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Equity Incentive Plans and Stock-Based Compensation (Details 5) (USD $) | 1 Months Ended | 3 Months Ended | 0 Months Ended | 12 Months Ended | 0 Months Ended | 1 Months Ended |  |
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Apr. 30, 2009 | Jun. 30, 2012 | Apr. 24, 2014 | Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012 | Sep. 27, 2013 | Apr. 30, 2012 | Mar. 31, 2006 | Dec. 31, 2011
Stock-Based Compensation |  |  |  |  |  |  |  |  |  |
Number of shares reserved under the 2006 Purchase Plan |  |  |  | 31,400,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized |  |  |  |  | 8,400,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized |
Increase in shares approved for issuance | 6,500,000 rmbs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAdditionalNumberOfSharesAuthorized | 6,500,000 rmbs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAdditionalNumberOfSharesAuthorized |  |  |  |  |  |  |  |
Stock Compensation Plan |  |  |  |  |  |  |  |  |  |
Stock-Based Compensation |  |  |  |  |  |  |  |  |  |
Increase in shares approved for issuance |  |  | 10,000,000 rmbs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAdditionalNumberOfSharesAuthorized / us-gaap_AwardTypeAxis = us-gaap_StockCompensationPlanMember |  |  |  |  |  |  |
Shares available for issuance |  |  |  | 10,724,228.000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant / us-gaap_AwardTypeAxis = us-gaap_StockCompensationPlanMember |  |  |  |  |  |
Valuation assumptions |  |  |  |  |  |  |  |  |  |
Dividend yield (as a percent) |  |  |  | 0.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate / us-gaap_AwardTypeAxis = us-gaap_StockCompensationPlanMember | 0.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate / us-gaap_AwardTypeAxis = us-gaap_StockCompensationPlanMember | 0.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate / us-gaap_AwardTypeAxis = us-gaap_StockCompensationPlanMember |  |  |  |
Employee Stock Purchase Plans |  |  |  |  |  |  |  |  |  |
Stock-Based Compensation |  |  |  |  |  |  |  |  |  |
Number of employee stock purchase plans |  |  |  | 1 rmbs_EmployeeStockPurchasePlansNumber / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember | 1 rmbs_EmployeeStockPurchasePlansNumber / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember | 1 rmbs_EmployeeStockPurchasePlansNumber / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember |  |  |  |
Minimum number of hours of weekly employment in order to qualify for eligibility in the plan |  |  |  | 20 hours | 20 hours | 20 hours |  |  |  |
Number of shares reserved under the 2006 Purchase Plan |  |  |  |  |  |  |  |  | 1,600,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember |
Employee Stock Purchase Plan, Number Of Additional SharesToBe Authorized |  |  |  |  |  |  | 1,500,000 rmbs_EmployeeStockPurchasePlanNumberOfAdditionalSharesToBeAuthorized / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized |  |  |  |  |  |  | 1,500,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember | 1,500,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember |  |
Minimum number of months of employment in a fiscal year in order to qualify for eligibility in the plan |  |  |  | 5 months | 5 months | 5 months |  |  |  |
Offering period (in months) |  |  |  | 6 months | 6 months | 6 months |  |  |  |
Percentage of the price at the beginning of the offering period or price at the end of each offering period to derive purchase price |  |  |  | 85.00%rmbs_EmployeeStockPurchasePlanPercentageOfPriceAtBeginningOfOfferingPeriodOrPriceAtEndOfEachOfferingPeriodToDerivePurchasePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember | 85.00%rmbs_EmployeeStockPurchasePlanPercentageOfPriceAtBeginningOfOfferingPeriodOrPriceAtEndOfEachOfferingPeriodToDerivePurchasePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember | 85.00%rmbs_EmployeeStockPurchasePlanPercentageOfPriceAtBeginningOfOfferingPeriodOrPriceAtEndOfEachOfferingPeriodToDerivePurchasePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember |  |  |  |
Maximum share value per employee in any calendar year |  |  |  | 25,000 rmbs_EmployeeStockPurchasePlanMaximumShareValueUptoWhichEmployeesMayPurchaseShares / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember | 25,000 rmbs_EmployeeStockPurchasePlanMaximumShareValueUptoWhichEmployeesMayPurchaseShares / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember | 25,000 rmbs_EmployeeStockPurchasePlanMaximumShareValueUptoWhichEmployeesMayPurchaseShares / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember |  |  |  |
Shares issued under employee stock purchase plans |  |  |  | 596,188 us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember | 1,063,283 us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember | 731,449 us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember |  |  |  |
Weighted average price per share of shares issued (in dollars per share) |  |  |  | 8.25 rmbs_EmployeeStockPurchasePlansWeightedAveragePricePerShare / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember | 4.87 rmbs_EmployeeStockPurchasePlansWeightedAveragePricePerShare / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember | 4.21 rmbs_EmployeeStockPurchasePlansWeightedAveragePricePerShare / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember |  |  |  |
Shares available for issuance |  |  |  | 923,044 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember |  |  |  |  |  |
Stock-based compensation |  |  |  | 2,600,000 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember | 1,500,000 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember | 2,200,000 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember |  |  |  |
Unrecognized compensation cost net of expected forfeitures |  |  |  | 700,000 us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember |  |  |  |  |  |
Expected weighted-average period for recognition of compensation cost (in years) |  |  |  | 4 months |  |  |  |  |  |
Valuation assumptions |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate |  |  |  |  | 0.10%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember | 0.20%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember |  |  |  |
Expected stock price volatility rate minimum (as a percent) |  |  |  | 39.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember | 44.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember | 56.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember |  |  |  |
