) [Member] | Interest Rate Contracts [Member]	'	'	'
Derivative [Line Items]	'	'	'
Derivative instruments not designated as hedging instruments, net	$0	$0	$0

Comprehensive_Income_Component

Comprehensive Income - Components of Total Comprehensive Income (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Comprehensive Income Net Of Tax [Abstract]	'	'	'	'	'	'	'	'	'	'	'
Net income	$19,660	$22,170	$22,219	$21,579	$21,214	$19,334	$21,049	$21,010	$85,628	$82,607	$75,610
Available for sale ("AFS") securities:	'	'	'	'	'	'	'	'	'	'	'
AFS securities with OTTI charges during the period	'	'	'	'	'	'	'	'	-7,534	-10,840	-33,580
Related income tax effect	'	'	'	'	'	'	'	'	2,637	3,794	11,753
Less : OTTI charges recognized in net income	'	'	'	'	'	'	'	'	7,332	7,376	20,414
Related income tax effect	'	'	'	'	'	'	'	'	-2,566	-2,582	-7,145
Reclassification of previous noncredit OTTI to credit OTTI	'	'	'	'	'	'	'	'	12,425	5,887	12,622
Related income tax effect	'	'	'	'	'	'	'	'	-4,349	-2,061	-4,418
Net unrealized gains (losses) on AFS securities with OTTI	'	'	'	'	'	'	'	'	7,945	1,574	-354
Net change in unrealized (losses) gains on AFS securities arising during the period	'	'	'	'	'	'	'	'	-1,082	5,471	10,917
Related income tax effect	'	'	'	'	'	'	'	'	379	-1,915	-3,821
Net reclassification adjustment for gains included in net income	'	'	'	'	'	'	'	'	-1,216	-16	-1,418
Related income tax effect	'	'	'	'	'	'	'	'	426	6	496
Total AFS securities - all other	'	'	'	'	'	'	'	'	-1,493	3,546	6,174
Net effect of AFS securities on other comprehensive income	'	'	'	'	'	'	'	'	6,452	5,120	5,820
Held to maturity ("HTM") securities:	'	'	'	'	'	'	'	'	'	'	'
Unrealized loss related to the call of HTM securities transferred from AFS to the HTM portfolio	'	'	'	'	'	'	'	'	0	0	0
Related income tax effect	'	'	'	'	'	'	'	'	0	0	0
Accretion on the unrealized loss for securities transferred from AFS to the HTM investment portfolio prior to call or maturity	'	'	'	'	'	'	'	'	8	7	8
Related income tax effect	'	'	'	'	'	'	'	'	-3	-3	-3
Net effect of HTM securities on other comprehensive income	'	'	'	'	'	'	'	'	5	4	5
Defined benefit pension plan:	'	'	'	'	'	'	'	'	'	'	'
Net actuarial loss during the period	'	'	'	'	'	'	'	'	20,305	-10,206	-20,591
Related income tax effect	'	'	'	'	'	'	'	'	-7,107	3,572	7,206
Amortization of transition asset recognized in net income	'	'	'	'	'	'	'	'	0	0	0
Related income tax effect	'	'	'	'	'	'	'	'	0	0	0
Amortization of prior service cost recognized in net income	'	'	'	'	'	'	'	'	1	1	1
Related income tax effect	'	'	'	'	'	'	'	'	0	0	0
Amortization of net actuarial loss recognized in net income	'	'	'	'	'	'	'	'	4,821	4,199	2,427
Related income tax effect	'	'	'	'	'	'	'	'	-1,776	-1,680	-970
Net effect of change in defined benefit pension plan on other comprehensive income	'	'	'	'	'	'	'	'	16,244	-4,114	-11,927
Total change in other comprehensive income, net of tax	'	'	'	'	'	'	'	'	22,701	1,010	-6,102
Comprehensive income, net of tax	'	'	'	'	'	'	'	'	$108,329	$83,617	$69,508

Comprehensive_Income_Component1

Comprehensive Income - Components of Accumulated Other Comprehensive Income (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'	'
Balance at January 1, 2013	($65,748)	'	'
Other comprehensive income before reclassification	-829	'	'
Amounts reclassified from accumulated other comprehensive income	23,530	'	'
Net current-period other comprehensive income, net of tax	22,701	1,010	-6,102
Balance at December 31, 2013	-43,047	-65,748	'
Unrealized Gains/Losses on AFS Securities [Member]	'	'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'	'
Balance at January 1, 2013	-29,687	'	'
Other comprehensive income before reclassification	-834	'	'
Amounts reclassified from accumulated other comprehensive income	7,286	'	'
Net current-period other comprehensive income, net of tax	6,452	'	'
Balance at December 31, 2013	-23,235	'	'
Accretion on the Unrealized Loss for Securities Transferred from AFS to the HTM [Member]	'	'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'	'
Balance at January 1, 2013	-72	'	'
Other comprehensive income before reclassification	5	'	'
Amounts reclassified from accumulated other comprehensive income	0	'	'
Net current-period other comprehensive income, net of tax	5	'	'
Balance at December 31, 2013	-67	'	'
Defined Benefit Pension Items [Member]	'	'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'	'
Balance at January 1, 2013	-35,989	'	'
Other comprehensive income before reclassification	0	'	'
Amounts reclassified from accumulated other comprehensive income	16,244	'	'
Net current-period other comprehensive income, net of tax	16,244	'	'
Balance at December 31, 2013	($19,745)	'	'

Comprehensive_Income_Reclassif

Comprehensive Income - Reclassifications Out of Accumulated Other Comprehensive Income (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Available for sale ("AFS") securities:	'	'	'
Reclassification of previous noncredit OTTI to credit OTTI	$12,425	$5,887	$12,622
Net reclassification adjustment for losses (gains) included in net income	-1,216	'	'
Total before tax	11,209	'	'
Related income tax effect	-3,923	'	'
Net of tax	7,286	'	'
Pension plan:	'	'	'
Change in pension asset	20,305	-10,206	-20,591
Amortization of transition asset	1	'	'
Recognized net actuarial loss	4,821	'	'
Total before tax	20,305	-10,206	-20,591
Related income tax effect	-8,883	'	'
Net effect of change in defined benefit pension plan on other comprehensive income	16,244	-4,114	-11,927
Total reclassifications for the period	$23,530	'	'

United_Bankshares_Inc_Parent_C2

United Bankshares, Inc. (Parent Company Only) Financial Information - Condensed Balance Sheets (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Condensed Balance Sheet Statements, Captions [Line Items]	'	'	'	'
Cash and due from banks	$134,808,000	$157,539,000	'	'
Securities available for sale	775,284,000	625,625,000	'	'
Securities held to maturity	38,293,000	42,695,000	'	'
Other investment securities	73,093,000	60,310,000	'	'
Other assets	322,634,000	329,202,000	'	'
Total Assets	8,735,324,000	8,420,013,000	'	'
Accrued expenses and other liabilities	63,427,000	73,232,000	'	'
Shareholders' equity (including other accumulated comprehensive loss of $43,047 and $65,748 at December 31, 2013 and 2012, respectively)	1,041,732,000	992,251,000	968,844,000	793,012,000
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	8,735,324,000	8,420,013,000	'	'
United Bankshares [Member]	'	'	'	'
Condensed Balance Sheet Statements, Captions [Line Items]	'	'	'	'
Cash and due from banks	43,613,000	30,585,000	'	'
Securities available for sale	1,925,000	3,271,000	'	'
Securities held to maturity	20,000	225,000	'	'
Other investment securities	125,000	162,000	'	'
Bank subsidiaries	1,139,786,000	1,100,880,000	'	'
Nonbank subsidiaries	6,396,000	6,355,000	'	'
Other assets	11,751,000	10,069,000	'	'
Total Assets	1,203,616,000	1,151,547,000	'	'
Junior subordinated debentures of subsidiary trusts	128,868,000	128,868,000	'	'
Accrued expenses and other liabilities	33,016,000	30,428,000	'	'
Shareholders' equity (including other accumulated comprehensive loss of $43,047 and $65,748 at December 31, 2013 and 2012, respectively)	1,041,732,000	992,251,000	'	'
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$1,203,616,000	$1,151,547,000	'	'

United_Bankshares_Inc_Parent_C3

United Bankshares, Inc. (Parent Company Only) Financial Information - Condensed Balance Sheets (Parenthetical) (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Condensed Balance Sheet Statements, Captions [Line Items]	'	'
Accumulated other comprehensive loss	($43,047)	($65,748)
United Bankshares [Member]	'	'
Condensed Balance Sheet Statements, Captions [Line Items]	'	'
Accumulated other comprehensive loss	$43,047	$65,748

United_Bankshares_Inc_Parent_C4

United Bankshares, Inc. (Parent Company Only) Financial Information - Condensed Statements of Income (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Condensed Income Statements, Captions [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Net interest income	$69,186	$67,630	$66,203	$66,822	$69,672	$70,014	$69,055	$68,966	$269,841	$277,707	$260,728
Income before income taxes	'	'	'	'	'	'	'	'	125,044	121,481	110,376
Applicable income tax benefit	-9,252	-10,433	-9,576	-10,155	-9,983	-9,099	-9,905	-9,887	-39,416	-38,874	-34,766
Net income	19,660	22,170	22,219	21,579	21,214	19,334	21,049	21,010	85,628	82,607	75,610
United Bankshares [Member]	'	'	'	'	'	'	'	'	'	'	'
Condensed Income Statements, Captions [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Dividends from banking subsidiaries	'	'	'	'	'	'	'	'	69,500	67,600	68,323
Net interest income	'	'	'	'	'	'	'	'	74	119	417
Bank subsidiaries	'	'	'	'	'	'	'	'	17,665	15,854	13,000
Nonbank subsidiaries	'	'	'	'	'	'	'	'	27	27	27
Other income	'	'	'	'	'	'	'	'	555	105	414
Total Income	'	'	'	'	'	'	'	'	87,821	83,705	82,181
Operating expenses	'	'	'	'	'	'	'	'	20,595	20,879	20,431
Income before income taxes	'	'	'	'	'	'	'	'	67,226	62,826	61,750
Applicable income tax benefit	'	'	'	'	'	'	'	'	-709	-1,487	-2,025
Income Before Equity in Undistributed Net Income of Subsidiaries	'	'	'	'	'	'	'	'	67,935	64,313	63,775
Bank subsidiaries	'	'	'	'	'	'	'	'	17,652	18,186	11,710
Nonbank subsidiaries	'	'	'	'	'	'	'	'	41	108	125
Net income	'	'	'	'	'	'	'	'	$85,628	$82,607	$75,610

United_Bankshares_Inc_Parent_C5

United Bankshares, Inc. (Parent Company Only) Financial Information - Condensed Statements of Cash Flows (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Condensed Cash Flow Statements, Captions [Line Items]	'	'	'
Net income	$85,628	$82,607	$75,610
Amortization of net periodic pension costs	4,094	3,567	912
Stock-based compensation	1,786	1,908	1,133
Net (gain) loss on securities transactions	5,809	6,930	18,838
NET CASH PROVIDED BY OPERATING ACTIVITIES	142,199	129,439	118,567
NET CASH (USED IN) PROVIDED BY INVESTING ACTIVITIES	-373,109	-208,141	158,337
Cash dividends paid	-62,434	-62,333	-54,344
Acquisition of treasury stock	-93	-12	-18
Proceeds from sale of treasury stock from deferred compensation plan	77	130	74
Excess tax benefits from stock-based compensation arrangements	331	35	3,114
Proceeds from exercise of stock options	2,364	115	542
NET CASH PROVIDED BY (USED IN) FINANCING ACTIVITIES	215,450	-125,224	-102,290
Increase (Decrease) in Cash and Cash Equivalents	-15,460	-203,926	174,614
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR	432,077	636,003	461,389
CASH AND CASH EQUIVALENTS AT END OF YEAR	416,617	432,077	636,003
United Bankshares [Member]	'	'	'
Condensed Cash Flow Statements, Captions [Line Items]	'	'	'
Net income	85,628	82,607	75,610
Equity in undistributed net income of subsidiaries	-17,693	-18,294	-11,835
Amortization of net periodic pension costs	373	117	76
Stock-based compensation	1,786	1,908	1,133
Net (gain) loss on securities transactions	-556	-55	-12
Net change in other assets and liabilities	867	-1,553	-6,895
NET CASH PROVIDED BY OPERATING ACTIVITIES	70,405	64,730	58,077
Net proceeds from (purchases of) sales of securities	2,341	1,541	4,854
Net cash paid in acquisition of subsidiary	0	0	-8,576
Change in other investment securities	37	38	1,376
NET CASH (USED IN) PROVIDED BY INVESTING ACTIVITIES	2,378	1,579	-2,346
Cash dividends paid	-62,434	-62,333	-54,344
Net (repayment) liquidation of subsidiary trusts	0	-5,155	0
Acquisition of treasury stock	-93	-12	-18
Proceeds from sale of treasury stock from deferred compensation plan	77	130	74
Excess tax benefits from stock-based compensation arrangements	331	35	3,114
Proceeds from exercise of stock options	2,364	115	542
NET CASH PROVIDED BY (USED IN) FINANCING ACTIVITIES	-59,755	-67,220	-50,632
Increase (Decrease) in Cash and Cash Equivalents	13,028	-911	5,099
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR	30,585	31,496	26,397
CASH AND CASH EQUIVALENTS AT END OF YEAR	$43,613	$30,585	$31,496

