XML 118 R99.htm IDEA: XBRL DOCUMENT v3.25.0.1

Fair Value Measurements - Nonrecurring (Details) - USD ($)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Assets and liabilities measured at fair value
Valuation allowance	$ 26,200,000
Carrying value of other real estate owned	21,617,000	$ 5,123,000	$ 1,561,000	$ 2,356,000
OREO Valuation allowance	1,862,000	118,000	$ 856,000	$ 1,179,000
Impaired Loans | Reported Value Measurement
Assets and liabilities measured at fair value
Increase (decrease) of specific allocations within the provision for loan losses		6,500,000
Fair Value, Measurements, Nonrecurring
Assets and liabilities measured at fair value
Total	40,675,000	71,303,000
Fair Value, Measurements, Nonrecurring | Impaired Loans
Assets and liabilities measured at fair value
Total	19,058,000	66,180,000
Valuation allowance	7,200,000	11,100,000
Increase (decrease) of specific allocations within the provision for loan losses	3,900,000
Fair Value, Measurements, Nonrecurring | Impaired Loans | Reported Value Measurement
Assets and liabilities measured at fair value
Total	26,200,000	77,300,000
Fair Value, Measurements, Nonrecurring | Other Real Estate Owned
Assets and liabilities measured at fair value
Total	21,617,000	5,123,000
Carrying value of other real estate owned	21,600,000	5,100,000
Outstanding balance	23,500,000	5,200,000
OREO Valuation allowance	1,900,000	118,000
Fair Value, Measurements, Nonrecurring | Fair Value, Inputs, Level 3
Assets and liabilities measured at fair value
Total	40,675,000	71,303,000
Fair Value, Measurements, Nonrecurring | Fair Value, Inputs, Level 3 | Impaired Loans
Assets and liabilities measured at fair value
Total	19,058,000	66,180,000
Fair Value, Measurements, Nonrecurring | Fair Value, Inputs, Level 3 | Other Real Estate Owned
Assets and liabilities measured at fair value
Total	$ 21,617,000	$ 5,123,000

X

- Definition

Amount of allowance for credit losses related to recorded investment.

+ References

No definition available.

+ Details

Name:	osbc_ImpairedFinancingReceivableAllowancesForCreditLosses
Namespace Prefix:	osbc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Represents the amount of increase (decrease) in specific allocations within the provision for loan losses for impaired financing receivables.

+ References

No definition available.

+ Details

Name:	osbc_ImpairedFinancingReceivableIncreaseDecreaseOfSpecificAllocationsWithinProvisionForLoanLosses
Namespace Prefix:	osbc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Represents the gross carrying amount of real estate owned before the valuation allowance.

+ References

No definition available.

+ Details

Name:	osbc_RealEstateGross
Namespace Prefix:	osbc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

+ Details

Name:	us-gaap_AssetsFairValueDisclosure
Namespace Prefix:	us-gaap_
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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-3

+ Details

Name:	us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Carrying amount as of the balance sheet date of land and buildings obtained through foreclosure proceedings or defeasance in full or partial satisfaction of a debt arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481990/310-10-45-3

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 11
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481962/310-10-50-11

+ Details

Name:	us-gaap_RealEstateAcquiredThroughForeclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

For each period for which an income statement is required, disclosure of the changes in the allowance, including balances at end of period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.10(4))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479853/942-210-S99-1

+ Details

Name:	us-gaap_RealEstateOwnedValuationAllowance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Details

Name:	us-gaap_FairValueByAssetClassAxis=osbc_ImpairedLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FairValueByMeasurementBasisAxis=us-gaap_CarryingReportedAmountFairValueDisclosureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsNonrecurringMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FairValueByAssetClassAxis=osbc_OtherRealEstateOwnedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: