XML 21 R8.htm IDEA: XBRL DOCUMENT v3.10.0.1

Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) - $ / shares	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Consolidated Statements of Changes in Stockholders' Equity
Dividend declared and paid (per share)	$ 0.03	$ 0.03

X

- Definition

Presents the amount of dividend declared and paid per share, by the entity.

+ References

No definition available.

+ Details

Name:	osbc_DividendsDeclaredAndPaidPerShare
Namespace Prefix:	osbc_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

X

- References

No definition available.

+ Details

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