XML 109 R79.htm IDEA: XBRL DOCUMENT
v3.19.3.a.u2

Equity Incentive Plans and Stock-Based Compensation (Details 4) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2019 USD ($) plan $ / shares shares | Dec. 31, 2018 USD ($) plan $ / shares shares | Dec. 31, 2017 USD ($) plan $ / shares shares | Dec. 31, 2016 shares
Stock-Based Compensation |  |  |  |  |
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense | $ |  |  |  | $ 1,300,000 |
Stock Compensation Plan |  |  |  |  |
Stock-Based Compensation |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized | 400,000 | [1] | 5,500,000 |  |
Shares available for issuance | 6,826,863 |  | 10,074,046 | 5,051,147 | 7,305,368
Options granted (in shares) | 80,000 |  | 711,479 | 558,426 |
Valuation assumptions |  |  |  |  |
Dividend yield (as a percent) | 0.00% |  | 0.00% | 0.00% |
Share Based Compensation Arrangement by Share Based Payment Award, Equity Instruments, Other than Options Grants in Period Decrease in Available for Grant for Every Grant | 1.5 |  | 1.5 | 1.5 |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments, Other than Options, Forfeited in Period Increase in Available for Grant for Every Forfeiture | 1.5 |  | 1.5 | 1.5 |
Options |  |  |  |  |
Stock-Based Compensation |  |  |  |  |
Options granted (in shares) | 80,000 |  | 711,479 | 558,426 |
Estimated total grant date fair value | $ | $ 300,000 |  | $ 3,000,000.0 | $ 2,300,000 |
Stock-based compensation | $ | 1,000,000.0 |  | 1,700,000 | 2,800,000 |
Unrecognized compensation cost net of expected forfeitures | $ | $ 2,000,000.0 |  |  |  |
Expected weighted-average period for recognition of compensation cost (in years) | 2 years 3 months 18 days |  |  |  |
Total fair value of options vested | $ | $ 6,700,000 |  | $ 12,900,000 | $ 17,300,000 |
Valuation assumptions |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | 1,639,146 |  | 3,235,891 | 4,310,361 | 7,008,833
Expected stock price volatility rate minimum (as a percent) | 33.00% |  | 24.00% | 24.00% |
Expected stock price volatility rate maximum (as a percent) | 36.00% |  | 32.00% | 32.00% |
Risk free interest rate minimum (as a percent) | 1.40% |  | 2.60% | 1.80% |
Risk free interest rate maximum (as a percent) | 1.60% |  | 2.80% | 2.00% |
Expected term (in years) |  |  | 5 years 9 months 18 days |  |
Weighted average grant date fair value (in dollars per share) | $ / shares | $ 4.36 |  | $ 4.23 | $ 4.09 |
Restricted Stock and Stock Units |  |  |  |  |
Stock-Based Compensation |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Requisite Service Period | 4 years |  |  |  |
Stock-based compensation | $ | $ 23,900,000 |  | $ 18,600,000 | $ 22,900,000 |
Unrecognized compensation cost net of expected forfeitures | $ | $ 33,200,000 |  |  |  |
Expected weighted-average period for recognition of compensation cost (in years) | 2 years 4 months 24 days |  |  |  |
Total fair value of nonvested equity stock units at grant date | $ | $ 43,000,000.0 |  | $ 38,100,000 | $ 40,000,000.0 |
Valuation assumptions |  |  |  |  |
Weighted-average fair value of purchase rights granted under the purchase plan (in dollars per share) | $ / shares | $ 10.17 |  | $ 12.77 | $ 13.02 |
Nonvested equity stock and stock units |  |  |  |  |
Nonvested at the beginning of the period (in shares) | 4,859,135 |  | 5,861,349 | 4,863,056 |
Granted (in shares) | 4,233,701 |  | 2,978,558 | 3,075,396 |
