XML 110 R93.htm IDEA: XBRL DOCUMENT
v3.20.4

Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk - Fair Value of Derivatives (Details) | 1 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2019 USD ($) item | Dec. 31, 2020 USD ($) item | Dec. 31, 2019 USD ($) item | Dec. 31, 2018 USD ($)
Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk |  |  |  |
Loan pool hedge | $ 50,000,000.0 |  | $ 50,000,000.0 |
Term of interest rate risk cash flow hedge | 5 years |  |  |
Interest Rate Swap [Member] |  |  |  |
Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk |  |  |  |
Notional Amount | $ 25,800,000 | $ 25,800,000 | 25,800,000 |
Designated as Hedging Instrument [Member] |  |  |  |
Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk |  |  |  |
Derivative assets designated as hedging instruments, fair value |  | 2,697,000 |  |
Derivative liabilities designated as hedging instruments, fair value | $ 3,150,000 | $ 6,380,000 | $ 3,150,000 |
Designated as Hedging Instrument [Member] | Interest Rate Products | OSBC Affiliates |  |  |  |
Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk |  |  |  |
Derivative, number of transactions | item | 2 | 2 | 2 |
Notional Amount | $ 75,774,000 | $ 75,774,000 | $ 75,774,000 |
Derivative assets designated as hedging instruments, fair value |  | 2,697,000 |  |
Derivative liabilities designated as hedging instruments, fair value | 3,150,000 | 6,380,000 | 3,150,000 |
Not Designated as Hedging Instrument [Member] |  |  |  |
Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk |  |  |  |
Derivative assets designated as hedging instruments, fair value | 3,170,000 | 7,531,000 | 3,170,000 |
Derivative liabilities designated as hedging instruments, fair value | $ 2,973,000 | $ 6,779,000 | $ 2,973,000 |
Not Designated as Hedging Instrument [Member] | Interest Rate Products | Commercial Loan Customers |  |  |  |
Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk |  |  |  |
Derivative, number of transactions | item | 25 | 28 | 25 |
Notional Amount | $ 177,872,000 | $ 189,126,000 | $ 177,872,000 |
Derivative assets designated as hedging instruments, fair value | 2,920,000 | 6,691,000 | 2,920,000 |
Derivative liabilities designated as hedging instruments, fair value | 2,920,000 | $ 6,691,000 | $ 2,920,000 |
Weighted average maturity |  | 4 years 8 months 12 days | 5 years 10 months 24 days |
Not Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] |  |  |  |
Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk |  |  |  |
Notional Amount | 177,900,000 |  | $ 177,900,000 |
Cash collateral pledged with financial institutions, dollars | 114,000 | $ 17,200,000 | 114,000 |
Investment securities pledged with financial institutions, dollars | $ 11,000,000.0 | $ 0 | $ 11,000,000.0 |
Number of correspondent financial institutions where investment securities are pledged |  | 1 |  | 1
Not Designated as Hedging Instrument [Member] | Interest Rate Lock Commitments and Forward Contracts |  |  |  |
Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk |  |  |  |
Derivative, number of transactions | item | 87 | 205 | 87 |
Notional Amount | $ 23,667,000 | $ 84,472,000 | $ 23,667,000 |
Derivative assets designated as hedging instruments, fair value | $ 250,000 | $ 840,000 | $ 250,000 |
Not Designated as Hedging Instrument [Member] | Other Contracts |  |  |  |
Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk |  |  |  |
Derivative, number of transactions | item | 4 | 4 | 4 |
Notional Amount | $ 28,176,000 | $ 26,523,000 | $ 28,176,000 |
Derivative liabilities designated as hedging instruments, fair value | 53,000 | 88,000 | 53,000 |
Not Designated as Hedging Instrument [Member] | Forward Contracts [Member] |  |  |  |
Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk |  |  |  |
Notional Amount | 13,500,000 | $ 46,500,000 | 13,500,000 |
Interest Income [Member] |  |  |  |
Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk |  |  |  |
Amount to be reclassified as a reduction to interest expense during the next twelve months | 182,000 |  | 182,000 |
Interest Expense [Member] |  |  |  |
Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk |  |  |  |
Amount to be reclassified as a reduction to interest expense during the next twelve months | $ 167,000 |  | $ 167,000 |

X
- Definition Carrying amount as of the balance sheet date of loan pool hedge for securities. + References No definition available. + Details
Name: | osbc_LoanPoolHedgeOfSecurities
Namespace Prefix: | osbc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Represents the number of financial institutions where investment securities are pledged. + References No definition available. + Details
Name: | osbc_NumberOfFinancialInstitutionsInvestmentSecuritiesPledged
Namespace Prefix: | osbc_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Carrying amount as of the balance sheet date of cash collateral held for borrowed securities, for which the cash is restricted as to withdrawal or usage. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.1) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.(a),2) -URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910 + Details
Name: | us-gaap_CashCollateralForBorrowedSecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value of all asset derivatives designated as cash flow hedging instruments. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4B -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5624163-113959 + Details
Name: | us-gaap_CashFlowHedgeDerivativeInstrumentAssetsAtFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value of all liability derivatives designated as cash flow hedging instruments. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4B -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5624163-113959 + Details
Name: | us-gaap_CashFlowHedgeDerivativeInstrumentLiabilitiesAtFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Average remaining period until maturity of the derivative contract, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
Name: | us-gaap_DerivativeAverageRemainingMaturity1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
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 Nominal or face amount used to calculate payment on derivative. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5580258-113959 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5579245-113959 + Details
Name: | us-gaap_DerivativeNotionalAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | instant

X
- Definition The number of derivative instruments of a particular group held by the entity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5579245-113959 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5580258-113959 + Details
Name: | us-gaap_DerivativeNumberOfInstrumentsHeld
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition The estimated net amount of unrealized gains or losses on interest rate cash flow hedges as of the balance sheet date expected to be reclassified to earnings within the next twelve months. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=121549185&loc=d3e80748-113994 + Details
Name: | us-gaap_InterestRateCashFlowHedgeGainLossToBeReclassifiedDuringNext12MonthsNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Maximum period the entity is hedging its exposure to the variability in future cash flows for forecasted transactions, excluding those forecasted transactions related to the payment of variable interest on existing financial instruments, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=121549185&loc=d3e80748-113994 + Details
Name: | us-gaap_MaximumLengthOfTimeHedgedInInterestRateCashFlowHedge1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition The carrying amount as of the date of the latest financial statement presented of securities which are owned but transferred to serve as collateral for debt facilities other than FHLB loans, repurchase agreements and letter of credit arrangements, and for which the transferee does not have the right by contract or custom to sell or re-pledge them to an unrelated party. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 30 -Section 50 -Paragraph 1A -Subparagraph (b)(1)(i) -URI http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729 + Details
Name: | us-gaap_PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesForOtherDebtFacilities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

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

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

X
- Details
Name: | srt_CounterpartyNameAxis=osbc_OsbcAffiliatesMember
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: | srt_CounterpartyNameAxis=osbc_CommercialLoanCustomersMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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

X
- Details
Name: | us-gaap_IncomeStatementLocationAxis=us-gaap_InterestExpenseMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |