XML 52 R41.htm IDEA: XBRL DOCUMENT v3.20.2

Securities - Unrealized Loss Positions (Details)	Jun. 30, 2020 USD ($) security	Dec. 31, 2019 USD ($) security
Securities Available-for-Sale, Number of Securities
Less than 12 months in an unrealized loss position | security	21	19
Greater than 12 months in an unrealized loss position | security	11	15
Total	32	34
Securities Available-for-Sale, Unrealized Losses
Less than 12 months in an unrealized loss position	$ 2,820,000	$ 2,602,000
Greater than 12 months in an unrealized loss position	2,956,000	1,181,000
Total	5,776,000	3,783,000
Securities Available-for-Sale, Fair Value
Less than 12 months in an unrealized loss position	66,055,000	129,582,000
Greater than 12 months in an unrealized loss position	55,022,000	45,240,000
Total	$ 121,077,000	$ 174,822,000
US Government Corporations and Agencies Securities [Member]
Securities Available-for-Sale, Number of Securities
Greater than 12 months in an unrealized loss position | security	4	4
Total	4	4
Securities Available-for-Sale, Unrealized Losses
Greater than 12 months in an unrealized loss position	$ 174,000	$ 165,000
Total	174,000	165,000
Securities Available-for-Sale, Fair Value
Greater than 12 months in an unrealized loss position	7,276,000	8,337,000
Total	$ 7,276,000	$ 8,337,000
Mortgage Backed Securities, Issued by US Government Agencies [Member]
Securities Available-for-Sale, Number of Securities
Less than 12 months in an unrealized loss position | security		3
Greater than 12 months in an unrealized loss position | security		2
Total		5
Securities Available-for-Sale, Unrealized Losses
Less than 12 months in an unrealized loss position		$ 10,000
Greater than 12 months in an unrealized loss position		9,000
Total		19,000
Securities Available-for-Sale, Fair Value
Less than 12 months in an unrealized loss position		3,018,000
Greater than 12 months in an unrealized loss position		843,000
Total		$ 3,861,000
US States and Political Subdivisions Debt Securities [Member]
Securities Available-for-Sale, Number of Securities
Less than 12 months in an unrealized loss position | security	1	6
Greater than 12 months in an unrealized loss position | security	2	2
Total	3	8
Securities Available-for-Sale, Unrealized Losses
Less than 12 months in an unrealized loss position	$ 7,000	$ 1,665,000
Greater than 12 months in an unrealized loss position	1,128,000	766,000
Total	1,135,000	2,431,000
Securities Available-for-Sale, Fair Value
Less than 12 months in an unrealized loss position	890,000	41,043,000
Greater than 12 months in an unrealized loss position	5,466,000	6,593,000
Total	$ 6,356,000	$ 47,636,000
Collateralized Mortgage Obligations [Member]
Securities Available-for-Sale, Number of Securities
Less than 12 months in an unrealized loss position | security	8	2
Greater than 12 months in an unrealized loss position | security	1	2
Total	9	4
Securities Available-for-Sale, Unrealized Losses
Less than 12 months in an unrealized loss position	$ 944,000	$ 26,000
Greater than 12 months in an unrealized loss position	6,000	12,000
Total	950,000	38,000
Securities Available-for-Sale, Fair Value
Less than 12 months in an unrealized loss position	11,867,000	9,054,000
Greater than 12 months in an unrealized loss position	522,000	1,209,000
Total	$ 12,389,000	$ 10,263,000
Asset-backed Securities [Member]
Securities Available-for-Sale, Number of Securities
Less than 12 months in an unrealized loss position | security	9	4
Greater than 12 months in an unrealized loss position | security	2	1
Total	11	5
Securities Available-for-Sale, Unrealized Losses
Less than 12 months in an unrealized loss position	$ 1,223,000	$ 839,000
Greater than 12 months in an unrealized loss position	1,185,000	48,000
Total	2,408,000	887,000
Securities Available-for-Sale, Fair Value
Less than 12 months in an unrealized loss position	36,955,000	54,540,000
Greater than 12 months in an unrealized loss position	30,055,000	3,238,000
Total	$ 67,010,000	$ 57,778,000
Collateralized loan obligations
Securities Available-for-Sale, Number of Securities
Less than 12 months in an unrealized loss position | security	3	4
Greater than 12 months in an unrealized loss position | security	2	4
Total	5	8
Securities Available-for-Sale, Unrealized Losses
Less than 12 months in an unrealized loss position	$ 646,000	$ 62,000
Greater than 12 months in an unrealized loss position	463,000	181,000
Total	1,109,000	243,000
Securities Available-for-Sale, Fair Value
Less than 12 months in an unrealized loss position	16,343,000	21,927,000
Greater than 12 months in an unrealized loss position	11,703,000	25,020,000
Total	$ 28,046,000	$ 46,947,000

X

- Definition

Represents the number of investment positions of securities categorized neither as held-to-maturity nor trading securities, that have been in a loss position for less than twelve months.

+ References

No definition available.

+ Details

Name:	osbc_AvailableForSaleSecuritiesInUnrealizedLossPositionLessThan12MonthsQualitativeDisclosureNumberOfPositions
Namespace Prefix:	osbc_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Represents the number of investment positions of securities categorized neither as held-to-maturity nor trading securities, that have been in a loss position for twelve months or longer.

+ References

No definition available.

+ Details

Name:	osbc_AvailableForSaleSecuritiesInUnrealizedLossPositions12MonthsOrLongerQualitativeDisclosureNumberOfPositions
Namespace Prefix:	osbc_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer.

+ References

No definition available.

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale in a continuous loss position.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27337-111563

+ Details

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

X

- References

No definition available.

+ Details

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

X

- Definition

This item represents the aggregate fair value of investments in debt and equity securities in an unrealized loss position which are categorized neither as held-to-maturity nor trading securities.

+ References

No definition available.

+ Details

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

X

- References

No definition available.

+ Details

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

X

- Definition

Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for less than twelve months.

+ References

No definition available.

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for less than twelve months.

+ References

No definition available.

+ Details

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

X

- References

No definition available.

+ Details

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

X

- Definition

This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for twelve months or longer.

+ References

No definition available.

+ Details

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

X

- Definition

Number of investment positions in available-for-sale investments in a continuous unrealized loss position for which an other-than-temporary impairment (OTTI) has not been recognized in the income statement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27290-111563

+ Details

Name:	us-gaap_AvailableforsaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositions1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USGovernmentCorporationsAndAgenciesSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=osbc_MortgageBackedSecuritiesIssuedByUSGovernmentAgenciesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USStatesAndPoliticalSubdivisionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CollateralizedMortgageObligationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_AssetBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CollateralizedLoanObligationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: