XML 48 R37.htm IDEA: XBRL DOCUMENT
v3.25.3

Accounting Policies (Details) | 9 Months Ended
--- | ---
Sep. 30, 2025
Minimum |
Summary of Significant Accounting Policies [Line Items] |
Period of sustained performance required to change from non-performing to performing status | 6 months

X
- Definition -- None. No documentation exists for this element. -- + References No definition available. + Details
Name: | source_SummaryOfSignificantAccountingPoliciesLineItems
Namespace Prefix: | source_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the period of sustained performance required to change loan from non-performing to performing. + References No definition available. + Details
Name: | source_SustainedPerformancePeriodRequiredForPerformingStatus
Namespace Prefix: | source_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |