Commitments and Contingencies (Details) (Commitment to invest in venture, USD $) In Millions, unless otherwise specified	Jun. 30, 2012 loan
Commitment to invest in venture
Commitments
Unfunded commitments	$ 1.7
Number of loans with future funding commitments	14
Value of loans with future funding commitments	$ 116.1

Represents the value of loans with future funding commitments.

No definition available.

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