Significant Component of Deferred Tax Assets (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Deferred Tax Assets [Line Items]
Net operating loss carryforwards	$ 79,050	$ 66,209
Start-up and organizational costs	38,562	41,529
Research and development credit carryforwards	26,112	25,058
Stock compensation	1,181	1,028
Capitalized acquisition costs	11,376	12,323
Deferred revenue	534us-gaap_DeferredTaxAssetsDeferredIncome	1,074us-gaap_DeferredTaxAssetsDeferredIncome
Depreciation	208ziop_DeferredTaxAssetsDepreciation	129ziop_DeferredTaxAssetsDepreciation
Other	1,547us-gaap_DeferredTaxAssetsOther	1,254us-gaap_DeferredTaxAssetsOther
Deferred Tax Assets Gross	158,570us-gaap_DeferredTaxAssetsGross	148,604us-gaap_DeferredTaxAssetsGross
Less valuation allowance	(158,570)	(148,604)
Net deferred tax assets	$ 0us-gaap_DeferredTaxAssetsNet	$ 0us-gaap_DeferredTaxAssetsNet

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from deferred income.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.

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

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences not separately disclosed.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible research tax credit carryforwards.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from compensation and benefits costs.

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Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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Deferred Tax Assets, Capitalized Acquisition Costs

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Deferred Tax Assets, Depreciation

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Deferred Tax Assets, Start Up and Organizational Costs

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