Other Current Assets (Details) (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010
Other Current Assets [Abstract]
Prepaid expenses	$ 15,725	$ 16,272
Receivable from collaborative partner	14,633	16,628
Other non-trade receivables	2,227	4,003
Other current assets	7,393	8,555
Total other current assets	$ 39,978	$ 45,458