Consolidated Statements of Changes in (Deficit) Equity (USD $) In Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Income (loss) [Member]	Accumulated Deficit [Member]	Blackstone Mortgage Trust Inc [Member]	Non-Controlling Interests [Member]
Balance at Dec. 31, 2011	$ (128,939)	$ 222	$ 597,049	$ (40,584)	$ (667,111)	$ (110,424)	$ (18,515)
Shares of class A common stock issued	10,000	50	9,950			10,000
Restricted class A common stock earned	997	4	993			997
Shares issued upon exercise of warrants		17	(17)
Deferred directors' compensation	1,027		1,027			1,027
Other comprehensive income	10,705			10,695		10,695	10
Deconsolidation of subsidiaries	29,889			29,889		29,889
Net income	279,804				181,024	181,024	98,780
Dividends declared on common stock	(49,764)				(49,764)	(49,764)
Distributions to non-controlling interests	(266)						(266)
Balance at Dec. 31, 2012	153,453	293	609,002		(535,851)	73,444	80,009
Shares of class A common stock issued	633,807	265	633,549			633,807
Adjustment to par value for reverse stock split and charter amendment		(263)	263
Restricted class A common stock earned	1,064		1,057			1,064
Issuance of convertible notes	8,826		8,826			8,826
Deferred directors' compensation	289		289			289
Other comprehensive income	798			798		798
Consolidation of subsidiaries	11,962				5,727	5,727	6,235
Net income	25,424				15,032	15,032	10,392
Dividends declared on common stock	(21,078)				(21,078)	(21,078)
Contributions from non-controlling interests	15,000						15,000
Distributions to non-controlling interests	(72,795)						(72,795)
Balance at Dec. 31, 2013	756,750	295	1,252,986	798	(536,170)	717,909	38,841
Shares of class A common stock issued	766,143	288	765,855			766,143
Restricted class A common stock earned	7,983		7,983			7,983
Dividends reinvested			205		(205)
Deferred directors' compensation	375		375			375
Other comprehensive income	(15,822)			(15,822)		(15,822)
Net income	100,494				90,045	90,045	10,449
Dividends declared on common stock	(101,262)				(101,262)	(101,262)
Distributions to non-controlling interests	(13,775)						(13,775)
Balance at Dec. 31, 2014	$ 1,500,886	$ 583	$ 2,027,404	$ (15,024)	$ (547,592)	$ 1,465,371	$ 35,515