This item represents the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. This item includes income or expense related to stock-based compensation based on the investor's grant of stock to employees of an equity method investee.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.12)

-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-Section 45

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 9

-Article 5

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 28

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

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Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

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-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

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-Paragraph 19

-Subparagraph c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Equity Method Investments (Schedule Of Losses On Equity Method Investments) (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended															12 Months Ended					12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Segment, Continuing Operations [Member]	Dec. 31, 2011 Segment, Continuing Operations [Member]	Dec. 31, 2012 Segment, Discontinued Operations [Member]	Dec. 31, 2011 Segment, Discontinued Operations [Member]	Dec. 31, 2012 Janssen AI [Member]	Dec. 31, 2011 Janssen AI [Member]	Dec. 31, 2010 Janssen AI [Member]	Dec. 31, 2012 Janssen AI [Member] Segment, Continuing Operations [Member]	Dec. 31, 2011 Janssen AI [Member] Segment, Continuing Operations [Member]	Dec. 31, 2012 Proteostasis [Member]	Dec. 31, 2011 Proteostasis [Member]	May 31, 2011 Proteostasis [Member]	Dec. 31, 2012 Proteostasis [Member] Segment, Continuing Operations [Member]	Dec. 31, 2011 Proteostasis [Member] Segment, Continuing Operations [Member]	Dec. 31, 2012 Alkermes Plc [Member]	Dec. 31, 2011 Alkermes Plc [Member]	Sep. 16, 2011 Alkermes Plc [Member]	Dec. 31, 2012 Alkermes Plc [Member] Segment, Discontinued Operations [Member]	Dec. 31, 2011 Alkermes Plc [Member] Segment, Discontinued Operations [Member]
Schedule of Equity Method Investments [Line Items]
Carrying amount, beginning balance	$ 675.8	$ 209.0	$ 235.0					$ 130.6	$ 209.0	$ 235.0			$ 17.3		$ 20.0			$ 527.9		$ 528.6
Addition	76.9	548.6						76.9						20.0					528.6
Net loss on equity method investments	(221.8)	(81.1)	(26.0)	(104.5)	(81.1)	(7.2)	(0.7)	(218.5)	(78.4)	(26.0)	(101.2)	(78.4)	(3.3)	(2.7)		(3.3)	(2.7)	7.2	0.7		(7.2)	(0.7)
Disposal of equity method investment	(394.2)																	(394.2)
Impairment of equity method investment	(117.3)			(117.3)				(678.9)			(117.3)
Reclassification to available for sale investment	(126.5)																	(126.5)
Reclass of excess of losses over investment to current liabilities	11.0							11.0
Carrying amount, ending balance	$ 14.0	$ 675.8	$ 209.0						$ 130.6	$ 209.0			$ 14.0	$ 17.3	$ 20.0			$ 528.6	$ 527.9	$ 528.6