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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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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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 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 payments to date for reimbursement for clinical materials transferred to Sanofi.

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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 potential development and regulatory milestone payments under the agreement.

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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 sotagliflozin. This represents the amount of the upfront payment allocated to the funding 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 sotagliflozin. This represents the amount of the upfront payment allocated to the license 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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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 total payments received to date under the agreement.

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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 expense that was incurred under a clinical development funding agreement as a result of entering into the Sanofi transaction.

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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
	Aug. 31, 2016 USD ($)	Nov. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Oct. 31, 2014 USD ($)	Oct. 31, 2014 EUR (€)	Sep. 30, 2016 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Collaboration and License Agreements [Abstract]
Sanofi Total Payments						$ 301.8	$ 301.8
Sanofi Upfront Payment		$ 300.0
Sanofi Clinical Materials Payment						1.8	1.8
Sanofi Development and Regulatory Milestone Payments		430.0
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							52.7
Sanofi Triggered Expense						4.5
Ipsen Total Payments						$ 30.9	30.9
Ipsen Maximum Regulatory And Commercial Milestones				$ 27.0
Ipsen Maximum Sales Milestones \| €					€ 72
Ipsen Total Upfront Payments			$ 24.5
Ipsen Milestone Payment	$ 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							$ 6.8	$ 2.3