XML 56 R43.htm IDEA: XBRL DOCUMENT v3.25.2

Loan and Lease Financings (Details 4) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2025 USD ($)	Jun. 30, 2024 USD ($)	Jun. 30, 2025 USD ($) item	Jun. 30, 2024 USD ($) item	Jun. 30, 2025 USD ($)	Jun. 30, 2024 USD ($)
Loan modifications to borrowers experiencing financial difficulties
Percent of Total Segment of Financing Receivable	0.06%	0.21%	0.06%	0.58%
Commitments to lend additional amounts	$ 2,800	$ 0	$ 2,800	$ 0	$ 2,800	$ 0
Weighted Average Interest Rate Reduction					0.00%	0.00%
Weighted Average Term Extension Modification (in months)					11 months	9 months
Weighted Average Payment Delay (in months)					6 months	6 months
Combination Weighted Average Payment Delay and Term Extension (in months)					3 months	5 months
Loan modifications to borrowers experiencing financial difficulties subsequent default | item			1	0
Loans and Leases Receivable Evaluated for Impairment	250	250	$ 250	$ 250	$ 250	$ 250
Payment Delay
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties	0	0	0	0
Term Extension
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties	4,026	0	4,524	108
Interest Rate Reduction
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties	0	0	0	0
Combination Payment Delay and Term Extension
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties	$ 0	$ 14,268	$ 0	$ 38,470
Current
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties					9,093	49,363
30 to 59 Days Past Due
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties					0	140
60 to 89 Days Past Due
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties					0	0
90 Days or More Past Due
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties					7,863	0
Total Past Due
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties					$ 7,863	$ 140
Commercial and agricultural
Loan modifications to borrowers experiencing financial difficulties
Percent of Total Segment of Financing Receivable	0.48%	0.82%	0.48%	0.84%
Weighted Average Interest Rate Reduction					0.00%	0.00%
Weighted Average Term Extension Modification (in months)					12 months	9 months
Weighted Average Payment Delay (in months)					6 months	6 months
Combination Weighted Average Payment Delay and Term Extension (in months)					0 months	10 months
Commercial and agricultural | Payment Delay
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties	$ 0	$ 0	$ 0	$ 0
Commercial and agricultural | Term Extension
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties	4,026	0	4,026	108
Commercial and agricultural | Interest Rate Reduction
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties	0	0	0	0
Commercial and agricultural | Combination Payment Delay and Term Extension
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties	$ 0	$ 5,920	$ 0	$ 5,920
Commercial and agricultural | Current
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties					$ 5,028	$ 6,493
Commercial and agricultural | 30 to 59 Days Past Due
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties					0	140
Commercial and agricultural | 60 to 89 Days Past Due
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties					0	0
Commercial and agricultural | 90 Days or More Past Due
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties					0	0
Commercial and agricultural | Total Past Due
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties					$ 0	$ 140
Construction equipment
Loan modifications to borrowers experiencing financial difficulties
Percent of Total Segment of Financing Receivable			0.04%
Weighted Average Interest Rate Reduction					0.00%
Weighted Average Term Extension Modification (in months)					5 months
Weighted Average Payment Delay (in months)					0 months
Combination Weighted Average Payment Delay and Term Extension (in months)					0 months
Construction equipment | Payment Delay
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties			$ 0
Construction equipment | Term Extension
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties			498
Construction equipment | Interest Rate Reduction
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties			0
Construction equipment | Combination Payment Delay and Term Extension
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties			$ 0
Construction equipment | Current
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties					$ 498
Construction equipment | 30 to 59 Days Past Due
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties					0
Construction equipment | 60 to 89 Days Past Due
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties					0
Construction equipment | 90 Days or More Past Due
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties					0
Construction equipment | Total Past Due
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties					$ 0
Commercial real estate
Loan modifications to borrowers experiencing financial difficulties
Weighted Average Interest Rate Reduction					0.00%
Weighted Average Term Extension Modification (in months)					0 months
Weighted Average Payment Delay (in months)					6 months
Combination Weighted Average Payment Delay and Term Extension (in months)					0 months
Commercial real estate | Current
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties					$ 981
Commercial real estate | 30 to 59 Days Past Due
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties					0
Commercial real estate | 60 to 89 Days Past Due
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties					0
Commercial real estate | 90 Days or More Past Due
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties					0
Commercial real estate | Total Past Due
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties					$ 0
Auto and light truck
Loan modifications to borrowers experiencing financial difficulties
Percent of Total Segment of Financing Receivable		0.83%		3.22%
Weighted Average Interest Rate Reduction					0.00%	0.00%
Weighted Average Term Extension Modification (in months)					0 months	0 months
Weighted Average Payment Delay (in months)					0 months	0 months
Combination Weighted Average Payment Delay and Term Extension (in months)					3 months	3 months
Auto and light truck | Payment Delay
Loan modifications to borrowers experiencing financial difficulties
Financing Receivable, Troubled Debt Restructuring, Subsequent Default		$ 0		$ 0
Auto and light truck | Term Extension
Loan modifications to borrowers experiencing financial difficulties
Financing Receivable, Troubled Debt Restructuring, Subsequent Default		0		0
Auto and light truck | Interest Rate Reduction
Loan modifications to borrowers experiencing financial difficulties
Financing Receivable, Troubled Debt Restructuring, Subsequent Default		0		0
Auto and light truck | Combination Payment Delay and Term Extension
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties		$ 8,348		$ 32,550
Auto and light truck | Current
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties					$ 0	$ 32,550
Auto and light truck | 30 to 59 Days Past Due
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties					0	0
Auto and light truck | 60 to 89 Days Past Due
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties					0	0
Auto and light truck | 90 Days or More Past Due
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties					7,863	0
Auto and light truck | Total Past Due
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties					$ 7,863	$ 0
Medium and heavy duty truck
Loan modifications to borrowers experiencing financial difficulties
Weighted Average Interest Rate Reduction					0.00%	0.00%
Weighted Average Term Extension Modification (in months)					0 months	0 months
Weighted Average Payment Delay (in months)					0 months	0 months
Combination Weighted Average Payment Delay and Term Extension (in months)					4 months	6 months
Medium and heavy duty truck | Current
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties					$ 2,586	$ 10,320
Medium and heavy duty truck | 30 to 59 Days Past Due
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties					0	0
Medium and heavy duty truck | 60 to 89 Days Past Due
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties					0	0
Medium and heavy duty truck | 90 Days or More Past Due
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties					0	0
Medium and heavy duty truck | Total Past Due
Loan modifications to borrowers experiencing financial difficulties
Loan modifications to borrowers experiencing financial difficulties					$ 0	$ 0

X

- Definition

Financing receivable, loan modification [Line Items]

+ References

No definition available.

+ Details

Name:	source_FinancingReceivableLoanModificationLineItems
Namespace Prefix:	source_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

FinancingReceivableModifiedWeightedAveragePaymentDelayAndTermExtensionFromModification

+ References

No definition available.

+ Details

Name:	source_FinancingReceivableModifiedWeightedAveragePaymentDelayAndTermExtensionFromModification
Namespace Prefix:	source_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Definition

FinancingReceivableModifiedWeightedAveragePaymentDelayFromModification

+ References

No definition available.

+ Details

Name:	source_FinancingReceivableModifiedWeightedAveragePaymentDelayFromModification
Namespace Prefix:	source_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Number of loan modifications to borrowers experiencing financial difficulties which subsequent defaulted within 12 months of modification

+ References

No definition available.

+ Details

Name:	source_LoanModificationsToBorrowersExperiencingFinancialDifficultiesSubsequentDefault
Namespace Prefix:	source_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Represents the amount of loans and leases where the internal credit quality grade is at or below a predetermined classification which are included in comprehensive analysis.

+ References

No definition available.

+ Details

Name:	source_LoansAndLeasesReceivableEvaluatedForImpairment
Namespace Prefix:	source_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Amortized cost excluding accrued interest, of financing receivable modified during period for debtor experiencing financial difficulty.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-42

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestModifiedPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

Percentage, excluding accrued interest, of financing receivable modified during period for debtor experiencing financial difficulty to total financing receivables.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-42

+ Details

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

X

- Definition

Amortized cost of financing receivable with payment default in current period and modified within previous 12 months preceding payment default for debtor experiencing financial difficulty.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 12A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481933/310-10-55-12A

Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 34
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-34

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 44
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-44

+ Details

Name:	us-gaap_FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

Percentage of decrease in weighted average contractual interest rate of financing receivable modified for debtor experiencing financial difficulty.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 12A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481933/310-10-55-12A

+ Details

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

X

- Definition

Period of increase in weighted average maturity of financing receivable modified for debtor experiencing financial difficulty, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 12A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481933/310-10-55-12A

+ Details

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

X

- Definition

Amount of commitment to lend additional funds to debtor experiencing financial difficulty for which creditor has modified terms of financing receivable.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 310
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481746/310-40-50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 36
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-36

+ Details

Name:	us-gaap_LoansAndLeasesReceivableImpairedCommitmentToLend
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Details

Name:	us-gaap_LoanRestructuringModificationAxis=us-gaap_PaymentDeferralMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_LoanRestructuringModificationAxis=us-gaap_ExtendedMaturityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_LoanRestructuringModificationAxis=us-gaap_ContractualInterestRateReductionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_LoanRestructuringModificationAxis=us-gaap_ExtendedMaturityAndInterestRateReductionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancialAssetNotPastDueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancingReceivables30To59DaysPastDueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancingReceivables60To89DaysPastDueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancialAssetPastDueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=source_CommercialAndAgriculturalLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=source_ConstructionEquipmentFinancingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=us-gaap_CommercialRealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=source_AutoAndLightTruckMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=source_MediumAndHeavyDutyTruckMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: