Acquisitions and Divestitures (Details) $ / shares in Units, $ in Thousands			3 Months Ended								12 Months Ended			24 Months Ended
	Dec. 31, 2016 USD ($) property item	Dec. 29, 2016 USD ($) ft² item	Dec. 31, 2016 USD ($) property item	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($) ft²	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2016 USD ($) property item $ / shares	Dec. 31, 2015 USD ($) ft² property item $ / shares	Dec. 31, 2014 USD ($)	Dec. 31, 2016 USD ($) property item
Liabilities assumed:
Revenues			$ 184,477	$ 204,705	$ 199,992	$ 195,493	$ 186,223	$ 192,145	$ 178,660	$ 178,849	$ 784,667	$ 735,877	$ 702,875
Net income (loss)			122,721	$ 105,813	$ 112,071	$ 27,046	96,648	$ 117,116	$ 117,640	$ 120,779	367,651	452,183	500,538
Bargain purchase gains											8,406
Depreciation and amortization											61,571	27,232	16,622
Gain on derivative financial instruments, net											70,734	21,598	$ 20,451
Goodwill	$ 140,437		140,437				140,437				140,437	140,437		$ 140,437
Medical Office Portfolio
Acquisitions
Weighted average occupancy percentage		94.00%
Area of property | ft²		1,900,000
Debt incurred to fund acquisition		$ 491,200
Number of acquired properties closed | item		34
Purchase price		$ 758,800
Assets acquired:
Properties	686,984		686,984								686,984			686,984
Intangible assets	85,596		85,596								85,596			85,596
Other assets	511		511								511			511
Total assets acquired	773,091		773,091								773,091			773,091
Liabilities assumed:
Accounts payable, accrued expenses and other liabilities	14,327		14,327								14,327			14,327
Total liabilities assumed	14,327		14,327								14,327			14,327
Net assets acquired	758,764		$ 758,764								758,764			$ 758,764
Net income (loss)	(9,700)
Bargain purchase gains		0
Acquisition related costs	9,500
Goodwill		$ 0
Pro forma revenue and net income
Revenues	$ 400
Woodstar Portfolio And Ireland Portfolio
Pro forma revenue and net income
Revenues											854,416	914,355
Net income attributable to STWD											$ 341,972	$ 441,150
Net income per share - Basic | $ / shares											$ 1.42	$ 1.87
Net income per share - Diluted | $ / shares											$ 1.41	$ 1.87
Management fee expense addition											$ 4,921	$ 11,121
Woodstar Portfolio
Acquisitions
Number of properties in portfolio investment | item	32		32								32			32
Number of acquired properties closed | item											14	18
Number of units acquired | item											3,710	5,238		8,948
Purchase price												$ 324,000
Assets acquired:
Cash and cash equivalents	$ 6,254		$ 6,254								$ 6,254			$ 6,254
Properties	245,430		245,430				339,040				245,430	339,040		245,430
Intangible assets	8,174		8,174				11,337				8,174	11,337		8,174
Other assets	16,417		16,417				652				16,417	652		16,417
Total assets acquired	276,275		276,275				351,029				276,275	351,029		276,275
Liabilities assumed:
Accounts payable, accrued expenses and other liabilities	19,666		19,666				18,030				19,666	18,030		19,666
Secured financing agreements	150,763		150,763				8,982				150,763	8,982		150,763
Total liabilities assumed	170,429		170,429				27,012				170,429	27,012		170,429
Net assets acquired	105,846		105,846				$ 324,017				105,846	$ 324,017		105,846
Revenues											32,800
Net income (loss)											4,700
Bargain purchase gains											8,400
Depreciation and amortization											14,800
Acquisition related costs											900
Goodwill	$ 0		$ 0								$ 0			$ 0
Ireland Portfolio
Acquisitions
Number of properties in portfolio investment | property	13		13								13			13
Area of property | ft²							600,000					600,000
Debt incurred to fund acquisition							$ 328,600					$ 328,600
Assets acquired:
Restricted cash							10,829					10,829
Properties							445,369					445,369
Intangible assets							59,529					59,529
Other assets							2,508					2,508
Total assets acquired							518,235					518,235
Liabilities assumed:
Accounts payable, accrued expenses and other liabilities							17,552					17,552
Secured financing agreements							283,010					283,010
Total liabilities assumed							300,562					300,562
Net assets acquired							217,673					217,673
Bargain purchase gains												0
Goodwill							0					0
REO Portfolio
Assets acquired:
Properties	$ 123,819		$ 123,819				128,218				$ 123,819	128,218		$ 123,819
Intangible assets	25,638		25,638				19,381				25,638	19,381		25,638
Other assets	2,978		2,978				4,973				2,978	4,973		2,978
Total assets acquired	152,435		152,435				152,572				152,435	152,572		152,435
Liabilities assumed:
Accounts payable, accrued expenses and other liabilities	7,358		7,358				6,998				7,358	6,998		7,358
Total liabilities assumed	7,358		7,358				6,998				7,358	6,998		7,358
Non-controlling interests	6,462		6,462				6,904				6,462	6,904		6,462
Net assets acquired	138,615		138,615				$ 138,670				138,615	$ 138,670		138,615
Bargain purchase gains											8,800
REO Portfolio | ASU 2015-16
Assets acquired:
Properties	88,773		88,773								88,773			88,773
Intangible assets	19,116		19,116								19,116			19,116
Other assets	2,862		2,862								2,862			2,862
Total assets acquired	110,751		110,751								110,751			110,751
Liabilities assumed:
Accounts payable, accrued expenses and other liabilities	5,386		5,386								5,386			5,386
Total liabilities assumed	5,386		5,386								5,386			5,386
Non-controlling interests	5,492		5,492								5,492			5,492
Net assets acquired	99,873		99,873								99,873			99,873
REO Portfolio | ASU 2015-16 | Amount As Previously Reported
Assets acquired:
Properties	71,496		71,496								71,496			71,496
Intangible assets	25,387		25,387								25,387			25,387
Other assets	2,862		2,862								2,862			2,862
Total assets acquired	99,745		99,745								99,745			99,745
Liabilities assumed:
Accounts payable, accrued expenses and other liabilities	3,202		3,202								3,202			3,202
Total liabilities assumed	3,202		3,202								3,202			3,202
Non-controlling interests	5,492		5,492								5,492			5,492
Net assets acquired	91,051		91,051								91,051			91,051
REO Portfolio | ASU 2015-16 | Reclassification Adjustment
Assets acquired:
Properties	17,277		17,277								17,277			17,277
Intangible assets	(6,271)		(6,271)								(6,271)			(6,271)
Total assets acquired	11,006		11,006								11,006			11,006
Liabilities assumed:
Accounts payable, accrued expenses and other liabilities	2,184		2,184								2,184			2,184
Total liabilities assumed	2,184		2,184								2,184			2,184
Net assets acquired	$ 8,822		$ 8,822								$ 8,822			$ 8,822
Net Leased Office Property | Ireland Portfolio
Acquisitions
Number of acquired properties closed | property												12
Multifamily Property | Ireland Portfolio
Acquisitions
Number of acquired properties closed | property												1
Investment and Servicing Segment | REO Portfolio
Acquisitions
Number of properties in portfolio investment | property	10		10								10			10
Number of acquired properties closed | property											9	14
Purchase price											$ 8,200	$ 138,700
Liabilities assumed:
Revenues											12,300
Net income (loss)											8,000
Bargain purchase gains											8,800
Depreciation and amortization											5,500
Acquisition related costs											1,000
Goodwill	$ 0		$ 0								0			$ 0
Investment and Servicing Segment | Net Leased Office Property | REO Portfolio
Acquisitions
Purchase price											$ 129,800