Income Taxes - Details of Deferred Tax Asset (Liability), Net (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Deferred tax asset:
Allowance for loan losses	$ 9,742	$ 14,702
Impairments realized on investment securities	490	490
Fixed assets	4,720	4,354
Net operating loss carry forwards	111,593	96,117
Unrealized loss on investment securities	95	4,872
Alternative minimum tax credits	2,010	2,010
Other	6,603us-gaap_DeferredTaxAssetsOther	4,585us-gaap_DeferredTaxAssetsOther
Total deferred tax asset before valuation allowance	135,253us-gaap_DeferredTaxAssetsGross	127,130us-gaap_DeferredTaxAssetsGross
Less: valuation allowance	(132,646)	(119,349)
Deferred tax liability:
Core deposit intangible amortization		103
Goodwill amortization	1,610	297
Deferred loan costs	2,211	2,496
Other	300us-gaap_DeferredTaxLiabilitiesOther	310us-gaap_DeferredTaxLiabilitiesOther
Total deferred tax liability	4,121us-gaap_DeferredIncomeTaxLiabilities	3,206us-gaap_DeferredIncomeTaxLiabilities
Net deferred tax (liability) asset	$ (1,514)us-gaap_DeferredTaxAssetsLiabilitiesNet	$ 4,575us-gaap_DeferredTaxAssetsLiabilitiesNet

Deferred tax assets unrealized losses on investment securities.

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Deferred tax liabilities goodwill amortization.

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Amount of deferred tax liability attributable to taxable temporary differences.

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Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards, net of deferred tax liability attributable to taxable temporary differences.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from the provision for loan losses.

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