Business Combination - Additional Information (Detail) (USD $)
1 Months Ended
Sep. 16, 2011
Business Acquisition [Line Items]  
Loans acquired $ 46,800,000
Assumed deposit liabilities 179,196,000
Goodwill resulting from acquisition 8,660,000
Identifiable assets core deposit intangible 2,402,000
Core deposit intangible, weighted average useful life 10 years
Fair value discount on loan acquired 700,000
Non-credit quality portion
 
Business Acquisition [Line Items]  
Fair value discount on loan acquired 100,000
Credit quality portion
 
Business Acquisition [Line Items]  
Fair value discount on loan acquired $ 600,000
Mississippi Gulf Coast branches
 
Business Acquisition [Line Items]  
Number of branches acquired 7
Bogalusa, Louisiana
 
Business Acquisition [Line Items]  
Number of branches acquired 1