Summary of Significant Accounting Policies (Policies)	12 Months Ended
Dec. 31, 2013
Accounting Policies [Abstract]
Financial Statement Presentation	Financial Statement Presentation The accompanying consolidated financial statements include the accounts of Rambus and its wholly owned subsidiaries, Rambus K.K., located in Tokyo, Japan, Cryptography Research, Inc., located in California, U.S.A., Unity Semiconductor Corporation, located in California, U.S.A., Mozaik Multimedia, Inc., located in California, U.S.A., and Rambus Ltd., located in George Town, Grand Cayman Islands, British West Indies, which includes Rambus Chip Technologies (India) Private Limited, Rambus Deutschland GmbH, located in Pforzheim, Germany, Kamiyacho IP Holdings, Rambus Korea, Inc., located in Seoul, Korea and Rambus France, located in Paris, France. In addition, Rambus International Ltd. and Rambus Delaware LLC are also subsidiaries. All intercompany accounts and transactions have been eliminated in the accompanying consolidated financial statements. Investments in entities with less than 20% ownership by Rambus and in which Rambus does not have the ability to significantly influence the operations of the investee are accounted for using the cost method and are included in other assets.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. Actual results could differ from those estimates.
Reclassifications	Reclassifications Certain prior year balances were reclassified to conform to the current year’s presentation. None of these reclassifications had an impact on reported net income (loss) or cash flows for any of the periods presented.
Revenue Recognition	Revenue Recognition Overview Rambus recognizes revenue when persuasive evidence of an arrangement exists, Rambus has delivered the product or performed the service, the fee is fixed or determinable and collection is reasonably assured. If any of these criteria are not met, Rambus defers recognizing the revenue until such time as all criteria are met. Determination of whether or not these criteria have been met may require the Company to make judgments, assumptions and estimates based upon current information and historical experience. Certain revenue contracts consist of service fees associated with integration of Rambus' solutions into its customers’ products and fees associated with providing training, evaluation and test equipment to its customers. Under the accounting guidance, if the deliverables have standalone value upon delivery, Rambus accounts for each deliverable separately. When multiple deliverables included in an arrangement are separated into different units of accounting, the arrangement consideration is allocated to the identified separate units based on a relative selling price hierarchy. Rambus determines the relative selling price for a deliverable based on its best estimate of selling price (“BESP”). Rambus has determined that vendor-specific objective evidence of selling price for each deliverable is not available as there lacks a consistent number of standalone sales and third-party evidence is not a practical alternative due to differences in its service offerings compared to other parties and the availability of relevant third-party pricing information. Rambus determined BESP by considering its overall pricing objectives and market conditions. Significant pricing practices taken into consideration include discounting practices, the size and volume of transactions, the customer demographic, the geographic area where services are sold, price lists, go-to-market strategy, historical standalone sales and contract prices. The determination of BESP is made through consultation with and approval by management, taking into consideration the go-to-market strategy. As the go-to-market strategies evolve, Rambus may modify its pricing practices in the future, which could result in changes in relative selling prices. In most cases, the relative values of the undelivered components are not material to the overall arrangement and are typically delivered within twelve months after the core product has been delivered. In such agreements, selling price is determined for each component and any difference between the total of the separate BESP and total contract consideration (i.e. discount) is allocated pro-rata across each of the components in the arrangement. During 2013, the Company expanded its business strategy of monetizing its patent portfolio to include the sale of selected intellectual property. The Company's Memory and Interface Division ("MID") business continues to grow its patent portfolio and actively engage with various external parties to monetize the patent portfolio and explore new revenue opportunities. As the sales of such patents developed by the MID business unit under this expanded strategy represents a component of the Company's ongoing major or central operations, the Company records the related proceeds as revenue. As patent sales executed under this expanded strategy represent a component of the Company's ongoing major or central operations and activities, it will record the related proceeds as revenue. The Company will recognize the revenue when there is persuasive evidence of a sales arrangement, fees are fixed or determinable, delivery has occurred and collectibility is reasonably assured. These requirements are generally fulfilled upon closing of the patent sale transaction. Rambus’ revenue consists of royalty revenue and contract and other revenue derived from MID, Cryptography Research Inc. ("CRI") and Lighting and Display Technologies ("LDT") operating segments. Royalty revenue consists of patent license and solutions license royalties. Contract and other revenue consists of fixed license fees, fixed engineering fees and service fees associated with integration of Rambus’ technology solutions into its customers’ products as well as sale of LED edge-lit products.
Royalty Revenue	Royalty Revenue Rambus recognizes royalty revenue upon notification by its customers and when deemed collectible. The terms of the royalty agreements generally either require customers to give Rambus notification and to pay the royalties within a specified period or are based on a fixed royalty that is due within a specified period. Many of Rambus’ customers have the right to cancel their licenses. In such arrangements, revenue is only recognized to the extent that is consistent with the cancellation provisions. Cancellation provisions within such contracts generally provide for a prospective cancellation with no refund of fees already remitted by customers for products provided and payment for services rendered prior to the date of cancellation. Rambus has two types of royalty revenue: (1) patent license royalties and (2) solutions license royalties. Patent licenses - Rambus licenses its broad portfolio of patented inventions to companies who use these inventions in the development and manufacture of their own products. Such licensing agreements may cover the license of part, or all, of Rambus' patent portfolio. The contractual terms of the agreements generally provide for payments over an extended period of time. For the licensing agreements with fixed royalty payments, Rambus generally recognizes revenue from these arrangements as amounts become due. For the licensing agreements with variable royalty payments which can be based on either a percentage of sales or number of units sold, Rambus earns royalties at the time that the customers’ sales occur. Rambus’ customers, however, do not report and pay royalties owed for sales in any given quarter until after the conclusion of that quarter. As Rambus is unable to estimate the customers’ sales in any given quarter to determine the royalties due to Rambus, it recognizes royalty revenues based on royalties reported by customers during the quarter and when other revenue recognition criteria are met. In addition, Rambus may enter into certain settlements of patent infringement disputes. The amount of consideration received upon any settlement (including but not limited to past royalty payments, future royalty payments and punitive damages) is allocated to each element of the settlement based on the fair value of each element. In addition, revenues related to past royalties are recognized upon execution of the agreement by both parties, provided that the amounts are fixed or determinable, there are no significant undelivered obligations and collectability is reasonably assured. Rambus does not recognize any revenues prior to execution of the agreement since there is no reliable basis on which it can estimate the amounts for royalties related to previous periods or assess collectability. Elements that are related to royalty revenue in nature (including but not limited to past royalty payments and future royalty payments) will be recorded as royalty revenue in the consolidated statements of operations. Elements that are not related to royalty revenue in nature (including but not limited to punitive damage and settlement) will be recorded as gain from settlement which is reflected as a separate line item within the operating expenses section in the consolidated statements of operations. Solutions licenses - Rambus develops proprietary and industry-standard products that it provides to its customers under solutions license agreements. These arrangements include royalties, which can be based on either a percentage of sales or number of units sold. Rambus earns royalties on such licensed products sold worldwide by its customers at the time that the customers’ sales occur. Rambus’ customers, however, do not report and pay royalties owed for sales in any given quarter until after the conclusion of that quarter. As Rambus is unable to estimate the customers’ sales in any given quarter to determine the royalties due to Rambus, it recognizes royalty revenues based on royalties reported by customers during the quarter and when other revenue recognition criteria are met.
Contract and Other Revenue	Contract and Other Revenue Rambus recognizes revenue from the sale of LED edge-lit products when risk of loss and title have transferred to customers, provided all other revenue recognition criteria have been met. Revenue from distributors is recognized on the shipment or delivery of the related products, provided all other revenue recognition criteria have been met. The Company's agreements with these distributors have terms which are generally consistent with the standard terms and conditions for the sale of the Company's products to end users, and do not provide for product rotation or pricing allowances. The Company accrues for sales returns and warranty based on the standard market experience, none of which are currently material. Rambus generally recognizes revenue using percentage of completion for development contracts related to licenses of its solutions that involve significant engineering and integration services. For agreements accounted for using the percentage-of-completion method, Rambus determines progress to completion using input measures based upon contract costs incurred.
Goodwill and Intangible Assets	Goodwill Goodwill represents the excess of the purchase price over the fair value of the net tangible and identifiable intangible assets acquired in each business combination. Goodwill is not subject to amortization, but is subject to at least an annual assessment for impairment, applying a fair-value based test. The Company performs its impairment analysis of goodwill on an annual basis during the fourth quarter of the year unless conditions arise that warrant a more frequent evaluation. Goodwill is allocated to the various reporting units which are generally operating segments. The goodwill impairment test involves a two-step process. In the first step, the Company compares the fair value of each reporting unit to its carrying value. The fair values of the reporting units are estimated using an income or discounted cash flows approach. Under the income approach, the Company measures fair value of the reporting unit based on a projected cash flow method using a discount rate determined by its management which is commensurate with the risk inherent in its current business model. The Company’s discounted cash flow projections are based on its annual financial forecasts developed internally by management for use in managing its business. If the fair value of the reporting unit exceeds its carrying value, goodwill is not impaired and no further testing is required. If the fair value of the reporting unit is less than the carrying value, the Company must perform the second step of the impairment test to measure the amount of impairment loss. In the second step, the reporting unit's fair value is allocated to all of the assets and liabilities of the reporting unit, including any unrecognized intangible assets, in a hypothetical analysis that calculates the implied fair value of goodwill in the same manner as if the reporting unit was being acquired by a market participant in a business combination. If the implied fair value of the reporting unit's goodwill is less than the carrying value, the difference is recorded as an impairment loss. In the third quarter of 2013, the Company performed an interim goodwill impairment analysis due to the curtailment of operations for its Mobile Technology Division ("MTD") reporting unit which resulted in an impairment of all of the MTD reporting unit's goodwill. See Note 6, "Intangible Assets and Goodwill" for further details. The Company also performed its annual goodwill impairment analysis as of December 31, 2013 and determined that the fair value of the reporting units with goodwill exceeded their carrying values. Intangible Assets Intangible assets are comprised of existing technology, customer contracts and contractual relationships, and other intangible assets. Identifiable intangible assets resulting from the acquisitions of entities accounted for using the purchase method of accounting are estimated by management based on the fair value of assets received. Identifiable intangible assets are being amortized over the period of estimated benefit using the straight-line method and estimated useful lives ranging from 1 to 10 years.
Property, Plant and Equipment	Property, Plant and Equipment Property, plant and equipment includes computer equipment, computer software, machinery, leasehold improvements, furniture and fixtures and buildings. Computer equipment, computer software, machinery and furniture and fixtures are stated at cost and generally depreciated on a straight-line basis over an estimated useful life of 3, 3 to 5, 7 and 3 years, respectively. The Company undertook a series of structural improvements to ready the Sunnyvale and Brecksville facilities for its use. The Company concluded that its requirement to fund construction costs and responsibility for cost overruns resulted in the Company being considered the owner of the buildings during the construction period for accounting purposes. Upon completion of construction, the Company concluded that it retained sufficient continuing involvement to preclude de-recognition of the buildings under the Financial Accounting Standards Board ("FASB") authoritative guidance applicable to sale leaseback for real estate. As such, the Company continues to account for the buildings as owned real estate and to record an imputed financing obligation for its obligation to the legal owners. The buildings will be depreciated on a straight-line basis over an estimated useful life of approximately 39 years. See Note 10, “Balance Sheet Details,” and Note 12, “Commitments and Contingencies,” for additional details. Leasehold improvements are amortized on a straight-line basis over the shorter of their estimated useful lives or the initial terms of the leases. Upon disposal, assets and related accumulated depreciation are removed from the accounts and the related gain or loss is included in the results from operations.
Long-Lived Assets Impairment	Long-lived Asset Impairment The Company evaluates long-lived assets (including property, plant and equipment and intangible assets) for impairment whenever events or changes in circumstances indicate the carrying value of an asset group may not be recoverable. The carrying value is not recoverable if it exceeds the undiscounted cash flows resulting from the use of the asset group and its eventual disposition. The Company’s estimates of future cash flows attributable to its long-lived asset groups require significant judgment based on its historical and anticipated results and are subject to many factors. Factors that the Company considers important which could trigger an impairment review include significant negative industry or economic trends, significant loss of clients, and significant changes in the manner of its use of the acquired assets or the strategy for its overall business. When the Company determines that the carrying value of the long-lived asset groups may not be recoverable based upon the existence of one or more of the above indicators of impairment, the Company measures the potential impairment based on a projected discounted cash flow method using a discount rate determined by the Company to be commensurate with the risk inherent in the Company’s current business model. An impairment loss is recognized only if the carrying amount of the long-lived asset group is not recoverable and exceeds its fair value. The impairment charge is recorded to reduce the pre-impairment carrying amount of the long-lived assets based on the relative carrying amount of those assets, though not to reduce the carrying amount of an asset below its fair value. Different assumptions and judgments could materially affect the calculation of the fair value of the long-lived assets. During 2013, the Company recognized an impairment of its long-lived assets related to its LDT asset group and CRI favorable contract asset group. During 2012, the Company recognized an impairment of its long-lived and intangible assets related to its LDT asset group. See Note 6, "Intangible Assets and Goodwill" for further details. During 2011, Rambus did not recognize any impairment of its long-lived assets.
Litigation	Litigation Rambus is involved in certain legal proceedings. Based upon consultation with outside counsel handling its defense in these matters and an analysis of potential results, if Rambus believes that a loss arising from such matters is probable and can be reasonably estimated, Rambus records the estimated liability in its consolidated financial statements. If only a range of estimated losses can be determined, Rambus records an amount within the range that, in its judgment, reflects the most likely outcome; if none of the estimates within that range is a better estimate than any other amount, Rambus records the low end of the range. Any such accrual would be charged to expense in the appropriate period. Rambus recognizes litigation expenses in the period in which the litigation services were provided.
Income Taxes	Income Taxes Income taxes are accounted for using an asset and liability approach, which requires the recognition of deferred tax assets and liabilities for expected future tax events that have been recognized differently in Rambus' consolidated financial statements and tax returns. The measurement of current and deferred tax assets and liabilities is based on provisions of the enacted tax law and the effects of future changes in tax laws or rates are not anticipated. A valuation allowance is established when necessary to reduce deferred tax assets to amounts expected to be realized based on available evidence. In addition, the calculation of the Company's tax liabilities involves dealing with uncertainties in the application of complex tax regulations. As a result, the Company reports a liability for unrecognized tax benefits resulting from uncertain tax positions taken or expected to be taken in its tax return. The Company considers many factors when evaluating and estimating its tax positions and tax benefits, which may require periodic adjustments and which may not accurately anticipate actual outcomes.
Stock-Based Compensation and Equity Incentive Plans	Stock-Based Compensation and Equity Incentive Plans The Company maintained stock plans covering a broad range of equity grants including stock options, nonvested equity stock and equity stock units and performance based instruments. In addition, the Company sponsors an Employee Stock Purchase Plan (“ESPP”), whereby eligible employees are entitled to purchase Common Stock semi-annually, by means of limited payroll deductions, at a 15% discount from the fair market value of the Common Stock as of specific dates. The Company determines compensation expense associated with restricted stock units based on the fair value of its common stock on the date of grant. The Company determines compensation expense associated with stock options based on the estimated grant date fair value method using the Black-Scholes Merton valuation model. The Company generally recognizes compensation expense using a straight-line amortization method over the respective vesting period for awards that are ultimately expected to vest. Accordingly, stock-based compensation expense for 2013, 2012 and 2011 has been reduced for estimated forfeitures. When estimating forfeitures, the Company considers voluntary termination behaviors as well as trends of actual option forfeitures. The Company will only recognize a tax benefit from stock-based awards in additional paid-in capital if an incremental tax benefit is realized after all other tax attributes currently available have been utilized. In addition, the Company has elected to account for the indirect effects of stock-based awards on other tax attributes, such as the research tax credits, through the consolidated statement of operations as part of the tax effect of stock-based compensation.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash equivalents are highly liquid investments with original maturity of three months or less at the date of purchase. The Company maintains its cash balances with high quality financial institutions. Cash equivalents are invested in highly-rated and highly-liquid money market securities and certain U.S. government sponsored obligations.
Marketable Securities	Marketable Securities Available-for-sale securities are carried at fair value, based on quoted market prices, with the unrealized gains or losses reported, net of tax, in stockholders’ equity as part of accumulated other comprehensive income (loss). The amortized cost of debt securities is adjusted for amortization of premiums and accretion of discounts to maturity, both of which are included in interest and other income, net. Realized gains and losses are recorded on the specific identification method and are included in interest and other income, net. The Company reviews its investments in marketable securities for possible other than temporary impairments on a regular basis. If any loss on investment is believed to be a credit loss, a charge will be recognized in operations. In evaluating whether a credit loss on a debt security has occurred, the Company considers the following factors: 1) the Company’s intent to sell the security, 2) if the Company intends to hold the security, whether or not it is more likely than not that the Company will be required to sell the security before recovery of the security’s amortized cost basis and 3) even if the Company intends to hold the security, whether or not the Company expects the security to recover the entire amortized cost basis. Due to the high credit quality and short term nature of the Company’s investments, there have been no credit losses recorded to date. The classification of funds between short-term and long-term is based on whether the securities are available for use in operations or other purposes.
Non-Marketable Securities	Non-Marketable Securities The Company has an investment in a non-marketable security of a private company which is carried at cost. The Company monitors the investment for other-than-temporary impairment and records appropriate reductions in carrying value when necessary. The non-marketable security is classified within other assets in the consolidated balance sheets.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The carrying value of cash equivalents, accounts receivable and accounts payable approximate their fair values due to their relatively short maturities as of December 31, 2013 and 2012. Marketable securities are comprised of available-for-sale securities that are reported at fair value with the related unrealized gains and losses included in accumulated other comprehensive income (loss), a component of stockholders’ equity, net of tax. Fair value of the marketable securities is determined based on quoted market prices. The fair market value of the Company's convertible notes fluctuates with interest rates and with the market price of the stock, but does not affect the carrying value of the debt on the balance sheet.
Research and Development	Research and Development Costs incurred in research and development, which include engineering expenses, such as salaries and related benefits, stock-based compensation, depreciation, professional services and overhead expenses related to the general development of Rambus’ products, are expensed as incurred. Software development costs are capitalized beginning when a product’s technological feasibility has been established and ending when a product is available for general release to customers. Rambus has not capitalized any software development costs since the period between establishing technological feasibility and general customer release is relatively short and as such, these costs have not been material.
Computation of Earnings (Loss) Per Share	Computation of Earnings (Loss) Per Share Basic earnings (loss) per share is calculated by dividing the net income (loss) by the weighted average number of common shares outstanding during the period. Diluted earnings (loss) per share is calculated by dividing the earnings (loss) by the weighted average number of common shares and potentially dilutive securities outstanding during the period. Potentially dilutive common shares consist of incremental common shares issuable upon exercise of stock options, employee stock purchases, restricted stock and restricted stock units, and shares issuable upon the conversion of convertible notes. The dilutive effect of outstanding shares is reflected in diluted earnings per share by application of the treasury stock method. This method includes consideration of the amounts to be paid by the employees, the amount of excess tax benefits that would be recognized in equity if the instrument was exercised and the amount of unrecognized stock-based compensation related to future services. No potential dilutive common shares are included in the computation of any diluted per share amount when a net loss is reported. The Company reported approximately 4.8 million shares issued to Samsung as contingently redeemable common stock due to the contractual put rights associated with those shares. As such, the Company used the two-class method for reporting earnings per share for those periods where the contingently redeemable common stock was outstanding (until August 2011) prior to Samsung's redemption of the shares.
Comprehensive Income (Loss)	Comprehensive Income (Loss) Comprehensive income (loss) is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources, including foreign currency translation adjustments and unrealized gains and losses on marketable securities. Other comprehensive income (loss), net of tax, is presented in the consolidated statements of comprehensive income (loss).
Credit Concentration	Credit Concentration As of December 31, 2013 and 2012, the Company’s cash, cash equivalents and marketable securities were invested with various financial institutions in the form of corporate notes, bonds and commercial paper, money market funds, U.S. government bonds and notes, and municipal bonds and notes. The Company’s exposure to market risk for changes in interest rates relates primarily to its investment portfolio. The Company places its investments with high credit issuers and, by investment policy, attempts to limit the amount of credit exposure to any one issuer. As stated in the Company’s investment policy, it will ensure the safety and preservation of the Company’s invested funds by limiting default risk and market risk. The Company has no investments denominated in foreign country currencies and therefore is not subject to foreign exchange risk from these assets. The Company mitigates default risk by investing in high credit quality securities and by positioning its portfolio to respond appropriately to a significant reduction in a credit rating of any investment issuer or guarantor. The portfolio includes only marketable securities with active secondary or resale markets to enable portfolio liquidity. The Company's accounts receivable are derived from revenue earned from customers located in the U.S. and internationally. As of December 31, 2013, one customer accounted for approximately 73% of the total $2.3 million of accounts receivable. The Company's accounts receivable balance as of December 31, 2012 was not material.
Foreign Currency Translation	Foreign Currency Remeasurement The Company’s foreign subsidiaries currently use the U.S. dollar as the functional currency. Remeasurement adjustments for non-functional currency monetary assets and liabilities are translated into U.S. dollars at the exchange rate in effect at the balance sheet date. Revenue, expenses, gains or losses are translated at the average exchange rate for the period, and non-monetary assets and liabilities are translated at historical rates. The remeasurement gains and losses of these foreign subsidiaries as well as gains and losses from foreign currency transactions are included in other expense, net in the consolidated statements of operations, and are not material for any periods presented.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2013

The accompanying consolidated financial statements include the accounts of Rambus and its wholly owned subsidiaries, Rambus K.K., located in Tokyo, Japan, Cryptography Research, Inc., located in California, U.S.A., Unity Semiconductor Corporation, located in California, U.S.A., Mozaik Multimedia, Inc., located in California, U.S.A., and Rambus Ltd., located in George Town, Grand Cayman Islands, British West Indies, which includes Rambus Chip Technologies (India) Private Limited, Rambus Deutschland GmbH, located in Pforzheim, Germany, Kamiyacho IP Holdings, Rambus Korea, Inc., located in Seoul, Korea and Rambus France, located in Paris, France. In addition, Rambus International Ltd. and Rambus Delaware LLC are also subsidiaries. All intercompany accounts and transactions have been eliminated in the accompanying consolidated financial statements. Investments in entities with less than 20% ownership by Rambus and in which Rambus does not have the ability to significantly influence the operations of the investee are accounted for using the cost method and are included in other assets.

Use of Estimates

The preparation of financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. Actual results could differ from those estimates.

Reclassifications

Certain prior year balances were reclassified to conform to the current year’s presentation. None of these reclassifications had an impact on reported net income (loss) or cash flows for any of the periods presented.

Revenue Recognition

Overview

Rambus recognizes revenue when persuasive evidence of an arrangement exists, Rambus has delivered the product or performed the service, the fee is fixed or determinable and collection is reasonably assured. If any of these criteria are not met, Rambus defers recognizing the revenue until such time as all criteria are met. Determination of whether or not these criteria have been met may require the Company to make judgments, assumptions and estimates based upon current information and historical experience.

Certain revenue contracts consist of service fees associated with integration of Rambus' solutions into its customers’ products and fees associated with providing training, evaluation and test equipment to its customers. Under the accounting guidance, if the deliverables have standalone value upon delivery, Rambus accounts for each deliverable separately. When multiple deliverables included in an arrangement are separated into different units of accounting, the arrangement consideration is allocated to the identified separate units based on a relative selling price hierarchy. Rambus determines the relative selling price for a deliverable based on its best estimate of selling price (“BESP”). Rambus has determined that vendor-specific objective evidence of selling price for each deliverable is not available as there lacks a consistent number of standalone sales and third-party evidence is not a practical alternative due to differences in its service offerings compared to other parties and the availability of relevant third-party pricing information. Rambus determined BESP by considering its overall pricing objectives and market conditions. Significant pricing practices taken into consideration include discounting practices, the size and volume of transactions, the customer demographic, the geographic area where services are sold, price lists, go-to-market strategy, historical standalone sales and contract prices. The determination of BESP is made through consultation with and approval by management, taking into consideration the go-to-market strategy. As the go-to-market strategies evolve, Rambus may modify its pricing practices in the future, which could result in changes in relative selling prices. In most cases, the relative values of the undelivered components are not material to the overall arrangement and are typically delivered within twelve months after the core product has been delivered. In such agreements, selling price is determined for each component and any difference between the total of the separate BESP and total contract consideration (i.e. discount) is allocated pro-rata across each of the components in the arrangement.

During 2013, the Company expanded its business strategy of monetizing its patent portfolio to include the sale of selected intellectual property. The Company's Memory and Interface Division ("MID") business continues to grow its patent portfolio and actively engage with various external parties to monetize the patent portfolio and explore new revenue opportunities. As the sales of such patents developed by the MID business unit under this expanded strategy represents a component of the Company's ongoing major or central operations, the Company records the related proceeds as revenue. As patent sales executed under this expanded strategy represent a component of the Company's ongoing major or central operations and activities, it will record the related proceeds as revenue. The Company will recognize the revenue when there is persuasive evidence of a sales arrangement, fees are fixed or determinable, delivery has occurred and collectibility is reasonably assured. These requirements are generally fulfilled upon closing of the patent sale transaction.

Rambus’ revenue consists of royalty revenue and contract and other revenue derived from MID, Cryptography Research Inc. ("CRI") and Lighting and Display Technologies ("LDT") operating segments. Royalty revenue consists of patent license and solutions license royalties. Contract and other revenue consists of fixed license fees, fixed engineering fees and service fees associated with integration of Rambus’ technology solutions into its customers’ products as well as sale of LED edge-lit products.

Royalty Revenue

Rambus recognizes royalty revenue upon notification by its customers and when deemed collectible. The terms of the royalty agreements generally either require customers to give Rambus notification and to pay the royalties within a specified period or are based on a fixed royalty that is due within a specified period. Many of Rambus’ customers have the right to cancel their licenses. In such arrangements, revenue is only recognized to the extent that is consistent with the cancellation provisions. Cancellation provisions within such contracts generally provide for a prospective cancellation with no refund of fees already remitted by customers for products provided and payment for services rendered prior to the date of cancellation. Rambus has two types of royalty revenue: (1) patent license royalties and (2) solutions license royalties.

Patent licenses - Rambus licenses its broad portfolio of patented inventions to companies who use these inventions in the development and manufacture of their own products. Such licensing agreements may cover the license of part, or all, of Rambus' patent portfolio. The contractual terms of the agreements generally provide for payments over an extended period of time. For the licensing agreements with fixed royalty payments, Rambus generally recognizes revenue from these arrangements as amounts become due. For the licensing agreements with variable royalty payments which can be based on either a percentage of sales or number of units sold, Rambus earns royalties at the time that the customers’ sales occur. Rambus’ customers, however, do not report and pay royalties owed for sales in any given quarter until after the conclusion of that quarter. As Rambus is unable to estimate the customers’ sales in any given quarter to determine the royalties due to Rambus, it recognizes royalty revenues based on royalties reported by customers during the quarter and when other revenue recognition criteria are met.

In addition, Rambus may enter into certain settlements of patent infringement disputes. The amount of consideration received upon any settlement (including but not limited to past royalty payments, future royalty payments and punitive damages) is allocated to each element of the settlement based on the fair value of each element. In addition, revenues related to past royalties are recognized upon execution of the agreement by both parties, provided that the amounts are fixed or determinable, there are no significant undelivered obligations and collectability is reasonably assured. Rambus does not recognize any revenues prior to execution of the agreement since there is no reliable basis on which it can estimate the amounts for royalties related to previous periods or assess collectability. Elements that are related to royalty revenue in nature (including but not limited to past royalty payments and future royalty payments) will be recorded as royalty revenue in the consolidated statements of operations. Elements that are not related to royalty revenue in nature (including but not limited to punitive damage and settlement) will be recorded as gain from settlement which is reflected as a separate line item within the operating expenses section in the consolidated statements of operations.

Solutions licenses - Rambus develops proprietary and industry-standard products that it provides to its customers under solutions license agreements. These arrangements include royalties, which can be based on either a percentage of sales or number of units sold. Rambus earns royalties on such licensed products sold worldwide by its customers at the time that the customers’ sales occur. Rambus’ customers, however, do not report and pay royalties owed for sales in any given quarter until after the conclusion of that quarter. As Rambus is unable to estimate the customers’ sales in any given quarter to determine the royalties due to Rambus, it recognizes royalty revenues based on royalties reported by customers during the quarter and when other revenue recognition criteria are met.

Contract and Other Revenue

Rambus recognizes revenue from the sale of LED edge-lit products when risk of loss and title have transferred to customers, provided all other revenue recognition criteria have been met. Revenue from distributors is recognized on the shipment or delivery of the related products, provided all other revenue recognition criteria have been met. The Company's agreements with these distributors have terms which are generally consistent with the standard terms and conditions for the sale of the Company's products to end users, and do not provide for product rotation or pricing allowances. The Company accrues for sales returns and warranty based on the standard market experience, none of which are currently material.

Rambus generally recognizes revenue using percentage of completion for development contracts related to licenses of its solutions that involve significant engineering and integration services. For agreements accounted for using the percentage-of-completion method, Rambus determines progress to completion using input measures based upon contract costs incurred.

Goodwill and Intangible Assets

Goodwill

Goodwill represents the excess of the purchase price over the fair value of the net tangible and identifiable intangible assets acquired in each business combination. Goodwill is not subject to amortization, but is subject to at least an annual assessment for impairment, applying a fair-value based test. The Company performs its impairment analysis of goodwill on an annual basis during the fourth quarter of the year unless conditions arise that warrant a more frequent evaluation.

Goodwill is allocated to the various reporting units which are generally operating segments. The goodwill impairment test involves a two-step process. In the first step, the Company compares the fair value of each reporting unit to its carrying value. The fair values of the reporting units are estimated using an income or discounted cash flows approach.

Under the income approach, the Company measures fair value of the reporting unit based on a projected cash flow method using a discount rate determined by its management which is commensurate with the risk inherent in its current business model. The Company’s discounted cash flow projections are based on its annual financial forecasts developed internally by management for use in managing its business. If the fair value of the reporting unit exceeds its carrying value, goodwill is not impaired and no further testing is required. If the fair value of the reporting unit is less than the carrying value, the Company must perform the second step of the impairment test to measure the amount of impairment loss. In the second step, the reporting unit's fair value is allocated to all of the assets and liabilities of the reporting unit, including any unrecognized intangible assets, in a hypothetical analysis that calculates the implied fair value of goodwill in the same manner as if the reporting unit was being acquired by a market participant in a business combination. If the implied fair value of the reporting unit's goodwill is less than the carrying value, the difference is recorded as an impairment loss.

In the third quarter of 2013, the Company performed an interim goodwill impairment analysis due to the curtailment of operations for its Mobile Technology Division ("MTD") reporting unit which resulted in an impairment of all of the MTD reporting unit's goodwill. See Note 6, "Intangible Assets and Goodwill" for further details. The Company also performed its annual goodwill impairment analysis as of December 31, 2013 and determined that the fair value of the reporting units with goodwill exceeded their carrying values.

Intangible Assets

Intangible assets are comprised of existing technology, customer contracts and contractual relationships, and other intangible assets. Identifiable intangible assets resulting from the acquisitions of entities accounted for using the purchase method of accounting are estimated by management based on the fair value of assets received. Identifiable intangible assets are being amortized over the period of estimated benefit using the straight-line method and estimated useful lives ranging from 1 to 10 years.

Property, Plant and Equipment

Property, plant and equipment includes computer equipment, computer software, machinery, leasehold improvements, furniture and fixtures and buildings. Computer equipment, computer software, machinery and furniture and fixtures are stated at cost and generally depreciated on a straight-line basis over an estimated useful life of 3, 3 to 5, 7 and 3 years, respectively. The Company undertook a series of structural improvements to ready the Sunnyvale and Brecksville facilities for its use. The Company concluded that its requirement to fund construction costs and responsibility for cost overruns resulted in the Company being considered the owner of the buildings during the construction period for accounting purposes. Upon completion of construction, the Company concluded that it retained sufficient continuing involvement to preclude de-recognition of the buildings under the Financial Accounting Standards Board ("FASB") authoritative guidance applicable to sale leaseback for real estate. As such, the Company continues to account for the buildings as owned real estate and to record an imputed financing obligation for its obligation to the legal owners. The buildings will be depreciated on a straight-line basis over an estimated useful life of approximately 39 years. See Note 10, “Balance Sheet Details,” and Note 12, “Commitments and Contingencies,” for additional details. Leasehold improvements are amortized on a straight-line basis over the shorter of their estimated useful lives or the initial terms of the leases. Upon disposal, assets and related accumulated depreciation are removed from the accounts and the related gain or loss is included in the results from operations.

Long-Lived Assets Impairment

Long-lived Asset Impairment

The Company evaluates long-lived assets (including property, plant and equipment and intangible assets) for impairment whenever events or changes in circumstances indicate the carrying value of an asset group may not be recoverable. The carrying value is not recoverable if it exceeds the undiscounted cash flows resulting from the use of the asset group and its eventual disposition. The Company’s estimates of future cash flows attributable to its long-lived asset groups require significant judgment based on its historical and anticipated results and are subject to many factors. Factors that the Company considers important which could trigger an impairment review include significant negative industry or economic trends, significant loss of clients, and significant changes in the manner of its use of the acquired assets or the strategy for its overall business.

When the Company determines that the carrying value of the long-lived asset groups may not be recoverable based upon the existence of one or more of the above indicators of impairment, the Company measures the potential impairment based on a projected discounted cash flow method using a discount rate determined by the Company to be commensurate with the risk inherent in the Company’s current business model. An impairment loss is recognized only if the carrying amount of the long-lived asset group is not recoverable and exceeds its fair value. The impairment charge is recorded to reduce the pre-impairment carrying amount of the long-lived assets based on the relative carrying amount of those assets, though not to reduce the carrying amount of an asset below its fair value. Different assumptions and judgments could materially affect the calculation of the fair value of the long-lived assets. During 2013, the Company recognized an impairment of its long-lived assets related to its LDT asset group and CRI favorable contract asset group. During 2012, the Company recognized an impairment of its long-lived and intangible assets related to its LDT asset group. See Note 6, "Intangible Assets and Goodwill" for further details. During 2011, Rambus did not recognize any impairment of its long-lived assets.

Litigation

Rambus is involved in certain legal proceedings. Based upon consultation with outside counsel handling its defense in these matters and an analysis of potential results, if Rambus believes that a loss arising from such matters is probable and can be reasonably estimated, Rambus records the estimated liability in its consolidated financial statements. If only a range of estimated losses can be determined, Rambus records an amount within the range that, in its judgment, reflects the most likely outcome; if none of the estimates within that range is a better estimate than any other amount, Rambus records the low end of the range. Any such accrual would be charged to expense in the appropriate period. Rambus recognizes litigation expenses in the period in which the litigation services were provided.

Income Taxes

Income taxes are accounted for using an asset and liability approach, which requires the recognition of deferred tax assets and liabilities for expected future tax events that have been recognized differently in Rambus' consolidated financial statements and tax returns. The measurement of current and deferred tax assets and liabilities is based on provisions of the enacted tax law and the effects of future changes in tax laws or rates are not anticipated. A valuation allowance is established when necessary to reduce deferred tax assets to amounts expected to be realized based on available evidence.

In addition, the calculation of the Company's tax liabilities involves dealing with uncertainties in the application of complex tax regulations. As a result, the Company reports a liability for unrecognized tax benefits resulting from uncertain tax positions taken or expected to be taken in its tax return. The Company considers many factors when evaluating and estimating its tax positions and tax benefits, which may require periodic adjustments and which may not accurately anticipate actual outcomes.

Stock-Based Compensation and Equity Incentive Plans

The Company maintained stock plans covering a broad range of equity grants including stock options, nonvested equity stock and equity stock units and performance based instruments. In addition, the Company sponsors an Employee Stock Purchase Plan (“ESPP”), whereby eligible employees are entitled to purchase Common Stock semi-annually, by means of limited payroll deductions, at a 15% discount from the fair market value of the Common Stock as of specific dates.

The Company determines compensation expense associated with restricted stock units based on the fair value of its common stock on the date of grant. The Company determines compensation expense associated with stock options based on the estimated grant date fair value method using the Black-Scholes Merton valuation model. The Company generally recognizes compensation expense using a straight-line amortization method over the respective vesting period for awards that are ultimately expected to vest. Accordingly, stock-based compensation expense for 2013, 2012 and 2011 has been reduced for estimated forfeitures. When estimating forfeitures, the Company considers voluntary termination behaviors as well as trends of actual option forfeitures. The Company will only recognize a tax benefit from stock-based awards in additional paid-in capital if an incremental tax benefit is realized after all other tax attributes currently available have been utilized. In addition, the Company has elected to account for the indirect effects of stock-based awards on other tax attributes, such as the research tax credits, through the consolidated statement of operations as part of the tax effect of stock-based compensation.

Cash and Cash Equivalents

Cash equivalents are highly liquid investments with original maturity of three months or less at the date of purchase. The Company maintains its cash balances with high quality financial institutions. Cash equivalents are invested in highly-rated and highly-liquid money market securities and certain U.S. government sponsored obligations.

Marketable Securities

Available-for-sale securities are carried at fair value, based on quoted market prices, with the unrealized gains or losses reported, net of tax, in stockholders’ equity as part of accumulated other comprehensive income (loss). The amortized cost of debt securities is adjusted for amortization of premiums and accretion of discounts to maturity, both of which are included in interest and other income, net. Realized gains and losses are recorded on the specific identification method and are included in interest and other income, net. The Company reviews its investments in marketable securities for possible other than temporary impairments on a regular basis. If any loss on investment is believed to be a credit loss, a charge will be recognized in operations. In evaluating whether a credit loss on a debt security has occurred, the Company considers the following factors: 1) the Company’s intent to sell the security, 2) if the Company intends to hold the security, whether or not it is more likely than not that the Company will be required to sell the security before recovery of the security’s amortized cost basis and 3) even if the Company intends to hold the security, whether or not the Company expects the security to recover the entire amortized cost basis. Due to the high credit quality and short term nature of the Company’s investments, there have been no credit losses recorded to date. The classification of funds between short-term and long-term is based on whether the securities are available for use in operations or other purposes.

Non-Marketable Securities

The Company has an investment in a non-marketable security of a private company which is carried at cost. The Company monitors the investment for other-than-temporary impairment and records appropriate reductions in carrying value when necessary. The non-marketable security is classified within other assets in the consolidated balance sheets.

Fair Value of Financial Instruments

The carrying value of cash equivalents, accounts receivable and accounts payable approximate their fair values due to their relatively short maturities as of December 31, 2013 and 2012. Marketable securities are comprised of available-for-sale securities that are reported at fair value with the related unrealized gains and losses included in accumulated other comprehensive income (loss), a component of stockholders’ equity, net of tax. Fair value of the marketable securities is determined based on quoted market prices. The fair market value of the Company's convertible notes fluctuates with interest rates and with the market price of the stock, but does not affect the carrying value of the debt on the balance sheet.

Research and Development

Costs incurred in research and development, which include engineering expenses, such as salaries and related benefits, stock-based compensation, depreciation, professional services and overhead expenses related to the general development of Rambus’ products, are expensed as incurred. Software development costs are capitalized beginning when a product’s technological feasibility has been established and ending when a product is available for general release to customers. Rambus has not capitalized any software development costs since the period between establishing technological feasibility and general customer release is relatively short and as such, these costs have not been material.

Computation of Earnings (Loss) Per Share

Basic earnings (loss) per share is calculated by dividing the net income (loss) by the weighted average number of common shares outstanding during the period. Diluted earnings (loss) per share is calculated by dividing the earnings (loss) by the weighted average number of common shares and potentially dilutive securities outstanding during the period. Potentially dilutive common shares consist of incremental common shares issuable upon exercise of stock options, employee stock purchases, restricted stock and restricted stock units, and shares issuable upon the conversion of convertible notes. The dilutive effect of outstanding shares is reflected in diluted earnings per share by application of the treasury stock method. This method includes consideration of the amounts to be paid by the employees, the amount of excess tax benefits that would be recognized in equity if the instrument was exercised and the amount of unrecognized stock-based compensation related to future services. No potential dilutive common shares are included in the computation of any diluted per share amount when a net loss is reported. The Company reported approximately 4.8 million shares issued to Samsung as contingently redeemable common stock due to the contractual put rights associated with those shares. As such, the Company used the two-class method for reporting earnings per share for those periods where the contingently redeemable common stock was outstanding (until August 2011) prior to Samsung's redemption of the shares.

Comprehensive Income (Loss)

Comprehensive income (loss) is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources, including foreign currency translation adjustments and unrealized gains and losses on marketable securities. Other comprehensive income (loss), net of tax, is presented in the consolidated statements of comprehensive income (loss).

Credit Concentration

As of December 31, 2013 and 2012, the Company’s cash, cash equivalents and marketable securities were invested with various financial institutions in the form of corporate notes, bonds and commercial paper, money market funds, U.S. government bonds and notes, and municipal bonds and notes. The Company’s exposure to market risk for changes in interest rates relates primarily to its investment portfolio. The Company places its investments with high credit issuers and, by investment policy, attempts to limit the amount of credit exposure to any one issuer. As stated in the Company’s investment policy, it will ensure the safety and preservation of the Company’s invested funds by limiting default risk and market risk. The Company has no investments denominated in foreign country currencies and therefore is not subject to foreign exchange risk from these assets.

The Company mitigates default risk by investing in high credit quality securities and by positioning its portfolio to respond appropriately to a significant reduction in a credit rating of any investment issuer or guarantor. The portfolio includes only marketable securities with active secondary or resale markets to enable portfolio liquidity.

The Company's accounts receivable are derived from revenue earned from customers located in the U.S. and internationally. As of December 31, 2013, one customer accounted for approximately 73% of the total $2.3 million of accounts receivable. The Company's accounts receivable balance as of December 31, 2012 was not material.

Foreign Currency Translation

Foreign Currency Remeasurement

The Company’s foreign subsidiaries currently use the U.S. dollar as the functional currency. Remeasurement adjustments for non-functional currency monetary assets and liabilities are translated into U.S. dollars at the exchange rate in effect at the balance sheet date. Revenue, expenses, gains or losses are translated at the average exchange rate for the period, and non-monetary assets and liabilities are translated at historical rates. The remeasurement gains and losses of these foreign subsidiaries as well as gains and losses from foreign currency transactions are included in other expense, net in the consolidated statements of operations, and are not material for any periods presented.