Liability For Early Exercise Of Options, Current

No definition available.

Name:	sibn_LiabilityForEarlyExerciseOfOptionsCurrent
Namespace Prefix:	sibn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Notes Receivable, Forgiveness

+ References

No definition available.

+ Details

Name:	sibn_NotesReceivableForgiveness
Namespace Prefix:	sibn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Share-Based Compensation Arrangement By Share-Based Payment Award, Expiration Period For Individual Owning More Than 10% Of Outstanding Shares

+ References

No definition available.

+ Details

Name:	sibn_ShareBasedCompensationArrangementByShareBasedPaymentAwardExpirationPeriodForIndividualOwningMoreThanTenPercentOfOutstandingShares
Namespace Prefix:	sibn_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Share-Based Compensation Arrangement By Share-Based Payment Award, Offering Period Interval

+ References

No definition available.

+ Details

Name:	sibn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOfferingPeriodInterval
Namespace Prefix:	sibn_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Options, Early Exercise, Common Stock Subject To Repurchase

+ References

No definition available.

+ Details

Name:	sibn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsEarlyExerciseCommonStockSubjectToRepurchase
Namespace Prefix:	sibn_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Share-Based Compensation Arrangement By Share-Based Payment Award, Options, Exercise Price As Percent Of Fair Market Value

+ References

No definition available.

+ Details

Name:	sibn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisePriceAsPercentOfFairMarketValue
Namespace Prefix:	sibn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Option, Exercise Price As Percent Of Fair Market Value For Individual Owning More Than 10% Of Outstanding Shares

+ References

No definition available.

+ Details

Name:	sibn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisePriceAsPercentOfFairMarketValueForIndividualOwningMoreThanTenPercentOfOutstandingShares
Namespace Prefix:	sibn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Share-Based Compensation Arrangement By Share-Based Payment Award, Plan Modification, Options Modified

+ References

No definition available.

+ Details

Name:	sibn_ShareBasedCompensationArrangementByShareBasedPaymentAwardPlanModificationOptionsModified
Namespace Prefix:	sibn_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- 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

- Definition

Aggregate number of common shares reserved for future issuance.

+ References

Reference 1: 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_CommonStockCapitalSharesReservedForFutureIssuance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- 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

- 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

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

+ References

+ Details

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

- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, 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_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
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

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

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

- Definition

An excess of the fair value of the modified award over the fair value of the award immediately before the modification.

+ 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)(2)(iii)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

+ Details

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

- Definition

Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

+ References

No definition available.

+ Details

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

- Definition

Period from grant date that an equity-based award expires, 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)(2)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

+ Details

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Purchase price of common stock expressed as a percentage of its fair value.

+ References

No definition available.

+ Details

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_StatementScenarioAxis=us-gaap_ScenarioForecastMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VestingAxis=us-gaap_ShareBasedCompensationAwardTrancheOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VestingAxis=us-gaap_ShareBasedCompensationAwardTrancheTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=sibn_A2008StockOptionPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=sibn_A2018EquityIncentivePlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=sibn_A2018EmployeeStockPurchasePlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Stock-Based Incentive Compensation Plans - Narrative (Details) - USD ($)	1 Months Ended			12 Months Ended		49 Months Ended
	Oct. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Sep. 30, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted, weighted-average grant date fair value (in dollars per share)				$ 3.98	$ 1.80
Early exercise of stock options, share subject to repurchase (in shares)		16,117		74,019	16,117
Liability for early exercise of unvested stock options		$ 65,000		$ 331,000	$ 65,000
Forgiveness of notes receivable				$ 0	400,000
Stock options granted (in shares)				100,080
Grant price of stock options granted (in dollars per share)				$ 8.88
Unrecognized compensation cost				$ 4,500,000
Unrecognized compensation cost, expected period for recognition (in years)				2 years 3 months 15 days
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price of option as percent of fair market value when individual owns more than 10% of shares outstanding (percent)				110.00%
Incentive Stock Options \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price of option as percent of fair market value (percent)				100.00%
Nonqualified Stock Options \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price of option as percent of fair market value (percent)				85.00%
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period (in years)				10 years
Expiration period when individual holds more than 10% of shares outstanding (in years)				5 years
Award vesting period (in years)				4 years
Stock-based compensation expense				$ 2,312,000	$ 1,875,000
Restricted Stock Units \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)				2 years
Restricted Stock Units \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)				4 years
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted (in shares)			564,098
Grant price of stock options granted (in dollars per share)		$ 4.68	$ 5.94
Stock-based compensation expense				$ 600,000
Number of options with modification of terms (in shares)		394,652
Performance Shares \| Forecast
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense to be recognized related to modification of terms						$ 800,000
Performance Shares \| Vesting Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)			4 years
Stock options granted (in shares)			408,544
Performance Shares \| Vesting Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)			3 years
Stock options granted (in shares)			155,554
2008 Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)		5,350,080			5,350,080
2018 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)				2,576,538
2018 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)	515,307
Purchase price of common stock as a percent of fair market value (percent)				85.00%
Employees stock purchase program offering period interval (in months)				6 months
Stock-based compensation expense	$ 100,000
Unrecognized compensation cost				$ 300,000