The number of shares under options to be issued.

No definition available.

Name:	fwbi_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsToBeIssued
Namespace Prefix:	fwbi_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of monthly installments in which stock options granted will vest.

+ References

No definition available.

+ Details

Name:	fwbi_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestingInNumberOfMonthlyInstallments
Namespace Prefix:	fwbi_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value of options. Excludes equity instruments options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

+ References

No definition available.

+ Details

Name:	fwbi_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsFairValue
Namespace Prefix:	fwbi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- 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=120381028&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=122041274&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=120381028&loc=d3e5070-113901

+ Details

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

- References

No definition available.

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationAggregateDisclosuresAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of cost to be recognized for 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 2
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

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

- Definition

Exercise or strike price stated in the contract for options indexed to the issuer's equity shares.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 40
-Section 50
-Paragraph 5
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=123477628&loc=d3e90205-114008

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 480
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (f)(1)
-URI http://asc.fasb.org/extlink&oid=109262807&loc=d3e22047-110879

+ Details

Name:	us-gaap_OptionIndexedToIssuersEquityStrikePrice1
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

+ 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=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- 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=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option 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)(1)(iv)(3)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
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

Number of fully vested and expected to vest options outstanding that can be converted into shares under option plan. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

+ 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 (e)(1)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- 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:	dtr-types: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=120381028&loc=d3e5070-113901

+ Details

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

- Definition

Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

+ 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)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Number of options vested.

+ References

No definition available.

+ Details

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

- Details

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

- Details

Name:	us-gaap_IncomeStatementLocationAxis=us-gaap_GeneralAndAdministrativeExpenseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementLocationAxis=us-gaap_ResearchAndDevelopmentExpenseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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

- Details

Name:	us-gaap_VestingAxis=fwbi_Phase2CombinationTrialMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VestingAxis=fwbi_USPhase1ClinicalTrialMember
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=fwbi_NewSapirsteinAwardsMember
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_VestingAxis=us-gaap_ShareBasedCompensationAwardTrancheThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

Name:	us-gaap_PlanNameAxis=fwbi_Plan2020Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_SubsidiarySaleOfStockAxis=us-gaap_EmployeeStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=fwbi_Plan2014Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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

Stock Options, Summary (Details)			12 Months Ended
Stock Options, Summary (Details)	Jun. 30, 2021 USD ($) Installment $ / shares shares	Jan. 02, 2020 USD ($) Installment $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($)
Stock Options [Abstract]
Unrecognized expense \| $				$ 25,000
Weighted average fair value of stock options granted (in dollars per share) \| $ / shares			$ 9.05	$ 8.90
Service-based Milestone [Member]
Stock Options [Abstract]
Stock options (in shares)			91,362
Share-based compensation expense \| $			$ 552,000
Service-based Milestone [Member] \| General and Administrative Expense [Member]
Stock Options [Abstract]
Share-based compensation expense \| $			435,000
Service-based Milestone [Member] \| Research and Development Expense [Member]
Stock Options [Abstract]
Share-based compensation expense \| $			$ 117,000
Performance-based Milestone [Member]
Stock Options [Abstract]
Stock options (in shares)			95,500
Share-based compensation expense \| $			$ 623,000
Performance-based Milestone [Member] \| General and Administrative Expense [Member]
Stock Options [Abstract]
Share-based compensation expense \| $			253,000
Performance-based Milestone [Member] \| Research and Development Expense [Member]
Stock Options [Abstract]
Share-based compensation expense \| $			$ 370,000
Enrollment of Phase 2 Option 2 Clinical Trial [Member]
Stock Options [Abstract]
Stock options (in shares)			43,750
Stock options fair value \| $			$ 427,000
Topline Data for Phase 2 Option 2 Clinical Trial [Member]
Stock Options [Abstract]
Stock options (in shares)			21,000
Stock options fair value \| $			$ 148,000
Phase 2 Combination Trial [Member]
Stock Options [Abstract]
Stock options (in shares)			750
Stock options fair value \| $			$ 8,000
U.S Phase 1 Clinical Trial [Member]
Stock Options [Abstract]
Stock options (in shares)			10,000
Stock options fair value \| $			$ 40,000
Stock Options [Member]
Stock Options [Abstract]
Share-based compensation expense \| $			$ 0
New Sapirstein Awards [Member]
Stock Options [Abstract]
Stock options (in shares)	90,000
Exercise price (in dollars per share) \| $ / shares	$ 8.50
Stock options vesting period			18 months
Stock options vesting, number of monthly installments \| Installment	18
Unrecognized expense \| $	$ 359,000
New Sapirstein Awards [Member] \| Stock Options Vesting Over 18 Months [Member]
Stock Options [Abstract]
Stock options (in shares)	30,000
New Sapirstein Awards [Member] \| Stock Options Vest Immediately [Member]
Stock Options [Abstract]
Stock options (in shares)	20,000
New Sapirstein Awards [Member] \| Stock Options Milestone-based Vesting [Member]
Stock Options [Abstract]
Stock options (in shares)	40,000
New Schneiderman Award [Member]
Stock Options [Abstract]
Stock options (in shares)	28,500
Exercise price (in dollars per share) \| $ / shares	$ 8.50
Unrecognized expense \| $	$ 192,000
New Schneiderman Award, Stock Options 1 [Member]
Stock Options [Abstract]
Stock options (in shares)	25,000
Stock options vesting period			2 years 1 month
Stock options vesting, number of monthly installments \| Installment	25
New Schneiderman Award, Stock Options 1 [Member] \| Stock Options Vest Immediately [Member]
Stock Options [Abstract]
Stock options (in shares)	7,986
New Schneiderman Award, Stock Options 1 [Member] \| Stock Options Vesting in 2 Years and 1 Month [Member]
Stock Options [Abstract]
Stock options (in shares)	17,014
New Schneiderman Award, Stock Options 2 [Member]
Stock Options [Abstract]
Stock options (in shares)	3,500
Stock options vesting period			19 months
Stock options vesting, number of monthly installments \| Installment	19
New Schneiderman Award, Stock Options 2 [Member] \| Stock Options Vest Immediately [Member]
Stock Options [Abstract]
Stock options (in shares)	1,750
New Schneiderman Award, Stock Options 2 [Member] \| Stock Options Vesting in 19 Months [Member]
Stock Options [Abstract]
Stock options (in shares)	1,750
2020 Plan [Member]
Stock Options [Abstract]
Stock options cancelled (in shares)			(8,604)
2020 Plan [Member] \| Minimum [Member]
Stock Options [Abstract]
Strike prices (in dollars per share) \| $ / shares			$ 9.23
2020 Plan [Member] \| Maximum [Member]
Stock Options [Abstract]
Strike prices (in dollars per share) \| $ / shares			$ 14.30
2020 Plan [Member] \| Performance-based Milestone [Member]
Stock Options [Abstract]
Stock options (in shares)				1,000
Stock options vesting period				10 years
Strike prices (in dollars per share) \| $ / shares				$ 9.70
Stock options fair value \| $				$ 8,000
2020 Plan [Member] \| Board Member [Member]
Stock Options [Abstract]
Stock options term			10 years
2020 Plan [Member] \| Employee Stock [Member]
Stock Options [Abstract]
Stock options (in shares)			35,100
Stock options term			10 years
Stock options vesting period			3 years
Stock options fair value \| $			$ 247,000
2020 Plan [Member] \| Employee Stock [Member] \| Minimum [Member]
Stock Options [Abstract]
Strike prices (in dollars per share) \| $ / shares			$ 6.40
2020 Plan [Member] \| Employee Stock [Member] \| Maximum [Member]
Stock Options [Abstract]
Strike prices (in dollars per share) \| $ / shares			$ 15.40
2020 Plan [Member] \| Stock Options [Member] \| Board Member [Member]
Stock Options [Abstract]
Stock options (in shares)			21,646
Stock options fair value \| $			$ 153,000
2020 Plan [Member] \| Stock Options [Member] \| Board Member [Member] \| Minimum [Member]
Stock Options [Abstract]
Strike prices (in dollars per share) \| $ / shares			$ 6.40
2020 Plan [Member] \| Stock Options [Member] \| Board Member [Member] \| Maximum [Member]
Stock Options [Abstract]
Strike prices (in dollars per share) \| $ / shares			$ 9.70
2014 Plan [Member]
Stock Options [Abstract]
Stock options cancelled (in shares)			(134,477)	(48,722)
2014 Plan [Member] \| Minimum [Member]
Stock Options [Abstract]
Strike prices (in dollars per share) \| $ / shares			$ 8.50	$ 8.50
2014 Plan [Member] \| Maximum [Member]
Stock Options [Abstract]
Strike prices (in dollars per share) \| $ / shares			$ 36.00	$ 44.80
2014 Plan [Member] \| Service-based Milestone [Member]
Stock Options [Abstract]
Stock options (in shares)				60,008
Share-based compensation expense \| $				$ 361,000
2014 Plan [Member] \| Service-based Milestone [Member] \| General and Administrative Expense [Member]
Stock Options [Abstract]
Share-based compensation expense \| $				341,000
2014 Plan [Member] \| Service-based Milestone [Member] \| Research and Development Expense [Member]
Stock Options [Abstract]
Share-based compensation expense \| $				$ 20,000
2014 Plan [Member] \| Performance-based Vesting Conditions [Member]
Stock Options [Abstract]
Stock options (in shares)				5,000
2014 Plan [Member] \| Performance-based Vesting Conditions [Member] \| General and Administrative Expense [Member]
Stock Options [Abstract]
Share-based compensation fair value granted \| $				$ 20,000
2014 Plan [Member] \| Board Member [Member]
Stock Options [Abstract]
Stock options (in shares)				46,000
Stock options term				10 years
Strike prices (in dollars per share) \| $ / shares				$ 9.70
Stock options fair value \| $				$ 210,000
2014 Plan [Member] \| Chief Financial Officer [Member]
Stock Options [Abstract]
Stock options (in shares)		30,000		33,500
Exercise price (in dollars per share) \| $ / shares		$ 8.50		$ 10.30
Stock options to purchase of common stock vested (in shares)				633
Stock options term				10 years
Stock options vesting period		3 years		3 years
Stock options vesting, number of monthly installments \| Installment		36
Unrecognized expense \| $				$ 24,000
Strike prices (in dollars per share) \| $ / shares				$ 10.30
Stock options fair value \| $		$ 24,000		$ 281,000	$ 23,000
Stock options to be issued (in shares)		3,500
Stock options to purchase of common stock unvested (in shares)				2,867
2014 Plan [Member] \| Employees [Member]
Stock Options [Abstract]
Stock options (in shares)				204,000
Stock options to purchase of common stock vested (in shares)				144,000
Stock options term				10 years
Stock options vesting period				3 years
Strike prices (in dollars per share) \| $ / shares				$ 8.50
Stock options fair value \| $				$ 1,400,000
2014 Plan [Member] \| Employees [Member] \| Performance-based Milestone [Member]
Stock Options [Abstract]
Stock options to purchase of common stock vested (in shares)				60,000