Stockholders' Equity and Non-Controlling Interests - Equity Incentive Plans (Details) - USD ($)	1 Months Ended			3 Months Ended		6 Months Ended
	Apr. 30, 2018	Mar. 31, 2017	May 31, 2015	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	May 31, 2017
Equity Incentive Plans
Granted (in shares)						451,835
Restricted stock units
Equity Incentive Plans
Share-based compensation expense, before tax						$ 6,400,000
Starwood Property Trust, Inc. Equity Plan and Manager Equity Plan
Equity Incentive Plans
Number of shares of authorized for issuance								11,000,000
Number of shares available for future grants				8,800,000		8,800,000
Starwood Property Trust, Inc. Equity Plan
Equity Incentive Plans
Granted (in shares)						451,835
Starwood Property Trust, Inc. Manager Equity Plan | Restricted stock units
Equity Incentive Plans
Share-based compensation expense, before tax				$ 3,200,000	$ 3,300,000		$ 6,200,000
Granted (in shares)	775,000	1,000,000	675,000
Awards granted, fair value	$ 16,329,000	$ 22,240,000	$ 16,511,000
Award vesting period	3 years	3 years	3 years