Summary of Significant Accounting Policies (Schedule of Revenue by Major Customers) (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Genentech [Member] | Avastin [Member]
Entity Wide Revenue Major Customer [Line Items]
Percentage of total revenue (in Percent)	33.00%	30.00%	34.00%	31.00%
Genentech [Member] | Herceptin [Member]
Entity Wide Revenue Major Customer [Line Items]
Percentage of total revenue (in Percent)	32.00%	36.00%	33.00%	35.00%
Genentech [Member] | Lucentis [Member]
Entity Wide Revenue Major Customer [Line Items]
Percentage of total revenue (in Percent)	14.00%	15.00%	17.00%	18.00%
Elan [Member] | Tysabri [Member]
Entity Wide Revenue Major Customer [Line Items]
Percentage of total revenue (in Percent)	12.00%	14.00%	11.00%	12.00%