XML 68 R55.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Loans - Accretable Discount on Purchased Loans (Details) $ in Thousands | 3 Months Ended
--- | ---
Jun. 30, 2018 USD ($)
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward] |
Beginning balance | $ 694
Purchases | 11,269
Accretion | (1,057)
Transfers | (135)
Ending balance | 10,771
PCI |
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward] |
Purchases | 1,551
Purchases | 6,536
Accretion | (176)
Transfers | (2)
Transfers | (133)
Ending balance | 1,373
Ending balance | 6,403
Non-PCI |
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward] |
Beginning balance | 694
Purchases | 3,182
Accretion | (881)
Ending balance | $ 2,995

X
- Definition Amount of accretable and non-accretable yield on acquired loans not accounted for as debt securities with evidence of deterioration of credit quality. + References No definition available. + Details
Name: | osbc_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableAndNonAccretableYield
Namespace Prefix: | osbc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of additions to the accretable and non-accretable yield on acquired loans not accounted for as debt securities with evidence of deterioration of credit quality. + References No definition available. + Details
Name: | osbc_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableAndNonAccretableYieldAdditions
Namespace Prefix: | osbc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of reduction, resulting from a reclassification to held-for-sale, in the accretable and non-accretable yield on acquired loans not accounted for as debt securities with evidence of deterioration of credit quality. + References No definition available. + Details
Name: | osbc_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableAndNonAccretableYieldTransfersToLoansHeldForSale
Namespace Prefix: | osbc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of non-accretable discount on acquired loans not accounted for as debt securities with evidence of deterioration of credit quality. + References No definition available. + Details
Name: | osbc_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesNonAccretableYield
Namespace Prefix: | osbc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of additions to the non-accretable yield the investor's initial investment in acquired loans not accounted for as debt securities with evidence of deterioration of credit quality. + References No definition available. + Details
Name: | osbc_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesNonAccretableYieldAdditions
Namespace Prefix: | osbc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of reduction, resulting from a reclassification to held-for-sale, in non-accretable yield on acquired loans not accounted for as debt securities with evidence of deterioration of credit quality. + References No definition available. + Details
Name: | osbc_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesNonAccretableYieldTransfersToLoansHeldForSale
Namespace Prefix: | osbc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of the excess of a loan's cash flows expected to be collected over the investor's initial investment in acquired loans not accounted for as debt securities with evidence of deterioration of credit quality. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=82894903&loc=d3e15032-111544 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 15 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=82894507&loc=d3e13503-111538 + Details
Name: | us-gaap_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYield
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of accretion recognized for the excess of a loan's cash flows expected to be collected over the investor's initial investment in acquired loans not accounted for as debt securities, with evidence of deterioration of credit quality. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 15 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=82894507&loc=d3e13503-111538 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=82894903&loc=d3e15032-111544 + Details
Name: | us-gaap_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYieldAccretion
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of additions to the excess of a loan's cash flows expected to be collected over the investor's initial investment in acquired loans not accounted for as debt securities with evidence of deterioration of credit quality. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 15 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=82894507&loc=d3e13503-111538 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=82894903&loc=d3e15032-111544 + Details
Name: | us-gaap_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYieldAdditions
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
Name: | us-gaap_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYieldMovementScheduleRollForward
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of reduction, resulting from a reclassification to held-for-sale, in the excess of a loan's cash flows expected to be collected over the investor's initial investment in acquired loans not accounted for as debt securities with evidence of deterioration of credit quality. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=82894903&loc=d3e15032-111544 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 15 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=82894507&loc=d3e13503-111538 + Details
Name: | us-gaap_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYieldTransfersToLoansHeldForSale
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | osbc_CreditLossStatusAxis=osbc_FinancialAssetAcquiredWithCreditDeteriorationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | osbc_CreditLossStatusAxis=osbc_FinancialAssetAcquiredAndNoCreditDeteriorationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |