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Regulatory Capital (Regulatory Capital Ratios) (Details) - First Business Bank - USD ($) $ in Thousands | Mar. 31, 2019 | Dec. 31, 2018
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Compliance with Regulatory Capital Requirements under Banking Regulations |  |
Total capital | $ 224,649 | $ 220,474
Total capital to risk-weighted assets | 11.83% | 11.49%
Total capital, Minimum Required for Capital Adequacy Purposes | $ 151,978 | $ 153,456
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 | $ 199,472 | $ 189,422
Capital Required for Capital Adequacy Plus Conservation Buffer to Risk Weighted Assets | 10.50% | 9.875%
Total capital, Minimum Required to be Well Capitalized Under Prompt Corrective Action Requirements | $ 189,973 | $ 191,820
Total capital to risk-weighted assets, Minimum Required to be Well Capitalized Under Prompt Corrective Action Requirements | 10.00% | 10.00%
Tier 1 capital | $ 200,924 | $ 197,093
Tier 1 capital to risk-weighted assets | 10.58% | 10.27%
Tier 1 capital, Minimum Required for Capital Adequacy Purposes | $ 113,984 | $ 115,092
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 | $ 161,477 | $ 151,058
Tier One Risk Based Capital Required for Capital Adequacy Plus Conservation Buffer to Risk Weighted Assets | 8.50% | 7.875%
Tier 1 capital, Minimum Required to be Well Capitalized Under Prompt Corrective Action Requirements | $ 151,978 | $ 153,456
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 | $ 200,924 | $ 197,093
Common equity tier 1 capital to risk-weighted assets | 10.58% | 10.27%
Common equity tier 1 capital, Minimum Required for Capital Adequacy Purposes | $ 85,488 | $ 86,319
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 | $ 132,981 | $ 122,285
Common Equity Tier One Capital Required for Capital Adequacy Plus Conservation Buffer to Risk Weighted Assets | 7.00% | 6.375%
Common equity tier 1 capital, Minimum Required to Be Well Capitalized Under Prompt Corrective Action Requirements | $ 123,482 | $ 124,683
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 | $ 200,924 | $ 197,093
Tier 1 leverage capital to average assets | 10.28% | 10.20%
Tier 1 leverage capital, Minimum Required for Capital Adequacy Purposes | $ 78,152 | $ 77,301
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 | $ 78,152 | $ 77,301
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 | $ 97,691 | $ 96,626
Tier 1 leverage capital to average assets, Minimum Required to be Well Capitalized Under Prompt Corrective Action Requirements | 5.00% | 5.00%

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