XML 134 R120.htm IDEA: XBRL DOCUMENT
v3.20.4

Commitments and Contingencies (Details) - USD ($) $ in Thousands | Dec. 31, 2020 | Dec. 31, 2019
--- | --- | ---
Commitments to extend credit, primarily commercial loans |  |
Lending Related Commitments by Type [Line Items] |  |
Lending related commitments | $ 654,093 | $ 555,374
Standby letters of credit |  |
Lending Related Commitments by Type [Line Items] |  |
Lending related commitments | $ 8,086 | $ 8,918

X
- Definition Lending related commitments. + References No definition available. + Details
Name: | fbiz_LendingRelatedCommitments
Namespace Prefix: | fbiz_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition [Line Items] for Lending Related Commitments by Type [Table] + References No definition available. + Details
Name: | fbiz_LendingRelatedCommitmentsByTypeLineItems
Namespace Prefix: | fbiz_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | fbiz_LendingRelatedCommitmentsByTypeAxis=us-gaap_CommitmentsToExtendCreditMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | fbiz_LendingRelatedCommitmentsByTypeAxis=us-gaap_StandbyLettersOfCreditMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |