Other Financial Information (Narrative) (Details) (USD $)	9 Months Ended	12 Months Ended
Sep. 30, 2011	Dec. 31, 2010
Other Financial Information
Collaborative receivables, current	$ 17,544,000	$ 18,856,000
Unbilled receivables related to costs incurred to produce pre-launch commercial products	12,928,000	13,165,000
Unbilled receivables from GSK in connection with company's cost-sharing agreements	3,483,000	5,166,000
Collaboration receivables, non-current	25,276,000	29,225,000
BENLYSTA inventory prior to capitalization	101,639,000	112,822,000
Related inventories purchased or manufactured prior to the date the company began capitalizing BENLYSTA inventory	0
Collaboration payable	33,552,000	12,984,000
Prepaid expenses and other current assets	13,958,000	5,569,000
Aggregate inventory of raw materials and work in progress	$ 3,365,000

Amounts due to our collaborative partners in connection with various cost sharing provisions of our collaboration agreements.

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Amounts due from our collaborative partners in connection with various cost sharing provisions of our collaboration agreements which are expected to be collected within one year(or one operating cycle, if longer) from the date of the balance sheet.

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Amounts due from our collaborative partners in connection with various cost sharing provisions of our collaboration agreements which are expected to be collected after one year from the date of the balance sheet.

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Inventories that were either purchased or manufactured prior to the date the Company began capitalizing. These costs were expensed in the period purchased or manufactured as research and development expenses.

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Other Financial Information [Abstract].

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The aggregate carrying amount as of the balance sheet date of items held by the entity which are partially completed at the time of measurement and unprocessed items that will go through the production process and become part of the final product. Includes supplies used directly or indirectly in the manufacturing or production process. This element may be used when the reporting entity combines work in process and raw materials into an aggregate amount.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 6

-Subparagraph a

-Article 5

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-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.6(a)(3),(4))

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 8

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 43

-Section A

-Paragraph 4

-Chapter 3

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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-Name Accounting Standards Codification

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