XML 43 R33.htm IDEA: XBRL DOCUMENT
v3.26.1

Note 2 - Summary of Significant Accounting Policies (Details Textual) - USD ($) $ in Thousands | 9 Months Ended |  |  |
--- | --- | --- | --- | ---
Sep. 30, 2025 | Jun. 30, 2026 | Dec. 31, 2025 | Dec. 31, 2022
Investment Plan, Maximum Amount. Approved |  |  |  | $ 20,000
Inventory, Net |  | $ 358 | $ 373 |
Equipment Constructed for Resale [Member] |  |  |  |
Inventory, Net |  | 176 | 176 |
Spare Parts [Member] |  |  |  |
Inventory, Net |  | 182 | 197 |
In Process Equipment [Member] |  |  |  |
Inventory, Net |  | 52 | $ 53 |
Minimum [Member] |  |  |  |
Debt Securities, Held-to-maturity, Maturity Term (Month) | 3 months |  |  |
Maximum [Member] |  |  |  |
Debt Securities, Held-to-maturity, Maturity Term (Month) | 36 months |  |  |
Asset Pledged as Collateral [Member] | Letter of Credit [Member] |  |  |  |
Restricted Cash and Investments |  | 2,574 |  |
Asset Pledged as Collateral [Member] | Letter of Credit [Member] | Varying Maturity Dates Expiring No Later Than June 30, 2027 [Member] |  |  |  |
Restricted Cash and Investments |  | 2,250 |  |
Asset Pledged as Collateral [Member] | Letter of Credit [Member] | Varying Maturity Dates Expiring No Later Than October 8, 2028 [Member] |  |  |  |
Restricted Cash and Investments |  | $ 324 |  |

X
- Definition Maturity term of debt security, held-to-maturity securities. + References No definition available. + Details
Name: | ftek_DebtSecuritiesHeldtomaturityMaturityTerm
Namespace Prefix: | ftek_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Maximum amount approved for investment plan. + References No definition available. + Details
Name: | ftek_InvestmentPlanMaximumAmountApproved
Namespace Prefix: | ftek_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S50 -Paragraph 3 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480657/210-10-S50-3 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 852 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 10 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481372/852-10-55-10 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483467/210-10-45-1 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(6)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 + Details
Name: | us-gaap_InventoryNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Cash and investments whose use in whole or in part is restricted for the long-term, generally by contractual agreements or regulatory requirements. For use in an unclassified balance sheet. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 954 -SubTopic 210 -Name Accounting Standards Codification -Section 45 -Paragraph 4 -Publisher FASB -URI https://asc.fasb.org/1943274/2147477220/954-210-45-4 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 954 -SubTopic 210 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org/1943274/2147478600/954-210-50-2 + Details
Name: | us-gaap_RestrictedCashAndInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_PublicUtilitiesInventoryAxis=ftek_EquipmentConstructedForResaleMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilitiesInventoryAxis=ftek_SparePartsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilitiesInventoryAxis=ftek_InProcessEquipmentMember
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_PledgedStatusAxis=us-gaap_AssetPledgedAsCollateralMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PledgingPurposeAxis=us-gaap_LetterOfCreditMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis=ftek_VaryingMaturityDatesExpiringNoLaterThanJune302027Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis=ftek_VaryingMaturityDatesExpiringNoLaterThanOctober82028Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |