XML 66 R53.htm IDEA: XBRL DOCUMENT
v3.25.3

DEBT SECURITIES - Schedule of Realized Gains and Losses on Debt Securities (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2025 | Mar. 31, 2025 | Sep. 30, 2024 | Mar. 31, 2024 | Sep. 30, 2025 | Sep. 30, 2024
Realized gains and losses on debt securities |  |  |  |  |  |
Gross gains on debt securities | $ 0 |  | $ 0 |  | $ 9 | $ 1
Gross (losses) on debt securities | (13) |  | (11) |  | (15,558) | (6,818)
Realized net gains (losses) on debt securities | $ (13) |  | $ (11) |  | $ (15,549) | $ (6,817)
Debt securities available for sale, sold |  | $ 205,600 |  | $ 108,200 |  |
Pre-tax loss on debt securities |  | 15,500 |  | 6,800 |  |
Debt securities available for sale sold, tax benefit |  | $ 4,100 |  | $ 1,800 |  |

X
- Definition Debt Securities, Available-for-Sale, Realized Loss, Before Tax + References No definition available. + Details
Name: | buse_DebtSecuritiesAvailableForSaleRealizedLossBeforeTax
Namespace Prefix: | buse_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Debt Securities, Available-For-Sale, Sold At Par Value, Tax Expense (Benefit) + References No definition available. + Details
Name: | buse_DebtSecuritiesAvailableForSaleSoldAtParValueTaxExpenseBenefit
Namespace Prefix: | buse_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_AvailableForSaleSecuritiesGrossRealizedGainLossAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with interest rate reset through auction process, sold at par value. + References No definition available. + Details
Name: | us-gaap_AvailableforsaleSecuritiesSoldAtPar
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of realized gain on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 9 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-9 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleRealizedGain
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of realized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 9 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-9 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleRealizedGainLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of realized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 9 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-9 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleRealizedLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration