Annual report pursuant to Section 13 and 15(d)

Income Taxes - Schedule of Reconciliation of Income Taxes at Statutory Federal Income Tax Rate to Net Income Taxes (Detail)

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Income Taxes - Schedule of Reconciliation of Income Taxes at Statutory Federal Income Tax Rate to Net Income Taxes (Detail) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
U.S. federal taxes (benefit) at statutory rate $ (24,186) $ (8,722) $ (6,353)
State federal income tax benefit (1,160) (1,995) (1,593)
Unutilized (utilized) net operating losses 7,455 11,731 9,392
Stock-based compensation 288 223 224
Research and development credits    (885) (732)
Tax assets not benefited 143 1,105 957
Nondeductible warrant expense 17,414 (1,482) (1,756)
Other 46 25 (139)
Total $ 0 $ 0 $ 0