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Employee Benefit Plans (Details) - USD ($) $ in Thousands | 12 Months Ended | 24 Months Ended | 36 Months Ended
--- | --- | --- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2017 | Dec. 31, 2017
Employee Benefit Plans |  |  |  |  |
Company obligations under Voluntary Deferred Compensation Plan for Executives | $ 1,700 | $ 1,600 | $ 1,900 | $ 1,700 | $ 1,700
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% |
Percentage of compensation contributed to the Plan matched by employer |  |  |  | 3.00% |
Participants vesting as percentage of discretionary matching contributions |  |  |  |  | 100.00%
Expense relating to the 401(k) plan | $ 698 | $ 464 | $ 477 |  |

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- Definition Aggregate carrying value as of the balance sheet date of the liabilities for all deferred compensation arrangements. Represents currently earned compensation under compensation arrangements that is not actually paid until a later date. + References No definition available. + Details
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- Definition Amount of cost for defined contribution plan. + 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=49170846&loc=d3e28014-114942 + Details
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- 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
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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 employer matches of the employee's percentage contribution matched. + 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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