XML 93 R81.htm IDEA: XBRL DOCUMENT
v3.20.4

Deposits - Additional Information (Details) - USD ($) $ in Millions | Dec. 31, 2020 | Dec. 31, 2019
--- | --- | ---
Disclosure Text Block [Abstract] |  |
Time Deposits, at or Above FDIC Insurance Limit | $ 23.3 | $ 48.2
Brokered Certificates of Deposit | 32.0 | 7.4
Related Party Deposit Liabilities | $ 4.3 | $ 5.2

X
- Definition Represents brokered certificates of deposit. + References No definition available. + Details
Name: | fusb_BrokeredCertificatesOfDeposit
Namespace Prefix: | fusb_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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

X
- Definition Amount of deposits held by the entity for a related party (entity, shareholder, employee). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(k)) -URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08(k)(1)) -URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690 + Details
Name: | us-gaap_RelatedPartyDepositLiabilities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of time deposit liabilities, including certificates of deposit, in denominations that meet or exceed the Federal Deposit Insurance Corporation (FDIC) insurance limit. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 405 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=116652737&loc=d3e64164-112818 + Details
Name: | us-gaap_TimeDepositsAtOrAboveFDICInsuranceLimit
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant