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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
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       31,400,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized         8,400,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized  
Increase in shares approved for issuance 6,500,000rmbs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAdditionalNumberOfSharesAuthorized 6,500,000rmbs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAdditionalNumberOfSharesAuthorized                
Stock Compensation Plan                    
Stock-Based Compensation                    
Increase in shares approved for issuance     10,000,000rmbs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAdditionalNumberOfSharesAuthorized
/ us-gaap_AwardTypeAxis
= us-gaap_StockCompensationPlanMember
             
Shares available for issuance       10,724,228.000us-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       1rmbs_EmployeeStockPurchasePlansNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockMember
1rmbs_EmployeeStockPurchasePlansNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockMember
1rmbs_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                 1,600,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockMember
 
Employee Stock Purchase Plan, Number Of Additional SharesToBe Authorized             1,500,000rmbs_EmployeeStockPurchasePlanNumberOfAdditionalSharesToBeAuthorized
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockMember
     
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized             1,500,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockMember
1,500,000us-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       25,000rmbs_EmployeeStockPurchasePlanMaximumShareValueUptoWhichEmployeesMayPurchaseShares
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockMember
25,000rmbs_EmployeeStockPurchasePlanMaximumShareValueUptoWhichEmployeesMayPurchaseShares
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockMember
25,000rmbs_EmployeeStockPurchasePlanMaximumShareValueUptoWhichEmployeesMayPurchaseShares
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockMember
       
Shares issued under employee stock purchase plans       596,188us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockMember
1,063,283us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockMember
731,449us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockMember
       
Weighted average price per share of shares issued (in dollars per share)       8.25rmbs_EmployeeStockPurchasePlansWeightedAveragePricePerShare
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockMember
4.87rmbs_EmployeeStockPurchasePlansWeightedAveragePricePerShare
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockMember
4.21rmbs_EmployeeStockPurchasePlansWeightedAveragePricePerShare
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockMember
       
Shares available for issuance       923,044us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockMember
           
Stock-based compensation       2,600,000us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockMember
1,500,000us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockMember
2,200,000us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockMember
       
Unrecognized compensation cost net of expected forfeitures       700,000us-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)       3.57us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockMember
1.96us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockMember
1.58us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockMember
       
Weighted-Average Grant-Date Fair Value                    
Granted (in dollars per share)       3.57us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockMember
1.96us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockMember
1.58us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockMember
       
Stock Option Plans                    
Stock-Based Compensation                    
Options granted (in shares)       2,370,313us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
2,084,276us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
7,789,220us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
       
Estimated total grant date fair value       10,100,000rmbs_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodTotalFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
5,400,000rmbs_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodTotalFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
32,700,000rmbs_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodTotalFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
       
Stock-based compensation       9,300,000us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
10,400,000us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
15,000,000us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
       
Unrecognized compensation cost net of expected forfeitures       13,600,000us-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       55,300,000rmbs_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOptionsVestedTotalFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
64,300,000rmbs_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOptionsVestedTotalFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
80,000,000rmbs_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOptionsVestedTotalFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
       
Total intrinsic value of options exercised       4,400,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
1,300,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
200,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
       
Total proceeds received and receivable from employee stock option exercises       6,300,000rmbs_ProceedsAndProceedsReceivableFromStockOptionsExercised
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
3,300,000rmbs_ProceedsAndProceedsReceivableFromStockOptionsExercised
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
1,000,000rmbs_ProceedsAndProceedsReceivableFromStockOptionsExercised
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
       
Valuation assumptions                    
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number       11,441,646us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
11,377,146us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
13,094,815us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
      14,587,596us-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)       4.26us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
2.60us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
3.57us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
       
Shares including nonvested equity stock and stock units                    
Stock-Based Compensation                    
Stock-based compensation       2,800,000us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= rmbs_RestrictedStockAndStockUnitsMember
3,100,000us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= rmbs_RestrictedStockAndStockUnitsMember
5,300,000us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= rmbs_RestrictedStockAndStockUnitsMember
       
Unrecognized compensation cost net of expected forfeitures       3,900,000us-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       4,100,000rmbs_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedGrantsInPeriodTotalFairValue
/ us-gaap_AwardTypeAxis
= rmbs_RestrictedStockAndStockUnitsMember
3,300,000rmbs_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedGrantsInPeriodTotalFairValue
/ us-gaap_AwardTypeAxis
= rmbs_RestrictedStockAndStockUnitsMember
4,800,000rmbs_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedGrantsInPeriodTotalFairValue
/ us-gaap_AwardTypeAxis
= rmbs_RestrictedStockAndStockUnitsMember
       
Valuation assumptions                    
Weighted-average fair value of purchase rights granted under the purchase plan (in dollars per share)       10.40us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= rmbs_RestrictedStockAndStockUnitsMember
6.92us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= rmbs_RestrictedStockAndStockUnitsMember
6.43us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= rmbs_RestrictedStockAndStockUnitsMember
       
Nonvested equity stock and stock units                    
Nonvested at the beginning of the period (in shares)       629,649us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= rmbs_RestrictedStockAndStockUnitsMember
922,491us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= rmbs_RestrictedStockAndStockUnitsMember
763,510us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= rmbs_RestrictedStockAndStockUnitsMember
       
Granted (in shares)       390,502us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= rmbs_RestrictedStockAndStockUnitsMember
473,074us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= rmbs_RestrictedStockAndStockUnitsMember
742,009us-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)       673,864us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= rmbs_RestrictedStockAndStockUnitsMember
629,649us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= rmbs_RestrictedStockAndStockUnitsMember
922,491us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= rmbs_RestrictedStockAndStockUnitsMember
       
Weighted-Average Grant-Date Fair Value                    
Nonvested at the beginning of the period (in dollars per share)       8.56us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= rmbs_RestrictedStockAndStockUnitsMember
10.24us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= rmbs_RestrictedStockAndStockUnitsMember
18.02us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= rmbs_RestrictedStockAndStockUnitsMember
       
Granted (in dollars per share)       10.40us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= rmbs_RestrictedStockAndStockUnitsMember
6.92us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= rmbs_RestrictedStockAndStockUnitsMember
6.43us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= rmbs_RestrictedStockAndStockUnitsMember
       
Vested (in dollars per share)       9.85us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= rmbs_RestrictedStockAndStockUnitsMember
9.81us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= rmbs_RestrictedStockAndStockUnitsMember
17.38us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= rmbs_RestrictedStockAndStockUnitsMember
       
Forfeited (in dollars per share)       7.69us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= rmbs_RestrictedStockAndStockUnitsMember
9.18us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= rmbs_RestrictedStockAndStockUnitsMember
11.77us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= rmbs_RestrictedStockAndStockUnitsMember
       
Nonvested at the end of the period (in dollars per share)       9.23us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= rmbs_RestrictedStockAndStockUnitsMember
8.56us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= rmbs_RestrictedStockAndStockUnitsMember
10.24us-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)           1,795,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod
/ us-gaap_PlanNameAxis
= rmbs_StockOptionsWithMarketConditionMember
       
Valuation assumptions                    
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number       1,315,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_PlanNameAxis
= rmbs_StockOptionsWithMarketConditionMember
1,315,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_PlanNameAxis
= rmbs_StockOptionsWithMarketConditionMember