XML 84 R74.htm IDEA: XBRL DOCUMENT
v3.7.0.1

Regulatory Capital (Regulatory Capital Ratios) (Details) - USD ($) $ in Thousands | Jun. 30, 2017 | Dec. 31, 2016
--- | --- | ---
Compliance with Regulatory Capital Requirements under Banking Regulations |  |
Total capital (to risk-weighted assets) | $ 209,791 | $ 204,117
Total capital to risk-weighted assets | 11.91% | 11.74%
Total capital, Minimum Required for Capital Adequacy Purposes | $ 140,904 | $ 139,101
Total capital to risk-weighted assets, Minimum Required for Capital Adequacy Purposes | 8.00% | 8.00%
Capital Required for Capital Adequacy Plus Capital Conservation Buffer | $ 162,921 | $ 149,968
Capital Required for Capital Adequacy Plus Conservation Buffer to Risk Weighted Assets | 9.25% | 8.625%
Tier 1 capital (to risk-weighted assets) | $ 164,404 | $ 160,964
Tier 1 capital to risk-weighted assets | 9.33% | 9.26%
Tier 1 capital, Minimum Required for Capital Adequacy Purposes | $ 105,678 | $ 104,326
Tier 1 capital to risk-weighted assets, Minimum Required for Capital Adequacy Purposes | 6.00% | 6.00%
Tier One Risk Based Capital Required for Capital Adequacy Plus Capital Conservation Buffer | $ 127,694 | $ 115,193
Tier One Risk Based Capital Required for Capital Adequacy Plus Conservation Buffer to Risk Weighted Assets | 7.25% | 6.625%
Common equity tier 1 capital | $ 154,392 | $ 150,960
Common equity tier 1 capital to risk-weighted assets | 8.77% | 8.68%
Common equity tier 1 capital, Minimum Required for Capital Adequacy Purposes | $ 79,259 | $ 78,244
Common equity tier 1 capital to risk-weighted assets, Minimum Required for Capital Adequacy Purposes | 4.50% | 4.50%
Common Equity Tier One Capital Required for Capital Adequacy Plus Capital Conservation Buffer | $ 101,275 | $ 89,111
Common Equity Tier One Capital Required for Capital Adequacy Plus Conservation Buffer to Risk Weighted Assets | 5.75% | 5.125%
Tier 1 leverage capital (to adjusted assets) | $ 164,404 | $ 160,964
Tier 1 leverage capital to average assets | 9.28% | 9.07%
Tier 1 leverage capital, Minimum Required for Capital Adequacy Purposes | $ 70,899 | $ 70,985
Tier 1 leverage capital to average assets, Minimum Required for Capital Adequacy Purposes | 4.00% | 4.00%
Tier One Leverage Capital Required for Capital Adequacy Plus Capital Conservation Buffer | $ 70,899 | $ 70,985
Tier One Leverage Capital Required for Capital Adequacy Plus Conservation Buffer to Risk Weighted Assets | 4.00% | 4.00%
First Business Bank |  |
Compliance with Regulatory Capital Requirements under Banking Regulations |  |
Total capital (to risk-weighted assets) | $ 207,707 | $ 147,811
Total capital to risk-weighted assets | 11.83% | 11.55%
Total capital, Minimum Required for Capital Adequacy Purposes | $ 140,476 | $ 102,362
Total capital to risk-weighted assets, Minimum Required for Capital Adequacy Purposes | 8.00% | 8.00%
Capital Required for Capital Adequacy Plus Capital Conservation Buffer | $ 162,426 | $ 110,360
Capital Required for Capital Adequacy Plus Conservation Buffer to Risk Weighted Assets | 9.25% | 8.625%
Total capital, Minimum Required to be Well Capitalized Under Prompt Corrective Action Requirements | $ 175,596 | $ 127,953
Total capital to risk-weighted assets, Minimum Required to be Well Capitalized Under Prompt Corrective Action Requirements | 10.00% | 10.00%
Tier 1 capital (to risk-weighted assets) | $ 186,030 | $ 134,208
Tier 1 capital to risk-weighted assets | 10.59% | 10.49%
Tier 1 capital, Minimum Required for Capital Adequacy Purposes | $ 105,357 | $ 76,772
Tier 1 capital to risk-weighted assets, Minimum Required for Capital Adequacy Purposes | 6.00% | 6.00%
Tier One Risk Based Capital Required for Capital Adequacy Plus Capital Conservation Buffer | $ 127,307 | $ 84,769
Tier One Risk Based Capital Required for Capital Adequacy Plus Conservation Buffer to Risk Weighted Assets | 7.25% | 6.625%
Tier 1 capital, Minimum Required to be Well Capitalized Under Prompt Corrective Action Requirements | $ 140,476 | $ 102,362
Tier 1 capital to risk weighted assets, Minimum Required to be Well Capitalized Under Prompt Corrective Action Requirements | 8.00% | 8.00%
Common equity tier 1 capital | $ 186,030 | $ 134,208
Common equity tier 1 capital to risk-weighted assets | 10.59% | 10.49%
Common equity tier 1 capital, Minimum Required for Capital Adequacy Purposes | $ 79,018 | $ 57,579
Common equity tier 1 capital to risk-weighted assets, Minimum Required for Capital Adequacy Purposes | 4.50% | 4.50%
Common Equity Tier One Capital Required for Capital Adequacy Plus Capital Conservation Buffer | $ 100,967 | $ 65,576
Common Equity Tier One Capital Required for Capital Adequacy Plus Conservation Buffer to Risk Weighted Assets | 5.75% | 5.125%
Common equity tier 1 capital, Minimum Required to Be Well Capitalized Under Prompt Corrective Action Requirements | $ 114,137 | $ 83,170
Common equity tier 1 capital to risk-weighted assets, Minimum Required to Be Well Capitalized Under Prompt Corrective Action Requirements | 6.50% | 6.50%
Tier 1 leverage capital (to adjusted assets) | $ 186,030 | $ 134,208
Tier 1 leverage capital to average assets | 10.52% | 10.40%
Tier 1 leverage capital, Minimum Required for Capital Adequacy Purposes | $ 70,714 | $ 51,600
Tier 1 leverage capital to average assets, Minimum Required for Capital Adequacy Purposes | 4.00% | 4.00%
Tier One Leverage Capital Required for Capital Adequacy Plus Capital Conservation Buffer | $ 70,714 | $ 51,600
Tier One Leverage Capital Required for Capital Adequacy Plus Conservation Buffer to Risk Weighted Assets | 4.00% | 4.00%
Tier 1 leverage capital, Minimum Required to be Well Capitalized Under Prompt Corrective Action Requirements | $ 88,393 | $ 64,500
Tier 1 leverage capital to average assets, Minimum Required to be Well Capitalized Under Prompt Corrective Action Requirements | 5.00% | 5.00%
First Business Bank - Milwaukee |  |
Compliance with Regulatory Capital Requirements under Banking Regulations |  |
Total capital (to risk-weighted assets) |  | $ 24,347
Total capital to risk-weighted assets |  | 11.02%
Total capital, Minimum Required for Capital Adequacy Purposes |  | $ 17,680
Total capital to risk-weighted assets, Minimum Required for Capital Adequacy Purposes |  | 8.00%
Capital Required for Capital Adequacy Plus Capital Conservation Buffer |  | $ 19,062
Capital Required for Capital Adequacy Plus Conservation Buffer to Risk Weighted Assets |  | 8.625%
Total capital, Minimum Required to be Well Capitalized Under Prompt Corrective Action Requirements |  | $ 22,101
Total capital to risk-weighted assets, Minimum Required to be Well Capitalized Under Prompt Corrective Action Requirements |  | 10.00%
Tier 1 capital (to risk-weighted assets) |  | $ 22,323
Tier 1 capital to risk-weighted assets |  | 10.10%
Tier 1 capital, Minimum Required for Capital Adequacy Purposes |  | $ 13,260
Tier 1 capital to risk-weighted assets, Minimum Required for Capital Adequacy Purposes |  | 6.00%
Tier One Risk Based Capital Required for Capital Adequacy Plus Capital Conservation Buffer |  | $ 14,642
Tier One Risk Based Capital Required for Capital Adequacy Plus Conservation Buffer to Risk Weighted Assets |  | 6.625%
Tier 1 capital, Minimum Required to be Well Capitalized Under Prompt Corrective Action Requirements |  | $ 17,680
Tier 1 capital to risk weighted assets, Minimum Required to be Well Capitalized Under Prompt Corrective Action Requirements |  | 8.00%
Common equity tier 1 capital |  | $ 22,323
Common equity tier 1 capital to risk-weighted assets |  | 10.10%
Common equity tier 1 capital, Minimum Required for Capital Adequacy Purposes |  | $ 9,945
Common equity tier 1 capital to risk-weighted assets, Minimum Required for Capital Adequacy Purposes |  | 4.50%
Common Equity Tier One Capital Required for Capital Adequacy Plus Capital Conservation Buffer |  | $ 11,327
Common Equity Tier One Capital Required for Capital Adequacy Plus Conservation Buffer to Risk Weighted Assets |  | 5.125%
Common equity tier 1 capital, Minimum Required to Be Well Capitalized Under Prompt Corrective Action Requirements |  | $ 14,365
Common equity tier 1 capital to risk-weighted assets, Minimum Required to Be Well Capitalized Under Prompt Corrective Action Requirements |  | 6.50%
Tier 1 leverage capital (to adjusted assets) |  | $ 22,323
Tier 1 leverage capital to average assets |  | 9.15%
Tier 1 leverage capital, Minimum Required for Capital Adequacy Purposes |  | $ 9,758
Tier 1 leverage capital to average assets, Minimum Required for Capital Adequacy Purposes |  | 4.00%
Tier One Leverage Capital Required for Capital Adequacy Plus Capital Conservation Buffer |  | $ 9,758
Tier One Leverage Capital Required for Capital Adequacy Plus Conservation Buffer to Risk Weighted Assets |  | 4.00%
Tier 1 leverage capital, Minimum Required to be Well Capitalized Under Prompt Corrective Action Requirements |  | $ 12,198
Tier 1 leverage capital to average assets, Minimum Required to be Well Capitalized Under Prompt Corrective Action Requirements |  | 5.00%
Alterra Bank |  |
Compliance with Regulatory Capital Requirements under Banking Regulations |  |
Total capital (to risk-weighted assets) |  | $ 31,699
Total capital to risk-weighted assets |  | 13.27%
Total capital, Minimum Required for Capital Adequacy Purposes |  | $ 19,106
Total capital to risk-weighted assets, Minimum Required for Capital Adequacy Purposes |  | 8.00%
Capital Required for Capital Adequacy Plus Capital Conservation Buffer |  | $ 20,599
Capital Required for Capital Adequacy Plus Conservation Buffer to Risk Weighted Assets |  | 8.625%
Total capital, Minimum Required to be Well Capitalized Under Prompt Corrective Action Requirements |  | $ 23,882
Total capital to risk-weighted assets, Minimum Required to be Well Capitalized Under Prompt Corrective Action Requirements |  | 10.00%
Tier 1 capital (to risk-weighted assets) |  | $ 28,685
Tier 1 capital to risk-weighted assets |  | 12.01%
Tier 1 capital, Minimum Required for Capital Adequacy Purposes |  | $ 14,329
Tier 1 capital to risk-weighted assets, Minimum Required for Capital Adequacy Purposes |  | 6.00%
Tier One Risk Based Capital Required for Capital Adequacy Plus Capital Conservation Buffer |  | $ 15,822
Tier One Risk Based Capital Required for Capital Adequacy Plus Conservation Buffer to Risk Weighted Assets |  | 6.625%
Tier 1 capital, Minimum Required to be Well Capitalized Under Prompt Corrective Action Requirements |  | $ 19,106
Tier 1 capital to risk weighted assets, Minimum Required to be Well Capitalized Under Prompt Corrective Action Requirements |  | 8.00%
Common equity tier 1 capital |  | $ 28,685
Common equity tier 1 capital to risk-weighted assets |  | 12.01%
Common equity tier 1 capital, Minimum Required for Capital Adequacy Purposes |  | $ 10,747
Common equity tier 1 capital to risk-weighted assets, Minimum Required for Capital Adequacy Purposes |  | 4.50%
Common Equity Tier One Capital Required for Capital Adequacy Plus Capital Conservation Buffer |  | $ 12,240
Common Equity Tier One Capital Required for Capital Adequacy Plus Conservation Buffer to Risk Weighted Assets |  | 5.125%
Common equity tier 1 capital, Minimum Required to Be Well Capitalized Under Prompt Corrective Action Requirements |  | $ 15,524
Common equity tier 1 capital to risk-weighted assets, Minimum Required to Be Well Capitalized Under Prompt Corrective Action Requirements |  | 6.50%
Tier 1 leverage capital (to adjusted assets) |  | $ 28,685
Tier 1 leverage capital to average assets |  | 10.58%
Tier 1 leverage capital, Minimum Required for Capital Adequacy Purposes |  | $ 10,842
Tier 1 leverage capital to average assets, Minimum Required for Capital Adequacy Purposes |  | 4.00%
Tier One Leverage Capital Required for Capital Adequacy Plus Capital Conservation Buffer |  | $ 10,842
Tier One Leverage Capital Required for Capital Adequacy Plus Conservation Buffer to Risk Weighted Assets |  | 4.00%
Tier 1 leverage capital, Minimum Required to be Well Capitalized Under Prompt Corrective Action Requirements |  | $ 13,552
Tier 1 leverage capital to average assets, Minimum Required to be Well Capitalized Under Prompt Corrective Action Requirements |  | 5.00%

X
- Definition Capital Required for Capital Adequacy Plus Capital Conservation Buffer + References No definition available. + Details
Name: | fbiz_CapitalRequiredforCapitalAdequacyPlusCapitalConservationBuffer
Namespace Prefix: | fbiz_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Capital Required for Capital Adequacy Plus Conservation Buffer to Risk Weighted Assets + References No definition available. + Details
Name: | fbiz_CapitalRequiredforCapitalAdequacyPlusConservationBuffertoRiskWeightedAssets
Namespace Prefix: | fbiz_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Common Equity Tier One Capital Required for Capital Adequacy Plus Capital Conservation Buffer + References No definition available. + Details
Name: | fbiz_CommonEquityTierOneCapitalRequiredforCapitalAdequacyPlusCapitalConservationBuffer
Namespace Prefix: | fbiz_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Common Equity Tier One Capital Required for Capital Adequacy Plus Conservation Buffer to Risk Weighted Assets + References No definition available. + Details
Name: | fbiz_CommonEquityTierOneCapitalRequiredforCapitalAdequacyPlusConservationBuffertoRiskWeightedAssets
Namespace Prefix: | fbiz_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Common Equity Tier One Capital Required for Capital Adequacy to Risk-Weighted Assets + References No definition available. + Details
Name: | fbiz_CommonEquityTierOneCapitalRequiredforCapitalAdequacytoRiskWeightedAssets
Namespace Prefix: | fbiz_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Common Equity Tier One Capital Required to be Well Capitalized to Risk-Weighted Assets + References No definition available. + Details
Name: | fbiz_CommonEquityTierOneCapitalRequiredtobeWellCapitalizedtoRiskWeightedAssets
Namespace Prefix: | fbiz_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Common Equity Tier One Capital to Risk-Weighted Assets + References No definition available. + Details
Name: | fbiz_CommonEquityTierOneCapitaltoRiskWeightedAssets
Namespace Prefix: | fbiz_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Common Equity Tier One Capital to be Well Capitalized + References No definition available. + Details
Name: | fbiz_CommonEquityTierOneCapitaltobeWellCapitalized
Namespace Prefix: | fbiz_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Tier One Leverage Capital Required for Capital Adequacy Plus Capital Conservation Buffer + References No definition available. + Details
Name: | fbiz_TierOneLeverageCapitalRequiredforCapitalAdequacyPlusCapitalConservationBuffer
Namespace Prefix: | fbiz_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Tier One Leverage Capital Required for Capital Adequacy Plus Conservation Buffer to Risk Weighted Assets + References No definition available. + Details
Name: | fbiz_TierOneLeverageCapitalRequiredforCapitalAdequacyPlusConservationBuffertoRiskWeightedAssets
Namespace Prefix: | fbiz_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Tier One Risk Based Capital Required for Capital Adequacy Plus Capital Conservation Buffer + References No definition available. + Details
Name: | fbiz_TierOneRiskBasedCapitalRequiredforCapitalAdequacyPlusCapitalConservationBuffer
Namespace Prefix: | fbiz_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Tier One Risk Based Capital Required for Capital Adequacy Plus Conservation Buffer to Risk Weighted Assets + References No definition available. + Details
Name: | fbiz_TierOneRiskBasedCapitalRequiredforCapitalAdequacyPlusConservationBuffertoRiskWeightedAssets
Namespace Prefix: | fbiz_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The amount of total capital as defined in the regulations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 948 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6490092&loc=d3e47304-110998 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=84167132&loc=d3e65071-112826 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=84167132&loc=d3e65071-112826 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 948 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=6490092&loc=d3e47080-110998 + Details
Name: | us-gaap_Capital
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The minimum amount of Total Capital required for capital adequacy purposes under the regulatory framework for prompt corrective action. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=84167132&loc=d3e65071-112826 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958568-112826 + Details
Name: | us-gaap_CapitalRequiredForCapitalAdequacy
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The minimum Total risk based capital ratio (total capital divided by risk weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958568-112826 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=84167132&loc=d3e65071-112826 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958570-112826 + Details
Name: | us-gaap_CapitalRequiredForCapitalAdequacyToRiskWeightedAssets
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The amount of Total Capital required to be categorized as well as capitalized under the regulatory framework for prompt corrective action. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958568-112826 + Details
Name: | us-gaap_CapitalRequiredToBeWellCapitalized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The Total risk based capital ratio (total capital divided by risk weighted assets) required to be categorized as "well capitalized", in the regulatory framework for prompt corrective action. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958568-112826 + Details
Name: | us-gaap_CapitalRequiredToBeWellCapitalizedToRiskWeightedAssets
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Total Capital divided by risk weighted assets as defined in the regulations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=84167132&loc=d3e65071-112826 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958568-112826 + Details
Name: | us-gaap_CapitalToRiskWeightedAssets
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of Common Equity Tier One Risk-based Capital, as defined by regulatory framework. + References No definition available. + Details
Name: | us-gaap_CommonEquityTierOneCapital
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of Common Equity Tier 1 Risk-based Capital required to be categorized as adequately capitalized under regulatory framework for prompt corrective action. + References No definition available. + Details
Name: | us-gaap_CommonEquityTierOneCapitalRequiredForCapitalAdequacy
