Quarterly report pursuant to Section 13 or 15(d)

Acquisition - Additional Information (Detail)

v3.2.0.727
Acquisition - Additional Information (Detail)
$ / shares in Units, $ in Thousands
 3 Months Ended 6 Months Ended 12 Months Ended
Aug. 31, 2014
USD ($)
branch
$ / shares
Jun. 30, 2015
USD ($)
Sep. 30, 2014
USD ($)
Jun. 30, 2014
USD ($)
Jun. 30, 2015
USD ($)
Jun. 30, 2014
USD ($)
Dec. 31, 2014
USD ($)
Loans At Acquisition Date [Line Items]              
Merger and integration expense   $ 136   $ 72 $ 1,747 $ 157  
Amortization of subordinated debentures   41     79    
Central Bancorp, Inc [Member]              
Loans At Acquisition Date [Line Items]              
Common stock, price per share after acquisition | $ / shares $ 17.64            
Consideration paid $ 50,000            
Consideration paid for redemption of preferred stock and cumulative unpaid dividends 28,675            
Total assets acquired 1,267,921            
Total liabilities assumed 1,174,669            
Total identifiable net assets 93,252            
Loans 297,272            
Total deposits $ 1,098,997            
Number of branch locations | branch 23            
Bargain purchase gain, net of deferred taxes $ 14,577            
Merger and integration expense   136     1,700   $ 6,600
Core deposit intangible $ 2,213            
Core deposit intangible, useful life 10 years            
Amortization expense of core deposit intangible   95     190    
Certificates of deposit $ 11,300            
Amortization of certificates of deposit   1,500     3,100    
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Gain Recognized, Amount     $ 8,000        
Central Bancorp, Inc [Member] | Subordinated Debentures [Member]              
Loans At Acquisition Date [Line Items]              
Discount on subordinated debentures $ 8,300   $ 8,300        
Amortization of subordinated debentures   $ 41     $ 79