Regulatory_Matters_Additional_

Regulatory Matters - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Regulated Operations [Abstract]	'	'
Average reserve balances to be maintained by subsidiary banks	$245,566,000	$239,755,000
Average reserve balances required by subsidiary banks	438,761,000	89,439,000
Retained net profits available for distribution to United Bankshares, Inc. by its banking subsidiaries as dividends	35,547,000	'
Maximum loan to parent company by subsidiaries as percentage it's of capital and surplus	10.00%	'
Maximum amount of loan to parent company by subsidiaries	$77,648,000	'

Regulatory_Matters_Capital_Amo

Regulatory Matters - Capital Amounts and Ratios (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
United Bankshares [Member]	'	'
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]	'	'
Total Capital to Risk-Weighted Assets, Actual Amount	$971,401	$941,448
Tier 1 Capital to Risk-Weighted Assets, Actual Amount	886,094	857,091
Tier 1 Capital to Average Assets, Amount	886,094	857,091
Total Capital to Risk-Weighted Assets, Actual Ratio	13.70%	13.70%
Tier 1 Capital to Risk-Weighted Assets, Actual Ratio	12.50%	12.40%
Tier 1 Capital to Average Assets, Actual Ratio	10.70%	10.60%
Total Capital to Risk-Weighted Assets, For Capital Adequacy Purposes, Amount	566,836	551,114
Tier 1 Capital to Risk-Weighted Assets, For Capital Adequacy Purposes, Amount	283,418	275,557
Tier 1 Capital to Average Assets, For Capital Adequacy Purposes, Amount	330,614	322,941
Total Capital to Risk-Weighted Assets, For Capital Adequacy, Ratio	8.00%	8.00%
Tier 1 Capital to Risk-Weighted Assets, For Capital Adequacy Purposes, Ratio	4.00%	4.00%
Tier 1 Capital to Average Assets, For Capital Adequacy Purposes, Ratio	4.00%	4.00%
Total Capital to Risk-Weighted Assets, To Be Well Capitalized, Amount	708,545	688,892
Tier 1 Capital to Risk-Weighted Assets, To Be Well Capitalized, Amount	425,127	413,335
Tier 1 Capital to Average Assets, To Be Well Capitalized, Amount	413,267	403,676
Total Capital to Risk-Weighted Assets, To Be Well Capitalized, Ratio	10.00%	10.00%
Tier 1 Capital to Risk-Weighted Assets, To Be Well Capitalized, Ratio	6.00%	6.00%
Tier 1 Capital to Average Assets To Be Well Capitalized, Ratio	5.00%	5.00%
United Bank (WV) [Member]	'	'
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]	'	'
Total Capital to Risk-Weighted Assets, Actual Amount	525,517	511,451
Tier 1 Capital to Risk-Weighted Assets, Actual Amount	485,038	473,044
Tier 1 Capital to Average Assets, Amount	485,038	473,044
Total Capital to Risk-Weighted Assets, Actual Ratio	12.50%	12.70%
Tier 1 Capital to Risk-Weighted Assets, Actual Ratio	11.60%	11.80%
Tier 1 Capital to Average Assets, Actual Ratio	9.70%	9.80%
Total Capital to Risk-Weighted Assets, For Capital Adequacy Purposes, Amount	336,100	321,957
Tier 1 Capital to Risk-Weighted Assets, For Capital Adequacy Purposes, Amount	168,050	160,978
Tier 1 Capital to Average Assets, For Capital Adequacy Purposes, Amount	199,209	193,775
Total Capital to Risk-Weighted Assets, For Capital Adequacy, Ratio	8.00%	8.00%
Tier 1 Capital to Risk-Weighted Assets, For Capital Adequacy Purposes, Ratio	4.00%	4.00%
Tier 1 Capital to Average Assets, For Capital Adequacy Purposes, Ratio	4.00%	4.00%
Total Capital to Risk-Weighted Assets, To Be Well Capitalized, Amount	420,125	402,446
Tier 1 Capital to Risk-Weighted Assets, To Be Well Capitalized, Amount	252,075	241,468
Tier 1 Capital to Average Assets, To Be Well Capitalized, Amount	249,012	242,218
Total Capital to Risk-Weighted Assets, To Be Well Capitalized, Ratio	10.00%	10.00%
Tier 1 Capital to Risk-Weighted Assets, To Be Well Capitalized, Ratio	6.00%	6.00%
Tier 1 Capital to Average Assets To Be Well Capitalized, Ratio	5.00%	5.00%
United Bank (VA) [Member]	'	'
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]	'	'
Total Capital to Risk-Weighted Assets, Actual Amount	412,120	404,405
Tier 1 Capital to Risk-Weighted Assets, Actual Amount	376,255	368,488
Tier 1 Capital to Average Assets, Amount	376,255	368,488
Total Capital to Risk-Weighted Assets, Actual Ratio	14.40%	14.10%
Tier 1 Capital to Risk-Weighted Assets, Actual Ratio	13.10%	12.80%
Tier 1 Capital to Average Assets, Actual Ratio	11.20%	11.20%
Total Capital to Risk-Weighted Assets, For Capital Adequacy Purposes, Amount	229,656	229,769
Tier 1 Capital to Risk-Weighted Assets, For Capital Adequacy Purposes, Amount	114,828	114,884
Tier 1 Capital to Average Assets, For Capital Adequacy Purposes, Amount	134,613	132,158
Total Capital to Risk-Weighted Assets, For Capital Adequacy, Ratio	8.00%	8.00%
Tier 1 Capital to Risk-Weighted Assets, For Capital Adequacy Purposes, Ratio	4.00%	4.00%
Tier 1 Capital to Average Assets, For Capital Adequacy Purposes, Ratio	4.00%	4.00%
Total Capital to Risk-Weighted Assets, To Be Well Capitalized, Amount	287,070	287,211
Tier 1 Capital to Risk-Weighted Assets, To Be Well Capitalized, Amount	172,242	172,327
Tier 1 Capital to Average Assets, To Be Well Capitalized, Amount	$168,266	$165,197
Total Capital to Risk-Weighted Assets, To Be Well Capitalized, Ratio	10.00%	10.00%
Tier 1 Capital to Risk-Weighted Assets, To Be Well Capitalized, Ratio	6.00%	6.00%
Tier 1 Capital to Average Assets To Be Well Capitalized, Ratio	5.00%	5.00%

Fair_Value_Measurements_Additi

Fair Value Measurements - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Discount rates utilized, minimum	3.75%	'
Discount rates utilized, maximum	19.00%	'
Nonrecurring fair value adjustments on loans held for sale	$0	'
Fair value measurement of intangible assets	$0	$0
Trust Preferred Collateralized Debt Obligations [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Decrease in fair value of securities	17.00%	'
Increase in discount rates, basis point	200.00%	'

Fair_Value_Measurements_Schedu

Fair Value Measurements - Schedule of Financial Assets and Liabilities Measured at Fair Value (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Total available for sale securities	$775,284	$625,625
Derivative financial assets	3,224	2,367
Derivative financial liabilities	1,194	4,281
U.S. Treasury Securities and Obligations of U.S. Government Corporations and Agencies [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Total available for sale securities	171,754	337,522
State and Political Subdivisions [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Total available for sale securities	62,709	80,428
Residential Mortgage-Backed Securities, Agency [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Total available for sale securities	216,464	106,510
Residential Mortgage-Backed Securities, Non-agency [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Total available for sale securities	16,532	25,045
Asset-Backed Securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Total available for sale securities	9,227	11,709
Trust Preferred Collateralized Debt Obligations [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Total available for sale securities	43,449	40,613
Commercial Mortgage-Backed Securities Agency [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Total available for sale securities	233,432	'
Fair Value, Measurements, Recurring [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	771,414	619,239
Available for sale equity securities	3,870	6,386
Total available for sale securities	775,284	625,625
Fair Value, Measurements, Recurring [Member] | U.S. Treasury Securities and Obligations of U.S. Government Corporations and Agencies [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	171,754	337,522
Fair Value, Measurements, Recurring [Member] | State and Political Subdivisions [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	62,709	80,428
Fair Value, Measurements, Recurring [Member] | Residential Mortgage-Backed Securities, Agency [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	216,464	106,510
Fair Value, Measurements, Recurring [Member] | Residential Mortgage-Backed Securities, Non-agency [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	16,532	25,045
Fair Value, Measurements, Recurring [Member] | Asset-Backed Securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	9,227	11,709
Fair Value, Measurements, Recurring [Member] | Trust Preferred Collateralized Debt Obligations [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	43,449	40,613
Fair Value, Measurements, Recurring [Member] | Single Issue Trust Preferred Securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	12,632	12,129
Fair Value, Measurements, Recurring [Member] | Other Corporate Securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	5,215	5,283
Fair Value, Measurements, Recurring [Member] | Financial Services Industry [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale equity securities	2,292	5,382
Fair Value, Measurements, Recurring [Member] | Equity Mutual Funds [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale equity securities	434	55
Fair Value, Measurements, Recurring [Member] | Other Equity Securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale equity securities	1,144	949
Fair Value, Measurements, Recurring [Member] | Interest Rate Contracts [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Derivative financial assets	3,224	2,367
Derivative financial liabilities	1,194	4,281
Fair Value, Measurements, Recurring [Member] | Commercial Mortgage-Backed Securities Agency [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	233,432	'
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Total available for sale securities	2,796	3,807
Derivative financial assets	0	0
Derivative financial liabilities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	502	499
Available for sale equity securities	2,294	3,308
Total available for sale securities	2,796	3,807
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member] | U.S. Treasury Securities and Obligations of U.S. Government Corporations and Agencies [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member] | State and Political Subdivisions [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member] | Residential Mortgage-Backed Securities, Agency [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member] | Residential Mortgage-Backed Securities, Non-agency [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member] | Asset-Backed Securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member] | Trust Preferred Collateralized Debt Obligations [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member] | Single Issue Trust Preferred Securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	502	499
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member] | Other Corporate Securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member] | Financial Services Industry [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale equity securities	716	2,304
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member] | Equity Mutual Funds [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale equity securities	434	55
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member] | Other Equity Securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale equity securities	1,144	949
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member] | Interest Rate Contracts [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Derivative financial assets	0	0
Derivative financial liabilities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member] | Commercial Mortgage-Backed Securities Agency [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	0	'
Significant Other Observable Inputs (Level 2) [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Total available for sale securities	729,039	581,205
Derivative financial assets	3,224	2,367
Derivative financial liabilities	1,194	4,281
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	727,463	578,127
Available for sale equity securities	1,576	3,078
Total available for sale securities	729,039	581,205
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | U.S. Treasury Securities and Obligations of U.S. Government Corporations and Agencies [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	171,754	337,522
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | State and Political Subdivisions [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	62,709	80,428
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Residential Mortgage-Backed Securities, Agency [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	216,464	106,510
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Residential Mortgage-Backed Securities, Non-agency [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	16,532	25,045
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Asset-Backed Securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	9,227	11,709
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Trust Preferred Collateralized Debt Obligations [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	0	0
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Single Issue Trust Preferred Securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	12,130	11,630
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Other Corporate Securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	5,215	5,283
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Financial Services Industry [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale equity securities	1,576	3,078
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Equity Mutual Funds [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale equity securities	0	0
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Other Equity Securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale equity securities	0	0
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Interest Rate Contracts [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Derivative financial assets	3,224	2,367
Derivative financial liabilities	1,194	4,281
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Commercial Mortgage-Backed Securities Agency [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	233,432	'
Significant Unobservable Inputs (Level 3) [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Total available for sale securities	43,449	40,613
Derivative financial assets	0	0
Derivative financial liabilities	0	0
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	43,449	40,613
Available for sale equity securities	0	0
Total available for sale securities	43,449	40,613
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member] | U.S. Treasury Securities and Obligations of U.S. Government Corporations and Agencies [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	0	0
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member] | State and Political Subdivisions [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	0	0
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member] | Residential Mortgage-Backed Securities, Agency [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	0	0
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member] | Residential Mortgage-Backed Securities, Non-agency [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	0	0
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member] | Asset-Backed Securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	0	0
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member] | Trust Preferred Collateralized Debt Obligations [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	43,449	40,613
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member] | Single Issue Trust Preferred Securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	0	0
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member] | Other Corporate Securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	0	0
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member] | Financial Services Industry [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale equity securities	0	0
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member] | Equity Mutual Funds [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale equity securities	0	0
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member] | Other Equity Securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale equity securities	0	0
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member] | Interest Rate Contracts [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Derivative financial assets	0	0
Derivative financial liabilities	0	0
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member] | Commercial Mortgage-Backed Securities Agency [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available for sale debt securities	$0	'

