Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Non-Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items]
Other real estate owned	$ 6,533	$ 7,298
Fair Value, Measurements, Nonrecurring [Member] | Models with Significant Unobservable Market Parameters (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items]
Other real estate owned	6,533	7,298
Impaired loans, net	9,737	8,866
Total	16,270	16,164
Fair Value, Measurements, Nonrecurring [Member] | Reported Value Measurement [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items]
Other real estate owned	6,533	7,298
Impaired loans, net	9,737	8,866
Total	16,270	16,164
Fair Value, Measurements, Nonrecurring [Member] | Reported Value Measurement [Member] | Quoted Market Prices in an Active Market (Level 1) [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items]
Other real estate owned	0	0
Impaired loans, net	0	0
Total	0	0
Fair Value, Measurements, Nonrecurring [Member] | Reported Value Measurement [Member] | Models with Significant Observable Market Parameters (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items]
Other real estate owned	0	0
Impaired loans, net	0	0
Total	$ 0	$ 0