Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Statement [Abstract]
Net income	$ 32,417	$ 38,439	$ 78,512	$ 51,555
Other comprehensive income:
Unrealized gain (loss) on foreign currency remeasurement	15,732	1,894	(4,336)	1,930
Unrealized (loss) gain on derivative financial instruments	(3,308)		28
Comprehensive income	44,841	40,333	74,204	53,485
Comprehensive income attributable to non-controlling interests	(3,133)	(4,973)	(13,833)	(5,024)
Comprehensive income attributable to Blackstone Mortgage Trust, Inc.	$ 41,708	$ 35,360	$ 60,371	$ 48,461