Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2021	May 04, 2021
Cover [Abstract]
Document Type	10-Q
Document Fiscal Period Focus	Q1
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Amendment Flag	false
Document Fiscal Year Focus	2021
Current Fiscal Year End Date	--12-31
Entity File Number	000-30111
Entity Registrant Name	Lexicon Pharmaceuticals, Inc.
Entity Central Index Key	0001062822
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	76-0474169
Entity Address, Address Line One	8800 Technology Forest Place
Entity Address, City or Town	The Woodlands
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77381
City Area Code	281
Local Phone Number	863-3000
Title of 12(b) Security	Common Stock, par value $0.001
Trading Symbol	LXRX
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		144,387,799