Recent Accounting Pronouncements (Details) - USD ($) $ in Millions	Jan. 01, 2018	Jan. 01, 2017
Recent Accounting Pronouncements [Abstract]
Adjustment to Accumulated Deficit to ASC606	$ 14.2
Accumulated Excess Tax Benefits Recognized as Deferred Tax Assets		$ 6.1
Adjustment to Accumulated Deficit		$ 2.0

Lexicon will adopt ASU 2016-09, "Stock Compensation." This represents the adjustment to accumulated deficit as a result of making an entity-wide accounting policy election to account for forfeitures of share-based payment awards as they occur instead of estimating the number of awards that are expected to vest.

No definition available.

Name:	lxrx_AdjustmenttoAccumulatedDeficit
Namespace Prefix:	lxrx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant