Annual report pursuant to Section 13 and 15(d)

Income Taxes - Additional Information (Detail)

v3.3.1.900
Income Taxes - Additional Information (Detail) - USD ($)
 12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Income Tax Disclosure [Abstract]      
Unrecognized tax benefits that would affect our effective tax rate if recognized $ 900,000 $ 1,500,000 $ 1,000,000
Lapse of statute of limitations (831,000) 0 0
Decrease in unrecognized tax benefits related to non-qualified stock option 0 165,000 0
Addition in unrecognized tax benefits except increase in accrued interest   676,000 0
Accrued interest on uncertain tax benefits 20,000 52,000 45,000
Accrued interest related to uncertain tax positions, net of federal tax benefit 67,000 366,000 $ 403,000
Increase in deferred tax assets, allowance for loan losses and net operating loss carryforwards   18,100,000  
Valuation allowance 0    
Federal [Member]      
Operating Loss Carryforwards [Line Items]      
Net operating loss carryforwards 15,600,000    
State [Member]      
Operating Loss Carryforwards [Line Items]      
Net operating loss carryforwards $ 248,200,000    
Central Bancorp, Inc [Member]      
Operating Loss Carryforwards [Line Items]      
Increase in deferred tax assets   $ 18,300,000