Loans - Unpaid Principal and Carrying Value (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Loans
Held-for-investment - Unpaid Principal Balance	$ 1,680,992	$ 1,708,543
Held for sale, at fair value - Unpaid Principal Balance	200,872	178,907
Held at fair value - Unpaid Principal Balance	165,502	79,089
Total Unpaid Principal Balance	2,047,366	1,966,539
Carrying Value
Held-for-investment - Carrying Value	1,586,157	1,585,088
Held for sale, at fair value - Carrying Value	206,706	181,797
Held at fair value - Carrying Value	170,128	81,592
Total Carrying Value	$ 1,962,991	$ 1,848,477

Fair value portion of loans intended to be sold or transferred to securitizations in the near term.

No definition available.

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Balance Type:	debit
Period Type:	instant

- Definition

The amount of unpaid principal balance of loans held at fair value.

+ References

No definition available.

+ Details

Name:	sld_LoansHeldFairValueUnpaidPrincipalBalance
Namespace Prefix:	sld_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of unpaid principal balance for loans held for investment.

+ References

No definition available.

+ Details

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Namespace Prefix:	sld_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of unpaid principal balance of loans held for sale at fair value.

+ References

No definition available.

+ Details

Name:	sld_LoansHeldForSaleFairValueUnpaidPrincipalBalance
Namespace Prefix:	sld_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of unpaid principal balance for loans receivable.

+ References

No definition available.

+ Details

Name:	sld_LoansReceivableUnpaidPrincipalBalance
Namespace Prefix:	sld_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=65884687&loc=d3e4428-111522

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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

- Definition

Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

+ References

No definition available.

+ Details

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

- Definition

Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes loans held for sale. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(a))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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

- References

No definition available.

+ Details

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

- References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration