Estimated Net Operating Loss Carryforwards And Research and Development Credit Carryforwards for Federal and State Tax (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2011
Operating Loss Carryforwards and Research and Development Credit Carryforwards [Line Items]
Loss carryforward, federal	457,459
Loss carryforward, state	79,197
Research and development credit carryforwards, federal	18,448
Research and development credit carryforwards, state	7,588
Federal [Member]
Operating Loss Carryforwards and Research and Development Credit Carryforwards [Line Items]
Operating loss expiration date	2012 through 2031
State [Member]
Operating Loss Carryforwards and Research and Development Credit Carryforwards [Line Items]
Operating loss expiration date	2012 through 2016
Research and Development Credit Carryforwards [Member] \| Federal [Member]
Operating Loss Carryforwards and Research and Development Credit Carryforwards [Line Items]
Research and development credit carryforwards date	2012 through 2031
Research and Development Credit Carryforwards [Member] \| State [Member]
Operating Loss Carryforwards and Research and Development Credit Carryforwards [Line Items]
Research and development credit carryforwards date	2012 through 2026

The tax effect as of the balance sheet date of the amount of excess of tax deductions over gross income in a year which cannot be used on the tax return of the country of domicile in the current year but can be carried forward to reduce taxable income or income taxes payable in a future year, for which there must be sufficient tax-basis income to utilize a portion or all of the carryforward amount to realize the deferred tax asset.

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The tax effect as of the balance sheet date of the amount of excess of tax deductions over gross income in a year which cannot be used on the tax return of a state or local jurisdiction in the current year but can be carried forward to reduce taxable income or income taxes payable in a future year, for which there must be sufficient tax-basis income to utilize a portion or all of the carryforward amount to realize the deferred tax asset.

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