Expected stock price volatility rate maximum (as a percent) |  |  |  | 44.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember | 48.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember | 63.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember |  |  |  |
Risk free interest rate minimum (as a percent) |  |  |  | 0.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember |  |  |  |  |  |
Risk free interest rate maximum (as a percent) |  |  |  | 0.10%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember |  |  |  |  |  |
Expected term (in years) |  |  |  |  | 0 years 6 months | 0 years 6 months |  |  |  |
Weighted-average fair value of purchase rights granted under the purchase plan (in dollars per share) |  |  |  | 3.57 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember | 1.96 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember | 1.58 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember |  |  |  |
Weighted-Average Grant-Date Fair Value |  |  |  |  |  |  |  |  |  |
Granted (in dollars per share) |  |  |  | 3.57 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember | 1.96 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember | 1.58 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockMember |  |  |  |
Stock Option Plans |  |  |  |  |  |  |  |  |  |
Stock-Based Compensation |  |  |  |  |  |  |  |  |  |
Options granted (in shares) |  |  |  | 2,370,313 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | 2,084,276 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | 7,789,220 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |  |  |  |
Estimated total grant date fair value |  |  |  | 10,100,000 rmbs_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodTotalFairValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | 5,400,000 rmbs_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodTotalFairValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | 32,700,000 rmbs_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodTotalFairValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |  |  |  |
Stock-based compensation |  |  |  | 9,300,000 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | 10,400,000 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | 15,000,000 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |  |  |  |
Unrecognized compensation cost net of expected forfeitures |  |  |  | 13,600,000 us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |  |  |  |  |  |
Expected weighted-average period for recognition of compensation cost (in years) |  |  |  | 1 year 11 months 19 days |  |  |  |  |  |
Total fair value of options vested |  |  |  | 55,300,000 rmbs_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOptionsVestedTotalFairValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | 64,300,000 rmbs_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOptionsVestedTotalFairValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | 80,000,000 rmbs_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOptionsVestedTotalFairValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |  |  |  |
Total intrinsic value of options exercised |  |  |  | 4,400,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | 1,300,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | 200,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |  |  |  |
Total proceeds received and receivable from employee stock option exercises |  |  |  | 6,300,000 rmbs_ProceedsAndProceedsReceivableFromStockOptionsExercised / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | 3,300,000 rmbs_ProceedsAndProceedsReceivableFromStockOptionsExercised / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | 1,000,000 rmbs_ProceedsAndProceedsReceivableFromStockOptionsExercised / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |  |  |  |
Valuation assumptions |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number |  |  |  | 11,441,646 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | 11,377,146 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | 13,094,815 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |  |  |  | 14,587,596 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Expected stock price volatility rate minimum (as a percent) |  |  |  | 40.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | 45.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | 57.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |  |  |  |
Expected stock price volatility rate maximum (as a percent) |  |  |  | 44.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | 47.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | 68.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |  |  |  |
Risk free interest rate minimum (as a percent) |  |  |  | 2.10%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | 0.80%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | 0.60%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |  |  |  |
Risk free interest rate maximum (as a percent) |  |  |  | 2.20%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | 1.50%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | 0.90%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |  |  |  |
Weighted average grant date fair value (in dollars per share) |  |  |  | 4.26 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | 2.60 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | 3.57 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |  |  |  |
Shares including nonvested equity stock and stock units |  |  |  |  |  |  |  |  |  |
Stock-Based Compensation |  |  |  |  |  |  |  |  |  |
Stock-based compensation |  |  |  | 2,800,000 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember | 3,100,000 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember | 5,300,000 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember |  |  |  |
Unrecognized compensation cost net of expected forfeitures |  |  |  | 3,900,000 us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember |  |  |  |  |  |
Expected weighted-average period for recognition of compensation cost (in years) |  |  |  | 2 years 3 months 11 days |  |  |  |  |  |
Total fair value of nonvested equity stock units at grant date |  |  |  | 4,100,000 rmbs_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedGrantsInPeriodTotalFairValue / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember | 3,300,000 rmbs_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedGrantsInPeriodTotalFairValue / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember | 4,800,000 rmbs_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedGrantsInPeriodTotalFairValue / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember |  |  |  |
