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Employee Benefit Plans (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Old Second Bancorp, Inc. Voluntary Deferred Compensation Plan for Executives |  |  |
Employee Benefit Plans |  |  |
Company obligations under Voluntary Deferred Compensation Plan for Executives | $ 1,600 | $ 1,900 | $ 1,800
Old Second Bancorp Inc Employees 401(k) Savings Plan and Trust |  |  |
Employee Benefit Plans |  |  |
Company's discretionary matching contributions to the Plan (as a percent) | 100.00% | 100.00% | 100.00%
Percentage of compensation contributed to the Plan matched by employer | 2.00% | 2.00% | 2.00%
Participants vesting as percentage of discretionary matching contributions | 100.00% | 100.00% | 100.00%
Expense relating to the 401(k) plan | $ 464 | $ 477 | $ 468

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- Definition The amount of the cost recognized during the period for defined contribution plans. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 70 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6414718&loc=d3e28014-114942 + Details
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- Definition Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan. + References No definition available. + Details
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- Definition Percentage of employer's matching contributions to a defined contribution plan that vests in a given year. + References No definition available. + Details
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- Details
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- Details
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