Annual report pursuant to Section 13 and 15(d)

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Narrative) (Details)

v2.4.1.9
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Narrative) (Details) (USD $)
12 Months Ended
Dec. 31, 2014
loan
Dec. 31, 2013
Federal Home Loan Bank requires Bank to maintain percentage of stock equal to outstanding borrowings 4.50%ubsh_FederalHomeLoanBankRequiresBankToMaintainPercentageOfStockEqualToOutstandingBorrowings  
Percentage of Federal Reserve Bank of Richmond reserve 6.00%ubsh_RequiredPercentageOfCommonStockInvestmentPercentageToOutstandingCapital  
Number of loan portfolio level segments 2ubsh_NumberOfLoanPortfolioLevelSegments  
Number of loan class levels for reporting purposes 14ubsh_NumberOfLoanClassLevelsForReportingPurposes  
Number of loan class levels for reporting purposes within commercial loan portfolio segment 7ubsh_NumberOfLoanClassLevelsForReportingPurposesWithinCommercialLoanPortfolioSegment  
Number of loan class levels for reporting purposes within consumer loan portfolio segment 7ubsh_NumberOfLoanClassLevelsForReportingPurposesWithinConsumerLoanPortfolioSegment  
Held to maturity debt securities $ 0us-gaap_HeldToMaturitySecurities  
Held for trading securities 0us-gaap_TradingSecurities  
Future payments, contractual term 6 months  
Accruals for uncertain tax positions 0us-gaap_LiabilityForUncertainTaxPositionsCurrent  
Impairment charges for goodwill or intangible assets 0us-gaap_GoodwillImpairmentLoss  
Goodwill 293,522,000us-gaap_Goodwill 59,400,000us-gaap_Goodwill
Liabilities for post retirement benefits payable to other beneficiaries $ 3,800,000ubsh_LiabilitiesForPostRetirementBenefitsPayableToOtherBeneficiaries $ 3,300,000ubsh_LiabilitiesForPostRetirementBenefitsPayableToOtherBeneficiaries
Minimum [Member]    
Commercial loans on nonaccrual status, period 90 days  
Period of updating independent appraisal 12 months  
Interest rate lock commitments period 30 days  
Estimated useful life of bank premises 3 years  
Percentage of fair value of the derivative instruments for the hedge to be highly effective 80.00%ubsh_PercentageOfFairValueOfDerivativeInstrumentForHedgeToBeHighlyEffective
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
 
Maximum tax benefit realized 50.00%ubsh_PercentageOfLikelihoodOfTaxBenefitsBeingRealizedUponSettlement
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
 
Maximum [Member]    
Maximum period for net realizable value 180 days  
Commercial loans on nonaccrual status, period 180 days  
Period of updating independent appraisal 24 months  
Period past due to charge off consumer loans 120 days  
Interest rate lock commitments period 120 days  
Estimated useful life of bank premises 40 years  
Percentage of fair value of the derivative instruments for the hedge to be highly effective 125.00%ubsh_PercentageOfFairValueOfDerivativeInstrumentForHedgeToBeHighlyEffective
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Core Deposits [Member] | Minimum [Member]    
Intangible assets, amortization period 4 years  
Core Deposits [Member] | Maximum [Member]    
Intangible assets, amortization period 14 years