Valuation assumptions |  |  |  |  |  |  |  |  |  |
Weighted-average fair value of purchase rights granted under the purchase plan (in dollars per share) |  |  |  | 10.40 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember | 6.92 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember | 6.43 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember |  |  |  |
Nonvested equity stock and stock units |  |  |  |  |  |  |  |  |  |
Nonvested at the beginning of the period (in shares) |  |  |  | 629,649 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember | 922,491 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember | 763,510 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember |  |  |  |
Granted (in shares) |  |  |  | 390,502 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember | 473,074 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember | 742,009 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember |  |  |  |
Vested (in shares) |  |  |  | (262,580)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember | (478,214)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember | (393,383)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember |  |  |  |
Forfeited (in shares) |  |  |  | (83,707)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember | (287,702)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember | (189,645)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember |  |  |  |
Nonvested at the end of the period (in shares) |  |  |  | 673,864 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember | 629,649 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember | 922,491 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember |  |  |  |
Weighted-Average Grant-Date Fair Value |  |  |  |  |  |  |  |  |  |
Nonvested at the beginning of the period (in dollars per share) |  |  |  | 8.56 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember | 10.24 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember | 18.02 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember |  |  |  |
Granted (in dollars per share) |  |  |  | 10.40 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember | 6.92 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember | 6.43 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember |  |  |  |
Vested (in dollars per share) |  |  |  | 9.85 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember | 9.81 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember | 17.38 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember |  |  |  |
Forfeited (in dollars per share) |  |  |  | 7.69 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember | 9.18 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember | 11.77 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember |  |  |  |
Nonvested at the end of the period (in dollars per share) |  |  |  | 9.23 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember | 8.56 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember | 10.24 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = rmbs_RestrictedStockAndStockUnitsMember |  |  |  |
Minimum | Employee Stock Purchase Plans |  |  |  |  |  |  |  |  |  |
Valuation assumptions |  |  |  |  |  |  |  |  |  |
Expected term (in years) |  |  |  | 0 years 0 months 7 days |  |  |  |  |  |
Minimum | Stock Option Plans |  |  |  |  |  |  |  |  |  |
Valuation assumptions |  |  |  |  |  |  |  |  |  |
Expected term (in years) |  |  |  | 6 years | 5 years 4 months 24 days | 5 years 6 months |  |  |  |
Maximum | Employee Stock Purchase Plans |  |  |  |  |  |  |  |  |  |
Valuation assumptions |  |  |  |  |  |  |  |  |  |
Expected term (in years) |  |  |  | 0 years 6 months |  |  |  |  |  |
Maximum | Stock Option Plans |  |  |  |  |  |  |  |  |  |
Valuation assumptions |  |  |  |  |  |  |  |  |  |
Expected term (in years) |  |  |  | 6 years 1 month 6 days | 5 years 6 months | 5 years 8 months 12 days |  |  |  |
Option One |  |  |  |  |  |  |  |  |  |
Stock-Based Compensation |  |  |  |  |  |  |  |  |  |
Required service period |  |  |  | 60 months |  |  |  |  |  |
Option Two |  |  |  |  |  |  |  |  |  |
Stock-Based Compensation |  |  |  |  |  |  |  |  |  |
Required service period |  |  |  | 48 months |  |  |  |  |  |
Stock Options with Market Condition [Member] |  |  |  |  |  |  |  |  |  |
Stock-Based Compensation |  |  |  |  |  |  |  |  |  |
Options granted (in shares) |  |  |  |  |  | 1,795,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod / us-gaap_PlanNameAxis = rmbs_StockOptionsWithMarketConditionMember |  |  |  |
Valuation assumptions |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number |  |  |  | 1,315,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_PlanNameAxis = rmbs_StockOptionsWithMarketConditionMember | 1,315,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_PlanNameAxis = rmbs_StockOptionsWithMarketConditionMember |  |  |  |  |

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- Definition Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 14.F) -URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1)(i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 14 -Section F + Details
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- Definition Unrecognized cost of unvested share-based compensation awards. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iv)(3) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(3) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(2) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(2) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(iii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The estimated measure of the maximum percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period. + References No definition available. + Details
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- Definition The risk-free interest rate assumption that is used in valuing an option on its own shares. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(iv) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Number of additional shares authorized for issuance under an established share-based compensation plan. + References No definition available. + Details
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- Definition The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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