Subsequent Events (Details) (Subsequent Event, USD $) In Millions, unless otherwise specified	1 Months Ended
Apr. 30, 2013
PDGF
Subsequent Event [Line Items]
Research and Development Expense (Excluding Acquired in Process Cost)	$ 10
Substantive Milestone Payments	40
ANG2
Subsequent Event [Line Items]
Research and Development Expense (Excluding Acquired in Process Cost)	10
Substantive Milestone Payments	$ 5
New Laboratory and Office Facilities
Subsequent Event [Line Items]
Area of Real Estate Property	297,000
Number of New Buildings to be Constructed	2
Initial Term of Lease	15 years
Number of Renewal Options	3
Lease Extension Terms	5 years
Tarrytown Lease
Subsequent Event [Line Items]
Area of Real Estate Property	360,000

- Definition

The costs incurred 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 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, excluding in-process research and development acquired in a business combination consummated during the period. Excludes software research and development, which has a separate concept.

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