XML 59 R44.htm IDEA: XBRL DOCUMENT
v3.22.0.1

Mortgage Banking Derivatives (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2021
Not Designated as Hedging Instrument [Member] | Mortgage Banking Derivatives. |
Mortgage Banking Derivatives |
Schedule of the effect of fair value and cash flow hedge accounting | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ |  | 2021 |  | 2020 |
Forward contracts: | ​ | ​ | ​ | ​ | ​ | ​ | ​
Notional amount | ​ | $ | 20,000 | ​ | $ | 46,500 | ​
Fair value | ​ |  | 17 | ​ |  | (228) | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Rate lock commitments: | ​ | ​ | ​ | ​ | ​ | ​ | ​
Notional amount | ​ | $ | 14,414 | ​ | $ | 37,972 | ​
Fair value | ​ |  | 491 | ​ |  | 1,068 | ​

X
- References No definition available. + Details
Name: | us-gaap_DerivativeInstrumentDetailAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the location and amount of derivative instruments and nonderivative instruments designated as hedging instruments reported before netting adjustments, and the amount of gain (loss) on derivative instruments and nonderivative instruments designated and qualified as hedging instruments. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4E -URI http://asc.fasb.org/extlink&oid=125515794&loc=SL5624181-113959 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=125515794&loc=SL5618551-113959 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -URI http://asc.fasb.org/extlink&oid=125515794&loc=SL5624171-113959 + Details
Name: | us-gaap_ScheduleOfDerivativeInstrumentsGainLossInStatementOfFinancialPerformanceTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

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

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