Debt Obligations	9 Months Ended
Sep. 30, 2019
Debt Obligations [Abstract]
Debt Disclosure	Debt Obligations Convertible Debt. In November 2014, Lexicon completed an offering of $87.5 million in aggregate principal amount of its 5.25% Convertible Senior Notes due 2021 (the “Convertible Notes”). The conversion feature did not meet the criteria for bifurcation as required by generally accepted accounting principles and the entire principal amount was recorded as long-term debt on the Company’s condensed consolidated balance sheets. The Convertible Notes are governed by an indenture (the “Indenture”), dated as of November 26, 2014, between the Company and Wells Fargo Bank, N.A., as trustee. The Convertible Notes bear interest at a rate of 5.25% per year, payable semiannually in arrears on June 1 and December 1 of each year, beginning on June 1, 2015. The Convertible Notes mature on December 1, 2021. The Company may not redeem the Convertible Notes prior to the maturity date, and no sinking fund is provided for the Convertible Notes. Holders of the Convertible Notes may convert their Convertible Notes at their option at any time prior to the close of business on the business day immediately preceding the maturity date. Upon conversion, the Company will deliver for each $1,000 principal amount of converted Convertible Notes a number of shares of its common stock equal to the conversion rate, as described in the Indenture. The conversion rate is initially 118.4553 shares of common stock per $1,000 principal amount of Convertible Notes (equivalent to an initial conversion price of $8.442 per share of common stock). The conversion rate is subject to adjustment in some events but will not be adjusted for any accrued and unpaid interest. In addition, following certain corporate events that occur prior to the maturity date, the Company will increase the conversion rate for a holder who elects to convert its Convertible Notes in connection with such a corporate event in certain circumstances. If the Company undergoes a fundamental change, holders may require the Company to repurchase for cash all or any portion of their Convertible Notes at a fundamental change repurchase price equal to 100% of the principal amount of the Convertible Notes to be repurchased, plus accrued and unpaid interest to, but excluding, the fundamental change repurchase date. In connection with the issuance of the Convertible Notes, the Company incurred $3.4 million of debt issuance costs. The debt issuance costs are amortized as interest expense over the expected life of the Convertible Notes using the effective interest method. The Company determined the expected life of the debt was equal to the seven-year term of the Convertible Notes. As of September 30, 2019, the balance of unamortized debt issuance costs was $1.0 million, which offsets long-term debt on the condensed consolidated balance sheets. The fair value of the Convertible Notes was $76.0 million as of September 30, 2019 and was determined using Level 2 inputs based on the indicative pricing published by certain investment banks or trading levels of the Convertible Notes, which are not listed on any securities exchange or quoted on an inter-dealer automated quotation system. Mortgage Loan. In August 2018, a wholly owned subsidiary of Lexicon entered into a term loan and security agreement, refinancing the previously existing mortgage on its facilities in The Woodlands, Texas (the “Property”). The Company recorded the refinancing as a debt extinguishment, with no recognition of gain or loss on the transaction. The loan agreement provides for a $12.9 million mortgage on the Property and has a two-year term with a 10-year amortization. The mortgage loan bears interest at a rate per annum equal to the greater of (a) the 30-day LIBOR rate plus 5.5% and (b) 7.5% and provides for a balloon payment of $10.3 million due in August 2020. Lexicon incurred $0.4 million of debt issuance costs in connection with the mortgage loan, which offsets debt on the condensed consolidated balance sheets and are amortized as interest expense over the two-year term of the loan agreement. As of September 30, 2019, the balance of unamortized debt issuance costs was $0.2 million. The condensed consolidated balance sheet includes mortgage debt of $11.3 million as of September 30, 2019 and is included in current portion of long-term debt. The buildings and land that serve as collateral for the mortgage loan are included in property and equipment at $59.2 million and $2.7 million, respectively, before accumulated depreciation, as of September 30, 2019. The fair value of the loan agreement approximates its carrying value. The fair value of the loan agreement was determined using Level 2 inputs using discounted cash flow analysis, based on the Company’s estimated current incremental borrowing rate. BioPharma Term Loan. In December 2017, Lexicon entered into a loan agreement with BioPharma Credit PLC and BioPharma Credit Investments IV Sub LP under which $150.0 million was funded in December 2017 (the “BioPharma Term Loan”). The BioPharma Term Loan matures in December 2022, bears interest at 9% per year, subject to additional interest if an event of default occurs and is continuing, and is payable quarterly. The BioPharma Term Loan is subject to mandatory prepayment provisions that require prepayment upon a change of control or receipt of proceeds from certain non-ordinary course transfers of assets. The Company may prepay the BioPharma Term Loan in whole at its option at any time. Any prepayment of the BioPharma Term Loan is subject to customary make-whole premiums and prepayment premiums. The Company’s obligations under the BioPharma Term Loan are secured by a first lien security interest in substantially all of the assets of the Company and certain of its subsidiaries, other than its facilities in The Woodlands, Texas. The loan agreement contains certain customary representations and warranties, affirmative and negative covenants and events of default applicable to the Company and certain of its subsidiaries, including among other things, covenants restricting dispositions, fundamental changes in the business, mergers or acquisitions, indebtedness, encumbrances, distributions, investments, transactions with affiliates and subordinated debt. If an event of default occurs and is continuing, all amounts outstanding under the BioPharma Term Loan may be declared immediately due and payable. In connection with the BioPharma Term Loan, the Company incurred $4.1 million of debt issuance costs. The debt issuance costs are amortized as interest expense over the expected life of the BioPharma Term Loan using the effective interest method. The Company determined the expected life of the debt was equal to the five-year term of the BioPharma Term Loan. As of September 30, 2019, the balance of unamortized debt issuance costs was $2.6 million, which offsets long-term debt on the condensed consolidated balance sheets. The fair value of the BioPharma Term Loan approximates its carrying value. The fair value of the BioPharma Term Loan was determined using Level 2 inputs using discounted cash flow analysis, based on the Company’s estimated current incremental borrowing rate.

