Represents accelerated vesting provision upon eligible retirement from the Company, minimum requisite service period.

No definition available.

Name:	buse_AcceleratedVestingProvisionMinimumRequisiteServicePeriod
Namespace Prefix:	buse_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The value of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

No definition available.

+ Details

Name:	buse_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodValue
Namespace Prefix:	buse_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI https://asc.fasb.org/extlink&oid=128089324&loc=d3e5070-113901

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(01)
-URI https://asc.fasb.org/extlink&oid=128089324&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of vesting of award under share-based payment arrangement.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI https://asc.fasb.org/extlink&oid=128089324&loc=d3e5070-113901

+ Details

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_RestrictedStockUnitsRSUMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=buse_MarketBasedPerformanceStockUnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=buse_PerformanceBasedPerformanceStockUnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_PerformanceSharesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=buse_DeferredStockUnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=buse_The2020EquityIncentivePlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_TitleOfIndividualAxis=buse_ManagementViceChairmanOfBoardMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_TitleOfIndividualAxis=buse_DirectorsAndAdvisoryDirectorsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Stock-Based Compensation - Award Grants and Activity (Details) - USD ($) $ in Millions		9 Months Ended	12 Months Ended
	Mar. 23, 2022	Sep. 30, 2022	Dec. 31, 2021
Additional disclosures
Period over which cost will be recognized		2 years 7 months 6 days	2 years 10 months 24 days
RSU Awards
Additional disclosures
Granted (in shares)		156,483
Market Based Performance Stock Units
Additional disclosures
Granted (in shares)	78,233
Grant date fair value of the award	$ 2.1
Market Based Performance Stock Units \| Minimum
Additional disclosures
Vesting percentage	0.00%
Market Based Performance Stock Units \| Maximum
Additional disclosures
Granted (in shares)	125,173
Vesting percentage	160.00%
Performance Based Performance Stock Units
Additional disclosures
Granted (in shares)	78,233
Grant date fair value of the award	$ 2.0
Performance Based Performance Stock Units \| Minimum
Additional disclosures
Vesting percentage	0.00%
Performance Based Performance Stock Units \| Maximum
Additional disclosures
Granted (in shares)	125,173
Vesting percentage	160.00%
PSU Awards
Additional disclosures
Granted (in shares)	38,774	195,240
Grant date fair value of the award	$ 1.0
PSU Awards \| Minimum
Additional disclosures
Vesting percentage	0.00%
PSU Awards \| Maximum
Additional disclosures
Granted (in shares)	77,548
Vesting percentage	200.00%
DSU Awards
Additional disclosures
Granted (in shares)		32,658
2020 Equity Incentive Plan \| RSU Awards \| Members of management, including the Vice-Chairman of the Board
Additional disclosures
Granted (in shares)	156,483
Grant date fair value of the award	$ 4.0
Accelerated vesting provision, minimum requisite service period	1 year
Vesting percentage	100.00%
2020 Equity Incentive Plan \| RSU Awards \| Members of management, including the Vice-Chairman of the Board \| Minimum
Additional disclosures
Period over which cost will be recognized	1 year
2020 Equity Incentive Plan \| RSU Awards \| Members of management, including the Vice-Chairman of the Board \| Maximum
Additional disclosures
Period over which cost will be recognized	5 years
2020 Equity Incentive Plan \| DSU Awards \| Directors and Advisory Directors
Additional disclosures
Granted (in shares)	32,658
Grant date fair value of the award	$ 0.8
Period over which cost will be recognized	1 year
Vesting percentage	100.00%