Consolidated Statements of Comprehensive Income (Loss) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Statement [Abstract]
Net income	$ 23,601	$ 10,526	$ 75,157	$ 15,696
Other comprehensive loss:
Unrealized loss on foreign currency remeasurement	(8,932)		(7,003)
Comprehensive income	14,669	10,526	68,154	15,696
Comprehensive income attributable to non-controlling interests	(1,577)	(2,206)	(6,602)	(7,743)
Comprehensive income attributable to Blackstone Mortgage Trust, Inc.	$ 13,092	$ 8,320	$ 61,552	$ 7,953