Income Taxes - Schedule of Provision Computed by Applying Federal Statutory Rate (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended	120 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012
Unrealized gain on marketable securities	$ (1,052)
Changes in warrant value	3,664	(3,361)
Expected federal income tax benefit	(11,688)	(3,905)
Non-qualified stock compensation	152	172
Effect of change in valuation allowance	8,939	8,551
Income tax credits		(260)
State income taxes after credits	(1,067)	(1,197)
Total income tax expense (benefit)	$ (1,052)		$ (1,052)

Income Tax Reconciliation Gain On Change In Fair Value Of Warrant Liability

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- Definition

Income Tax Reconciliation Unrealized Gain On Marketable Securities

+ References

No definition available.

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- Definition

The sum of the current income tax expense or benefit and the deferred income tax expense or benefit pertaining to continuing operations.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

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The portion of the difference between total income tax expense or benefit as reported in the Income Statement and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to changes in the valuation allowance for deferred tax assets in the period.

+ References

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The amount of income tax expense or benefit for the period computed by applying the domestic federal statutory tax rates to pretax income from continuing operations.

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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The portion of the difference between total income tax expense or benefit as reported in the Income Statement for the period and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to differences in the deductibility of incentive stock options and other equity-based compensation costs in accordance with generally accepted accounting principles and enacted tax laws.

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The portion of the difference, between total income tax expense or benefit as reported in the Income Statement for the period and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations, that is attributable to state and local income tax expense or benefit.

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The portion of the difference between total income tax expense or benefit as reported in the Income Statement and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to research tax credits generated or utilized under enacted tax laws during the period.

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