Quarterly report pursuant to Section 13 or 15(d)

Loans and Leases - Additional Information (Detail)

v3.7.0.1
Loans and Leases - Additional Information (Detail)
$ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2016
USD ($)
SecurityLoan
Jun. 30, 2017
USD ($)
Property
Jun. 30, 2016
USD ($)
SecurityLoan
Dec. 31, 2016
USD ($)
Property
Dec. 31, 2015
USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]          
Accrued interest receivable   $ 11,167   $ 10,987  
Loans and leases receivable   $ 4,039,304   $ 3,812,340  
Number of real estate properties | Property   7   12  
Other real estate owned (OREO), net   $ 4,321   $ 7,484  
TDR loans receivable   $ 15,900   18,000  
Principal and interest due   3 months      
Reserves relating to loans included in allowance for loan losses   $ 3,500   3,400  
PCI Loans and Leases [Member]          
Accounts, Notes, Loans and Financing Receivable [Line Items]          
Loans and leases receivable $ 9,572 $ 8,064 $ 9,572 8,892 $ 14,573
Central Bancorp, Inc [Member]          
Accounts, Notes, Loans and Financing Receivable [Line Items]          
Number of real estate properties | Property   6      
Other real estate owned (OREO), net   $ 4,200   5,700  
Securities Pledged as Collateral [Member]          
Accounts, Notes, Loans and Financing Receivable [Line Items]          
Loans and leases receivable   1,000,000   1,000,000  
Loans and Finance Receivables [Member]          
Accounts, Notes, Loans and Financing Receivable [Line Items]          
Accrued interest receivable   $ 8,300   $ 8,200  
Commercial term [Member] | Commercial and industrial loans [Member]          
Accounts, Notes, Loans and Financing Receivable [Line Items]          
Number of Loans | SecurityLoan 1   2    
Recorded Investment $ 55   $ 85