Collaborative Agreements (Narrative) (Details) (USD $)	1 Months Ended	9 Months Ended			9 Months Ended		1 Months Ended	9 Months Ended	1 Months Ended	9 Months Ended		1 Months Ended	9 Months Ended	1 Months Ended	9 Months Ended			9 Months Ended			1 Months Ended
	May 31, 2011	Sep. 30, 2011	Dec. 31, 2010	Oct. 31, 2008	Sep. 30, 2011 Original Lilly Collaboration Agreement, As Amended - Lilly's Share Of Development And Commercialization Expense [Member]	Sep. 30, 2011 United States Launch Of BYDUREON [Member]	Jul. 31, 2011 European Union Launch Of BYDUREON [Member]	Sep. 30, 2011 Lilly Supply Agreement - Pen Device [Member]	Oct. 31, 2008 Lilly Supply Agreement - BYDUREON [Member]	Sep. 30, 2011 Lilly Supply Agreement - BYDUREON [Member]	Sep. 30, 2011 Lilly Agreement (Exenatide Commercialization and Development, Amended 2009) Inception To Date [Member]	May 31, 2009 Pen Device Supply Agreement (May 2009) Amylin Cost Sharing [Member]	Sep. 30, 2011 Pen Device Supply Agreement (May 2009) Amylin Cost Sharing [Member]	May 31, 2009 Pen Device Supply Agreement (May 2009) Lilly Cost Sharing [Member]	Sep. 30, 2011 Pen Device Supply Agreement (May 2009) Lilly Cost Sharing [Member]	Sep. 30, 2011 Takeda Agreement [Member]	Oct. 31, 2009 Takeda Agreement [Member]	Sep. 30, 2011 Outside United States [Member]	Sep. 30, 2011 Japan Launch Of BYDUREON [Member]	Sep. 30, 2011 BYDUREON [Member]	May 31, 2009 Pen Device Supply Agreement [Member]	Sep. 30, 2011 Lilly [Member]
Collaborative Agreements [Line Items]
Percentage of shared exenatide global development and commercialization expenses		47.00%			53.00%													100.00%
Total commercial milestone payments earned under the collaboration agreement							$ 15,000,000				$ 65,000,000
Remaining potential milestone payments						40,000,000													15,000,000	55,000,000
Capitalized amount associated with the construction and validation of the manufacturing facility (excluding pen device costs)		637,700,000
Capital expenditures associated with pen device		204,900,000																			204,900,000
Lilly's share of capital expenditures associated with the pen device		103,800,000
Total combined capital expenditures for manufacturing facility and pen device		842,600,000
Upfront payment received									125,000,000								75,000,000
Lilly's share of interest costs capitalized		50,000,000
Estimated life of the underlying assets over which deferred credit is being amortized, in years								11
Estimated life of underlying assets over which deferred credit is being amortized to revenues under collaborative agreements										10
Deferred collaborative revenue																60,600,000						75,000,000
Amount of credit to which Lilly would be entitled in the event of impairment of the manufacturing facility		48,100,000
Deferred revenue, net of current portion		53,125,000	58,750,000													53,100,000
Estimate of Lilly's share of capital investment in the manufacturing facility									55.00%
Lilly's share of cost of goods sold in the United States									equally
Lilly's share of cost of goods sold outside the United States									100.00%
Percentage of shared pen device capital investment												40.00%	40.00%	60.00%	60.00%
Reimbursements received to date		99,700,000
Proceeds from line of credit	165,000,000
Line of credit, max borrowing capacity				165,000,000
Percentage of interest rate on loan								5.51%
Due date of outstanding principal								May 23, 2014
Principal balance due		$ 165,000,000