Segment Information (Schedule Of Goodwill And Other Intangible Assets By Region) (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]
Total goodwill and other intangible assets	$ 99.0	$ 309.9
United States [Member]
Segment Reporting Information [Line Items]
Total goodwill and other intangible assets	79.4	192.1
Ireland [Member]
Segment Reporting Information [Line Items]
Total goodwill and other intangible assets	10.9	109.1
Rest Of world [Member]
Segment Reporting Information [Line Items]
Total goodwill and other intangible assets	$ 8.7	$ 8.7

Carrying amount as of the balance sheet date, which is the cumulative amount paid and (if applicable) the fair value of any noncontrolling interest in the acquiree, adjusted for any amortization recognized prior to the adoption of any changes in generally accepted accounting principles (as applicable) and for any impairment charges, in excess of the fair value of net assets acquired in one or more business combination transactions. It also includes the net carrying amount as of the balance sheet date of other indefinite-lived and finite-lived intangible assets that are not separately presented on the statement of financial position.

No definition available.

Name:	eln_GoodwillAndOtherIntangibleAssetsNet
Namespace Prefix:	eln_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant