Annual report pursuant to Section 13 and 15(d)

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

v3.6.0.2
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, 2016
Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Unrealized losses impaired loans $ 868 $ 2,756
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 17,800 27,900
Commercial and industrial loans [Member] | Impaired Loans [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Impaired loans 3,800 1,000
Consumer loans [Member] | Impaired Loans [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Impaired loans 419 1,700
Commercial property loans [Member] | Other Real Estate Owned [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Impaired loans 5,400 6,600
Residential property loans [Member] | Other Real Estate Owned [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Impaired loans 2,100 1,900
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 15,257 29,595
Other real estate owned 7,484 8,511
Significant Unobservable Inputs [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Impaired loans 6,767 1,044
Other real estate owned $ 0 $ 0