Arrangements with Symphony Icon, Inc.	12 Months Ended
Dec. 31, 2016
Arrangements with Symphony Icon Inc [Abstract]
Arrangements with Symphony Icon, Inc.	Arrangements with Symphony Icon, Inc. On June 15, 2007, Lexicon entered into a series of related agreements providing for the financing of the clinical development of certain of its drug candidates, including XERMELO, along with any other pharmaceutical compositions modulating the same targets as those drug candidates (the “Programs”). The agreements included a Novated and Restated Technology License Agreement pursuant to which the Company licensed to Symphony Icon, a then wholly-owned subsidiary of Symphony Icon Holdings LLC (“Holdings”), the Company’s intellectual property rights related to the Programs. Holdings contributed $45 million to Symphony Icon in order to fund the clinical development of the Programs. Under a Share Purchase Agreement, dated June 15, 2007, between the Company and Holdings, the Company issued and sold to Holdings 1,092,946 shares of its common stock on June 15, 2007 in exchange for $15 million and an exclusive purchase option (the “Purchase Option”) that gave the Company the right to acquire all of the equity of Symphony Icon, thereby allowing the Company to reacquire all of the Programs. On July 30, 2010, Lexicon entered into an Amended and Restated Purchase Option Agreement with Symphony Icon and Holdings and simultaneously exercised the Purchase Option, thereby reacquiring the Programs. Pursuant to the amended terms of the Purchase Option, Lexicon paid Holdings $10 million on July 30, 2010 and issued 1,891,074 shares of common stock to designees of Holdings on July 30, 2012 in satisfaction of an additional $35 million base payment obligation. Lexicon also agreed to make up to $45 million in additional contingent payments, which would consist of 50% of any consideration Lexicon receives pursuant to any licensing transaction (a “Licensing Transaction”) under which Lexicon grants a third party rights to commercialize XERMELO or other pharmaceutical compositions modulating the same target as XERMELO (the “LG103 Programs”), subject to certain exceptions. The contingent payments would be due if and when Lexicon received such consideration from a Licensing Transaction. In the event Lexicon received regulatory approval in the United States for the marketing and sale of any product resulting from the LG103 Programs prior to entering into a Licensing Transaction for the commercialization of such product in the United States, in lieu of any contingent payment from such a Licensing Transaction, Lexicon would pay Holdings the sum of $15 million and the amount of certain expenses Lexicon incurred after its exercise of the Purchase Option which were attributable to the development of such product, reduced by up to 50% of such sum on account of any contingent payments paid prior to such United States regulatory approval attributable to any such Licensing Transaction outside of the United States with respect to such product. In the event Lexicon made any such payment upon United States regulatory approval, Lexicon would have no obligation to make subsequent contingent payments attributable to any such Licensing Transactions for the commercialization of such product outside the United States until the proceeds of such Licensing Transactions exceed 50% of the payment made as a result of such United States regulatory approval. The contingent payments were payable in cash or a combination of cash and common stock, in Lexicon’s discretion, provided that no more than 50% of any contingent payment would be paid in common stock. In December 2014, Lexicon paid $5.8 million in cash and issued 666,111 shares of common stock to designees of Holdings in satisfaction of a $11.5 million contingent payment obligation as a result of receiving an upfront payment pursuant to Lexicon’s license and collaboration agreement with Ipsen. In April 2015, Lexicon paid $0.75 million in cash to Holdings in satisfaction of its contingent payment obligation as a result of receiving an additional upfront payment from Ipsen in March 2015. In September 2016, Lexicon paid $3.2 million in cash to Holdings in satisfaction of its contingent payment obligation as a result of receiving a milestone payment from Ipsen in August 2016 (see Note 16, Collaboration and License Agreements). In September 2016, Lexicon entered into an amendment (the “Amendment”) to the Purchase Option Agreement with Holdings and Symphony Icon pursuant to which Lexicon agreed to pay Holdings $21.0 million upon Lexicon’s receipt of regulatory approval in the United States for the marketing and sale of XERMELO, such buyout amount to be in lieu of any remaining payments which may be or become payable to Holdings under the Purchase Option Agreement. The buyout amount may be paid in cash or a combination of cash and common stock, in Lexicon’s discretion, provided that no more than 50% of any contingent payment will be paid in common stock. Had Lexicon received regulatory approval for XERMELO prior to December 31, 2016, the Company would have increased the fair value of the Symphony Icon purchase liability on its consolidated balance sheet as of December 31, 2016 by $2.1 million, with a corresponding increase to the increase in fair value of Symphony Icon, Inc. purchase liability on its consolidated statement of comprehensive loss for the year ended December 31, 2016. The increase in the contingent purchase liability reflects a greater likelihood that the Company will pay Holdings the buyout amount under the Amendment. Lexicon accounted for the exercise of the Purchase Option and acquisition of Symphony Icon as a business combination. In connection with its acquisition of Symphony Icon, Lexicon paid $10.0 million in cash, and has also agreed to pay Holdings additional base and contingent payments as discussed above. The fair value of the base and contingent consideration payments was $45.6 million and was estimated by applying a probability-based income approach utilizing an appropriate discount rate. This estimation was based on significant inputs that are not observable in the market, referred to as Level 3 inputs. Key assumptions include: (1) a discount rate of 14% for the base payments; (2) a discount rate of 18% for the contingent payments; and (3) a probability adjusted contingency. No discount rate was used in the valuation of the contingent consideration liability as of December 31, 2016 as the expected buyout is short-term in nature. As programs progress, the probability adjusted contingency is adjusted as necessary. Subsequent changes in the fair value of the Symphony Icon purchase consideration liability are recorded as increase or decrease in fair value of Symphony Icon purchase liability expense in the accompanying consolidated statements of comprehensive loss. The fair value of the Symphony Icon purchase consideration liability decreased by $0.7 million during the year ended December 31, 2016, increased by $5.9 million during the year ended December 31, 2015, and increased by $1.4 million during the year ended December 31, 2014. In August 2015, Lexicon announced that the pivotal TELESTAR Phase 3 clinical trial met its primary endpoint, showing the benefit of oral XERMELO in treating cancer patients with carcinoid syndrome that is not adequately controlled by the current standard of care. The increase in the contingent purchase liability during the year ended December 31, 2015 reflects a greater likelihood following the top-line results from the TELESTAR trial that the Company will achieve certain milestones with XERMELO, such as regulatory approval, that would trigger payments under the contingent liability.

