XML 74 R63.htm IDEA: XBRL DOCUMENT
v3.23.2

Commitments and Contingent Liabilities - Narrative (Details) $ in Thousands |  | 6 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | ---
Mar. 13, 2019 USD ($) | Jun. 30, 2023 USD ($) potentially_responsible_party | Dec. 31, 2022 USD ($) | Sep. 30, 2021 USD ($) | Mar. 26, 2020 party | Jun. 05, 2017 company
Product Liability Contingency |  |  |  |  |  |
Litigation settlement amount |  | $ 14,000 |  |  |  |
Number of companies that received a general notice letter (company) | company |  |  |  |  |  | 140
Present value of remedial work |  | 1,100,000 |  |  |  |
Undiscovered remedial work |  | $ 1,700,000 |  |  |  |
Anticipated clean period |  | 13 years |  |  |  |
Number of potentially responsible parties included in agreement | potentially_responsible_party |  | 100 |  |  |  |
Number of parties required to perform remedial design work | party |  |  |  |  | 2 |
Environmental Loss Contingency Statement Of Financial Position Extensible Enumeration Not Disclosed Flag |  | financial condition |  |  |  |
Accrual for environmental loss |  | $ 2,447 | $ 2,472 |  |  |
UPRR |  |  |  |  |  |
Product Liability Contingency |  |  |  |  |  |
Litigation settlement amount | $ 50,000 |  |  |  |  |
Litigation settlement amount, current | 2,000 |  |  |  |  |
Litigation settlement amount, non-current | $ 48,000 |  |  |  |  |
Payment period | 6 years |  |  |  |  |
Purchase commitment | $ 48,000 |  |  |  |  |
UPRR |  |  |  |  |  |
Product Liability Contingency |  |  |  |  |  |
Annual commitment amount | $ 8,000 |  |  | $ 6,000 |  |

X
- Definition Environmental Loss Contingency Statement Of Financial Position Extensible Enumeration Not Disclosed Flag + References No definition available. + Details
Name: | fstr_EnvironmentalLossContingencyStatementOfFinancialPositionExtensibleEnumerationNotDisclosedFlag
Namespace Prefix: | fstr_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Litigation Settlement, Amount Awarded to Other Party, Current + References No definition available. + Details
Name: | fstr_LitigationSettlementAmountAwardedToOtherPartyCurrent
Namespace Prefix: | fstr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Litigation Settlement, Amount Awarded to Other Party, Non-Current + References No definition available. + Details
Name: | fstr_LitigationSettlementAmountAwardedToOtherPartyNonCurrent
Namespace Prefix: | fstr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Litigation Settlement Installment Payment Term + References No definition available. + Details
Name: | fstr_LitigationSettlementInstallmentPaymentTerm
Namespace Prefix: | fstr_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Long-term Purchase Commitment, Annual Commitment Amount + References No definition available. + Details
Name: | fstr_LongtermPurchaseCommitmentAnnualCommitmentAmount
Namespace Prefix: | fstr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Number Of Companies Receiving General Notice Letter + References No definition available. + Details
Name: | fstr_NumberOfCompaniesReceivingGeneralNoticeLetter
Namespace Prefix: | fstr_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of Parties Required to Perform Remedial Work + References No definition available. + Details
Name: | fstr_NumberOfPartiesRequiredToPerformRemedialWork
Namespace Prefix: | fstr_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of Potentially Responsible Parties Included in Agreement + References No definition available. + Details
Name: | fstr_NumberOfPotentiallyResponsiblePartiesIncludedInAgreement
Namespace Prefix: | fstr_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Present Value of Proposed Remedial Work + References No definition available. + Details
Name: | fstr_PresentValueOfProposedRemedialWork
Namespace Prefix: | fstr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Remedial Work Anticipated Clean Up Period + References No definition available. + Details
Name: | fstr_RemedialWorkAnticipatedCleanUpPeriod
Namespace Prefix: | fstr_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Undiscovered Remedial Work + References No definition available. + Details
Name: | fstr_UndiscoveredRemedialWork
Namespace Prefix: | fstr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Total costs accrued as of the balance sheet date for environmental loss contingencies. + References Reference 1: http://www.xbrl.org/2003/role/recommendedDisclosureRef -Topic 410 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 10 -Subparagraph (d)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481931/410-30-50-10 Reference 2: http://www.xbrl.org/2003/role/recommendedDisclosureRef -Topic 410 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 10 -Subparagraph (d)(3) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481931/410-30-50-10 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Topic 410 -SubTopic 30 -Name Accounting Standards Codification -Section 55 -Paragraph 16 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481899/410-30-55-16 Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 450 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147483076/450-20-50-1 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 450 -SubTopic 20 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 5.Y.Q1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480102/450-20-S99-1 Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 410 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 7 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481931/410-30-50-7 + Details
Name: | us-gaap_AccrualForEnvironmentalLossContingencies
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount awarded to other party in judgment or settlement of litigation. + References No definition available. + Details
Name: | us-gaap_LitigationSettlementAmountAwardedToOtherParty
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The minimum amount the entity agreed to spend under the long-term purchase commitment. + References No definition available. + Details
Name: | us-gaap_LongTermPurchaseCommitmentAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
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 Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 450 -SubTopic 20 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 5.Y.Q2) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480102/450-20-S99-1 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 450 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147483076/450-20-50-1 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 450 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147483076/450-20-50-4 Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 450 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 9 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147483076/450-20-50-9 + Details
Name: | us-gaap_ProductLiabilityContingencyLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | srt_MajorCustomersAxis=fstr_UPRRMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=fstr_UprrMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |