Represents information pertaining to loan with total commitments outstanding amount.

No definition available.

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

- Definition

Represents the value of loans with future funding commitments.

+ References

No definition available.

+ Details

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

- Definition

Represents the value of loans with future funding commitments expected to fund.

+ References

No definition available.

+ Details

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

- Definition

Maximum amount to be expended to satisfy the terms of arrangements in which the entity has agreed to expend funds to procure goods or services.

+ References

No definition available.

+ Details

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

- Definition

Represents the outstanding amount of purchase commitment.

+ References

No definition available.

+ Details

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

- Definition

The number of derivative instruments of a particular group held by the entity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5579245-113959

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5580258-113959

+ Details

Name:	us-gaap_DerivativeNumberOfInstrumentsHeld
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

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

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateSwapMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_HedgingDesignationAxis=us-gaap_DesignatedAsHedgingInstrumentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=stwd_InfrastructureLendingSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByLiabilityClassAxis=us-gaap_CommitmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=stwd_CommercialAndResidentialLendingSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByLiabilityClassAxis=stwd_RevolversAndLettersOfCreditCommitmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByLiabilityClassAxis=stwd_DelayedDrawTermLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Commitments and Contingencies (Details) $ in Millions	Jun. 30, 2019 USD ($) item instrument	Jun. 30, 2018 item
Operating leases
Number of contracts \| item	249
Interest rate swaps \| Derivatives designated as hedging instruments
Operating leases
Number of contracts	10	1
Infrastructure Lending Segment
Operating leases
Outstanding	$ 16.8
Commitments \| Commercial and Residential Lending Segment
Operating leases
Value of loans with future funding commitments	2,200.0
Value of loans with future funding commitments expected to fund	2,000.0
Outstanding residential mortgage loan purchase commitment	0.0
Agreement to purchase	600.0
Commitments \| Infrastructure Lending Segment
Operating leases
Value of loans with future funding commitments	267.5
Revolvers and letters of credit \| Infrastructure Lending Segment
Operating leases
Value of loans with future funding commitments	184.8
Delayed draw term loans \| Infrastructure Lending Segment
Operating leases
Value of loans with future funding commitments	$ 82.7