Condensed Consolidated Statements Of Operations (USD $) In Thousands, except Per Share data	3 Months Ended	9 Months Ended
Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Condensed Consolidated Statements Of Operations [Abstract]
Collaboration revenue	$ 14,940	$ 14,350	$ 45,448	$ 45,876
Operating expenses:
Research and development	18,706	15,633	55,463	59,470
Selling, general and administrative	7,724	5,454	20,916	18,267
Total operating expenses	26,430	21,087	76,379	77,737
Loss from operations	(11,490)	(6,737)	(30,931)	(31,861)
Other income (expense), net	81	(174)	(301)	245
Net loss before income tax benefit	(11,409)	(6,911)	(31,232)	(31,616)
Income tax benefit	1,365	1,468	3,262	1,468
Net loss	$ (10,044)	$ (5,443)	$ (27,970)	$ (30,148)
Basic and diluted net loss per common share	$ (0.29)	$ (0.16)	$ (0.80)	$ (0.88)
Weighted average common shares used in the calculation of basic and diluted net loss per common share	34,909	34,570	34,821	34,198

Basic net loss per share is computed by dividing the net loss by the weighted-average number of common shares outstanding during the period. Diluted net loss per share is computed similarly to basic net loss per share, except that the denominator is increased to include all dilutive potential common shares, including outstanding options and warrants. Potentially dilutive common shares have been excluded from the diluted loss per common share computations in all periods presented because such securities have an anti-dilutive effect on loss per common share due to the Company's net loss.

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Revenue earned from the amortization of non refundable upfront cash payment and development milestone payments received under collaboration agreements over the expected performance period.

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Reporting entity's loss before income taxes.

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Weighted average common shares used in the calculation of basic and diluted net loss per share.

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

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The portion of consolidated profit or loss for the period, net of income taxes, which is attributable to the parent. If the entity does not present consolidated financial statements, the amount of profit or loss for the period, net of income taxes.

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Generally recurring costs associated with normal operations except for the portion of these expenses which can be clearly related to production and included in cost of sales or services. Includes selling, general and administrative expense.

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The net result for the period of deducting operating expenses from operating revenues.

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The net amount of other nonoperating income and expense, which does not qualify for separate disclosure on the income statement under materiality guidelines.

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The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.

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The aggregate total costs related to selling a firm's product and services, as well as all other general and administrative expenses. Direct selling expenses (for example, credit, warranty, and advertising) are expenses that can be directly linked to the sale of specific products. Indirect selling expenses are expenses that cannot be directly linked to the sale of specific products, for example telephone expenses, Internet, and postal charges. General and administrative expenses include salaries of non-sales personnel, rent, utilities, communication, etc.

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