Quarterly report pursuant to Section 13 or 15(d)

Loans - Additional Information (Detail)

v3.5.0.2
Loans - Additional Information (Detail)
$ in Thousands
 9 Months Ended
Sep. 30, 2016
USD ($)
Property
Sep. 30, 2015
USD ($)
Dec. 31, 2015
USD ($)
Property
Dec. 31, 2014
USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Accrued interest receivable $ 10,160   $ 9,501  
Loans receivable 3,513,687   $ 3,140,381  
Transfer of loans receivable to loans held for sale $ 0 $ 360    
Number of real estate properties | Property 15   14  
Other real estate owned (OREO), net $ 10,971   $ 8,511  
TDR loans receivable $ 14,900   17,200  
Principal and interest due 3 months      
Reserves relating to loans included in allowance for loan losses $ 595   1,000  
PCI Loans [Member]        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Loans receivable 10,007 $ 22,007 14,573 $ 43,475
Outstanding balance of PCI loans - the undiscounted sum of all amounts including amounts deemed principal, interest, fees and penalties 19,600   30,900  
Central Bancorp, Inc [Member]        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Other real estate owned (OREO), net 5,800   7,400  
Securities Pledged as Collateral [Member]        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Loans receivable 1,000,000   557,700  
Loans and Finance Receivables [Member]        
Accounts, Notes, Loans and Financing Receivable [Line Items]        
Accrued interest receivable $ 7,500   $ 7,900