Debt Obligations

Convertible Debt. In November 2014, Lexicon completed an offering of $87.5 million in aggregate principal amount of its 5.25% Convertible Senior Notes due 2021 (the “Convertible Notes”). The conversion feature did not meet the criteria for bifurcation as required by generally accepted accounting principles and the entire principal amount was recorded as long-term debt on the Company’s condensed consolidated balance sheets.

The Convertible Notes are governed by an indenture (the “Indenture”), dated as of November 26, 2014, between the Company and Wells Fargo Bank, N.A., as trustee. The Convertible Notes bear interest at a rate of 5.25% per year, payable semiannually in arrears on June 1 and December 1 of each year, beginning on June 1, 2015. The Convertible Notes mature on December 1, 2021. The Company may not redeem the Convertible Notes prior to the maturity date, and no sinking fund is provided for the Convertible Notes.

Holders of the Convertible Notes may convert their Convertible Notes at their option at any time prior to the close of business on the business day immediately preceding the maturity date. Upon conversion, the Company will deliver for each $1,000 principal amount of converted Convertible Notes a number of shares of its common stock equal to the conversion rate, as described in the Indenture. The conversion rate is initially 118.4553 shares of common stock per $1,000 principal amount of Convertible Notes (equivalent to an initial conversion price of $8.442 per share of common stock). The conversion rate is subject to adjustment in some events but will not be adjusted for any accrued and unpaid interest. In addition, following certain corporate events that occur prior to the maturity date, the Company will increase the conversion rate for a holder who elects to convert its Convertible Notes in connection with such a corporate event in certain circumstances.

If the Company undergoes a fundamental change, holders may require the Company to repurchase for cash all or any portion of their Convertible Notes at a fundamental change repurchase price equal to 100% of the principal amount of the Convertible Notes to be repurchased, plus accrued and unpaid interest to, but excluding, the fundamental change repurchase date.

In connection with the issuance of the Convertible Notes, the Company incurred $3.4 million of debt issuance costs. The debt issuance costs are amortized as interest expense over the expected life of the Convertible Notes using the effective interest method. The Company determined the expected life of the debt was equal to the seven-year term of the Convertible Notes. As of September 30, 2019, the balance of unamortized debt issuance costs was $1.0 million, which offsets long-term debt on the condensed consolidated balance sheets.

The fair value of the Convertible Notes was $76.0 million as of September 30, 2019 and was determined using Level 2 inputs based on the indicative pricing published by certain investment banks or trading levels of the Convertible Notes, which are not listed on any securities exchange or quoted on an inter-dealer automated quotation system.

Mortgage Loan. In August 2018, a wholly owned subsidiary of Lexicon entered into a term loan and security agreement, refinancing the previously existing mortgage on its facilities in The Woodlands, Texas (the “Property”). The Company recorded the refinancing as a debt extinguishment, with no recognition of gain or loss on the transaction. The loan agreement provides for a $12.9 million mortgage on the Property and has a two-year term with a 10-year amortization. The mortgage loan bears interest at a rate per annum equal to the greater of (a) the 30-day LIBOR rate plus 5.5% and (b) 7.5% and provides for a balloon payment of $10.3 million due in August 2020. Lexicon incurred $0.4 million of debt issuance costs in connection with the mortgage loan, which offsets debt on the condensed consolidated balance sheets and are amortized as interest expense over the two-year term of the loan agreement. As of September 30, 2019, the balance of unamortized debt issuance costs was $0.2 million. The condensed consolidated balance sheet includes mortgage debt of $11.3 million as of September 30, 2019 and is included in current portion of long-term debt. The buildings and land that serve as collateral for the mortgage loan are included in property and equipment at $59.2 million and $2.7 million, respectively, before accumulated depreciation, as of September 30, 2019. The fair value of the loan agreement approximates its carrying value. The fair value of the loan agreement was determined using Level 2 inputs using discounted cash flow analysis, based on the Company’s estimated current incremental borrowing rate.

BioPharma Term Loan. In December 2017, Lexicon entered into a loan agreement with BioPharma Credit PLC and BioPharma Credit Investments IV Sub LP under which $150.0 million was funded in December 2017 (the “BioPharma Term Loan”). The BioPharma Term Loan matures in December 2022, bears interest at 9% per year, subject to additional interest if an event of default occurs and is continuing, and is payable quarterly.

The BioPharma Term Loan is subject to mandatory prepayment provisions that require prepayment upon a change of control or receipt of proceeds from certain non-ordinary course transfers of assets. The Company may prepay the BioPharma Term Loan in whole at its option at any time. Any prepayment of the BioPharma Term Loan is subject to customary make-whole premiums and prepayment premiums.

The Company’s obligations under the BioPharma Term Loan are secured by a first lien security interest in substantially all of the assets of the Company and certain of its subsidiaries, other than its facilities in The Woodlands, Texas. The loan agreement contains certain customary representations and warranties, affirmative and negative covenants and events of default applicable to the Company and certain of its subsidiaries, including among other things, covenants restricting dispositions, fundamental changes in the business, mergers or acquisitions, indebtedness, encumbrances, distributions, investments, transactions with affiliates and subordinated debt. If an event of default occurs and is continuing, all amounts outstanding under the BioPharma Term Loan may be declared immediately due and payable.

In connection with the BioPharma Term Loan, the Company incurred $4.1 million of debt issuance costs. The debt issuance costs are amortized as interest expense over the expected life of the BioPharma Term Loan using the effective interest method. The Company determined the expected life of the debt was equal to the five-year term of the BioPharma Term Loan. As of September 30, 2019, the balance of unamortized debt issuance costs was $2.6 million, which offsets long-term debt on the condensed consolidated balance sheets.

The fair value of the BioPharma Term Loan approximates its carrying value. The fair value of the BioPharma Term Loan was determined using Level 2 inputs using discounted cash flow analysis, based on the Company’s estimated current incremental borrowing rate.