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Period of delay in payment financing receivable modified for debtor experiencing financial difficulty, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

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Accumulated amortized cost excluding accrued interest, of financing receivable modified for debtor experiencing financial difficulty.

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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.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
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Percentage of decrease in weighted average contractual interest rate of financing receivable modified for debtor experiencing financial difficulty.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
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Period of increase in weighted average maturity of financing receivable modified for debtor experiencing financial difficulty, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Data Type:	na
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Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=osbc_CommercialRealEstateOwnerOccupiedMember
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Data Type:	na
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