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

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.

No definition available.

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

Lexicon originally calculated the value of the Purchase Option as the difference between the fair value of the common stock issued to Holdings and the cash received from Holdings for the issuance of the common stock. This represents the fair value of the common stock issued to Holdings.

No definition available.

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

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

No definition available.

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

No definition available.

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

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.

No definition available.

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

No definition available.

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

No definition available.

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

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.

No definition available.

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

No definition available.

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

No definition available.

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

No definition available.

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

No definition available.

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

No definition available.

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

No definition available.

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

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.

No definition available.

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

No definition available.

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

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.

No definition available.

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

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.

No definition available.

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

Upon the adoption of a new accounting pronouncement regarding variable interest entities (formerly SFAS No. 167) on January 1, 2010, $2.3 million of structuring and legal fees originally allocated to noncontrolling interest was allocated to the value of the Purchase Option. This resulted in a cumulative-effect adjustment to retained earnings of $1.5 million, representing the additional amortization expense that would have been recorded through December 31, 2009. The unamortized balance of $3.1 million was recorded in prepaid expenses and other current assets as of December 31, 2009. This represents the $3.1 million unamortized balance.

No definition available.

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

Amount of the cumulative effect on retained earnings before related income tax effect.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 250

-SubTopic 10

-Section 50

-Paragraph 9

-URI http://asc.fasb.org/extlink&oid=6801783&loc=d3e22663-107794