XML 77 R67.htm IDEA: XBRL DOCUMENT
v3.21.2

Derivative Financial Instruments (Narrative) (Details) | 1 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Mar. 31, 2016 USD ($) contract | Sep. 30, 2021 USD ($) | Dec. 31, 2020 USD ($)
Derivative [Line Items] |  |  |
Deferred tax asset on gain on derivative |  | $ 62,000 |
Decrease in fair value of derivatives |  | 5,000 |
Cash flow hedge ineffectiveness |  | 0 |
Interest Rate Swap Agreements [Member] |  |  |
Derivative [Line Items] |  |  |
Interest rate swap notional amount | $ 30,000,000.0 | 20,000,000.0 |
Number of interest rate swap contracts | contract | 4 |  |
Fair value of interest rate swap contracts |  | $ (727,000) | $ (1,300,000)
Swap Contract 3 Year 5 Million [Member] |  |  |
Derivative [Line Items] |  |  |
Interest rate swap notional amount | $ 5,000,000.0 |  |
Derivative, maturity date | Sep. 17, 2019 |  |
Derivative, term of contract |  | 3 years |
Swap Contract 5 Year $5 Million [Member] |  |  |
Derivative [Line Items] |  |  |
Interest rate swap notional amount | $ 5,000,000.0 |  |
Derivative, maturity date | Mar. 17, 2021 |  |
Derivative, term of contract |  | 5 years |
Swap Contract- 7 year $5 Million [Member] |  |  |
Derivative [Line Items] |  |  |
Interest rate swap notional amount | $ 5,000,000.0 |  |
Derivative, maturity date | Mar. 17, 2023 |  |
Derivative, term of contract |  | 7 years |
Swap Contract 10 Year $15 Million [Member] |  |  |
Derivative [Line Items] |  |  |
Interest rate swap notional amount | $ 15,000,000.0 |  |
Derivative, maturity date | Mar. 17, 2026 |  |
Derivative, term of contract |  | 10 years |

X
- Definition Information on the swap contracts and the number of swaps + References No definition available. + Details
Name: | func_NumberOfInterestRateSwapContracts
Namespace Prefix: | func_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from derivative instruments. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32621-109319 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32632-109319 + Details
Name: | us-gaap_DeferredTaxAssetsDerivativeInstruments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value of liability associated with financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4B -Subparagraph (a),(c) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5624163-113959 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226003-175313 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 + Details
Name: | us-gaap_DerivativeAssetFairValueGrossLiability
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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 No definition available. + Details
Name: | us-gaap_DerivativeLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of decrease in the fair value of derivatives recognized in the income statement. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5618551-113959 + Details
Name: | us-gaap_DerivativeLossOnDerivative
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Date the derivative contract matures, in CCYY-MM-DD format. + References No definition available. + Details
Name: | us-gaap_DerivativeMaturityDates
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Nominal or face amount used to calculate payment on derivative. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5580258-113959 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5579245-113959 + Details
Name: | us-gaap_DerivativeNotionalAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | instant

X
- Definition Period the derivative contract is outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
Name: | us-gaap_DerivativeTermOfContract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition The net gain (loss) relating to components of the gain (loss) on the cash flow hedging instrument excluded from the assessment of cash flow hedge effectiveness. Recognized in earnings. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (d)(2) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5624171-113959 + Details
Name: | us-gaap_GainLossFromComponentsExcludedFromAssessmentOfCashFlowHedgeEffectivenessNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateSwapMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=func_SwapContract3Year5MillionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=func_SwapContract5Year5MillionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=func_SwapContract7Year5MillionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=func_SwapContract10Year15MillionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |