v3.6.0.2
Document and Entity Information - USD ($)
12 Months Ended
Dec. 31, 2016
Jan. 31, 2017
Jun. 30, 2016
Document and Entity Information [Abstract]      
Entity Registrant Name UNITED COMMUNITY BANKS INC    
Entity Central Index Key 0000857855    
Trading Symbol ucbi    
Entity Current Reporting Status Yes    
Entity Voluntary Filers No    
Current Fiscal Year End Date --12-31    
Entity Filer Category Large Accelerated Filer    
Entity Well-known Seasoned Issuer Yes    
Entity Common Stock, Shares Outstanding   70,960,282  
Entity Public Float     $ 1,261,158,381
Document Type 10-K    
Document Period End Date Dec. 31, 2016    
Amendment Flag false    
Document Fiscal Year Focus 2016    
Document Fiscal Period Focus FY