Vested (in shares) | (1,896,283) |  | (1,713,930) | (1,216,476) |
Forfeited (in shares) | (1,907,070) |  | (2,266,842) | (860,627) |
Nonvested at the end of the period (in shares) | 5,289,483 |  | 4,859,135 | 5,861,349 |
Weighted-Average Grant-Date Fair Value |  |  |  |  |
Nonvested at the beginning of the period (in dollars per share) | $ / shares | $ 12.71 |  | $ 12.68 | $ 12.33 |
Granted (in dollars per share) | $ / shares | 10.17 |  | 12.77 | 13.02 |
Vested (in dollars per share) | $ / shares | 12.40 |  | 12.39 | 12.15 |
Forfeited (in dollars per share) | $ / shares | 11.33 |  | 12.97 | 12.61 |
Nonvested at the end of the period (in dollars per share) | $ / shares | $ 11.27 |  | $ 12.71 | $ 12.68 |
Employee Stock Purchase Plan |  |  |  |  |
Stock-Based Compensation |  |  |  |  |
Number of employee stock purchase plans | plan | 1 |  | 1 | 1 |
Minimum number of hours of weekly employment in order to qualify for eligibility in the plan | 20 hours |  | 20 hours | 20 hours |
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% |  | 85.00% | 85.00% |
Maximum share value per employee in any calendar year | $ | $ 25,000 |  | $ 25,000 | $ 25,000 |
Shares issued under employee stock purchase plans | 629,438 |  | 541,395 | 615,370 |
Weighted average price per share of shares issued (in dollars per share) | $ / shares | $ 8.53 |  | $ 9.99 | $ 10.47 |
Shares available for issuance | 1,665,440 |  |  |  |
Stock-based compensation | $ | $ 1,500,000 |  | $ 1,400,000 | $ 1,700,000 |
Unrecognized compensation cost net of expected forfeitures | $ | $ 700,000 |  |  |  |
Expected weighted-average period for recognition of compensation cost (in years) | 4 months |  |  |  |
Valuation assumptions |  |  |  |  |
Expected stock price volatility rate minimum (as a percent) | 32.00% |  | 27.00% | 25.00% |
Expected stock price volatility rate maximum (as a percent) | 32.00% |  | 34.00% | 27.00% |
Risk free interest rate minimum (as a percent) | 1.60% |  | 2.05% | 0.98% |
Risk free interest rate maximum (as a percent) | 2.40% |  | 2.50% | 1.30% |
Expected term (in years) | 6 months |  | 6 months | 6 months |
Weighted-average fair value of purchase rights granted under the purchase plan (in dollars per share) | $ / shares | $ 3.13 |  | $ 2.59 | $ 3.07 |
Weighted-Average Grant-Date Fair Value |  |  |  |  |
Granted (in dollars per share) | $ / shares | $ 3.13 |  | $ 2.59 | $ 3.07 |
Minimum |  |  |  |  |
Stock-Based Compensation |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | 0.00% |  |  |  |
Minimum | Options |  |  |  |  |
Valuation assumptions |  |  |  |  |
Expected term (in years) | 5 years 1 month 6 days |  |  | 5 years 3 months 14 days |
Maximum |  |  |  |  |
Stock-Based Compensation |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | 200.00% |  |  |  |
Maximum | Options |  |  |  |  |
Valuation assumptions |  |  |  |  |
Expected term (in years) | 5 years 2 months 12 days |  |  | 5 years 4 months 24 days |
Option One |  |  |  |  |
Stock-Based Compensation |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Requisite Service Period | 60 months |  |  |  |
Option Two |  |  |  |  |
Stock-Based Compensation |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Requisite Service Period | 48 months |  |  |  |
[1] | Shares were reserved under the 2019 Inducement Plan adopted in the third quarter of 2019.

X
- Definition Represents the maximum share value that an employee may purchase under the plan in any calendar year, as measured at the purchase date. + References No definition available. + Details
Name: | rmbs_EmployeeStockPurchasePlanMaximumShareValueUptoWhichEmployeesMayPurchaseShares
Namespace Prefix: | rmbs_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Represents the minimum number of hours per week that employees are required to be employed in order to be eligible to participate in the Employee Stock Purchase Plan. + References No definition available. + Details
Name: | rmbs_EmployeeStockPurchasePlanMinimumNumberOfHoursPerWeekEmployeesToBeEmployedToBeEligibleToParticipateInPlan
Namespace Prefix: | rmbs_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the minimum number of months in a fiscal year that employees are required to be employed in order to be eligible to participate in the Employee Stock Purchase Plan. + References No definition available. + Details
Name: | rmbs_EmployeeStockPurchasePlanMinimumNumberOfMonthsInFiscalYearEmployeesToBeEmployedToBeEligibleToParticipateInPlan
Namespace Prefix: | rmbs_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the offering period expressed in number of months. + References No definition available. + Details
Name: | rmbs_EmployeeStockPurchasePlanOfferingPeriod
Namespace Prefix: | rmbs_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Employee Stock Purchase Plan, Percentage of the Price at Beginning of Offering Period or Price at End of Each Offering Period to Derive Purchase Price + References No definition available. + Details
Name: | rmbs_EmployeeStockPurchasePlanPercentageOfPriceAtBeginningOfOfferingPeriodOrPriceAtEndOfEachOfferingPeriodToDerivePurchasePrice
Namespace Prefix: | rmbs_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the number of Employee Stock Purchase Plans. + References No definition available. + Details
Name: | rmbs_EmployeeStockPurchasePlansNumber
Namespace Prefix: | rmbs_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the weighted average price per share of shares issued under the Employee Stock Purchase Plan. + References No definition available. + Details
Name: | rmbs_EmployeeStockPurchasePlansWeightedAveragePricePerShare
Namespace Prefix: | rmbs_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the total fair value of vested stock options. + References No definition available. + Details
Name: | rmbs_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOptionsVestedTotalFairValue
Namespace Prefix: | rmbs_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition For purposes of determining the number of shares available for grant under the 2006 Equity Incentive Plan, represents the multiplier by which the number of shares available for grant will increase, for every restricted stock award forfeited. + References No definition available. + Details
Name: | rmbs_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriodIncreaseInAvailableForGrantForEveryForfeiture
Namespace Prefix: | rmbs_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition For purposes of determining the number of shares available for grant under the 2006 Equity Incentive Plan, represents the multiplier by which the number of shares available for grant will decrease, for every restricted stock award granted. + References No definition available. + Details
Name: | rmbs_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodDecreaseInAvailableForGrantForEveryGrant
Namespace Prefix: | rmbs_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Represents the total fair value of nonvested equity stock units granted during the period. + References No definition available. + Details
Name: | rmbs_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedGrantsInPeriodTotalFairValue
Namespace Prefix: | rmbs_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Represents the total fair value of options for granted during the period. + References No definition available. + Details
Name: | rmbs_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodTotalFairValue
Namespace Prefix: | rmbs_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- 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://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5047-113901 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -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=115993241&loc=d3e301413-122809 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -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=109197908&loc=d3e5070-113901 + Details
Name: | us-gaap_AllocatedShareBasedCompensationExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Unrecognized cost of unvested share-based compensation awards. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
Name: | us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- 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://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
Name: | us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -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=109197908&loc=d3e5070-113901 + Details
Name: | us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Estimated period over which an employee is required to provide service in exchange for the equity-based payment award, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -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=109197908&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- 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://fasb.org/us-gaap/role/ref/legacyRef -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=109197908&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- 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://fasb.org/us-gaap/role/ref/legacyRef -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=109197908&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- 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://fasb.org/us-gaap/role/ref/legacyRef -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=109197908&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- 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://fasb.org/us-gaap/role/ref/legacyRef -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=109197908&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- 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://fasb.org/us-gaap/role/ref/legacyRef -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=109197908&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -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=109197908&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- 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://fasb.org/us-gaap/role/ref/legacyRef -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=109197908&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- 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://fasb.org/us-gaap/role/ref/legacyRef -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=109197908&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- 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
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The estimated measure of the minimum 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
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The maximum risk-free interest rate assumption that is used in valuing an option on its own shares. + References No definition available. + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The minimum risk-free interest rate assumption that is used in valuing an option on its own shares. + References No definition available. + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of additional shares authorized for issuance under an established share-based compensation plan. + References No definition available. + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- 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://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Net number of share options (or share units) granted during the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iv)(1) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- 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://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of options outstanding, including both vested and non-vested options. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Percentage of vesting of share-based compensation awards. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
Name: | us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(i) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 14.D.2) -URI http://asc.fasb.org/extlink&oid=115993241&loc=d3e301413-122809 + Details
Name: | us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of shares issued during the period as a result of an employee stock purchase plan. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(28)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_AwardTypeAxis=us-gaap_StockCompensationPlanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AwardTypeAxis=us-gaap_EmployeeStockOptionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AwardTypeAxis=rmbs_RestrictedStockAndStockUnitsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AwardTypeAxis=us-gaap_EmployeeStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VestingAxis=rmbs_OptionOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VestingAxis=rmbs_OptionTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |