XML 83 R71.htm IDEA: XBRL DOCUMENT v3.8.0.1

Derivatives, Hedging Activities and Financial Instruments with Off-Balance Sheet Risk - Effect of Fair Value (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Amount of Gain or (Loss) Recognized in Income on Derivative	$ 6	$ 161
Cash Flow Hedging
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Amount of Gain or (Loss) Recognized in OCI on Derivative	1,206	(504)
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income		(211)
Cash Flow Hedging | Interest Income (Expense)
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income	(74)	(211)
Interest Rate Products | Other Income (Expense)
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Amount of Gain or (Loss) Recognized in Income on Derivative	6	161
Interest Rate Products | Cash Flow Hedging
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Amount of Gain or (Loss) Recognized in OCI on Derivative	1,206	(504)
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income		(211)
Interest Rate Products | Cash Flow Hedging | Interest Income (Expense)
Financial Instruments with Off-Balance Sheet Risk and Derivative Transactions
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income	$ (74)	$ (211)

X

- Definition

Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959

+ Details

Name:	us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

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

X

- Definition

The amount of net gains or losses on interest rate cash flow hedges reclassified during the period to earnings from accumulated other comprehensive income upon the hedged transaction affecting earnings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959

+ Details

Name:	us-gaap_InterestRateCashFlowHedgeGainLossReclassifiedToEarningsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Amount of unrealized gain (loss) related to the increase or decrease in fair value of interest rate derivatives designated as cash flow hedging instruments, which was recorded in accumulated other comprehensive income to the extent that the cash flow hedge was determined to be effective.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959

+ Details

Name:	us-gaap_UnrealizedGainLossOnInterestRateCashFlowHedgesPretaxAccumulatedOtherComprehensiveIncomeLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Details

Name:	us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis=us-gaap_CashFlowHedgingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_IncomeStatementLocationAxis=osbc_InterestIncomeExpenseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_IncomeStatementLocationAxis=osbc_OtherIncomeExpenseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: