Arrangements with Symphony Icon Inc [Abstract]

No definition available.

Name:	lxrx_ArrangementsWithSymphonyIconIncAbstract
Namespace Prefix:	lxrx_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

This item represents the change in fair value of the Symphony Icon, Inc. purchase liability. In connection with the acquisition of Symphony Icon, Lexicon made an initial estimate of the fair value of the liability for the associated based and contingent payments. Changes in this liability, based on the development of the programs and the time until such payments are expected to be made, are recorded in Lexicon's consolidated statements of operations.

+ References

No definition available.

+ Details

Name:	lxrx_ChangeInFairValueOfSymphonyIconIncPurchaseLiability
Namespace Prefix:	lxrx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

On June 15, 2007, Symphony Icon Holdings LLC contributed $45 million to Symphony Icon in order to fund the clinical development of the Programs.

+ References

No definition available.

+ Details

Name:	lxrx_HoldingsContributionToIcon
Namespace Prefix:	lxrx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

+ References

No definition available.

+ Details

Name:	lxrx_LexiconPaidHoldingsCash
Namespace Prefix:	lxrx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

On June 15, 2007, Lexicon issued and sold to Symphony Icon Holdings LLC 7,650,622 shares of its common stock in exchange for $15 million and an exclusive purchase option that gave Lexicon the right to acquire all of the equity of Symphony Icon, thereby allowing the Company to reacquire all of the Programs.

+ References

No definition available.

+ Details

Name:	lxrx_LexiconReceivedCashFromHoldings
Namespace Prefix:	lxrx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

+ References

No definition available.

+ Details

Name:	lxrx_LexiconSoldSharesToHoldings
Namespace Prefix:	lxrx_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

In connection with its acquisition of Symphony Icon, Lexicon paid $10 million in cash, and also agreed to pay Holdings additional base and contingent payments. The fair value of the base and contingent consideration payments was $45.6 million at the date of acquisition and was estimated by applying a probability-based income approach utilizing an appropriate discount rate. This represents the acquisition date fair value.

+ References

No definition available.

+ Details

Name:	lxrx_SymphonFairValueOfBaseAndContingentPayments
Namespace Prefix:	lxrx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

In July 2010, Lexicon entered into an Amended and Restated Purchase Option Agreement with Symphony Icon and Holdings. In September 2016, Lexicon entered into an amendment to this agreement. This represents the buyout amount that Lexicon will pay Holdings in the event Lexicon receives regulatory approval in the U.S. for the marketing and sale of telotristat ethyl, such buyout amount to be in lieu of any remaining payments which may be or become payable to Holdings under the Purchase Option Agreement.

+ References

No definition available.

+ Details

Name:	lxrx_SymphonyAmendmentBuyout
Namespace Prefix:	lxrx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

+ References

No definition available.

+ Details

Name:	lxrx_SymphonyBasePaymentDiscountRate
Namespace Prefix:	lxrx_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

+ References

No definition available.

+ Details

Name:	lxrx_SymphonyBasePaymentInShares
Namespace Prefix:	lxrx_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

+ References

No definition available.

+ Details

Name:	lxrx_SymphonyBasePaymentObligation
Namespace Prefix:	lxrx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

+ References

No definition available.

+ Details

Name:	lxrx_SymphonyContingentPaymentDiscountRate
Namespace Prefix:	lxrx_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Contingent payments to Symphony Icon Holdings in the form of cash.

+ References

No definition available.

+ Details

Name:	lxrx_SymphonyContingentPaymentInCash
Namespace Prefix:	lxrx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

+ References

No definition available.

+ Details

Name:	lxrx_SymphonyContingentPaymentMaximum
Namespace Prefix:	lxrx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

+ References

No definition available.

+ Details

Name:	lxrx_SymphonyContingentPaymentPercentage
Namespace Prefix:	lxrx_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Contingent payments to Symphony Icon Holdings, in total.

+ References

No definition available.

+ Details

Name:	lxrx_SymphonyContingentPaymentTotal
Namespace Prefix:	lxrx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Contingent payments to Symphony Icon Holdings in the form of stock.

+ References

No definition available.

+ Details

Name:	lxrx_SymphonyContingentPaymentinShares
Namespace Prefix:	lxrx_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The contingent payments to Holdings 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 payment will be paid in common stock.

+ References

No definition available.

+ Details

Name:	lxrx_SymphonyPaymentInStockLimitation
Namespace Prefix:	lxrx_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

+ References

No definition available.

+ Details

Name:	lxrx_SymphonyRegulatoryApprovalPayment
Namespace Prefix:	lxrx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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 13,237,519 shares of common stock to designees of Holdings on July 30, 2012 in satisfaction of an additional $35 million base payment obligation. In the event Lexicon receives 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 will pay Holdings the sum of $15 million and the amount of certain expenses Lexicon incurred after its exercise of the Purchase Option which are attributable to the development of such product, reduced by up to 50% of such sum for the amount 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 makes any such payment upon United States regulatory approval, Lexicon will 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. This represents the percentage by which proceeds of Licensing Transactions must exceed regulatory approval payments in order for Lexicon to have an obligation to make subsequent contingent payments.

+ References

No definition available.

+ Details

Name:	lxrx_SymphonyRegulatoryApprovalPercentageLimit
Namespace Prefix:	lxrx_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

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 13,237,519 shares of common stock to designees of Holdings on July 30, 2012 in satisfaction of an additional $35 million base payment obligation. In the event Lexicon receives 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 will pay Holdings the sum of $15 million and the amount of certain expenses Lexicon incurred after its exercise of the Purchase Option which are attributable to the development of such product, reduced by up to 50% of such sum for the amount 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. This represents the percentage reduction of the regulatory approval payment by previous contingent payments.

+ References

No definition available.

+ Details

Name:	lxrx_SymphonyRegulatoryApprovalReductionPercentage
Namespace Prefix:	lxrx_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Arrangements with Symphony Icon, Inc. (Details) - USD ($) $ in Thousands	1 Months Ended				12 Months Ended
	Mar. 31, 2017	Sep. 30, 2016	Apr. 30, 2015	Dec. 31, 2014	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jul. 30, 2012	Jul. 30, 2010	Jun. 15, 2007
Arrangements with Symphony Icon Inc [Abstract]
Holdings Contribution To Icon										$ 45,000
Lexicon Sold Shares To Holdings										1,092,946
Lexicon Received Cash From Holdings										$ 15,000
Lexicon Paid Holdings Cash									$ 10,000
Symphony Fair Value Of Base And Contingent Payments									$ 45,600
Symphony Base Payment Discount Rate									14.00%
Symphony Contingent Payment Discount Rate									18.00%
Symphony Base Payment In Shares								1,891,074
Symphony Base Payment Obligation								$ 35,000
Symphony Contingent Payment Maximum									$ 45,000
Symphony Contingent Payment Percentage									50.00%
Symphony Regulatory Approval Payment									$ 15,000
Symphony Regulatory Approval Reduction Percentage									50.00%
Symphony Regulatory Approval Percentage Limit									50.00%
Symphony Payment In Stock Limitation									50.00%
Symphony Contingent Payment In Cash	$ 10,500	$ 3,200	$ 750	$ 5,800
Symphony Amendment Buyout		$ 21,000
Symphony Contingent Payment in Shares	659,905			666,111
Symphony Contingent Payment Total				$ 11,500
Increase (decrease) in fair value of Symphony Icon, Inc. purchase liability					$ 2,101	$ (703)	$ 5,927