Arrangements with Symphony Icon, Inc.

On June 15, 2007, Lexicon entered into a series of related agreements providing for the financing of the clinical development of certain of its drug candidates, including XERMELO, along with any other pharmaceutical compositions modulating the same targets as those drug candidates (the “Programs”). The agreements included a Novated and Restated Technology License Agreement pursuant to which the Company licensed to Symphony Icon, a then wholly-owned subsidiary of Symphony Icon Holdings LLC (“Holdings”), the Company’s intellectual property rights related to the Programs. Holdings contributed $45 million to Symphony Icon in order to fund the clinical development of the Programs.

Under a Share Purchase Agreement, dated June 15, 2007, between the Company and Holdings, the Company issued and sold to Holdings 1,092,946 shares of its common stock on June 15, 2007 in exchange for $15 million and an exclusive purchase option (the “Purchase Option”) that gave the Company the right to acquire all of the equity of Symphony Icon, thereby allowing the Company to reacquire all of the Programs. On July 30, 2010, Lexicon entered into an Amended and Restated Purchase Option Agreement with Symphony Icon and Holdings and simultaneously exercised the Purchase Option, thereby reacquiring the Programs. Pursuant to the amended terms of the Purchase Option, Lexicon paid Holdings $10 million on July 30, 2010 and issued 1,891,074 shares of common stock to designees of Holdings on July 30, 2012 in satisfaction of an additional $35 million base payment obligation.

