Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income Statement [Abstract]
Net income	$ 66,392	$ 67,778	$ 193,040	$ 146,288
Other comprehensive loss
Unrealized loss on foreign currency remeasurement	(10,128)	(23,148)	(25,472)	(27,484)
Unrealized gain on derivative financial instruments	5,882	14,891	11,841	14,920
Comprehensive income	62,146	59,521	179,409	133,724
Comprehensive income attributable to non-controlling interests	(1,598)	(890)	(8,119)	(14,724)
Comprehensive income attributable to Blackstone Mortgage Trust, Inc.	$ 60,548	$ 58,631	$ 171,290	$ 119,000