Fair Values of off-Balance Sheet Financial Instruments (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
Assets:
Cash and cash equivalents	$ 94,474	$ 44,618	$ 81,978	$ 39,252
Securities available-for-sale	246,842us-gaap_AvailableForSaleSecurities	254,746us-gaap_AvailableForSaleSecurities
Securities held-to-maturity	7,829us-gaap_HeldToMaturitySecurities	8,193us-gaap_HeldToMaturitySecurities
Other securities	7,235us-gaap_OtherInvestments	7,235us-gaap_OtherInvestments
Loans, net	712,088us-gaap_LoansReceivableNet	700,539us-gaap_LoansReceivableNet
Bank-owned life insurance	14,569us-gaap_BankOwnedLifeInsurance	14,463us-gaap_BankOwnedLifeInsurance
Liabilities:
Noninterest-bearing deposits	203,766	201,362
Interest-bearing deposits	780,877	691,413
Subordinated debentures	10,310us-gaap_SubordinatedDebt	10,310us-gaap_SubordinatedDebt
FHLB and other borrowings	49,446us-gaap_DebtAndCapitalLeaseObligations	89,450us-gaap_DebtAndCapitalLeaseObligations
Quoted Prices (Level 1)
Assets:
Cash and cash equivalents	94,474	44,618
Securities available-for-sale	969	972
Securities held-to-maturity	0	0
Other securities	0	0
Loans, net	0	0
Bank-owned life insurance	0	0
Liabilities:
Noninterest-bearing deposits	0	0
Interest-bearing deposits	0	0
Subordinated debentures	0	0
FHLB and other borrowings	0	0
Significant Other Observable Inputs (Level 2)
Assets:
Cash and cash equivalents	0	0
Securities available-for-sale	243,057	250,973
Securities held-to-maturity	9,385	9,994
Other securities	7,235	7,235
Loans, net	0	0
Bank-owned life insurance	14,569	14,463
Liabilities:
Noninterest-bearing deposits	203,766	201,362
Interest-bearing deposits	780,351	691,036
Subordinated debentures	0	0
FHLB and other borrowings	49,446	89,450
Significant Unobservable Inputs (Level 3)
Assets:
Cash and cash equivalents	0	0
Securities available-for-sale	2,816	2,801
Securities held-to-maturity	0	0
Other securities	0	0
Loans, net	728,369	715,849
Bank-owned life insurance	0	0
Liabilities:
Noninterest-bearing deposits	0	0
Interest-bearing deposits	0	0
Subordinated debentures	10,310	10,310
FHLB and other borrowings	0	0
Estimated Fair Value
Assets:
Cash and cash equivalents	94,474	44,618
Securities available-for-sale	246,842	254,746
Securities held-to-maturity	9,385	9,994
Other securities	7,235	7,235
Loans, net	728,369	715,849
Bank-owned life insurance	14,569	14,463
Liabilities:
Noninterest-bearing deposits	203,766	201,362
Interest-bearing deposits	780,351	691,036
Subordinated debentures	10,310	10,310
FHLB and other borrowings	$ 49,446	$ 89,450

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

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