Loan Securitization/Sale Activities (Details) (USD $)	3 Months Ended	9 Months Ended	12 Months Ended
Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011 loan	Sep. 30, 2011 segment loan M entity	Dec. 31, 2010 loan
Loan Securitization/Sale Activities
Number of contributed loans not qualifying for sale treatment				2	2
Balance of loans pledged to the securitization trust	$ 50,311,000			$ 50,311,000	$ 50,297,000
Related liability of the securitization trust	53,421,000			53,421,000	54,086,000
Carrying value of loans sold into a securitization	154,400,000
Proceeds from securitization of contributed loans	69,700,000	78,400,000	56,000,000
Gain on the sale of loan qualifying for sales treatment	5,100,000	3,400,000	1,900,000
Net gain on the sale of loan qualifying for sales treatment		2,900,000	1,800,000
Realized gains on the credit hedges that was terminated in connection with the loan being sold	2,200,000
Realized losses on the interest rate hedge that was terminated in connection with the loan being sold	$ 7,400,000	$ 500,000	$ 100,000
Number of contributed loans qualifying for sale treatment			3

Gain or loss resulting from the difference between the sale price and the carrying value when a financial asset transferred in a securitization, asset-backed financing arrangement, or similar transfer is accounted for as a sale, including those transactions in which the seller or transferor has continuing involvement with the financial assets that have been transferred.

Name:	stwd_AmountOfGainOrLossFromSaleOfFinancialAssetsInSecuritizations
Namespace Prefix:	stwd
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Net gain or loss resulting from the difference between the sale price and the carrying value when a financial asset transferred in a securitization, asset-backed financing arrangement, or similar transfer is accounted for as a sale, including those transactions in which the seller or transferor has continuing involvement with the financial assets that have been transferred.

+ Details

Name:	stwd_AmountOfNetGainOrLossFromSaleOfFinancialAssetsInSecuritizations
Namespace Prefix:	stwd
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the carrying amount of financial asset sold in a securitization arrangement during the period.

+ Details

Name:	stwd_CarryingValueOfFinancialAssetsSoldInSecuritizations
Namespace Prefix:	stwd
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the number of loans contributed to a securitization trust to raise funds through commercial mortgage securitization in transactions that did not qualify for sale treatment.

+ Details

Name:	stwd_CommercialMortgageSecuritizationNumberOfLoansNotQualifyingForSaleTreatment
Namespace Prefix:	stwd
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of loans contributed to a securitization trust to raise funds through commercial mortgage securitization in transactions that qualified for sale treatment.

+ Details

Name:	stwd_CommercialMortgageSecuritizationNumberOfLoansQualifyingForSaleTreatment
Namespace Prefix:	stwd
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the realized gain (loss) on the credit hedge that was terminated in connection with the loan being sold.

+ Details

Name:	stwd_CreditHedgeTerminationRealizedGainLoss
Namespace Prefix:	stwd
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the realized gain (loss) on the interest rate hedge that was terminated in connection with the loan being sold.

+ Details

Name:	stwd_InterestRateHedgeTerminationRealizedGainLoss
Namespace Prefix:	stwd
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	stwd_SecuritizationAndFinancingArrangementsDisclosureAbstract
Namespace Prefix:	stwd
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

This is the principal amount outstanding for securitized loans only (across all types of loans).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 20

-Section 50

-Paragraph 4

-Subparagraph (e)

-URI http://asc.fasb.org/extlink&oid=6942082&loc=d3e107314-111719

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 140

-Paragraph 17

-Subparagraph i

-Clause 4

-Subclause a

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS140-4/FIN46(R)-8

-Paragraph B11

-Subparagraph b

-Clause 6

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Name:	us-gaap_PrincipalAmountOutstandingOnLoansSecuritized
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The cash inflow from the securitization of loans held for investment. Securitization is the structured process whereby interests in loans and other receivables are packaged, underwritten, and sold in the form of asset-backed securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 26

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3574-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 12

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3179-108585

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 26, 31

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 102

-Paragraph 9

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 24

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3521-108585

+ Details

Name:	us-gaap_ProceedsFromSecuritizationsOfLoansHeldForInvestment
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

This includes both the securitized and unsecuritized portion of the total principal amount.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 140

-Paragraph 17

-Subparagraph i(4)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 20

-Section 50

-Paragraph 4

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6942082&loc=d3e107314-111719

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS140-4/FIN46(R)-8

-Paragraph B11

-Subparagraph b(1)(b), b(6)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Name:	us-gaap_SecuritizedAssetsAndAnyOtherFinancialAssetsManagedTogetherPrincipalAmountOutstanding
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant