XML 75 R64.htm IDEA: XBRL DOCUMENT
v3.22.1

Fair Value Measurements - Quantitative and Qualitative Information (Details) $ in Thousands | Mar. 31, 2022 USD ($) | Dec. 31, 2021 USD ($) | Mar. 31, 2021 USD ($)
--- | --- | --- | ---
Quantitative information about Level 3 fair value measurements |  |  |
Mortgage servicing rights, fair value | $ 10,376 | $ 7,097 |
Securities available-for-sale, at fair value | 1,816,450 | 1,692,488 |
Fair Value, Inputs, Level 3 [Member] |  |  |
Quantitative information about Level 3 fair value measurements |  |  |
Mortgage servicing rights, fair value | 10,376 | 7,097 |
Securities available-for-sale, at fair value | 13,833 | 14,092 |
States and political subdivisions |  |  |
Quantitative information about Level 3 fair value measurements |  |  |
Securities available-for-sale, at fair value | 236,408 | 256,465 |
States and political subdivisions | Fair Value, Inputs, Level 3 [Member] |  |  |
Quantitative information about Level 3 fair value measurements |  |  |
Securities available-for-sale, at fair value | 13,800 |  | $ 4,600
Collateralized mortgage obligations |  |  |
Quantitative information about Level 3 fair value measurements |  |  |
Securities available-for-sale, at fair value | 696,513 | 672,967 |
Fair Value, Measurements, Recurring [Member] |  |  |
Quantitative information about Level 3 fair value measurements |  |  |
Mortgage servicing rights, fair value | 10,376 | 7,097 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] |  |  |
Quantitative information about Level 3 fair value measurements |  |  |
Mortgage servicing rights, fair value | 10,376 | 7,097 |
Fair Value, Measurements, Recurring [Member] | States and political subdivisions |  |  |
Quantitative information about Level 3 fair value measurements |  |  |
Securities available-for-sale, at fair value | 236,408 | 256,465 |
Fair Value, Measurements, Recurring [Member] | States and political subdivisions | Fair Value, Inputs, Level 3 [Member] |  |  |
Quantitative information about Level 3 fair value measurements |  |  |
Securities available-for-sale, at fair value | 13,833 | 14,092 |
Fair Value, Measurements, Recurring [Member] | Collateralized mortgage obligations |  |  |
Quantitative information about Level 3 fair value measurements |  |  |
Securities available-for-sale, at fair value | $ 696,513 | $ 672,967 |
Fair Value, Measurements, Recurring [Member] | Measurement Input, Discount Rate | Mortgage Servicing Rights [Member] | Fair Value, Inputs, Level 3 [Member] | Minimum |  |  |
Quantitative information about Level 3 fair value measurements |  |  |
Servicing Asset, Measurement Input | 9.0 | 11.0 |
Fair Value, Measurements, Recurring [Member] | Measurement Input, Discount Rate | Mortgage Servicing Rights [Member] | Fair Value, Inputs, Level 3 [Member] | Maximum |  |  |
Quantitative information about Level 3 fair value measurements |  |  |
Servicing Asset, Measurement Input | 11.0 | 15.0 |
Fair Value, Measurements, Recurring [Member] | Measurement Input, Discount Rate | Mortgage Servicing Rights [Member] | Fair Value, Inputs, Level 3 [Member] | Weighted Average [Member] |  |  |
Quantitative information about Level 3 fair value measurements |  |  |
Servicing Asset, Measurement Input | 9.0 | 11.0 |
Fair Value, Measurements, Recurring [Member] | Measurement Input, Constant Prepayment Rate | Mortgage Servicing Rights [Member] | Fair Value, Inputs, Level 3 [Member] | Minimum |  |  |
Quantitative information about Level 3 fair value measurements |  |  |
Servicing Asset, Measurement Input | 5.7 | 0.0 |
Fair Value, Measurements, Recurring [Member] | Measurement Input, Constant Prepayment Rate | Mortgage Servicing Rights [Member] | Fair Value, Inputs, Level 3 [Member] | Maximum |  |  |
Quantitative information about Level 3 fair value measurements |  |  |
Servicing Asset, Measurement Input | 28.9 | 36.6 |
Fair Value, Measurements, Recurring [Member] | Measurement Input, Constant Prepayment Rate | Mortgage Servicing Rights [Member] | Fair Value, Inputs, Level 3 [Member] | Weighted Average [Member] |  |  |
Quantitative information about Level 3 fair value measurements |  |  |
Servicing Asset, Measurement Input | 6.2 | 11.9 |

X
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(6)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=124260329&loc=d3e26610-111562 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563 + Details
Name: | us-gaap_AvailableForSaleSecuritiesDebtSecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 50 -Section 45 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6469459&loc=d3e122501-111745 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 50 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6469459&loc=d3e122492-111745 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 50 -Section 50 -Paragraph 3 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=125521744&loc=d3e122625-111746 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 50 -Section 45 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6469459&loc=d3e122501-111745 + Details
Name: | us-gaap_ServicingAssetAtFairValueAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Value of input used to measure servicing asset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -URI http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258 + Details
Name: | us-gaap_ServicingAssetMeasurementInput
Namespace Prefix: | us-gaap_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_USStatesAndPoliticalSubdivisionsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_CollateralizedMortgageObligationsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputDiscountRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=osbc_MortgageServicingRightsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_WeightedAverageMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputConstantPrepaymentRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |