The percentage points added to the reference rate to compute the variable rate on the trust preferred securities.

No definition available.

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- Definition

Represents the fixed annual rate of cash distributions on the securities.

+ References

No definition available.

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- Definition

Represents the annual rate of cash distributions on the securities, which are payable quarterly.

+ References

No definition available.

+ Details

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- Definition

The reference rate for the variable rate of the trust preferred securities, such as LIBOR or the US treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ References

No definition available.

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- Definition

Represents the amortization period of the costs associated with the issuance of the trust preferred securities.

+ References

No definition available.

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- Definition

Represents the maturity period of trust preferred securities.

+ References

No definition available.

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- Definition

Amount of amortization expense attributable to debt issuance costs.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

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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.

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- Definition

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition

Including the current and noncurrent portions, the carrying value of junior subordinated long-term debt owed to unconsolidated subsidiary trusts as of the balance sheet date. Such debt places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets and was initially scheduled to be repaid after one year or beyond the normal operating cycle if longer.

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- Definition

The price per share at which the preferred stock of an entity that has priority over common stock in the distribution of dividends and in the event of liquidation of the entity is redeemed or may be called at. The redemption features of this preferred stock are solely within the control of the issuer.

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- Definition

The cash inflow from issuance of preferred stocks by a business trust or other special purpose entity, mainly established by a bank holding entity, to third party investors. The trust's assets are deeply subordinated debentures of the bank holding entity. Most trust preferred securities are subject to a mandatory redemption upon the repayment of the debentures.

+ References

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- Definition

Amount of cash inflow from contractual arrangement with the lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

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Junior Subordinated Debentures - Issuance (Details) - USD ($)				1 Months Ended	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Mar. 02, 2020	Feb. 24, 2020	Apr. 30, 2007	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2016
Junior subordinated debentures
Interest rate (as a percent)									5.75%
Junior subordinated debentures	$ 25,773,000					$ 25,773,000		$ 57,734,000
Unamortized debt issuance costs						$ 643,000	$ 36,000
Old Second Capital Trust II [Member]
Junior subordinated debentures
Proceeds from sale of cumulative trust preferred securities				$ 25,000,000.0
Maturity Period						30 years
Amortization period						30 years
Old Second Capital Trust II [Member] \| Debt Instrument, Redemption, Period One [Member]
Junior subordinated debentures
Cash distribution rate of trust preferred securities (as a percent)	4.40%				4.40%
Cash distribution fixed rate of trust preferred securities (as a percent)						6.77%
Old Second Capital Trust II [Member] \| Debt Instrument, Redemption, Period Two [Member]
Junior subordinated debentures
Basis points added to cash distribution floating rate base (as a percent)						1.50%
Old Second Capital Trust II [Member] \| Debt Instrument, Redemption, Period Two [Member] \| Debt Instrument, Variable Rate Base LIBOR [Member]
Junior subordinated debentures
Cash distribution, floating rate base						three-month LIBOR
Term note
Junior subordinated debentures
Proceeds from term note		$ 20,000,000	$ 20,000,000.0
Junior Subordinated Debt
Junior subordinated debentures
Junior Subordinated Debentures issuance cost	$ 1,000					$ 1,000		$ 644,000
Junior Subordinated Debt \| Old Second Capital Trust I
Junior subordinated debentures
Cash distribution rate of trust preferred securities (as a percent)		7.80%
Junior subordinated debentures		$ 32,600,000
Amortization period		30 years
Redemption price per share		$ 10.13
Proceeds from term note		$ 33,000,000.0
Unamortized debt issuance costs		$ 635,000
Junior Subordinated Debt \| Old Second Capital Trust II [Member]
Junior subordinated debentures
Junior subordinated debentures	$ 25,800,000					$ 25,800,000