Loan Payable, Extension Term

No definition available.

Name:	stwd_LoanPayableExtensionTerm
Namespace Prefix:	stwd_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Loan Payable, Number Of Extension Options

+ References

No definition available.

+ Details

Name:	stwd_LoanPayableNumberOfExtensionOptions
Namespace Prefix:	stwd_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of loan purchase commitment outstanding as of the balance sheet date.

+ References

No definition available.

+ Details

Name:	stwd_LoanPurchaseCommitment
Namespace Prefix:	stwd_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Loans Payable, Basis Spread

+ References

No definition available.

+ Details

Name:	stwd_LoansPayableBasisSpread
Namespace Prefix:	stwd_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Repayments Of Mortgage Loans On Real Estate

+ References

No definition available.

+ Details

Name:	stwd_RepaymentsOfMortgageLoansOnRealEstate
Namespace Prefix:	stwd_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=124435984&loc=d3e28551-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124429444&loc=SL124452920-239629

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 55
-Paragraph 69C
-URI http://asc.fasb.org/extlink&oid=123466577&loc=SL123495737-112612

Reference 6: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 55
-Paragraph 69B
-URI http://asc.fasb.org/extlink&oid=123466577&loc=SL123495735-112612

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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

- Definition

Including the current and noncurrent portions, aggregate carrying value as of the balance sheet date of loans payable (with maturities initially due after one year or beyond the operating cycle if longer).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16)(a)(2))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

+ Details

Name:	us-gaap_LoansPayable
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of increase in mortgage loan on real estate by entity with substantial portion of business acquiring and holding investment real estate or interest in real estate, from new investment.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 948
-SubTopic 310
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-29(Footnote 6))
-URI http://asc.fasb.org/extlink&oid=120402547&loc=d3e617274-123014

+ Details

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

- Definition

The cash inflow associated with the sale of receivables arising from the financing of goods and services.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3179-108585

+ Details

Name:	us-gaap_ProceedsFromSaleOfFinanceReceivables
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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_RelatedPartyTransactionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	srt_MortgageLoansOnRealEstateDescriptionLoanCategoryAxis=us-gaap_FirstMortgageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=srt_AffiliatedEntityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=stwd_DevelopmentAndRecapitalizationOfLuxuryRentalCabinsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LoansPayableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_SecuredOvernightFinancingRateSofrOvernightIndexSwapRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=stwd_ResidentialMortgageOriginatorMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=stwd_LoansHeldForSaleResidentialMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Related-Party Transactions - Investments in Loans and Securities (Details) $ in Thousands	1 Months Ended	3 Months Ended
	Mar. 31, 2022 USD ($) Item	Mar. 31, 2022 USD ($)	Mar. 31, 2021 USD ($)
Related-Party Transactions
Acquisitions/originations/additional funding		$ 3,824,520	$ 2,671,394
First mortgage loan participation
Related-Party Transactions
Repayments of mortgage loans on real estate	$ 99,000
Affiliated Entity \| Development and Recapitalization of Luxury Rental Cabins
Related-Party Transactions
Loans payable	$ 84,500	84,500
Loan number of extension options \| Item	3
Loan extension term	1 year
Affiliated Entity \| Development and Recapitalization of Luxury Rental Cabins \| Loans Payable
Related-Party Transactions
Amount issued	$ 200,000	$ 200,000
Maturity period	24 months
Affiliated Entity \| Development and Recapitalization of Luxury Rental Cabins \| SOFR
Related-Party Transactions
Loans payable, basis spread	6.50%	6.50%
Residential Mortgage Originator \| Affiliated Entity
Related-Party Transactions
Proceeds from sale of receivables		$ 4,400
Residential Mortgage Originator \| Affiliated Entity \| Residential Loans
Related-Party Transactions
Acquisitions/originations/additional funding		623,900
Loan purchase commitment	$ 306,700	$ 306,700