Annual report pursuant to Section 13 and 15(d)

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Non-Recurring Basis (Detail)

v3.3.1.900
Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Non-Recurring Basis (Detail) - Non-recurring Basis [Member] - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Unrealized losses impaired loans $ 2,756 $ 2,774
Unrealized losses other real estate owned 0 0
Real estate loans [Member] | Impaired Loans [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Impaired loans 27,900 30,000
Commercial and industrial loans [Member] | Impaired Loans [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Impaired loans 1,000 1,200
Consumer loans [Member] | Impaired Loans [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Impaired loans 1,700 1,200
Commercial property loans [Member] | Other Real Estate Owned [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Impaired loans 6,600 13,200
Residential property loans [Member] | Other Real Estate Owned [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Impaired loans 1,900 2,600
Quoted Prices in Active Markets for Identical Assets [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Impaired loans 0 0
Other real estate owned 0 0
Significant Observable Inputs with No Active Market with Identical Characteristics [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Impaired loans 29,595 32,171
Other real estate owned 8,511 15,790
Significant Unobservable Inputs [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Impaired loans 1,044 781
Other real estate owned $ 0 $ 0