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_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tier 1 Leverage Capital as defined in the regulations. Also called Core Capital. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958568-112826 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=84167132&loc=d3e65071-112826 + Details
Name: | us-gaap_TierOneLeverageCapital
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The minimum amount of Tier 1 Leverage Capital required for capital adequacy purposes under the regulatory framework for prompt corrective action. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=84167132&loc=d3e65071-112826 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958568-112826 + Details
Name: | us-gaap_TierOneLeverageCapitalRequiredForCapitalAdequacy
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The minimum amount of Tier 1 Leverage Capital for capital adequacy purposes divided by average assets as defined in the regulations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958568-112826 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=84167132&loc=d3e65071-112826 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958570-112826 + Details
Name: | us-gaap_TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The amount of Tier 1 Leverage Capital required to be categorized as well capitalized under the regulatory framework for prompt corrective action. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958568-112826 + Details
Name: | us-gaap_TierOneLeverageCapitalRequiredToBeWellCapitalized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The amount of Tier 1 Leverage Capital required to be categorized as well capitalized divided by average assets as defined in the regulatory framework for prompt corrective action. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958568-112826 + Details
Name: | us-gaap_TierOneLeverageCapitalRequiredToBeWellCapitalizedToAverageAssets
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Tier 1 Leverage Capital divided by average assets as defined in the regulations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958568-112826 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=84167132&loc=d3e65071-112826 + Details
Name: | us-gaap_TierOneLeverageCapitalToAverageAssets
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Tier 1 Risk Based Capital as defined in the regulations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958568-112826 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=84167132&loc=d3e65071-112826 + Details
Name: | us-gaap_TierOneRiskBasedCapital
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The minimum amount of Tier 1 Risk Based Capital required for capital adequacy purposes under the regulatory framework for prompt corrective action. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=84167132&loc=d3e65071-112826 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958568-112826 + Details
Name: | us-gaap_TierOneRiskBasedCapitalRequiredForCapitalAdequacy
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The minimum Tier One Capital Ratio (Tier one capital divided by risk-weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958568-112826 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958570-112826 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=84167132&loc=d3e65071-112826 + Details
Name: | us-gaap_TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The amount of Tier 1 Risk Based Capital required to be categorized as well capitalized under the regulatory framework for prompt corrective action. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958568-112826 + Details
Name: | us-gaap_TierOneRiskBasedCapitalRequiredToBeWellCapitalized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The Tier 1 capital ratio (Tier 1 capital divided by risk weighted assets) required to be categorized as "well capitalized" under the regulatory framework for prompt corrective action. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958568-112826 + Details
Name: | us-gaap_TierOneRiskBasedCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Tier 1 capital divided by risk weighted assets as defined by regulations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958568-112826 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=84167132&loc=d3e65071-112826 + Details
Name: | us-gaap_TierOneRiskBasedCapitalToRiskWeightedAssets
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | dei_LegalEntityAxis=fbiz_FirstBusinessBankMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=fbiz_FirstBusinessBankMilwaukeeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=fbiz_AlterraBankMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |