OREO (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Foreclosed Real Estate
Other repossessed assets			$ 200
OREO:
Other Real Estate, Beginning Balance	$ 216	$ 2,133	2,133
Additions, transfers from loans	324	609	660
Additions, fair value from Herget Financial acquisition	284
Proceeds from sales of OREO	(600)	$ (1,252)	(2,739)
Gain on sales of OREO	86		162
Other Real Estate, Ending Balance	310		$ 216
Commercial real estate
Foreclosed Real Estate
Other real estate owned held	100
Residential
Foreclosed Real Estate
Other real estate owned held	200
Residential real estate in the process of foreclosure	$ 1,300

Value transferred from commercial and mortgage loans to real estate owned (REO) in noncash transactions.

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- Definition

Additions of other real estate from fair value from acquisition. This includes prior real estate assets taken in settlement of troubled loans through surrender or foreclosure.

+ References

No definition available.

+ Details

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Namespace Prefix:	buse_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Represents the value of real estate loans in the process of foreclosure at period end.

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

The net gain (loss) resulting from sales and other disposals of other real estate owned, increases (decreases) in the valuation allowance for foreclosed real estate, and write-downs of other real estate owned after acquisition or physical possession.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-04.14(d))

-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 14

-Subparagraph d

-Article 9

+ Details

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Balance Type:	credit
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- Definition

Carrying amount as of the balance sheet date of assets other than real property that were received in full or partial satisfaction of a debt arrangement through foreclosure proceedings or defeasance.

+ References

+ Details

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- Definition

Carrying amount of other real estate not separately disclosed, including, but not limited to, real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations may also be included in real estate owned. This does not include real estate assets taken in settlement of troubled loans through surrender or foreclosure.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.10(4))

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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Period Type:	instant

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
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- Definition

The cash inflow associated with the sale of other real estate not otherwise defined in the taxonomy.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 12

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3179-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Carrying amount as of the balance sheet date of land and buildings obtained through foreclosure proceedings or defeasance in full or partial satisfaction of a debt arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 45

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4437-111522

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 28

-Article 12

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph c

-Subparagraph Schedule III

-Article 5

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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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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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

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- Details

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