Amount of liability recorded in balance sheet due to cash proceeds from early exercise of stock options.

No definition available.

Name:	ruby_AmountOfLiabilityRecordedInBalanceSheetDueToCashProceedsFromEarlyExerciseOfStockOptions
Namespace Prefix:	ruby_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of promissory note received from early exercise of stock options.

+ References

No definition available.

+ Details

Name:	ruby_AmountOfPromissoryNoteReceivedFromEarlyExerciseOfStockOptions
Namespace Prefix:	ruby_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount recorded in balance sheet due to promissory notes received from early exercise of stock options.

+ References

No definition available.

+ Details

Name:	ruby_AmountRecordedInBalanceSheetDueToPromissoryNotesReceivedFromEarlyExerciseOfStockOptions
Namespace Prefix:	ruby_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Proceeds from repayment of interest on promissory note.

+ References

No definition available.

+ Details

Name:	ruby_ProceedsFromRepaymentOfPromissoryNoteInterest
Namespace Prefix:	ruby_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Proceeds from repayment of principal balance of promissory note.

+ References

No definition available.

+ Details

Name:	ruby_ProceedsFromRepaymentOfPromissoryNotePrincipal
Namespace Prefix:	ruby_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount represents the value of share-based compensation arrangement by share-based payment award, options, grant date fair value.

+ References

No definition available.

+ Details

Name:	ruby_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantDateFairValue
Namespace Prefix:	ruby_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

+ 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=116856206&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=116856206&loc=d3e5070-113901

+ Details

Name:	us-gaap_AllocatedShareBasedCompensationExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of cash inflow from exercise of option under share-based payment 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 2A
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=SL79508275-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3255-108585

+ Details

Name:	us-gaap_ProceedsFromStockOptionsExercised
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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

- Definition

Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Gross number of share options (or share units) granted during the period.

+ References

No definition available.

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- 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

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

+ 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=116856206&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Weighted average price at which option holders acquired shares when converting their stock options into shares.

+ References

No definition available.

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of share options (or share units) exercised during the current 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)(2)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

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

Reference 5: 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

+ Details

Name:	us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	srt_TitleOfIndividualAxis=srt_ExecutiveOfficerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	ruby_VestingCriteriaAxis=ruby_VestingBasedOnPerformanceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=ruby_MarketBasedStockOptionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ruby_VestingCriteriaAxis=ruby_VestingBasedOnServiceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Stock-Based Compensation - Performance based stock options (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended			12 Months Ended
	Jun. 21, 2018	Oct. 31, 2018	Oct. 31, 2017	Apr. 30, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stock-Based Compensation
Proceeds from Stock Options Exercised					$ 2,413	$ 64	$ 37
Receivables from promissory note recorded in balance sheet				$ 0
Stock-based compensation expense			$ 1,000		41,271	27,528	17,903
Executive officer
Stock-Based Compensation
Options exercise price				$ 0.18
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period				1,400,000
Proceeds from Stock Options Exercised				$ 100
Amount of promissory note received from early exercise of stock options				200
Principal balance of promissory note repaid	$ 200
Interest on promissory note repaid	$ 100
Stock-based compensation, fair value					$ 4,300
Stock options.
Stock-Based Compensation
Options granted					3,059,004
Options exercise price					$ 1.68
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period					1,449,309
Aggregate intrinsic value of stock options exercised					$ 17,700	$ 3,700	$ 3,700
Weighted average grant-date fair value (per share)					$ 8.58	$ 8.71	$ 2.74
Aggregate Intrinsic value					$ 36,006	$ 126,367
Liability from early exercise of stock options				$ 100
Stock-based compensation expense						$ 2,200
Stock options. \| Performance-based vesting
Stock-Based Compensation
Options granted						447,000
Market-Based Stock Options
Stock-Based Compensation
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period					0
Aggregate intrinsic value of stock options exercised					$ 0
Weighted average grant-date fair value (per share)						$ 11.88
Market-Based Stock Options \| Vesting based on service period \| Executive officer
Stock-Based Compensation
Options granted		164,400
Options exercise price		$ 16.43
Stock-based compensation expense					900	$ 200
Market-Based Stock Options \| Performance-based vesting \| Executive officer
Stock-Based Compensation
Options granted		193,400
Options exercise price		$ 16.43
Stock-based compensation expense					$ 0