Recent Accounting Pronouncements Level 1 (Notes)	6 Months Ended
Jun. 30, 2017
Recent Accounting Pronouncements [Abstract]
New Accounting Pronouncements, Policy	Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09, “Revenue from Contracts with Customers”, which amends FASB ASC Topic 606. ASU 2014-09 provides a single, comprehensive revenue recognition model for all contracts with customers. This standard contains principles for the determination of the measurement of revenue and the timing of when such revenue is recognized. Revenue recognition will reflect the transfer of goods or services to customers at an amount that is expected to be earned in exchange for those goods or services. In August 2015, the FASB issued ASU No. 2015-14, “Revenue from Contracts with Customers: Deferral of Effective Date”, which defers the effective date of ASU 2014-09 by one year. ASU 2014-09 is now effective for annual periods after December 15, 2017 including interim periods within that reporting period. Early application is permitted only for annual periods beginning after December 15, 2016, including interim periods within that reporting period. Management plans to adopt ASU 2014-09 using the modified retrospective method. The Company does not expect that ASU 2014-09 will have a material impact on the recognition of revenue from product sales. Management is still in the process of evaluating the effect that this guidance will have on revenue recognition from the collaboration agreements. In January 2016, the FASB issued ASU No. 2016-01, “Recognition and Measurement of Financial Assets and Financial Liabilities.” ASU 2016-01 requires that most equity investments be measured at fair value, with subsequent changes in fair value recognized in net income. The pronouncement also impacts financial liabilities under the fair value option and the presentation and disclosure requirements for financial instruments. This pronouncement is effective for fiscal years, and interim periods within those years, beginning after December 15, 2017, and early adoption is not permitted. Management does not expect the adoption of this pronouncement to have a material impact on Lexicon’s consolidated financial statements. In February 2016, the FASB issued ASU No. 2016-02, “Leases.” ASU 2016-02 requires companies that lease assets to recognize a right-of-use asset and a lease liability, initially measured at the present value of the lease payments, in its balance sheet. The pronouncement will also require additional disclosures about the amount, timing and uncertainty of cash flows arising from leases. This pronouncement is effective for fiscal years, and interim periods within those years, beginning after December 15, 2018, and early adoption is permitted. Management is currently evaluating the impact of this pronouncement on Lexicon’s consolidated financial statements. In March 2016, the FASB issued ASU No. 2016-09, “Stock Compensation,” which is intended to simplify several aspects of the accounting for share-based payment award transactions. The Company adopted this pronouncement effective January 1, 2017. Upon adoption, the Company recognized approximately $6.1 million of accumulated excess tax benefits as deferred tax assets that under the previous guidance could not be recognized until the benefits were realized through a reduction in cash taxes paid. This part of the guidance is applied using a modified retrospective method with a cumulative-effect adjustment to the accumulated deficit for the excess tax benefits not previously recognized. However, given the full valuation allowance placed on the additional $6.1 million of deferred tax assets, the recognition of this provision of ASU 2016-09 had no impact to the Company’s accumulated deficit as of January 1, 2017. Additionally, the Company recorded an adjustment to accumulated deficit of $2.0 million as a result of making an entity-wide accounting policy election to account for forfeitures of share-based payment awards as they occur instead of estimating the number of awards that are expected to vest.

Recent Accounting Pronouncements

In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09, “Revenue from Contracts with Customers”, which amends FASB ASC Topic 606. ASU 2014-09 provides a single, comprehensive revenue recognition model for all contracts with customers. This standard contains principles for the determination of the measurement of revenue and the timing of when such revenue is recognized. Revenue recognition will reflect the transfer of goods or services to customers at an amount that is expected to be earned in exchange for those goods or services. In August 2015, the FASB issued ASU No. 2015-14, “Revenue from Contracts with Customers: Deferral of Effective Date”, which defers the effective date of ASU 2014-09 by one year. ASU 2014-09 is now effective for annual periods after December 15, 2017 including interim periods within that reporting period. Early application is permitted only for annual periods beginning after December 15, 2016, including interim periods within that reporting period. Management plans to adopt ASU 2014-09 using the modified retrospective method. The Company does not expect that ASU 2014-09 will have a material impact on the recognition of revenue from product sales. Management is still in the process of evaluating the effect that this guidance will have on revenue recognition from the collaboration agreements.

In January 2016, the FASB issued ASU No. 2016-01, “Recognition and Measurement of Financial Assets and Financial Liabilities.” ASU 2016-01 requires that most equity investments be measured at fair value, with subsequent changes in fair value recognized in net income. The pronouncement also impacts financial liabilities under the fair value option and the presentation and disclosure requirements for financial instruments. This pronouncement is effective for fiscal years, and interim periods within those years, beginning after December 15, 2017, and early adoption is not permitted. Management does not expect the adoption of this pronouncement to have a material impact on Lexicon’s consolidated financial statements.

In February 2016, the FASB issued ASU No. 2016-02, “Leases.” ASU 2016-02 requires companies that lease assets to recognize a right-of-use asset and a lease liability, initially measured at the present value of the lease payments, in its balance sheet. The pronouncement will also require additional disclosures about the amount, timing and uncertainty of cash flows arising from leases. This pronouncement is effective for fiscal years, and interim periods within those years, beginning after December 15, 2018, and early adoption is permitted. Management is currently evaluating the impact of this pronouncement on Lexicon’s consolidated financial statements.

In March 2016, the FASB issued ASU No. 2016-09, “Stock Compensation,” which is intended to simplify several aspects of the accounting for share-based payment award transactions. The Company adopted this pronouncement effective January 1, 2017. Upon adoption, the Company recognized approximately $6.1 million of accumulated excess tax benefits as deferred tax assets that under the previous guidance could not be recognized until the benefits were realized through a reduction in cash taxes paid. This part of the guidance is applied using a modified retrospective method with a cumulative-effect adjustment to the accumulated deficit for the excess tax benefits not previously recognized. However, given the full valuation allowance placed on the additional $6.1 million of deferred tax assets, the recognition of this provision of ASU 2016-09 had no impact to the Company’s accumulated deficit as of January 1, 2017. Additionally, the Company recorded an adjustment to accumulated deficit of $2.0 million as a result of making an entity-wide accounting policy election to account for forfeitures of share-based payment awards as they occur instead of estimating the number of awards that are expected to vest.