Collaboration and License Agreements [Abstract]

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In October 2014, Lexicon entered into a License and Collaboration Agreement with Ipsen Pharma SAS for the development and commercialization of Lexicon's drug candidate telotristat etiprate (LX1032) outside the United States and Japan. This represents the maximum regulatory and commercial launch milestone payments.

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- Definition

In October 2014, Lexicon entered into a License and Collaboration Agreement with Ipsen Pharma SAS for the development and commercialization of Lexicon's drug candidate telotristat ethyl. This represents the milestone payments received under the agreement.

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In October 2014, Lexicon entered into a License and Collaboration Agreement with Ipsen Pharma SAS for the development and commercialization of Lexicon's drug candidate telotristat etiprate (LX1032) outside the United States and Japan. This is the amount of the upfront payment allocated to the committee participation deliverable.

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- Definition

In October 2014, Lexicon entered into a License and Collaboration Agreement with Ipsen Pharma SAS for the development and commercialization of Lexicon's drug candidate telotristat etiprate (LX1032) outside the United States and Japan. This represents the amount of the upfront payment allocated to the development services deliverable.

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No definition available.

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In October 2014, Lexicon entered into a License and Collaboration Agreement with Ipsen Pharma SAS for the development and commercialization of Lexicon's drug candidate telotristat etiprate (LX1032) outside the United States and Japan. This represents the amount of the upfront payment allocated to the license deliverable.

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No definition available.

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In October 2014, Lexicon entered into a License and Collaboration Agreement with Ipsen Pharma SAS for the development and commercialization of Lexicon's drug candidate telotristat ethyl. This represents the total payments received to date under the agreement.

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In October 2014, Lexicon entered into a License and Collaboration Agreement with Ipsen Pharma SAS for the development and commercialization of Lexicon's drug candidate telotristat ethyl outside the United States and Japan. This represents the amount of product sales to Ipsen.

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In November 2015, Lexicon entered into a Collaboration and License Agreement with Sanofi for the worldwide development of Lexicon's diabetes drug candidate satagliflozin. This represents the maximum amount that Lexicon will fund of the planned type 2 diabetes development costs.

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In November 2015, Lexicon entered into a Collaboration and License Agreement with Sanofi for the worldwide development of Lexicon's diabetes drug candidate satagliflozin. This represents the development milestones relating to the achievement of positive results in certain Phase 3 clinical trials in type 2 diabetes patients.

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In November 2015, Lexicon entered into a Collaboration and License Agreement with Sanofi for the worldwide development of Lexicon's diabetes drug candidate satagliflozin. This represents the milestone based on the results of an outcomes study in type 2 diabetes patients the completion of which would likely occur after initial regulatory approval.

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In November 2015, Lexicon entered into a Collaboration and License Agreement with Sanofi for the worldwide development of Lexicon's diabetes drug candidate sotagliflozin. This represents the regulatory milestones relating to the first commercial sale following regulatory approval of sotagliflozin for type 1 and type 2 diabetes in each of the United States and Europe.

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In November 2015, Lexicon entered into a Collaboration and License Agreement with Sanofi for the worldwide development of Lexicon's diabetes drug candidate sotagliflozin. This represents the amount of the upfront payment allocated to the development services deliverable.

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In November 2015, Lexicon entered into a Collaboration and License Agreement with Sanofi for the worldwide development of Lexicon's diabetes drug candidate satagliflozin. This represents the potential sales milestones payments under the agreement.

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Collaboration and License Agreements (Details) € in Millions, $ in Millions	1 Months Ended				3 Months Ended		9 Months Ended		12 Months Ended
	Nov. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Oct. 31, 2014 USD ($)	Oct. 31, 2014 EUR (€)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Collaboration and License Agreements [Abstract]
Sanofi Upfront Payment	$ 300.0
Sanofi Development Milestones	110.0
Sanofi Regulatory Milestones	220.0
Sanofi Outcomes Study Milestone	100.0
Sanofi Sales Milestone Payments	990.0
Sanofi Commercialization Costs Funded by Lexicon Maximum Amount	100.0
Sanofi Revenue Allocated to License Deliverable	126.8
Sanofi Revenue Allocated to Development Deliverable	113.8
Sanofi Revenue Allocated to Funding Deliverable	$ 59.4
Sanofi Revenue Recognized							$ 39.5	$ 52.7
Ipsen Total Payments					$ 30.9		30.9
Ipsen Maximum Regulatory And Commercial Milestones			$ 21.0
Ipsen Maximum Sales Milestones \| €				€ 72
Ipsen Total Upfront Payments		$ 24.5
Ipsen Milestone Payment					$ 5.1	$ 6.4	5.1	6.4
Ipsen Revenue Allocated to License Deliverable									$ 1.4	$ 21.2
Ipsen Revenue Allocated to Development Deliverable			1.7
Ipsen Revenue Allocated to Committee Deliverable			$ 0.1
Ipsen Revenue Recognized							7.9	$ 6.8
Ipsen Product Sales							$ 0.8