Fair Value Measurement - Carrying Value and Estimated Fair Values of Financial Instruments (Detail) - USD ($)	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents, Carrying Value	$ 48,983,000	$ 32,980,000	$ 43,590,000	$ 77,331,000
Held to maturity securities, Carrying Value	4,775,000	0
Loans held for sale, Carrying Value	25,263,000	20,730,000
Loans held for sale, at fair value	9,839,000	0
Loans, net, Carrying Value	1,224,468,000	1,148,093,000
FHLB stock, Carrying Value	18,068,000	18,068,000
Accrued interest receivable, Carrying Value	5,768,000	5,763,000
FHLB advances, Carrying Value	(192,085,000)	(186,194,000)
Repurchase agreements and other, Carrying Value	(30,546,000)	(30,558,000)
Advance payments by borrowers for taxes and insurance, Carrying Value	(15,085,000)	(19,904,000)
Accrued interest payable, Carrying Value	(227,000)	(185,000)
Available for sale securities, Fair value	472,972,000	499,790,000
Held to maturity securities, Fair value	4,679,000	0
Reported Value Measurement
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents, Carrying Value	48,983,000	32,980,000
Available for sale securities, Carrying Value	472,972,000	499,790,000
Held to maturity securities, Carrying Value	4,775,000
Loans held for sale, Carrying Value	25,263,000	20,730,000
Loans held for sale, at fair value	9,839,000
Loans, net, Carrying Value	1,224,468,000	1,148,093,000
FHLB stock, Carrying Value	18,068,000	18,068,000
Accrued interest receivable, Carrying Value	5,768,000	5,763,000
Interest rate caps, Carrying Value	24,000	180,000
Purchased certificate of deposit option, Carrying Value	847,000	930,000
Checking, savings and money market accounts, Carrying Value	(982,536,000)	(912,536,000)
Certificates of deposit, Carrying Value	(456,711,000)	(435,300,000)
FHLB advances, Carrying Value	(192,085,000)	(186,194,000)
Repurchase agreements and other, Carrying Value	(30,546,000)	(30,558,000)
Advance payments by borrowers for taxes and insurance, Carrying Value	(15,085,000)	(19,904,000)
Accrued interest payable, Carrying Value	(227,000)	(185,000)
Written certificate of deposit option, Carrying Value	(847,000)	(930,000)
Estimate of Fair Value Measurement | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents, Fair Value	48,983,000	32,980,000
Checking, savings and money market accounts, Fair Value	(982,636,000)	(912,536,000)
Advance payments by borrowers for taxes and insurance, Fair Value	(15,085,000)
Estimate of Fair Value Measurement | Significant Other Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Loans held for sale, at fair value	26,317,000	21,528,000
Available for sale securities, Fair value	472,972,000	499,790,000
Held to maturity securities, Fair value	4,679,000
Accrued interest receivable, Fair Value	2,284,000	2,374,000
Purchased certificate of deposit option, Fair Value	847,000	930,000
Certificates of deposit, Fair Value	(462,628,000)	(442,268,000)
FHLB advances, Fair Value	(192,188,000)	(186,290,000)
Repurchase agreements and other, Fair Value	(32,312,000)	(32,817,000)
Accrued interest payable, Fair Value	(227,000)	(185,000)
Written certificate of deposit option, Fair Value	(847,000)	(930,000)
Estimate of Fair Value Measurement | Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Loans held for sale, at fair value	9,839,000
Loans, net, Fair Value	1,236,370,000	1,167,372,000
Accrued interest receivable, Fair Value	3,484,000	3,389,000
Interest rate caps, Fair Value	$ 24,000	$ 180,000