XML 103 R93.htm IDEA: XBRL DOCUMENT v3.19.3.a.u2

Regulatory & Capital Matters - Dividend Restrictions and Deferrals (Details)	12 Months Ended
	Dec. 31, 2019
Dividend Restrictions and Deferrals
Number of previous years retained profit considered for dividend payment	2 years
Minimum capital requirements, minimum percentage required	2.50%

X

- References

No definition available.

+ Details

Name:	osbc_DividendRestrictionsAndDeferralsAbstract
Namespace Prefix:	osbc_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Represents the number of previous years retained profits combined with the current years profits used to determine the amount of dividends that may be paid in any calendar year.

+ References

No definition available.

+ Details

Name:	osbc_DividendRestrictionsNumberOfPreviousYearsRetainedProfit
Namespace Prefix:	osbc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Definition

The minimum percentage of Tier 1 Common Capital required to be maintained in the next fiscal year following the latest fiscal year to prevent capital distribution limitations under regulatory capital rules.

+ References

No definition available.

+ Details

Name:	osbc_TierOneCommonEquityCapitalDistributionLimitationMinimumRegulatoryCapitalPercentageNextTwelveMonths
Namespace Prefix:	osbc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration