Annual report pursuant to Section 13 and 15(d)

ACQUISITIONS (Narrative) (Details)

v2.4.1.9
ACQUISITIONS (Narrative) (Details) (USD $)
12 Months Ended 0 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Jan. 01, 2014
Dec. 31, 2012
Business Acquisition [Line Items]        
Fair value of loans acquired with a deterioration of credit quality $ 105,788,000us-gaap_FinancingReceivableAcquiredWithDeterioratedCreditQuality $ 3,622,000us-gaap_FinancingReceivableAcquiredWithDeterioratedCreditQuality   $ 4,565,000us-gaap_FinancingReceivableAcquiredWithDeterioratedCreditQuality
Acquisition and conversion costs 20,345,000ubsh_AcquisitionAndConversionCosts 2,132,000ubsh_AcquisitionAndConversionCosts    
StellarOne Bank [Member]        
Business Acquisition [Line Items]        
Number of shares equivalent to each share of acquired entity     0.9739ubsh_BusinessAcquisitionNumberOfSharesEquivalentToEachShareOfAcquiredEntity
/ us-gaap_BusinessAcquisitionAxis
= ubsh_StellaroneBankMember
 
Number of common shares issued     22,147,874us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued
/ us-gaap_BusinessAcquisitionAxis
= ubsh_StellaroneBankMember
 
Value of Company common stock issued     549,489,000us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable
/ us-gaap_BusinessAcquisitionAxis
= ubsh_StellaroneBankMember
 
Fair value mark related to bank premises     3,200,000ubsh_FairValueAdjustmentOnAcquiredBankPremises
/ us-gaap_BusinessAcquisitionAxis
= ubsh_StellaroneBankMember
 
Acquired performing loans not expected to be collected     35,400,000ubsh_AcquiredPerformingLoansNotExpectedToBeCollected
/ us-gaap_BusinessAcquisitionAxis
= ubsh_StellaroneBankMember
 
Fair value of loans acquired with a deterioration of credit quality     145,454,000us-gaap_FinancingReceivableAcquiredWithDeterioratedCreditQuality
/ us-gaap_BusinessAcquisitionAxis
= ubsh_StellaroneBankMember
 
Core deposit intangible assets, amortization period     8 years  
Premium on acquired time deposits     10,800,000ubsh_PremiumOnAcquiredTimeDeposits
/ us-gaap_BusinessAcquisitionAxis
= ubsh_StellaroneBankMember
 
Premium accretion on acquired time deposits period     20 months  
Premium On Acquired FHLB Advances     3,200,000ubsh_PremiumOnAcquiredFhlbAdvances
/ us-gaap_BusinessAcquisitionAxis
= ubsh_StellaroneBankMember
 
Premium on acquired FHLB advances period     55 months  
Discount on acquired trust preferred capital notes     7,500,000ubsh_DiscountOnAcquiredTrustPreferredCapitalNotes
/ us-gaap_BusinessAcquisitionAxis
= ubsh_StellaroneBankMember
 
Discount on acquired trust preferred capital notes period     20 years  
Acquisition and conversion costs 20,345,000ubsh_AcquisitionAndConversionCosts
/ us-gaap_BusinessAcquisitionAxis
= ubsh_StellaroneBankMember
2,132,000ubsh_AcquisitionAndConversionCosts
/ us-gaap_BusinessAcquisitionAxis
= ubsh_StellaroneBankMember
   
StellarOne Bank [Member] | Performing Financing Receivable [Member]        
Business Acquisition [Line Items]        
Acquired performing loans, Fair value     2,100,000,000ubsh_AcquiredPerformingLoansFairValue
/ us-gaap_BusinessAcquisitionAxis
= ubsh_StellaroneBankMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember
 
Acquired performing loans, principal and interest payments receivable     $ 2,500,000,000ubsh_AcquiredPerformingLoansPrincipalAndInterestPaymentsReceivable
/ us-gaap_BusinessAcquisitionAxis
= ubsh_StellaroneBankMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember