XML 61 R56.htm IDEA: XBRL DOCUMENT
v3.20.1

Loans and Allowance for Loan Losses - Loans Modified in a Troubled Debt Restructuring (Details) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2020 USD ($) DebtSecurityNumber | Dec. 31, 2019 USD ($) DebtSecurityNumber
Number of Loans | DebtSecurityNumber | 5 | 5
Pre- Modification Outstanding Principal Balance | $ 282 | $ 282
Post- Modification Principal Balance | $ 129 | $ 136
Real Estate [Member] | Construction, Land Development and Other Land Loans [Member] |  |
Number of Loans | DebtSecurityNumber | 1 | 1
Pre- Modification Outstanding Principal Balance | $ 107 | $ 107
Post- Modification Principal Balance | $ 59 | $ 62
Real Estate [Member] | Secured by 1-4 Family Residential Properties [Member] |  |
Number of Loans | DebtSecurityNumber | 2 | 2
Pre- Modification Outstanding Principal Balance | $ 59 | $ 59
Post- Modification Principal Balance | $ 12 | $ 14
Commercial and Industrial Loans [Member] |  |
Number of Loans | DebtSecurityNumber | 2 | 2
Pre- Modification Outstanding Principal Balance | $ 116 | $ 116
Post- Modification Principal Balance | $ 58 | $ 60

X
- Definition Number of financing receivables that have been modified by troubled debt restructurings. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953676-111524 + Details
Name: | us-gaap_FinancingReceivableModificationsNumberOfContracts2
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, after troubled debt restructuring, of modified financing receivable. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953676-111524 + Details
Name: | us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount, before troubled debt restructuring, of financing receivable to be modified. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953676-111524 + Details
Name: | us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=fusb_RealEstate1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=fusb_ConstructionLandDevelopmentAndOtherLandLoansMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=fusb_SecuredBy1To4FamilyResidentialPropertiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=fusb_CommercialAndIndustrialLoansMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |