Collaborations (Details)	1 Months Ended	3 Months Ended												1 Months Ended		10 Months Ended	1 Months Ended					1 Months Ended			3 Months Ended	12 Months Ended		3 Months Ended	12 Months Ended	1 Months Ended	3 Months Ended	1 Months Ended	6 Months Ended	1 Months Ended		6 Months Ended	1 Months Ended	3 Months Ended	1 Months Ended
	Aug. 31, 2012 USD ($)	Mar. 31, 2014 USD ($)	Mar. 31, 2013 USD ($)	Mar. 31, 2014 Erbitux [Member] USD ($)	Mar. 31, 2013 Erbitux [Member] USD ($)	Mar. 31, 2014 Effient [Member] USD ($)	Mar. 31, 2013 Effient [Member] USD ($)	Mar. 31, 2014 Amylin [Member] USD ($)	Mar. 31, 2013 Amylin [Member] USD ($)	Mar. 31, 2014 Exenatide [Member] USD ($)	Mar. 31, 2013 Exenatide [Member] USD ($)	Mar. 31, 2014 Boerhringer Ingelheim (BI) [Member] USD ($)	Mar. 31, 2013 Boerhringer Ingelheim (BI) [Member] USD ($)	Oct. 31, 2013 Tanezumab [Member] USD ($)	Nov. 30, 2011 Sales [Member] Amylin [Member]	Oct. 31, 2011 Sales [Member] Outside the United States [Member] Exenatide [Member]	Aug. 31, 2012 Revenue Share [Member] Amylin [Member] USD ($)	Nov. 30, 2011 Revenue Share [Member] Amylin [Member] USD ($)	Nov. 30, 2011 Revenue Share [Member] United States [Member] Amylin [Member]	Nov. 30, 2011 Revenue Share [Member] Outside the United States [Member] Amylin [Member]	Nov. 30, 2011 Secured Note [Member] Amylin [Member]	Jun. 30, 2001 Profit and Development and Marketing Share [Member] Effient [Member]	Dec. 31, 2009 Research and Development Exp [Member] Baricitinib [Member]	Nov. 30, 2011 Milestone Payments, Development and Regulatory [Member] Amylin [Member] USD ($)	Mar. 31, 2011 Milestone Payments, Development and Regulatory [Member] BI compounds [Member] EUR (€)	Dec. 31, 2013 Milestone Payments, Development and Regulatory [Member] BI compounds [Member] USD ($)	Dec. 31, 2011 Milestone Payments, Development and Regulatory [Member] BI compounds [Member] USD ($)	Mar. 31, 2011 Milestone Payments, Development and Regulatory [Member] LLY compounds [Member] USD ($)	Dec. 31, 2013 Milestone Payments, Development and Regulatory [Member] LLY compounds [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 ($)	Oct. 31, 2013 Milestone Payments, Development and Regulatory [Member] Tanezumab [Member] USD ($)	Jun. 30, 2011 Milestone Payments, Sales-based [Member] TPG-Axon [Member] USD ($)	Dec. 31, 2009 Milestone Payments, Sales-based [Member] Baricitinib [Member] USD ($)	Oct. 31, 2013 Milestone Payments, Sales-based [Member] Tanezumab [Member] USD ($)	Jun. 30, 2011 Royalty Agreement Terms [Member] Solanezumab [Member]	Dec. 31, 2009 Royalty Agreement Terms [Member] Baricitinib [Member]	Jun. 30, 2011 Loan Commitment [Member] Exenatide Once Weekly [Member] USD ($)	Nov. 30, 2011 Upfront Payment [Member] Amylin [Member] USD ($)
Net product sales				$ 13,200,000	$ 25,300,000	$ 119,300,000	$ 115,900,000			$ 7,600,000	$ 64,100,000
Collaboration and other revenue		181,200,000	153,500,000	77,700,000	69,600,000							76,900,000	42,600,000
Revenue		4,683,100,000	5,602,000,000	90,900,000	94,900,000
Income related to the termination of the exenatide collaboratio		0	495,400,000					0	495,400,000
Research and development		1,109,300,000	1,348,100,000
Collaborative Arrangement, Income Statement Classification and Amounts		48,000,000	45,200,000
Collaborative Arrangement, Rights and Obligations, Terms																	1,260,000,000	1,200,000,000						150,000,000	(225,000,000)	(97,200,000)	(478,700,000)	(250,000,000)	(50,000,000)	(415,000,000)	(50,000,000)	(350,000,000)	(70,000,000)	(150,000,000)	(1,230,000,000)			(165,000,000)	250,000,000
Collaborative Arrangement, Rights and Obligations, Terms of Arrangement, Period																																				10 years
Debt Instrument, Interest Rate, Stated Percentage																					9.50%
Collaborative Arrangement, Rights and Obligations Percent															15.00%	100.00%			65.00%	35.00%		50.00%	30.00%														20.00%
Proceeds from prepayment of revenue-sharing obligation	1,210,000,000
Acquired in-process research and development														200,000,000
Amortization of Intangible Assets		$ 131,900,000	$ 146,100,000