Equity - Subordinated units (Details) - Class B Units - shares	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Number of units cancelled	0	0
SUNLIGHT FINANCIAL LLC
Class of Stock [Line Items]
Number of units issued	0	0
Number of units redeemed	0	0

The number of units cancelled during the year of each class of partners' capital account. Units represent shares of ownership of the general, limited, and preferred partners.

No definition available.

+ Details

Name:	sunl_PartnersCapitalAccountUnitsCancelled
Namespace Prefix:	sunl_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

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

- Definition

The number of units redeemed during the year of each class of partners' capital account. Units represent shares of ownership of the general, limited, and preferred partners.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 5
-Subparagraph (SAB Topic 4.F)
-URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187171-122770

+ Details

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

- Definition

Total units issued during the year due to the sale of units. All partners include general, limited and preferred partners.

+ References

+ Details

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

- Details

Name:	us-gaap_StatementClassOfStockAxis=sunl_PreferredClassBUnitMembersCapitalMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=sunl_SunlightFinancialLlcMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: