Property and Equipment (Details 2) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Buildings Reclassified To Held For Sale	$ 59.1lxrx_BuildingsReclassifiedToHeldForSale
Land Reclassified To Held For Sale	2.7lxrx_LandReclassifiedToHeldForSale
Accumulated Depreciation Reclassified To Held For Sale	$ 38.0

Buildings accumulated depreciation that has been reclassified to assets held for sale.

No definition available.

Name:	lxrx_AccumulatedDepreciationReclassifiedToHeldForSale
Namespace Prefix:	lxrx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant