Fair Value of Assets and Liabilities - Assets and Liabilities Measured at Fair Value on a Non-Recurring Basis (Parenthetical) (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items]
Reserve on impaired loans	$ 545	$ 1,514	$ 2,900
Fair Value, Measurements, Nonrecurring [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items]
Reserve on impaired loans	545	1,514
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items]
Reserve on impaired loans	$ 545	$ 1,514