Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Investment securities available-for-sale, Carrying Value	$ 293,051	$ 346,420
US Government-Sponsored Enterprises (GSEs) and Agency-Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Investment securities available-for-sale, Carrying Value	94,287	130,567
State and Municipal Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Investment securities available-for-sale, Carrying Value	23,295	14,264
Fair Value Measurements Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Investment securities available-for-sale, Carrying Value	293,051	346,420
Loans held for sale	13,437	9,466
Other assets	26,560	17,331
Total assets at fair value	333,048	373,217
Fair Value Measurements Recurring [Member] | Quoted Market Prices in an Active Market (Level 1) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Investment securities available-for-sale, Carrying Value	0	0
Loans held for sale	0	0
Other assets	0	0
Total assets at fair value	0	0
Fair Value Measurements Recurring [Member] | Models with Significant Observable Market Parameters (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Investment securities available-for-sale, Carrying Value	293,051	346,420
Loans held for sale	13,437	9,466
Other assets	0	0
Total assets at fair value	306,488	355,886
Fair Value Measurements Recurring [Member] | Models with Significant Unobservable Market Parameters (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Investment securities available-for-sale, Carrying Value	0	0
Loans held for sale	0	0
Other assets	26,560	17,331
Total assets at fair value	26,560	17,331
Fair Value Measurements Recurring [Member] | US Government-Sponsored Enterprises (GSEs) and Agency-Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Investment securities available-for-sale, Carrying Value	94,287	130,567
Fair Value Measurements Recurring [Member] | US Government-Sponsored Enterprises (GSEs) and Agency-Backed Securities [Member] | Quoted Market Prices in an Active Market (Level 1) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Investment securities available-for-sale, Carrying Value	0	0
Fair Value Measurements Recurring [Member] | US Government-Sponsored Enterprises (GSEs) and Agency-Backed Securities [Member] | Models with Significant Observable Market Parameters (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Investment securities available-for-sale, Carrying Value	94,287	130,567
Fair Value Measurements Recurring [Member] | US Government-Sponsored Enterprises (GSEs) and Agency-Backed Securities [Member] | Models with Significant Unobservable Market Parameters (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Investment securities available-for-sale, Carrying Value	0	0
Fair Value Measurements Recurring [Member] | Mortgage Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Investment securities available-for-sale, Carrying Value	147,646	171,069
Fair Value Measurements Recurring [Member] | Mortgage Backed Securities [Member] | Quoted Market Prices in an Active Market (Level 1) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Investment securities available-for-sale, Carrying Value	0	0
Fair Value Measurements Recurring [Member] | Mortgage Backed Securities [Member] | Models with Significant Observable Market Parameters (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Investment securities available-for-sale, Carrying Value	147,646	171,069
Fair Value Measurements Recurring [Member] | Mortgage Backed Securities [Member] | Models with Significant Unobservable Market Parameters (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Investment securities available-for-sale, Carrying Value	0	0
Fair Value Measurements Recurring [Member] | Asset-backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Investment securities available-for-sale, Carrying Value	27,823	30,520
Fair Value Measurements Recurring [Member] | Asset-backed Securities [Member] | Quoted Market Prices in an Active Market (Level 1) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Investment securities available-for-sale, Carrying Value	0	0
Fair Value Measurements Recurring [Member] | Asset-backed Securities [Member] | Models with Significant Observable Market Parameters (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Investment securities available-for-sale, Carrying Value	27,823	30,520
Fair Value Measurements Recurring [Member] | Asset-backed Securities [Member] | Models with Significant Unobservable Market Parameters (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Investment securities available-for-sale, Carrying Value	0	0
Fair Value Measurements Recurring [Member] | State and Municipal Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Investment securities available-for-sale, Carrying Value	23,295	14,264
Fair Value Measurements Recurring [Member] | State and Municipal Securities [Member] | Quoted Market Prices in an Active Market (Level 1) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Investment securities available-for-sale, Carrying Value	0
Fair Value Measurements Recurring [Member] | State and Municipal Securities [Member] | Models with Significant Observable Market Parameters (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Investment securities available-for-sale, Carrying Value	23,295	$ 14,264
Fair Value Measurements Recurring [Member] | State and Municipal Securities [Member] | Models with Significant Unobservable Market Parameters (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Investment securities available-for-sale, Carrying Value	$ 0