Fair_Value_Measurements_Schedu1

Fair Value Measurements - Schedule of Additional Information about Financial Assets and Liabilities Measured at Fair Value Utilized Level 3 (Detail) (Trust Preferred Collateralized Debt Obligations [Member], Fair Value, Measurements, Recurring [Member], USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Trust Preferred Collateralized Debt Obligations [Member] | Fair Value, Measurements, Recurring [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Balance, beginning of year	$40,613	$42,369
Included in earnings (or changes in net assets)	-6,456	-5,970
Included in other comprehensive income	14,520	4,214
Purchases, issuances, and settlements	-5,228	0
Transfers in and/or out of Level 3	0	0
Balance, ending of year	43,449	40,613
The amount of total gains or losses for the period included in earnings (or changes in net assets) attributable to the change in unrealized gains or losses relating to assets still held at reporting date	$0	$0

Fair_Value_Measurements_Summar

Fair Value Measurements - Summary of Financial Assets Measured at Fair Value on Nonrecurring Basis (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
YTD Losses, Impaired Loans	$1,886	$3,238
YTD Losses, OREO	2,548	3,677
Impaired Loans	45,883	50,985
OREO	38,182	49,484
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Impaired Loans	0	0
OREO	0	0
Significant Other Observable Inputs (Level 2) [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Impaired Loans	13,081	28,947
OREO	38,107	45,588
Significant Unobservable Inputs (Level 3) [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Impaired Loans	32,802	22,038
OREO	$75	$3,896

Fair_Value_Measurements_Summar1

Fair Value Measurements - Summary of Estimated Fair Values of Financial Instruments (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Cash and cash equivalents	$416,617,000	$432,077,000
Securities available for sale	775,284,000	625,625,000
Securities held to maturity	40,965,000	43,467,000
Other securities	73,093,000	60,310,000
Loans held for sale	4,236,000	17,762,000
Loans	6,704,583,000	6,511,416,000
Derivative financial assets	3,224,000	2,367,000
Deposits	6,621,571,000	6,752,986,000
Derivative financial liabilities	1,194,000	4,281,000
Carrying Amount [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Cash and cash equivalents	416,617,000	432,077,000
Securities available for sale	775,284,000	625,625,000
Securities held to maturity	40,965,000	43,467,000
Other securities	73,093,000	60,310,000
Loans held for sale	4,236,000	17,762,000
Loans	6,630,385,000	6,437,515,000
Derivative financial assets	3,224,000	2,367,000
Deposits	6,621,571,000	6,752,986,000
Short-term borrowings	430,754,000	314,962,000
Long-term borrowings	575,697,000	284,926,000
Derivative financial liabilities	1,194,000	4,281,000
Fair Value [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Cash and cash equivalents	416,617,000	432,077,000
Securities available for sale	775,284,000	625,625,000
Securities held to maturity	38,293,000	42,696,000
Other securities	70,072,000	57,643,000
Loans held for sale	4,236,000	17,762,000
Loans	6,657,376,000	6,473,974,000
Derivative financial assets	3,224,000	2,367,000
Deposits	6,641,070,000	6,776,012,000
Short-term borrowings	430,754,000	314,962,000
Long-term borrowings	553,796,000	277,899,000
Derivative financial liabilities	1,194,000	4,281,000
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Cash and cash equivalents	0	0
Securities available for sale	2,796,000	3,807,000
Securities held to maturity	0	0
Other securities	0	0
Loans held for sale	0	0
Loans	0	0
Derivative financial assets	0	0
Deposits	0	0
Short-term borrowings	0	0
Long-term borrowings	0	0
Derivative financial liabilities	0	0
Significant Other Observable Inputs (Level 2) [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Cash and cash equivalents	416,617,000	432,077,000
Securities available for sale	729,039,000	581,205,000
Securities held to maturity	35,773,000	36,999,000
Other securities	0	0
Loans held for sale	4,236,000	17,762,000
Loans	0	0
Derivative financial assets	3,224,000	2,367,000
Deposits	6,641,070,000	6,776,012,000
Short-term borrowings	430,754,000	314,962,000
Long-term borrowings	553,796,000	277,899,000
Derivative financial liabilities	1,194,000	4,281,000
Significant Unobservable Inputs (Level 3) [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Cash and cash equivalents	0	0
Securities available for sale	43,449,000	40,613,000
Securities held to maturity	2,520,000	5,697,000
Other securities	70,072,000	57,643,000
Loans held for sale	0	0
Loans	6,657,376,000	6,473,974,000
Derivative financial assets	0	0
Deposits	0	0
Short-term borrowings	0	0
Long-term borrowings	0	0
Derivative financial liabilities	$0	$0

