Basis of Presentation (Policies)	12 Months Ended
Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Principles of Consolidation	Principles of Consolidation The accompanying consolidated financial statements include Ligand and its wholly owned subsidiaries. All significant intercompany accounts and transactions have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with generally accepted accounting principles requires the use of estimates and assumptions that affect the reported amounts of assets and liabilities, including disclosure of contingent assets and contingent liabilities, at the date of the consolidated financial statements and the reported amounts of revenues and expenses, definite and indefinite lived intangible assets, inventory, goodwill, co-promote termination payments receivable and co-promote termination liabilities, uncertain tax positions, deferred revenue, lease exit liability and income tax net operating loss carryforwards during the reporting period. The Company’s critical accounting policies are those that are both most important to the Company’s financial condition and results of operations and require the most difficult, subjective or complex judgments on the part of management in their application, often as a result of the need to make estimates about the effect of matters that are inherently uncertain. Because of the uncertainty of factors surrounding the estimates or judgments used in the preparation of the consolidated financial statements, actual results may materially vary from these estimates.
Reclassifications	Reclassifications Certain reclassifications have been made to the previously issued statement of operations for comparability purposes. These reclassifications had no effect on the reported net income, stockholders' equity and operating cash flows as previously reported.
Income (Loss) Per Share	Income (Loss) Per Share Basic income (loss) per share is calculated by dividing net income or loss by the weighted average number of common shares and vested restricted stock units outstanding. Diluted income (loss) per share is computed by dividing net income or loss by the weighted average number of common shares and vested restricted stock units outstanding and the weighted average number of dilutive common stock equivalents, including stock options, non-vested restricted stock units, convertible notes and warrants. Common stock equivalents are only included in the diluted earnings per share calculation when their effect is dilutive.
Cash, Cash Equivalents and Short-term Investments	Cash and Cash Equivalents Cash and cash equivalents consist of cash, money market accounts, and certificates of deposit with original maturities of three months or less from the date of purchase. Short-term Investments Securities received by the Company as a result of a milestone payment from licensees are considered short-term investments and have been classified by management as available-for-sale. Such investments are carried at fair value, with unrealized gains and losses included in the statement of comprehensive income (loss). The Company determines the cost of investments based on the specific identification method.
Restricted Cash and Investments	Restricted Cash Restricted cash and investments consist of certificates of deposit held with a financial institution as collateral under a facility lease and third-party service provider arrangements.
Concentrations of Credit Risk	Concentrations of Business Risk Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash equivalents and investments. The Company invests its excess cash principally in United States government debt securities, investment grade corporate debt securities and certificates of deposit. The Company has established guidelines relative to diversification and maturities that maintain safety and liquidity. These guidelines are periodically reviewed and modified to take advantage of trends in yields and interest rates.
Inventory	Inventory Inventory, which consists of finished goods, is stated at the lower of cost or market value. The Company determines cost using the first-in, first-out method. The Company analyzes its inventory levels periodically and writes down inventory to its net realizable value if it has become obsolete, has a cost basis in excess of its expected net realizable value or is in excess of expected requirements.
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts The Company maintains an allowance for doubtful accounts based on the best estimate of the amount of probable losses in the Company’s existing accounts receivable. Accounts receivable that are outstanding longer than their contractual payment terms, ranging from 30 to 90 days, are considered past due. When determining the allowance for doubtful accounts, several factors are taken into consideration, including historical write-off experience and review of specific customer accounts for collectability. Account balances are charged off against the allowance after collection efforts have been exhausted and the potential for recovery is considered remote.
Property and Equipment, net	Depreciation of equipment is computed using the straight-line method over the estimated useful lives of the assets which range from three to ten years. Leasehold improvements are amortized using the straight-line method over their estimated useful lives or their related lease term, whichever is shorter.
Goodwill and Other Identifiable Intangible Assets	The Company accounts for goodwill in accordance with Accounting Standards Codification ("ASC"), 350, Goodwill and Other Intangibles. The Company performs its impairment analysis for goodwill and certain non-amortizing intangibles on at least an annual basis. The Company uses the income approach and the market approach, each weighted at 50%, for goodwill impairment analysis. For the income approach, the Company considers the present value of future cash flows and the carrying value of its assets and liabilities, including goodwill. The market approach is based on an analysis of revenue multiples of guideline public companies. If the carrying value of the assets and liabilities, including goodwill, were to exceed the Company’s estimation of the fair value, the Company would record an impairment charge in an amount equal to the excess of the carrying value of goodwill over the implied fair value of the goodwill. The Company performs an evaluation of goodwill as of December 31 of each year, absent any indicators of earlier impairment, to ensure that impairment charges, if applicable, are reflected in the Company's financial results before December 31 of each year. When it is determined that impairment has occurred, a charge to operations is recorded. Goodwill and other intangible asset balances are included in the identifiable assets of the business segment to which they have been assigned. Any goodwill impairment, as well as the amortization of other purchased intangible assets, is charged against the respective business segments’ operating income.
