Investment Securities (Details 3) (SEREF, USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended
Dec. 14, 2012	Sep. 30, 2013
SEREF
Equity securities
Number of shares acquired	9,140,000
Ownership percentage	4.00%
Value of shares acquired	$ 14.7
Fair value of investment		$ 15.0

Represents the percentage ownership acquired in the equity security investment.

No definition available.

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Namespace Prefix:	stwd_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration