Represents element information pertaining to allowance for loans and lease losses.

No definition available.

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- Definition

Period under consideration for ALLL methodology.

+ References

No definition available.

+ Details

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- Definition

Represents element information petaining to debt instrument redemption price.

+ References

No definition available.

+ Details

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- Definition

Amount of decline in loans portfolio.

+ References

No definition available.

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- Definition

Amount of growth in loans portfolio.

+ References

No definition available.

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- Definition

Fair value as of the balance sheet date of mortgage loans representing net future revenues from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

+ 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.

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- Definition

Business development involves the development of products and services, their delivery, design and their implementation. Business development includes a number of techniques designed to grow an economic enterprise. Such techniques include, but are not limited to, assessments of marketing opportunities and target markets, intelligence gathering on customers and competitors, generating leads for possible sales, follow-up sales activity, formal proposal writing and business model design. Business development involves evaluating a business and then realizing its full potential, using such tools as marketing, sales, information management and customer service.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section S99
-Paragraph 2
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Balance Type:	debit
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- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Percentage of principal amount of debt redeemed.

+ References

No definition available.

+ Details

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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.

+ References

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

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

+ Details

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- References

No definition available.

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- References

No definition available.

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Summary of Significant Accounting Policies - Premises and Equipment (Details) - USD ($)		12 Months Ended
	Jan. 28, 2020	Dec. 31, 2019	Dec. 31, 2018
Transfers and Servicing of Financial Assets
Mortgage loans serviced for others		$ 723,400,000	$ 711,100,000
Subsequent Events
Subordinated debentures		$ 57,734,000	$ 57,686,000
Old Second Capital Trust I
Subsequent Events
Cash distribution rate of trust preferred securities (as a percent)		7.80%
Junior Subordinated Debt
Subsequent Events
Subordinated debentures	$ 32,604,000
Junior Subordinated Debt \| Old Second Capital Trust I
Subsequent Events
Cash distribution rate of trust preferred securities (as a percent)	7.80%
Subordinated debentures		$ 32,600,000
Redemption Price	$ 10.00
Redemption Price percentage of liquidation amount	100.00%
7.8% subordinated debentures
Subsequent Events
Interest rate (as a percent)	7.80%
Finance Leases Portfolio Segment
Allowance for loans and lease losses
Growth in loan balance		40,900,000
Construction Loans \| Real Estate Portfolio Segment [Member]
Allowance for loans and lease losses
Decline in loan balance		$ 38,800,000
HELOC
Allowance for loans and lease losses
ALLL methodology period		2 years
Business Development		$ 0
Building [Member] \| Minimum [Member]
Premises and equipment
Useful lives		25 years
Building [Member] \| Maximum [Member]
Premises and equipment
Useful lives		40 years
Building Improvements [Member] \| Minimum [Member]
Premises and equipment
Useful lives		3 years
Building Improvements [Member] \| Maximum [Member]
Premises and equipment
Useful lives		15 years
Furniture and Fixtures [Member] \| Minimum [Member]
Premises and equipment
Useful lives		3 years
Furniture and Fixtures [Member] \| Maximum [Member]
Premises and equipment
Useful lives		10 years