Acquired in-process research and development	Acquired in-process research and development Intangible assets related to acquired IPR&D are considered to be indefinite-lived until the completion or abandonment of the associated research and development efforts. During the period the assets are considered to be indefinite-lived, they will not be amortized but will be tested for impairment on an annual basis and between annual tests if the Company becomes aware of any events occurring or changes in circumstances that would indicate a reduction in the fair value of the IPR&D projects below their respective carrying amounts. If and when development is complete, which generally occurs if and when regulatory approval to market a product is obtained, the associated assets would be deemed finite-lived and would then be amortized based on their respective estimated useful lives at that point in time.
Commercial license rights	Commercial license rights Commercial license rights represent a portfolio of future milestone and royalty payment rights acquired in accordance with the Royalty Stream and Milestone Payments Purchase Agreement entered into with Selexis SA ("Selexis") in April 2013. The portfolio consists of over 15 Selexis commercial license agreement programs with various pharmaceutical-company counterparties. The purchase price was $4.6 million, inclusive of acquisition costs. Individual commercial license rights acquired under the agreement are carried at allocated cost and approximate fair value. The carrying value of the license rights will be reduced on a pro-rata basis as revenue is realized over the term of the agreement. Declines in the fair value of individual license rights below their carrying value that are deemed to be other than temporary are reflected in earnings in the period such determination is made.
Contingent Liabilities	Contingent Liabilities In connection with the Company’s acquisition of CyDex in January 2011, the Company recorded a $17.6 million contingent liability, inclusive of the $4.3 million payment made in January 2012, for amounts potentially due to holders of the CyDex CVR's and former license holders. The initial fair value of the liability was determined using the income approach incorporating the estimated future cash flows from potential milestones and revenue sharing. These cash flows were then discounted to present value using a discount rate of 21.6%. The liability is periodically assessed based on events and circumstances related to the underlying milestones, and the change in fair value will be recorded in the Company’s consolidated statements of operations. The carrying amount of the liability may fluctuate significantly and actual amounts paid under the CVR agreements may be materially different than the carrying amount of the liability. The fair value of the liability at December 31, 2014 and 2013 was $11.5 million and $9.3 million, respectively. The Company recorded a fair value adjustment to increase the liability for CyDex related contingent liabilities of $5.7 million for the year ended December 31, 2014, $0.6 million decrease in the liability for the year ended December 31, 2013 and an increase in the liability of $3.4 million for the year ended December 31, 2012. Contingent liabilities decreased for cash payments to CVR holders and other contingency payments by $3.5 million during the year ended December 31, 2014, $1.0 million during the year ended December 31, 2013 and $8.0 million during the year ended December 31, 2012. In connection with the Company’s acquisition of Metabasis in January 2010, the Company issued Metabasis stockholders four tradable CVRs, one CVR from each of four respective series of CVR, for each Metabasis share. The CVRs will entitle Metabasis stockholders to cash payments as frequently as every six months as cash is received by the Company from proceeds from Metabasis’ partnership with Roche (which has been terminated) or the sale or partnering of any of the Metabasis drug development programs, among other triggering events. The acquisition-date fair value of the CVRs of $9.1 million was determined using quoted market prices of Metabasis common stock in active markets. The fair values of the CVRs are remeasured at each reporting date through the term of the related agreement. Changes in the fair values are reported in the statement of operations as income (decreases) or expense (increases). The carrying amount of the liability may fluctuate significantly based upon quoted market prices and actual amounts paid under the agreements may be materially different than the carrying amount of the liability. The fair value of the liability was $3.7 million and $4.2 million as of December 31, 2014 and 2013, respectively. The Company recorded a decrease in the liability for CVRs of $0.5 million during the year ended December 31, 2014, an increase of $4.2 million during the year ended December 31, 2013 and a decrease of $1.1 million during the year ended December 31, 2012. In connection with the Company’s acquisition of Neurogen in December 2009, the Company issued to Neurogen stockholders four CVRs; real estate, Aplindore, VR1 and H3, that entitle them to cash and/or shares of third-party stock under certain circumstances. The Company recorded the acquisition-date fair value of the CVRs as part of the purchase price. The acquisition-date fair value of the real estate CVR of $3.2 million was estimated using the net proceeds from a pending sale transaction and recorded as a payable to stockholders at December 31, 2009. In February 2010, the Company completed the sale of the real estate and subsequently distributed the proceeds to the holders of the real estate CVR. As a result and after final settlement of all related expenses, the real estate CVR was terminated in August 2010. In 2012, the Company received a notice from a collaborative partner that it was terminating its agreement related to VR1 for convenience and subsequently the Company recorded a decrease in the fair value of the liability for the related CVR of $0.2 million. Additionally, per the CVR agreement, no payment event date for the H3 program can occur after December 23, 2012 and the Company recorded a decrease in the fair value of the liability for the related CVR of $0.5 million as of that date. There are no remaining CVR obligations under the agreement with the former Neurogen shareholders.
