XML 69 R56.htm IDEA: XBRL DOCUMENT
v3.25.2

Variable Interest Entities (Details 2) $ in Thousands | 6 Months Ended |
--- | --- | ---
Jun. 30, 2025 USD ($) trust | Dec. 31, 2024 USD ($)
Variable Interest Entities [Abstract] |  |
Number of trusts sponsored | trust | 1 |
Percentage of ownership interest | 100.00% |
Subordinated Borrowing [Line Items] |  |
Amount of subordinated notes | $ 58,764 | $ 58,764
June 2007 issuance |  |
Subordinated Borrowing [Line Items] |  |
Amount of subordinated notes | $ 41,238 |
Interest rate (as a percent) | 7.22% |
Maturity date of subordinated notes | Jun. 15, 2037 |
August 2007 issuance |  |
Subordinated Borrowing [Line Items] |  |
Amount of subordinated notes | $ 17,526 |
Interest rate (as a percent) | 6.06% |
Maturity date of subordinated notes | Sep. 15, 2037 |
Basis spread on variable rate (as a percent) | 1.48% |

X
- Definition Maturity date of junior subordinated long-term debt owed to unconsolidated subsidiary trusts. + References No definition available. + Details
Name: | source_MaturityDateOfJuniorSubordinatedDebentureOwedToUnconsolidatedSubsidiaryTrust
Namespace Prefix: | source_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the number of trusts sponsored by the entity. + References No definition available. + Details
Name: | source_NumberOfTrustsSponsored
Namespace Prefix: | source_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition The percentage of ownership interest of common stock or equity participation held by a shareholder of the entity. + References No definition available. + Details
Name: | source_OwnershipPercentage
Namespace Prefix: | source_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Variable Interest Entities [Abstract] + References No definition available. + Details
Name: | source_VariableInterestEntitiesAbstract
Namespace Prefix: | source_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage points added to the reference rate to compute the variable rate on the debt instrument. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- 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 -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 944 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(16)(a)(2)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1 + Details
Name: | us-gaap_JuniorSubordinatedDebentureOwedToUnconsolidatedSubsidiaryTrust
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Stated interest rate of the subordinated debt. + References No definition available. + Details
Name: | us-gaap_SubordinatedBorrowingInterestRate
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- 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
Name: | us-gaap_SubordinatedBorrowingLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_SubordinatedBorrowingAxis=source_SubordinatedNoteIssuedinJune2007Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubordinatedBorrowingAxis=source_SubordinatedNoteIssuedinAugust2007Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |