Collaborations (Details)	12 Months Ended									1 Months Ended		12 Months Ended					3 Months Ended	1 Months Ended			1 Months Ended		12 Months Ended	3 Months Ended	12 Months Ended	1 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	11 Months Ended			1 Months Ended
	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Dec. 31, 2010 USD ($)	Dec. 31, 2012 Erbitux [Member] USD ($)	Dec. 31, 2011 Erbitux [Member] USD ($)	Dec. 31, 2010 Erbitux [Member] USD ($)	Dec. 31, 2012 Effient [Member] USD ($)	Dec. 31, 2011 Effient [Member] USD ($)	Dec. 31, 2010 Effient [Member] USD ($)	Aug. 31, 2012 Amylin [Member] USD ($)	Nov. 30, 2011 Amylin [Member] USD ($)	Dec. 31, 2011 Amylin [Member] USD ($)	Dec. 31, 2010 Amylin [Member] USD ($)	Dec. 31, 2012 Exenatide [Member] USD ($)	Dec. 31, 2011 Exenatide [Member] USD ($)	Dec. 31, 2010 Exenatide [Member] USD ($)	Mar. 31, 2011 Boerhringer Ingelheim (BI) [Member] USD ($)	Nov. 30, 2011 Sales NEW [Member] Amylin [Member]	Aug. 31, 2012 Revenue Share [Member] Amylin [Member] USD ($)	Dec. 31, 2012 Revenue Share [Member] Exenatide Once Weekly [Member] USD ($)	Nov. 30, 2011 Secured Note [Member] Amylin [Member] USD ($)	Dec. 31, 2012 Secured Note [Member] Amylin [Member]	Dec. 31, 2012 Profit and Development and Marketing Share [Member] Effient [Member]	Mar. 31, 2010 Prepaid Selling and Marketing Expense [Member] Duloxetine BI [Member] USD ($)	Dec. 31, 2012 Royalty Payments Received [Member] Solanezumab [Member] USD ($)	Dec. 31, 2009 Research and Development Exp [Member] Baricitinib [Member]	Nov. 30, 2011 Milestone Payments [Member] Amylin [Member] USD ($)	Sep. 30, 2011 Milestone Payments [Member] TPG-Axon [Member] USD ($)	Dec. 31, 2012 Milestone Payments [Member] BI compounds [Member] EUR (€)	Dec. 31, 2011 Milestone Payments [Member] BI compounds [Member] USD ($)	Dec. 31, 2012 Milestone Payments [Member] LLY compounds [Member] USD ($)	Dec. 31, 2012 Milestone Payments [Member] LLY optional compound [Member] USD ($)	Dec. 31, 2009 Milestone Payments, Development and Regulatory [Member] Baricitinib [Member] USD ($)	Dec. 31, 2012 Milestone Payments, Development and Regulatory [Member] Baricitinib [Member] USD ($)	Dec. 31, 2010 Milestone Payments, Development and Regulatory [Member] Baricitinib [Member] USD ($)	Dec. 31, 2009 Milestone Payments, Sales-based [Member] Baricitinib [Member] USD ($)	Jun. 30, 2011 Loan Commitment [Member] Exenatide Once Weekly [Member] USD ($)	Dec. 31, 2009 Royalty [Member] Baricitinib [Member]	Dec. 31, 2012 Funding Commitment [Member] Necitumumab [Member]	Dec. 31, 2012 United States [Member] USD ($)	Dec. 31, 2011 United States [Member] USD ($)	Dec. 31, 2010 United States [Member] USD ($)	Nov. 30, 2011 United States [Member] Revenue Share [Member] Amylin [Member]	Nov. 30, 2011 United States [Member] Gross Margin Share [Member] Exenatide [Member]	Nov. 30, 2011 United States [Member] Research and Development and Marketing and Selling Expense [Member] Exenatide [Member]	Nov. 30, 2011 Outside the United States [Member] Sales NEW [Member] Exenatide [Member]	Nov. 30, 2011 Outside the United States [Member] Revenue Share [Member] Amylin [Member]
Sales Revenue, Goods, Net	$ 21,970,400,000	$ 23,604,800,000	$ 22,442,200,000	$ 76,400,000	$ 87,600,000	$ 71,900,000	$ 457,200,000	$ 302,500,000	$ 115,000,000					$ 207,800,000	$ 179,600,000	$ 168,100,000
Collaboration and other revenue	633,000,000	681,700,000	633,800,000	320,600,000	321,600,000	314,200,000								70,100,000	243,100,000	262,500,000
Revenue	22,603,400,000	24,286,500,000	23,076,000,000	397,000,000	409,200,000	386,100,000								277,900,000	422,700,000	430,600,000																								12,313,100,000	12,977,200,000	12,865,600,000
Other Nonoperating Income (Expense)	(41,000,000)	(72,900,000)	128,600,000									0	0	787,800,000
Research and Development Expense	5,278,100,000	5,020,800,000	4,884,200,000
Proceeds from prepayment of revenue-sharing obligation	1,212,100,000	0	0							1,210,000,000
Deferred Revenue, Current																				490,000,000
Collaborative Arrangement, Income Statement Classification and Amounts	261,500,000	219,200,000	174,500,000
Collaborative Arrangement, Rights and Obligations											250,000,000								1,260,000,000					400,000,000	8		150,000,000	70,000,000	300,000,000	478,700,000	300,000,000	525,000,000	515,000,000	50,000,000	49,000,000	150,000,000
Collaborative Arrangement, Rights and Obligations Percent																		15.00%					50.00%			30.00%												20.00%					65.00%	50.00%	50.00%	100.00%	35.00%
Proceeds from Sales of Business, Affiliate and Productive Assets																					1,200,000,000
Debt Instrument, Interest Rate, Stated Percentage																						9.50%
Collaborative Arrangement, Rights and Obligations, Term of Arrangement																																							18 months
Acquired in-process research and development	0	388,000,000	50,000,000														388,000,000
Payments to Fund Long-term Loans to Related Parties																																					$ 165,000,000