Fair Value of Financial Instruments	Fair Value of Financial Instruments Fair value is defined as the exit price that would be received to sell an asset or paid to transfer a liability. Fair value is a market-based measurement that should be determined using assumptions that market participants would use in pricing an asset or liability. The Company establishes a three-level hierarchy to prioritize the inputs used in measuring fair value. The levels are described in the below with level 1 having the highest priority and level 3 having the lowest: Level 1 - Observable inputs such as quoted prices in active markets Level 2 - Inputs other than the quoted prices in active markets that are observable either directly or indirectly Level 3 - Unobservable inputs in which there is little or no market data, which require the Company to develop its own assumptions The carrying amount of the Company’s cash and cash equivalents, accounts receivable, accounts payable and accrued expenses approximate the fair value because of their short maturities. Other assets and liabilities that are carried at fair value include short-term investments, certain license liabilities in equity securities, certain co-promote termination asset and liability, and contingent consideration liabilities. For additional information, see Note 3 Fair Value Measurement The Company evaluates its financial instruments at each reporting period to determine if any transfers between the various three-level hierarchy have occurred and appropriately reclassifies its financial instruments to the appropriate level within the hierarchy.
Treasury Stock	Treasury Stock The Company may on occasion repurchase its common stock on the open market or in private transactions. When such stock is repurchased it is not constructively or formally retired and may be reissued if certain regulatory requirements are met; however, the Company may from time to time choose to retire the shares of common stock held in its treasury. The purchase price of the common stock repurchased is charged to treasury stock.
Revenue Recognition	Revenue Recognition Royalties on sales of products commercialized by the Company’s partners are recognized in the quarter reported by the respective partner. Generally, the Company receives royalty reports from its licensees approximately one quarter in arrears due to the fact that its agreements require partners to report product sales between 30 and 60 days after the end of the quarter. The Company recognizes royalty revenues when it can reliably estimate such amounts and collectability is reasonably assured. Under this accounting policy, the royalty revenues reported are not based upon estimates and such royalty revenues are typically reported to the Company by its partners in the same period in which payment is received. Revenue from material sales of Captisol is recognized upon transfer of title, which normally passes upon shipment to the customer, provided all other revenue recognition criteria have been met; however, we do not recognize revenue until all substantive customer acceptance requirements have been met, when applicable. The Company’s credit and exchange policy includes provisions for the return of product between 30 to 90 days, depending on the specific terms of the individual agreement, when that product (1) does not meet specifications, (2) is damaged in shipment (in limited circumstances where title does not transfer until delivery), or (3) is exchanged for an alternative grade of Captisol. All product returns are subject to approval by the Company and a 20% restocking fee. To date, product returns by customers have not been material to net material sales in any related period. The Company records revenue net of product returns, if any, and sales tax collected and remitted to government authorities during the period. The Company analyzes its revenue arrangements and other agreements to determine whether there are multiple elements that should be separated and accounted for individually or as a single unit of accounting. For multiple element contracts, arrangement consideration is allocated at the inception of the arrangement to all deliverables on the basis of relative selling price, using a hierarchy to determine selling price. Management first considers vendor-specific objective evidence ("VSOE"), then third-party evidence ("TPE") and if neither VSOE nor TPE exist, the Company uses its best estimate of selling price. Many of the Company's Captisol license arrangements involve the bundling of a license with the option to purchase Captisol material. Licenses are granted to pharmaceutical companies for the use of Captisol in the development of pharmaceutical compounds. The licenses may be granted for the use of the Captisol product for all phases of clinical trials and through commercial availability of the host drug or may be limited to certain phases of the clinical trial process. Management believes that the Company's licenses have stand-alone value at the outset of an arrangement because the customer obtains the right to use Captisol in its formulations without any additional input by the Company. Other nonrefundable, up-front license fees are recognized as revenue upon delivery of the license, if the license is determined to have standalone value that is not dependent on any future performance by the Company under the applicable collaboration agreement. Nonrefundable contingent event-based payments are recognized as revenue when the contingent event is met, which is usually the earlier of when payments are received or collections are assured, provided that it does not require future performance by the Company. The Company occasionally has sub-license obligations related to arrangements for which it receives license fees, milestones and royalties. The Company evaluates the determination of gross versus net reporting based on each individual agreement. Sales-based contingent payments from partners are accounted for similarly to royalties, with revenue recognized upon achievement of the sales targets assuming all other revenue recognition criteria for milestones are met. Revenue from development and regulatory milestones is recognized when earned, as evidenced by written acknowledgement from the collaborator, provided that (1) the milestone event is substantive, its achievability was not reasonably assured at the inception of the agreement, and the Company has no further performance obligations relating to that event, and (2) collectability is reasonably assured. If these criteria are not met, the milestone payment is recognized over the remaining period of the Company’s performance obligations under the arrangement. Revenue from research funding under our collaboration agreements is earned and recognized on a percentage-of completion basis as research hours are incurred in accordance with the provisions of each agreement.
Cost of Goods Sold	Cost of Material Sales The Company determines cost using the first-in, first-out method. Cost of material sales include all costs of purchase and other costs incurred in bringing the Captisol inventories to their present location and condition, costs to store, and distribute.
Preclinical Study and Clinical Trial Accruals	Preclinical Study and Clinical Trial Accruals Substantial portions of the Company’s preclinical studies and all of the Company’s clinical trials have been performed by third-party laboratories, contract research organizations, or other vendors ("CROs"). The Company accounts for a significant portion of its clinical study costs according to the terms of its contracts with CROs. The terms of its CRO contracts may result in payment flows that do not match the periods over which services are provided to us under such contracts. The Company's objective is to reflect the appropriate preclinical and clinical trial expenses in its financial statements in the same period as the services occur. As part of the process of preparing its financial statements, the Company relies on cost information provided by its CROs. The Company is also required to estimate certain of its expenses resulting from its obligations under its CRO contracts. Accordingly, the Company's preclinical study and clinical trial accrual is dependent upon the timely and accurate reporting of contract research organizations and other third-party vendors. The Company periodically evaluates its estimates to determine if adjustments are necessary or appropriate as more information becomes available concerning changing circumstances, and conditions or events that may affect such estimates. No material adjustments to preclinical study and clinical trial accrued expenses have been recognized to date.
Sale of Royalty Rights	Sale of Royalty Rights The Company previously sold to third parties the rights to future royalties of certain of its products. As part of the underlying royalty agreements, the partners have the right to offset a portion of any future royalty payments owed to the Company to the extent of previous milestone payments. Accordingly, the Company deferred a portion of the revenue associated with each tranche of royalty right sold, equal to the pro-rata share of the potential royalty offset. Such amounts associated with the offset rights against future royalty payments will reduce this balance upon receipt of future royalties from the respective partners.
Product Returns	Product Returns (Avinza and Oncology product lines) In connection with the sale of the Avinza and Oncology product lines, the Company retained the obligation for returns of product that were shipped to wholesalers prior to the close of the transactions. The accruals for product returns, which were recorded as part of the accounting for the sales transactions, are based on historical experience. Any subsequent changes to the Company’s estimate of product returns are accounted for as a component of discontinued operations.
Costs and Expenses	Research and Development Expenses Research and development expense consists of labor, material, equipment, and allocated facilities costs of the Company’s scientific staff who are working pursuant to the Company’s collaborative agreements and other research and development projects. Also included in research and development expenses are third-party costs incurred for the Company’s research programs including in-licensing costs, CRO costs and costs incurred by other research and development service vendors. We expense these costs as they are incurred. When we make payments for research and development services prior to the services being rendered, we record those amounts as prepaid assets on our consolidated balance sheet and we expense them as the services are provided.
Income Taxes	Income Taxes Income taxes are accounted for under the asset and liability method. This approach requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of differences between the tax basis of assets or liabilities and their carrying amounts in the consolidated financial statements. A valuation allowance is provided for deferred tax assets if it is more likely than not that these items will either expire before the Company is able to realize their benefit or if future deductibility is uncertain. As of December 31, 2014 and 2013, the Company had provided a full valuation allowance against its deferred tax assets as recoverability was uncertain. Developing the provision for income taxes requires significant judgment and expertise in federal and state income tax laws, regulations and strategies, including the determination of deferred tax assets and liabilities and, if necessary, any valuation allowances that may be required for deferred tax assets. Management's judgments and tax strategies are subject to audit by various taxing authorities. While the Company believes it has provided adequately for its income tax liabilities in its consolidated financial statements, adverse determinations by these taxing authorities could have a material adverse effect on the Company's consolidated financial condition and results of operations. The Company's ending deferred tax liability represents a future tax obligation for current tax amortization claimed on acquired IPR&D. As the Company cannot estimate when the IPR&D assets will be amortizable for financial reporting purposes, the deferred tax liability associated with the IPR&D assets cannot be used to support the realization of the Company's deferred tax assets. As a result, the Company is required to increase its valuation allowance and record a charge to deferred taxes.
Accounting for Share-Based Compensation	Accounting for Stock-Based Compensation The Company grants options and awards to employees, non-employee consultants, and non-employee directors. Only new shares of common stock are issued upon the exercise of stock options. Non-employee directors are accounted for as employees. Options and restricted stock granted to certain directors vest in equal monthly installments over one year from the date of grant. Options granted to employees vest 1/8 on the six month anniversary of the date of grant, and 1/48 each month thereafter for forty-two months. All option awards generally expire ten years from the date of grant. Stock-based compensation expense for awards to employees and non-employee directors is recognized on a straight-line basis over the vesting period until the last tranche vests.
Segment reporting	Segment Reporting Under Accounting Standards Codification No. 280, “Segment Reporting” (ASC 280), operating segments are defined as components of an enterprise about which separate financial information is available that is regularly evaluated by the entity’s chief operating decision maker, in deciding how to allocate resources and in assessing performance. The Company has evaluated ASC 280 and has identified two reportable segments: the development and commercialization of drugs using Captisol technology by CyDex Pharmaceuticals, Inc. and the biopharmaceutical company with a business model that is based upon the concept of developing or acquiring royalty revenue generating assets and coupling them with a lean corporate cost structure of Ligand Pharmaceuticals Incorporated.
Comprehensive Income (Loss)	Comprehensive Income (Loss) Comprehensive income (loss) represents net income (loss) adjusted for the change during the periods presented in unrealized gains and losses on available-for-sale securities less reclassification adjustments for realized gains or losses included in net income (loss). The unrealized gains or losses are reported on the Consolidated Statements of Comprehensive Income (Loss).

Basis of Presentation (Policies)

12 Months Ended

Dec. 31, 2014

Organization, Consolidation and Presentation of Financial Statements [Abstract]

The accompanying consolidated financial statements include Ligand and its wholly owned subsidiaries. All significant intercompany accounts and transactions have been eliminated in consolidation.

Use of Estimates

The preparation of consolidated financial statements in conformity with generally accepted accounting principles requires the use of estimates and assumptions that affect the reported amounts of assets and liabilities, including disclosure of contingent assets and contingent liabilities, at the date of the consolidated financial statements and the reported amounts of revenues and expenses, definite and indefinite lived intangible assets, inventory, goodwill, co-promote termination payments receivable and co-promote termination liabilities, uncertain tax positions, deferred revenue, lease exit liability and income tax net operating loss carryforwards during the reporting period. The Company’s critical accounting policies are those that are both most important to the Company’s financial condition and results of operations and require the most difficult, subjective or complex judgments on the part of management in their application, often as a result of the need to make estimates about the effect of matters that are inherently uncertain. Because of the uncertainty of factors surrounding the estimates or judgments used in the preparation of the consolidated financial statements, actual results may materially vary from these estimates.

Reclassifications

Certain reclassifications have been made to the previously issued statement of operations for comparability purposes. These reclassifications had no effect on the reported net income, stockholders' equity and operating cash flows as previously reported.

Income (Loss) Per Share

Basic income (loss) per share is calculated by dividing net income or loss by the weighted average number of common shares and vested restricted stock units outstanding. Diluted income (loss) per share is computed by dividing net income or loss by the weighted average number of common shares and vested restricted stock units outstanding and the weighted average number of dilutive common stock equivalents, including stock options, non-vested restricted stock units, convertible notes and warrants. Common stock equivalents are only included in the diluted earnings per share calculation when their effect is dilutive.

Cash, Cash Equivalents and Short-term Investments

Cash and Cash Equivalents

Cash and cash equivalents consist of cash, money market accounts, and certificates of deposit with original maturities of three months or less from the date of purchase.

Short-term Investments

Securities received by the Company as a result of a milestone payment from licensees are considered short-term investments and have been classified by management as available-for-sale. Such investments are carried at fair value, with unrealized gains and losses included in the statement of comprehensive income (loss). The Company determines the cost of investments based on the specific identification method.

Restricted Cash and Investments

Restricted Cash

Restricted cash and investments consist of certificates of deposit held with a financial institution as collateral under a facility lease and third-party service provider arrangements.

Concentrations of Credit Risk

Concentrations of Business Risk

Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash equivalents and investments.

The Company invests its excess cash principally in United States government debt securities, investment grade corporate debt securities and certificates of deposit. The Company has established guidelines relative to diversification and maturities that maintain safety and liquidity. These guidelines are periodically reviewed and modified to take advantage of trends in yields and interest rates.

Inventory

Inventory, which consists of finished goods, is stated at the lower of cost or market value. The Company determines cost using the first-in, first-out method. The Company analyzes its inventory levels periodically and writes down inventory to its net realizable value if it has become obsolete, has a cost basis in excess of its expected net realizable value or is in excess of expected requirements.

Allowance for Doubtful Accounts

The Company maintains an allowance for doubtful accounts based on the best estimate of the amount of probable losses in the Company’s existing accounts receivable. Accounts receivable that are outstanding longer than their contractual payment terms, ranging from 30 to 90 days, are considered past due. When determining the allowance for doubtful accounts, several factors are taken into consideration, including historical write-off experience and review of specific customer accounts for collectability. Account balances are charged off against the allowance after collection efforts have been exhausted and the potential for recovery is considered remote.

Property and Equipment, net

Depreciation of equipment is computed using the straight-line method over the estimated useful lives of the assets which range from three to ten years. Leasehold improvements are amortized using the straight-line method over their estimated useful lives or their related lease term, whichever is shorter.

Goodwill and Other Identifiable Intangible Assets

The Company accounts for goodwill in accordance with Accounting Standards Codification ("ASC"), 350, Goodwill and Other Intangibles. The Company performs its impairment analysis for goodwill and certain non-amortizing intangibles on at least an annual basis. The Company uses the income approach and the market approach, each weighted at 50%, for goodwill impairment analysis. For the income approach, the Company considers the present value of future cash flows and the carrying value of its assets and liabilities, including goodwill. The market approach is based on an analysis of revenue multiples of guideline public companies. If the carrying value of the assets and liabilities, including goodwill, were to exceed the Company’s estimation of the fair value, the Company would record an impairment charge in an amount equal to the excess of the carrying value of goodwill over the implied fair value of the goodwill. The Company performs an evaluation of goodwill as of December 31 of each year, absent any indicators of earlier impairment, to ensure that impairment charges, if applicable, are reflected in the Company's financial results before December 31 of each year. When it is determined that impairment has occurred, a charge to operations is recorded. Goodwill and other intangible asset balances are included in the identifiable assets of the business segment to which they have been assigned. Any goodwill impairment, as well as the amortization of other purchased intangible assets, is charged against the respective business segments’ operating income.

Acquired in-process research and development

Intangible assets related to acquired IPR&D are considered to be indefinite-lived until the completion or abandonment of the associated research and development efforts. During the period the assets are considered to be indefinite-lived, they will not be amortized but will be tested for impairment on an annual basis and between annual tests if the Company becomes aware of any events occurring or changes in circumstances that would indicate a reduction in the fair value of the IPR&D projects below their respective carrying amounts. If and when development is complete, which generally occurs if and when regulatory approval to market a product is obtained, the associated assets would be deemed finite-lived and would then be amortized based on their respective estimated useful lives at that point in time.

Commercial license rights

Commercial license rights represent a portfolio of future milestone and royalty payment rights acquired in accordance with the Royalty Stream and Milestone Payments Purchase Agreement entered into with Selexis SA ("Selexis") in April 2013. The portfolio consists of over 15 Selexis commercial license agreement programs with various pharmaceutical-company counterparties. The purchase price was $4.6 million, inclusive of acquisition costs. Individual commercial license rights acquired under the agreement are carried at allocated cost and approximate fair value. The carrying value of the license rights will be reduced on a pro-rata basis as revenue is realized over the term of the agreement. Declines in the fair value of individual license rights below their carrying value that are deemed to be other than temporary are reflected in earnings in the period such determination is made.

Contingent Liabilities

In connection with the Company’s acquisition of CyDex in January 2011, the Company recorded a $17.6 million contingent liability, inclusive of the $4.3 million payment made in January 2012, for amounts potentially due to holders of the CyDex CVR's and former license holders. The initial fair value of the liability was determined using the income approach incorporating the estimated future cash flows from potential milestones and revenue sharing. These cash flows were then discounted to present value using a discount rate of 21.6%. The liability is periodically assessed based on events and circumstances related to the underlying milestones, and the change in fair value will be recorded in the Company’s consolidated statements of operations. The carrying amount of the liability may fluctuate significantly and actual amounts paid under the CVR agreements may be materially different than the carrying amount of the liability. The fair value of the liability at December 31, 2014 and 2013 was $11.5 million and $9.3 million, respectively. The Company recorded a fair value adjustment to increase the liability for CyDex related contingent liabilities of $5.7 million for the year ended December 31, 2014, $0.6 million decrease in the liability for the year ended December 31, 2013 and an increase in the liability of $3.4 million for the year ended December 31, 2012. Contingent liabilities decreased for cash payments to CVR holders and other contingency payments by $3.5 million during the year ended December 31, 2014, $1.0 million during the year ended December 31, 2013 and $8.0 million during the year ended December 31, 2012.

In connection with the Company’s acquisition of Metabasis in January 2010, the Company issued Metabasis stockholders four tradable CVRs, one CVR from each of four respective series of CVR, for each Metabasis share. The CVRs will entitle Metabasis stockholders to cash payments as frequently as every six months as cash is received by the Company from proceeds from Metabasis’ partnership with Roche (which has been terminated) or the sale or partnering of any of the Metabasis drug development programs, among other triggering events. The acquisition-date fair value of the CVRs of $9.1 million was determined using quoted market prices of Metabasis common stock in active markets. The fair values of the CVRs are remeasured at each reporting date through the term of the related agreement. Changes in the fair values are reported in the statement of operations as income (decreases) or expense (increases). The carrying amount of the liability may fluctuate significantly based upon quoted market prices and actual amounts paid under the agreements may be materially different than the carrying amount of the liability. The fair value of the liability was $3.7 million and $4.2 million as of December 31, 2014 and 2013, respectively. The Company recorded a decrease in the liability for CVRs of $0.5 million during the year ended December 31, 2014, an increase of $4.2 million during the year ended December 31, 2013 and a decrease of $1.1 million during the year ended December 31, 2012.

In connection with the Company’s acquisition of Neurogen in December 2009, the Company issued to Neurogen stockholders four CVRs; real estate, Aplindore, VR1 and H3, that entitle them to cash and/or shares of third-party stock under certain circumstances. The Company recorded the acquisition-date fair value of the CVRs as part of the purchase price. The acquisition-date fair value of the real estate CVR of $3.2 million was estimated using the net proceeds from a pending sale transaction and recorded as a payable to stockholders at December 31, 2009. In February 2010, the Company completed the sale of the real estate and subsequently distributed the proceeds to the holders of the real estate CVR. As a result and after final settlement of all related expenses, the real estate CVR was terminated in August 2010. In 2012, the Company received a notice from a collaborative partner that it was terminating its agreement related to VR1 for convenience and subsequently the Company recorded a decrease in the fair value of the liability for the related CVR of $0.2 million. Additionally, per the CVR agreement, no payment event date for the H3 program can occur after December 23, 2012 and the Company recorded a decrease in the fair value of the liability for the related CVR of $0.5 million as of that date. There are no remaining CVR obligations under the agreement with the former Neurogen shareholders.

Fair Value of Financial Instruments

Fair value is defined as the exit price that would be received to sell an asset or paid to transfer a liability. Fair value is a market-based measurement that should be determined using assumptions that market participants would use in pricing an asset or liability. The Company establishes a three-level hierarchy to prioritize the inputs used in measuring fair value. The levels are described in the below with level 1 having the highest priority and level 3 having the lowest:

Level 1 - Observable inputs such as quoted prices in active markets

Level 2 - Inputs other than the quoted prices in active markets that are observable either directly or indirectly

Level 3 - Unobservable inputs in which there is little or no market data, which require the Company to develop its own assumptions

The carrying amount of the Company’s cash and cash equivalents, accounts receivable, accounts payable and accrued expenses approximate the fair value because of their short maturities. Other assets and liabilities that are carried at fair value include short-term investments, certain license liabilities in equity securities, certain co-promote termination asset and liability, and contingent consideration liabilities. For additional information, see Note 3 Fair Value Measurement

The Company evaluates its financial instruments at each reporting period to determine if any transfers between the various three-level hierarchy have occurred and appropriately reclassifies its financial instruments to the appropriate level within the hierarchy.

Treasury Stock

The Company may on occasion repurchase its common stock on the open market or in private transactions. When such stock is repurchased it is not constructively or formally retired and may be reissued if certain regulatory requirements are met; however, the Company may from time to time choose to retire the shares of common stock held in its treasury. The purchase price of the common stock repurchased is charged to treasury stock.

Revenue Recognition

Royalties on sales of products commercialized by the Company’s partners are recognized in the quarter reported by the respective partner. Generally, the Company receives royalty reports from its licensees approximately one quarter in arrears due to the fact that its agreements require partners to report product sales between 30 and 60 days after the end of the quarter. The Company recognizes royalty revenues when it can reliably estimate such amounts and collectability is reasonably assured. Under this accounting policy, the royalty revenues reported are not based upon estimates and such royalty revenues are typically reported to the Company by its partners in the same period in which payment is received.

Revenue from material sales of Captisol is recognized upon transfer of title, which normally passes upon shipment to the customer, provided all other revenue recognition criteria have been met; however, we do not recognize revenue until all substantive customer acceptance requirements have been met, when applicable. The Company’s credit and exchange policy includes provisions for the return of product between 30 to 90 days, depending on the specific terms of the individual agreement, when that product (1) does not meet specifications, (2) is damaged in shipment (in limited circumstances where title does not transfer until delivery), or (3) is exchanged for an alternative grade of Captisol. All product returns are subject to approval by the Company and a 20% restocking fee. To date, product returns by customers have not been material to net material sales in any related period. The Company records revenue net of product returns, if any, and sales tax collected and remitted to government authorities during the period.

The Company analyzes its revenue arrangements and other agreements to determine whether there are multiple elements that should be separated and accounted for individually or as a single unit of accounting. For multiple element contracts, arrangement consideration is allocated at the inception of the arrangement to all deliverables on the basis of relative selling price, using a hierarchy to determine selling price. Management first considers vendor-specific objective evidence ("VSOE"), then third-party evidence ("TPE") and if neither VSOE nor TPE exist, the Company uses its best estimate of selling price.

Many of the Company's Captisol license arrangements involve the bundling of a license with the option to purchase Captisol material. Licenses are granted to pharmaceutical companies for the use of Captisol in the development of pharmaceutical compounds. The licenses may be granted for the use of the Captisol product for all phases of clinical trials and through commercial availability of the host drug or may be limited to certain phases of the clinical trial process. Management believes that the Company's licenses have stand-alone value at the outset of an arrangement because the customer obtains the right to use Captisol in its formulations without any additional input by the Company.

Other nonrefundable, up-front license fees are recognized as revenue upon delivery of the license, if the license is determined to have standalone value that is not dependent on any future performance by the Company under the applicable collaboration agreement. Nonrefundable contingent event-based payments are recognized as revenue when the contingent event is met, which is usually the earlier of when payments are received or collections are assured, provided that it does not require future performance by the Company. The Company occasionally has sub-license obligations related to arrangements for which it receives license fees, milestones and royalties. The Company evaluates the determination of gross versus net reporting based on each individual agreement.

Sales-based contingent payments from partners are accounted for similarly to royalties, with revenue recognized upon achievement of the sales targets assuming all other revenue recognition criteria for milestones are met. Revenue from development and regulatory milestones is recognized when earned, as evidenced by written acknowledgement from the collaborator, provided that (1) the milestone event is substantive, its achievability was not reasonably assured at the inception of the agreement, and the Company has no further performance obligations relating to that event, and (2) collectability is reasonably assured. If these criteria are not met, the milestone payment is recognized over the remaining period of the Company’s performance obligations under the arrangement.

Revenue from research funding under our collaboration agreements is earned and recognized on a percentage-of completion basis as research hours are incurred in accordance with the provisions of each agreement.

Cost of Goods Sold

Cost of Material Sales

The Company determines cost using the first-in, first-out method. Cost of material sales include all costs of purchase and other costs incurred in bringing the Captisol inventories to their present location and condition, costs to store, and distribute.

Preclinical Study and Clinical Trial Accruals

Substantial portions of the Company’s preclinical studies and all of the Company’s clinical trials have been performed by third-party laboratories, contract research organizations, or other vendors ("CROs"). The Company accounts for a significant portion of its clinical study costs according to the terms of its contracts with CROs. The terms of its CRO contracts may result in payment flows that do not match the periods over which services are provided to us under such contracts. The Company's objective is to reflect the appropriate preclinical and clinical trial expenses in its financial statements in the same period as the services occur. As part of the process of preparing its financial statements, the Company relies on cost information provided by its CROs. The Company is also required to estimate certain of its expenses resulting from its obligations under its CRO contracts. Accordingly, the Company's preclinical study and clinical trial accrual is dependent upon the timely and accurate reporting of contract research organizations and other third-party vendors. The Company periodically evaluates its estimates to determine if adjustments are necessary or appropriate as more information becomes available concerning changing circumstances, and conditions or events that may affect such estimates. No material adjustments to preclinical study and clinical trial accrued expenses have been recognized to date.

Sale of Royalty Rights

The Company previously sold to third parties the rights to future royalties of certain of its products. As part of the underlying royalty agreements, the partners have the right to offset a portion of any future royalty payments owed to the Company to the extent of previous milestone payments. Accordingly, the Company deferred a portion of the revenue associated with each tranche of royalty right sold, equal to the pro-rata share of the potential royalty offset. Such amounts associated with the offset rights against future royalty payments will reduce this balance upon receipt of future royalties from the respective partners.

Product Returns

Product Returns (Avinza and Oncology product lines)

In connection with the sale of the Avinza and Oncology product lines, the Company retained the obligation for returns of product that were shipped to wholesalers prior to the close of the transactions. The accruals for product returns, which were recorded as part of the accounting for the sales transactions, are based on historical experience. Any subsequent changes to the Company’s estimate of product returns are accounted for as a component of discontinued operations.

Costs and Expenses

Research and Development Expenses

Research and development expense consists of labor, material, equipment, and allocated facilities costs of the Company’s scientific staff who are working pursuant to the Company’s collaborative agreements and other research and development projects. Also included in research and development expenses are third-party costs incurred for the Company’s research programs including in-licensing costs, CRO costs and costs incurred by other research and development service vendors. We expense these costs as they are incurred. When we make payments for research and development services prior to the services being rendered, we record those amounts as prepaid assets on our consolidated balance sheet and we expense them as the services are provided.

Income Taxes

Income taxes are accounted for under the asset and liability method. This approach requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of differences between the tax basis of assets or liabilities and their carrying amounts in the consolidated financial statements. A valuation allowance is provided for deferred tax assets if it is more likely than not that these items will either expire before the Company is able to realize their benefit or if future deductibility is uncertain. As of December 31, 2014 and 2013, the Company had provided a full valuation allowance against its deferred tax assets as recoverability was uncertain. Developing the provision for income taxes requires significant judgment and expertise in federal and state income tax laws, regulations and strategies, including the determination of deferred tax assets and liabilities and, if necessary, any valuation allowances that may be required for deferred tax assets. Management's judgments and tax strategies are subject to audit by various taxing authorities. While the Company believes it has provided adequately for its income tax liabilities in its consolidated financial statements, adverse determinations by these taxing authorities could have a material adverse effect on the Company's consolidated financial condition and results of operations.

The Company's ending deferred tax liability represents a future tax obligation for current tax amortization claimed on acquired IPR&D. As the Company cannot estimate when the IPR&D assets will be amortizable for financial reporting purposes, the deferred tax liability associated with the IPR&D assets cannot be used to support the realization of the Company's deferred tax assets. As a result, the Company is required to increase its valuation allowance and record a charge to deferred taxes.

Accounting for Share-Based Compensation

Accounting for Stock-Based Compensation

The Company grants options and awards to employees, non-employee consultants, and non-employee directors. Only new shares of common stock are issued upon the exercise of stock options. Non-employee directors are accounted for as employees. Options and restricted stock granted to certain directors vest in equal monthly installments over one year from the date of grant. Options granted to employees vest 1/8 on the six month anniversary of the date of grant, and 1/48 each month thereafter for forty-two months. All option awards generally expire ten years from the date of grant.

Stock-based compensation expense for awards to employees and non-employee directors is recognized on a straight-line basis over the vesting period until the last tranche vests.

Segment reporting

Segment Reporting

Under Accounting Standards Codification No. 280, “Segment Reporting” (ASC 280), operating segments are defined as components of an enterprise about which separate financial information is available that is regularly evaluated by the entity’s chief operating decision maker, in deciding how to allocate resources and in assessing performance. The Company has evaluated ASC 280 and has identified two reportable segments: the development and commercialization of drugs using Captisol technology by CyDex Pharmaceuticals, Inc. and the biopharmaceutical company with a business model that is based upon the concept of developing or acquiring royalty revenue generating assets and coupling them with a lean corporate cost structure of Ligand Pharmaceuticals Incorporated.

Comprehensive Income (Loss)

Comprehensive income (loss) represents net income (loss) adjusted for the change during the periods presented in unrealized gains and losses on available-for-sale securities less reclassification adjustments for realized gains or losses included in net income (loss). The unrealized gains or losses are reported on the Consolidated Statements of Comprehensive Income (Loss).