Variable_Interest_Entities_Add

Variable Interest Entities - Additional Information (Detail) (USD $)	1 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Aug. 20, 2012	Jul. 11, 2012	Dec. 31, 2013
Variable Interest Entity Not Primary Beneficiary Disclosures [Abstract]	'	'	'
Percentage of equity shares of each trust owned by the company	'	'	100.00%
Redemption trust preferred securities outstanding	'	$5	'
Redemption payment date	20-Aug-12	'	'
Redemption Price Percentage	104.58%	'	'
Redemption principal amount	$5.23	'	'

Variable_Interest_Entities_Sum

Variable Interest Entities - Summary of Quantitative Information Related to Significant Involvement in Unconsolidated Variable Interest Entities (Detail) (Trust Preferred Securities [Member], USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Trust Preferred Securities [Member]	'	'
Variable Interest Entity [Line Items]	'	'
Aggregate Assets	$201,186	$201,297
Aggregate Liabilities	194,453	194,636
Risk Of Loss	$6,733	$6,661

Quarterly_Financial_Data_Quart

Quarterly Financial Data - Quarterly Financial Data (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial Information Disclosure [Abstract]	'	'	'	'	'	'	'	'	'	'	'
Interest income	$77,639	$76,705	$75,485	$76,325	$79,668	$81,336	$81,105	$81,788	$306,154	$323,897	$316,522
Interest expense	8,453	9,075	9,282	9,503	9,996	11,322	12,050	12,822	36,313	46,190	55,794
Net interest income	69,186	67,630	66,203	66,822	69,672	70,014	69,055	68,966	269,841	277,707	260,728
Provision for credit losses	4,343	4,777	4,960	5,187	5,947	4,346	3,436	4,133	19,267	17,862	17,141
Mortgage banking income	262	605	739	965	851	819	483	318	'	'	'
Securities (losses) gains, net	-5,427	101	211	-694	-1,740	-2,188	-1,543	-1,459	-5,809	-6,930	-18,838
Other noninterest income	17,211	17,629	18,149	18,077	17,634	18,003	17,647	17,467	67,828	66,292	50,837
Noninterest expense	47,977	48,585	48,547	48,249	49,273	53,869	51,252	50,262	193,358	204,656	184,048
Income taxes	9,252	10,433	9,576	10,155	9,983	9,099	9,905	9,887	39,416	38,874	34,766
Net income	$19,660	$22,170	$22,219	$21,579	$21,214	$19,334	$21,049	$21,010	$85,628	$82,607	$75,610
Average shares outstanding (000s):	'	'	'	'	'	'	'	'	'	'	'
Basic	50,417,000	50,379,000	50,346,000	50,302,000	50,276,000	50,276,000	50,275,000	50,235,000	50,353,452	50,265,620	46,803,432
Diluted	50,564,000	50,473,000	50,402,000	50,332,000	50,295,000	50,295,000	50,308,000	50,301,000	50,426,078	50,298,019	46,837,363
Net income per share:	'	'	'	'	'	'	'	'	'	'	'
Basic	$0.39	$0.44	$0.44	$0.43	$0.42	$0.38	$0.42	$0.42	$1.70	$1.64	$1.62
Diluted	$0.39	$0.44	$0.44	$0.43	$0.42	$0.38	$0.42	$0.42	$1.70	$1.64	$1.61
Dividends per share	$0.32	$0.31	$0.31	$0.31	$0.31	$0.31	$0.31	$0.31	$1.25	$1.24	$1.21