Discontinued Operations (Schedule Of Revenue From Tysabri ROW) (Parenthetical) (Detail) (Elan Corp PLC [Member], Tysabri - ROW [Member])	Dec. 31, 2012
Elan Corp PLC [Member] \| Tysabri - ROW [Member]
Revenue [Line Items]
Share operating income loss percentage	50.00%

The net result of the Company's share of collaboration operating profit for the period after deducting operating expenses from operating revenues.

No definition available.

Name:	eln_ShareOperatingIncomeLossPercentage
Namespace Prefix:	eln_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant