XML 71 R55.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Acquisition of Loans (Details) - USD ($) $ in Thousands | Dec. 31, 2018 | Apr. 20, 2018
--- | --- | ---
Business Acquisition [Line Items] |  |
Fair Value | $ 10,965 |
PCI |  |
Business Acquisition [Line Items] |  |
Fair Value | 1,452 |
PCI | GCFC/ABC Bank |  |
Business Acquisition [Line Items] |  |
Fair Value | 10,965 | $ 11,360
Contractually required principal and interest payments | 18,106 | 19,447
Best estimate of contractual cash flows not expected to be collected | 5,969 | 6,537
Best estimate of contractual cash flows expected to be collected | 12,137 | 12,910
Non-PCI | GCFC/ABC Bank |  |
Business Acquisition [Line Items] |  |
Fair Value | 171,520 | 216,234
Contractually required principal and interest payments | 173,605 | 220,308
Best estimate of contractual cash flows not expected to be collected | 1,175 | 2,511
Best estimate of contractual cash flows expected to be collected | $ 172,430 | $ 217,797

X
- Definition Amount of cash flows not expected to be collected at acquisition of acquired loans not accounted for as debt securities with evidence of deterioration of credit quality. + References No definition available. + Details
Name: | osbc_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAcquiredDuringPeriodCashFlowsNotExpectedToBeCollectedAtAcquisition
Namespace Prefix: | osbc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

X
- Definition Fair value at acquisition of acquired loans not accounted for as debt securities with evidence of deterioration of credit quality. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -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://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=82894903&loc=d3e15032-111544 + Details
Name: | us-gaap_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAcquiredDuringPeriodAtAcquisitionAtFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of cash flows expected to be collected at acquisition of acquired loans not accounted for as debt securities with evidence of deterioration of credit quality. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -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://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=82894903&loc=d3e15032-111544 + Details
Name: | us-gaap_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAcquiredDuringPeriodCashFlowsExpectedToBeCollectedAtAcquisition
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of contractually required payments receivable at acquisition of acquired loans not accounted for as debt securities with evidence of deterioration of credit quality. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=82894903&loc=d3e15032-111544 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -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_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAcquiredDuringPeriodContractuallyRequiredPaymentsReceivableAtAcquisition
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_CreditLossStatusAxis=us-gaap_FinancialAssetAcquiredWithCreditDeteriorationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=osbc_GreaterChicagoFinancialCorpMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CreditLossStatusAxis=us-gaap_FinancialAssetAcquiredAndNoCreditDeteriorationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |