Business Combinations - Summary of Purchased Credit-Impaired Loans at Acquisition (Detail) (USD $)
In Thousands, unless otherwise specified
0 Months Ended
Dec. 15, 2014
Dec. 31, 2014
Business Combination Increase Decrease To Reflect Liabilities Acquired At Fair Value [Abstract]    
Contractually required principal and interest payments $ 11,956  
Non-accretable difference 2,929  
Cash flows expected to be collected 9,027  
Accretable discount 0  
Fair value of loans acquired with a deterioration of credit quality $ 9,027 $ 1,480