Annual report pursuant to Section 13 and 15(d)

Document and Entity Information

v3.8.0.1
Document and Entity Information - USD ($)
12 Months Ended
Dec. 31, 2017
Feb. 20, 2018
Jun. 30, 2017
Document and Entity Information [Abstract]      
Entity Registrant Name Union Bankshares Corp    
Entity Central Index Key 0000883948    
Document Type 10-K    
Document Period End Date Dec. 31, 2017    
Amendment Flag false    
Document Fiscal Year Focus 2017    
Document Fiscal Period Focus FY    
Current Fiscal Year End Date --12-31    
Entity Filer Category Large Accelerated Filer    
Entity Current Reporting Status Yes    
Entity Voluntary Filers No    
Entity Well-known Seasoned Issuer Yes    
Entity Public Float     $ 1,447,596,105
Entity Common Stock, Shares Outstanding   65,759,735