Stockholders' Equity - Equity Incentive Plans (Details) $ / shares in Units, $ in Thousands		1 Months Ended															12 Months Ended
	Jan. 15, 2014 USD ($) shares	Nov. 30, 2016 $ / shares shares	Aug. 31, 2016 $ / shares shares	May 31, 2016 $ / shares shares	Mar. 31, 2016 $ / shares shares	Nov. 30, 2015 $ / shares shares	Aug. 31, 2015 $ / shares shares	May 31, 2015 USD ($) $ / shares shares	Mar. 31, 2015 $ / shares shares	Nov. 30, 2014 $ / shares shares	Aug. 31, 2014 $ / shares shares	May 31, 2014 $ / shares shares	Mar. 31, 2014 $ / shares shares	Jan. 31, 2014 USD ($) shares	Jan. 31, 2014	Oct. 31, 2012 USD ($) shares	Dec. 31, 2016 item shares	Dec. 31, 2015 shares	Dec. 31, 2014 shares
Equity Incentive Plans
Number of equity incentive plans | item																	3
Awards granted (in shares)																	458,264
Starwood Property Trust, Inc. Equity Plan and Manager Equity Plan
Equity Incentive Plans
Number of shares of authorized for issuance																	2,262,760
Starwood Property Trust, Inc. Equity Plan
Equity Incentive Plans
Awards granted (in shares)																	436,700
Award vesting period																	3 years
Starwood Property Trust, Inc. Equity Plan | Restricted stock
Equity Incentive Plans
Awards granted (in shares)																	389,237	576,408	162,458
Starwood Property Trust, Inc. Equity Plan | Restricted stock units
Equity Incentive Plans
Awards granted (in shares)																	47,463	0	0
Starwood Property Trust, Inc. Manager Equity Plan
Equity Incentive Plans
Shares of common stock issued		144,093	65,211	117,083	606,166	126,154	95,696	136,261	387,299	92,865	86,328	152,316	138,288
Price per share | $ / shares		$ 22.06	$ 21.99	$ 19.64	$ 18.02	$ 20.22	$ 21.82	$ 24.17	$ 24.39	$ 22.97	$ 23.49	$ 23.99	$ 23.92
Starwood Property Trust, Inc. Manager Equity Plan | Restricted stock units
Equity Incentive Plans
Awards granted (in shares)	2,000,000							675,000						489,281		875,000
Awards granted, fair value | $	$ 55,420							$ 16,511						$ 14,776		$ 19,854
Award vesting period								3 years							3 years	3 years	3 years
Starwood Property Trust, Inc. Non-Executive Director Stock Plan
Equity Incentive Plans
Number of shares of authorized for issuance																	100,000
Awards granted (in shares)																	21,564
Number of shares available for future grants																	0
Starwood Property Trust, Inc. Non-Executive Director Stock Plan | Restricted stock units
Equity Incentive Plans
Awards granted (in shares)																	2,572