Goodwill and Intangible Assets - Additional Information (Detail) (USD $)
12 Months Ended
Dec. 31, 2014
Dec. 15, 2014
Aug. 29, 2014
Schedule Of Goodwill And Other Intangible Asset [Line Items]      
Goodwill associated with acquisition $ 28,834,000 $ 5,719,000  
Core deposit intangible asset 1,757,000    
Amortization expense for intangible assets 19,000    
CBI [Member]      
Schedule Of Goodwill And Other Intangible Asset [Line Items]      
Goodwill associated with acquisition 23,115,000   23,115,000
United Group Banking Company of Florida [Member]      
Schedule Of Goodwill And Other Intangible Asset [Line Items]      
Goodwill associated with acquisition 5,719,000 5,719,000  
Core deposit intangible asset 1,776,000    
Core Deposits [Member]      
Schedule Of Goodwill And Other Intangible Asset [Line Items]      
Amortized period of core deposit intangible 7 years    
Core deposit intangible, gross 1,776,000    
Core deposit intangible asset, accumulated amortization 19,000    
Amortization expense for intangible assets $ 18,000