Lexicon also agreed to make up to $45 million in additional contingent payments, which would consist of 50% of any consideration Lexicon receives pursuant to any licensing transaction (a “Licensing Transaction”) under which Lexicon grants a third party rights to commercialize XERMELO or other pharmaceutical compositions modulating the same target as XERMELO (the “LG103 Programs”), subject to certain exceptions. The contingent payments would be due if and when Lexicon received such consideration from a Licensing Transaction. In the event Lexicon received regulatory approval in the United States for the marketing and sale of any product resulting from the LG103 Programs prior to entering into a Licensing Transaction for the commercialization of such product in the United States, in lieu of any contingent payment from such a Licensing Transaction, Lexicon would pay Holdings the sum of $15 million and the amount of certain expenses Lexicon incurred after its exercise of the Purchase Option which were attributable to the development of such product, reduced by up to 50% of such sum on account of any contingent payments paid prior to such United States regulatory approval attributable to any such Licensing Transaction outside of the United States with respect to such product. In the event Lexicon made any such payment upon United States regulatory approval, Lexicon would have no obligation to make subsequent contingent payments attributable to any such Licensing Transactions for the commercialization of such product outside the United States until the proceeds of such Licensing Transactions exceed 50% of the payment made as a result of such United States regulatory approval. The contingent payments were payable in cash or a combination of cash and common stock, in Lexicon’s discretion, provided that no more than 50% of any contingent payment would be paid in common stock. In December 2014, Lexicon paid $5.8 million in cash and issued 666,111 shares of common stock to designees of Holdings in satisfaction of a $11.5 million contingent payment obligation as a result of receiving an upfront payment pursuant to Lexicon’s license and collaboration agreement with Ipsen. In April 2015, Lexicon paid $0.75 million in cash to Holdings in satisfaction of its contingent payment obligation as a result of receiving an additional upfront payment from Ipsen in March 2015. In September 2016, Lexicon paid $3.2 million in cash to Holdings in satisfaction of its contingent payment obligation as a result of receiving a milestone payment from Ipsen in August 2016 (see Note 16, Collaboration and License Agreements).

In September 2016, Lexicon entered into an amendment (the “Amendment”) to the Purchase Option Agreement with Holdings and Symphony Icon pursuant to which Lexicon agreed to pay Holdings $21.0 million upon Lexicon’s receipt of regulatory approval in the United States for the marketing and sale of XERMELO, such buyout amount to be in lieu of any remaining payments which may be or become payable to Holdings under the Purchase Option Agreement. The buyout amount may be paid in cash or a combination of cash and common stock, in Lexicon’s discretion, provided that no more than 50% of any contingent payment will be paid in common stock. Had Lexicon received regulatory approval for XERMELO prior to December 31, 2016, the Company would have increased the fair value of the Symphony Icon purchase liability on its consolidated balance sheet as of December 31, 2016 by $2.1 million, with a corresponding increase to the increase in fair value of Symphony Icon, Inc. purchase liability on its consolidated statement of comprehensive loss for the year ended December 31, 2016. The increase in the contingent purchase liability reflects a greater likelihood that the Company will pay Holdings the buyout amount under the Amendment.

Lexicon accounted for the exercise of the Purchase Option and acquisition of Symphony Icon as a business combination. In connection with its acquisition of Symphony Icon, Lexicon paid $10.0 million in cash, and has also agreed to pay Holdings additional base and contingent payments as discussed above. The fair value of the base and contingent consideration payments was $45.6 million and was estimated by applying a probability-based income approach utilizing an appropriate discount rate. This estimation was based on significant inputs that are not observable in the market, referred to as Level 3 inputs. Key assumptions include: (1) a discount rate of 14% for the base payments; (2) a discount rate of 18% for the contingent payments; and (3) a probability adjusted contingency. No discount rate was used in the valuation of the contingent consideration liability as of December 31, 2016 as the expected buyout is short-term in nature. As programs progress, the probability adjusted contingency is adjusted as necessary. Subsequent changes in the fair value of the Symphony Icon purchase consideration liability are recorded as increase or decrease in fair value of Symphony Icon purchase liability expense in the accompanying consolidated statements of comprehensive loss. The fair value of the Symphony Icon purchase consideration liability decreased by $0.7 million during the year ended December 31, 2016, increased by $5.9 million during the year ended December 31, 2015, and increased by $1.4 million during the year ended December 31, 2014. In August 2015, Lexicon announced that the pivotal TELESTAR Phase 3 clinical trial met its primary endpoint, showing the benefit of oral XERMELO in treating cancer patients with carcinoid syndrome that is not adequately controlled by the current standard of care. The increase in the contingent purchase liability during the year ended December 31, 2015 reflects a greater likelihood following the top-line results from the TELESTAR trial that the Company will achieve certain milestones with XERMELO, such as regulatory approval, that would trigger payments under the contingent liability.