XML 82 R71.htm IDEA: XBRL DOCUMENT
v3.22.2.2

Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk - Commitments (Details) - USD ($) | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2022 | Sep. 30, 2022 | Dec. 31, 2021
Company's contractual commitments due to letters of credit |  |  |
Total letters of credit | $ 33,237,000 | $ 33,237,000 | $ 33,288,000
Allowance for Credit Loss on Unfunded Commitments | 4,400,000 | 4,400,000 |
Allowance for Credit Loss Unfunded Commitment, Purchase Accounting Adjustment | 1,000,000.0 | 1,000,000.0 |
Decrease In Allowance for Credit Loss on unfunded Commitments | 749,000 |  |
Commercial unfunded commitments assumptions for increase in the allowance for credit losses |  | 973,000 |
Accretion of interest income for decrease in the allowance for credit losses |  | 224,000 |
Fixed [Member] |  |  |
Company's contractual commitments due to letters of credit |  |  |
Total letters of credit | 7,371,000 | 7,371,000 | 840,000
Variable [Member] |  |  |
Company's contractual commitments due to letters of credit |  |  |
Total letters of credit | 25,866,000 | 25,866,000 | 32,448,000
Commitments to Extend Credit to Borrowers [Member] |  |  |
Company's contractual commitments due to letters of credit |  |  |
Total letters of credit | 33,170,000 | 33,170,000 | 33,221,000
Commitments to Extend Credit to Borrowers [Member] | Fixed [Member] |  |  |
Company's contractual commitments due to letters of credit |  |  |
Total letters of credit | 7,371,000 | 7,371,000 | 840,000
Commitments to Extend Credit to Borrowers [Member] | Variable [Member] |  |  |
Company's contractual commitments due to letters of credit |  |  |
Total letters of credit | 25,799,000 | 25,799,000 | 32,381,000
Commitments to Extend Credit to Borrowers [Member] | Financial Standby Letter of Credit [Member] |  |  |
Company's contractual commitments due to letters of credit |  |  |
Total letters of credit | 18,424,000 | 18,424,000 | 17,858,000
Commitments to Extend Credit to Borrowers [Member] | Financial Standby Letter of Credit [Member] | Fixed [Member] |  |  |
Company's contractual commitments due to letters of credit |  |  |
Total letters of credit | 3,424,000 | 3,424,000 | 384,000
Commitments to Extend Credit to Borrowers [Member] | Financial Standby Letter of Credit [Member] | Variable [Member] |  |  |
Company's contractual commitments due to letters of credit |  |  |
Total letters of credit | 15,000,000 | 15,000,000 | 17,474,000
Commitments to Extend Credit to Borrowers [Member] | Performance Guarantee [Member] |  |  |
Company's contractual commitments due to letters of credit |  |  |
Total letters of credit | 14,746,000 | 14,746,000 | 15,363,000
Commitments to Extend Credit to Borrowers [Member] | Performance Guarantee [Member] | Fixed [Member] |  |  |
Company's contractual commitments due to letters of credit |  |  |
Total letters of credit | 3,947,000 | 3,947,000 | 456,000
Commitments to Extend Credit to Borrowers [Member] | Performance Guarantee [Member] | Variable [Member] |  |  |
Company's contractual commitments due to letters of credit |  |  |
Total letters of credit | 10,799,000 | 10,799,000 | 14,907,000
Commitments to Extend Credit Nonborrowers [Member] | Performance Guarantee [Member] |  |  |
Company's contractual commitments due to letters of credit |  |  |
Total letters of credit | 67,000 | 67,000 | 67,000
Commitments to Extend Credit Nonborrowers [Member] | Performance Guarantee [Member] | Variable [Member] |  |  |
Company's contractual commitments due to letters of credit |  |  |
Total letters of credit | 67,000 | 67,000 | 67,000
Letter of Credit [Member] | Unused lines of Credit [Member] |  |  |
Company's contractual commitments due to letters of credit |  |  |
Loan commitments | 977,014,000 | 977,014,000 | 979,890,000
Letter of Credit [Member] | Unused lines of Credit [Member] | Fixed [Member] |  |  |
Company's contractual commitments due to letters of credit |  |  |
Loan commitments | 197,499,000 | 197,499,000 | 84,225,000
Letter of Credit [Member] | Unused lines of Credit [Member] | Variable [Member] |  |  |
Company's contractual commitments due to letters of credit |  |  |
Loan commitments | $ 779,515,000 | $ 779,515,000 | $ 895,665,000

X
- Definition Amount of accretion of interest income for decrease in the allowance for credit losses. + References No definition available. + Details
Name: | osbc_AccretionOfInterestIncomeForDecreaseInAllowanceForCreditLosses
Namespace Prefix: | osbc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The amount of allowance for credit loss on unfunded commitments. + References No definition available. + Details
Name: | osbc_AllowanceForCreditLossOnUnfundedCommitments
Namespace Prefix: | osbc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of purchase accounting adjustment of allowance for credit loss unfunded commitment. + References No definition available. + Details
Name: | osbc_AllowanceForCreditLossUnfundedCommitmentPurchaseAccountingAdjustment
Namespace Prefix: | osbc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of commercial unfunded commitments assumptions for increase (decrease) in the allowance for credit losses. + References No definition available. + Details
Name: | osbc_CommercialUnfundedCommitmentsAssumptionsForIncreaseDecreaseInAllowanceForCreditLosses
Namespace Prefix: | osbc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The amount of increase (decrease) in allowance for credit loss on unfunded commitments. + References No definition available. + Details
Name: | osbc_IncreaseDecreaseInAllowanceForCreditLossOnUnfundedCommitments
Namespace Prefix: | osbc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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_DerivativeLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The face amount of financial liabilities, which are not recognized in the financial statements (off-balance sheet) because they fail to meet some other criterion for recognition. + References No definition available. + Details
Name: | us-gaap_FairValueDisclosureOffbalanceSheetRisksFaceAmountLiability
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The total amount of the contingent obligation under letters of credit outstanding as of the reporting date. + References No definition available. + Details
Name: | us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_UnderlyingAssetClassAxis=osbc_FixedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_UnderlyingAssetClassAxis=osbc_VariableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_GuaranteeObligationsByNatureAxis=us-gaap_FinancialStandbyLetterOfCreditMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_GuaranteeObligationsByNatureAxis=us-gaap_PerformanceGuaranteeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_CreditFacilityAxis=us-gaap_LetterOfCreditMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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