XML 105 R89.htm IDEA: XBRL DOCUMENT
v3.24.0.1

Mortgage Banking Derivatives (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
Mortgage Banking Derivatives |  |  |
Amount of loans sold to investors | $ 52,100 |  |
Proceeds from sale of loan to investors | 52,186 | $ 81,776 | $ 254,374
Gain on sale of loan | 1,477 | 2,022 | $ 9,300
Federal National Mortgage Association [Member] |  |  |
Mortgage Banking Derivatives |  |  |
Amount of loans sold to investors | $ 30,500 |  |
Federal National Mortgage Association [Member] | Customer Concentration Risk | Loan receivables |  |  |
Mortgage Banking Derivatives |  |  |
Percentage of concentration risk | 60.00% |  |
Federal Home Loan Mortgage Corporation [Member] |  |  |
Mortgage Banking Derivatives |  |  |
Amount of loans sold to investors | $ 9,800 |  |
Federal Home Loan Mortgage Corporation [Member] | Customer Concentration Risk | Loan receivables |  |  |
Mortgage Banking Derivatives |  |  |
Percentage of concentration risk | 19.30% |  |
Not Designated as Hedging Instrument | Forward Contracts [Member] |  |  |
Mortgage Banking Derivatives |  |  |
Notional or Contractual Amount | $ 6,000 | 2,750 |
Fair value | (46) | 20 |
Not Designated as Hedging Instrument | Interest Rate Lock Commitments [Member] |  |  |
Mortgage Banking Derivatives |  |  |
Notional or Contractual Amount | 1,312 | 2,548 |
Fair value | $ 36 | $ 56 |

X
- Definition Represents the amount of loans held for sale, sold during the period. + References No definition available. + Details
Name: | osbc_AmountOfLoansHeldForSaleSold
Namespace Prefix: | osbc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 42 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482810/280-10-50-42 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 21 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482907/825-10-50-21 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 20 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482907/825-10-50-20 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 275 -SubTopic 10 -Section 50 -Paragraph 18 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482861/275-10-50-18 Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 275 -SubTopic 10 -Section 50 -Paragraph 20 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482861/275-10-50-20 + Details
Name: | us-gaap_ConcentrationRiskPercentage1
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Fair value of the assets less the liabilities of a derivative or group of derivatives. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 825 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 10 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482907/825-10-50-10 + Details
Name: | us-gaap_DerivativeFairValueOfDerivativeNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

X
- Definition Nominal or face amount used to calculate payment on derivative. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 1B -Publisher FASB -URI https://asc.fasb.org//1943274/2147480434/815-10-50-1B Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 1A -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480434/815-10-50-1A + Details
Name: | us-gaap_DerivativeNotionalAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | instant

X
- Definition The gains (losses) included in earnings that represent the difference between the sale price and the carrying value of loans made to finance real estate acquisitions. This element refers to the gain (loss) and not to the cash proceeds of the sale. This element is a noncash adjustment to net income when calculating net cash generated by operating activities using the indirect method. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 45 -Paragraph 28 -Subparagraph (b) -SubTopic 10 -Topic 230 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482740/230-10-45-28 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name Accounting Standards Codification -Section 45 -Paragraph 1 -SubTopic 310 -Topic 944 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479616/944-310-45-1 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name Accounting Standards Codification -Section 45 -Paragraph 2 -SubTopic 310 -Topic 944 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479616/944-310-45-2 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Name Accounting Standards Codification -Section 50 -Paragraph 1 -SubTopic 310 -Topic 944 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479584/944-310-50-1 + Details
Name: | us-gaap_GainLossOnSaleOfMortgageLoans
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The cash inflow resulting from the sale of loans classified as held-for-sale, including proceeds from loans sold through mortgage securitization. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 230 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 16 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482740/230-10-45-16 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 230 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 21 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482740/230-10-45-21 + Details
Name: | us-gaap_ProceedsFromSaleOfLoansHeldForSale
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | srt_MajorCustomersAxis=osbc_FederalNationalMortgageAssociationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ConcentrationRiskByTypeAxis=us-gaap_CustomerConcentrationRiskMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ConcentrationRiskByBenchmarkAxis=us-gaap_AccountsReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_MajorCustomersAxis=osbc_FederalHomeLoanMortgageCorporationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_HedgingDesignationAxis=us-gaap_NondesignatedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_ForwardContractsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateLockCommitmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |