Collaborations (Details)	1 Months Ended	12 Months Ended									1 Months Ended	12 Months Ended			1 Months Ended		12 Months Ended	1 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	1 Months Ended	12 Months Ended				1 Months Ended	3 Months Ended	1 Months Ended	12 Months Ended	1 Months Ended		3 Months Ended	1 Months Ended	12 Months Ended	1 Months Ended	12 Months Ended
	Mar. 31, 2010 USD ($)	Dec. 31, 2011 USD ($)	Dec. 31, 2010 USD ($)	Dec. 31, 2009 USD ($)	Dec. 31, 2011 Erbitux [Member] USD ($)	Dec. 31, 2010 Erbitux [Member] USD ($)	Dec. 31, 2009 Erbitux [Member] USD ($)	Dec. 31, 2011 Effient [Member] USD ($)	Dec. 31, 2010 Effient [Member] USD ($)	Dec. 31, 2009 Effient [Member] USD ($)	Nov. 30, 2011 Amylin [Member] USD ($)	Dec. 31, 2011 Exenatide [Member] USD ($)	Dec. 31, 2010 Exenatide [Member] USD ($)	Dec. 31, 2009 Exenatide [Member] USD ($)	Jan. 31, 2011 Boerhringer Ingelheim (BI) [Member] USD ($)	Nov. 30, 2011 Sales NEW [Member] Amylin [Member]	Dec. 31, 2011 Sales NEW [Member] Exenatide [Member]	Nov. 30, 2011 Revenue Share [Member] Amylin [Member] USD ($)	Dec. 31, 2011 Gross Margin Share [Member] Exenatide [Member]	Sep. 30, 2010 Profit and Development and Marketing Share [Member] Effient [Member]	Dec. 31, 2011 Selling and Marketing Expense [Member] Necitumumab [Member]	Mar. 31, 2010 Prepaid Selling and Marketing Expense [Member] Duloxetine BI [Member] USD ($)	Dec. 31, 2011 Royalty Payments Received [Member] Solanezumab [Member] USD ($)	Dec. 31, 2011 Research and Development Exp [Member] Necitumumab [Member]	Dec. 31, 2011 Research and Development and Marketing and Selling Expense [Member] Exenatide [Member]	Dec. 31, 2011 Milestone Payments [Member] Necitumumab [Member] USD ($)	Nov. 30, 2011 Milestone Payments [Member] Amylin [Member] USD ($)	Sep. 30, 2011 Milestone Payments [Member] Solanezumab [Member] USD ($)	Jan. 31, 2011 Milestone Payments [Member] BI compounds [Member] EUR (€)	Dec. 31, 2011 Milestone Payments [Member] BI compounds [Member] USD ($)	Jan. 31, 2011 Milestone Payments [Member] LLY compounds [Member] USD ($)	Jan. 31, 2011 Milestone Payments [Member] LLY optional compound [Member] USD ($)	Jun. 30, 2011 Loan Commitment [Member] Exenatide Once Weekly [Member] USD ($)	Nov. 30, 2011 United States [Member] Revenue Share [Member] Amylin [Member]	Dec. 31, 2011 United States [Member] Research and Development Exp [Member] Necitumumab [Member]	Nov. 30, 2011 Outside the United States [Member] Revenue Share [Member] Amylin [Member]	Dec. 31, 2011 Outside the United States [Member] Research and Development Exp [Member] Necitumumab [Member]
Net product sales		$ 23,604,800,000	$ 22,442,200,000	$ 21,171,500,000	$ 87,600,000	$ 71,900,000	$ 92,500,000	$ 302,500,000	$ 115,000,000	$ 27,000,000		$ 179,600,000	$ 168,100,000	$ 147,700,000
Collaboration and other revenue		681,700,000	633,800,000	664,500,000	321,600,000	314,200,000	298,300,000					243,100,000	262,500,000	300,800,000
Revenue		24,286,500,000	23,076,000,000	21,836,000,000	409,200,000	386,100,000	390,800,000					422,700,000	430,600,000	448,500,000
Research and development		5,020,800,000	4,884,200,000	4,326,500,000
Collaborative Arrangement, Income Statement Classification and Amounts		219,200,000	174,500,000	319,200,000
Collaborative Arrangement, Rights and Obligations											250,000,000							1,200,000,000				400,000,000	8			250,000,000	150,000,000	70,000,000	300,000,000	478,700,000	650,000,000	525,000,000	165,000,000
Collaborative Arrangement, Rights and Obligations Percent																15.00%	100.00%	9.50%	50.00%	50.00%	50.00%			45.00%	50.00%									65.00%	45.00%	35.00%	72.50%
Acquired in-process research and development	$ 50,000,000	$ 388,000,000	$ 50,000,000	$ 90,000,000											$ 388,000,000