Consolidated Statements of Changes in Equity (Deficit) (USD $) In Thousands	Total	Class A Common Stock [Member]	Restricted Class A Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]	Total Blackstone Mortgage Trust, Inc Equity [Member]	Non-controlling Interests [Member]
Balance, beginning at Dec. 31, 2010	$ (411,187)	$ 219		$ 559,411	$ (50,462)	$ (920,355)	$ (411,187)
Restricted class A common stock earned	421	1	2	418			421
Allocation to non-controlling interests	24,533			37,156			37,156	(12,623)
Purchase of non-controlling interests	(142)			(142)			(142)
Deferred directors' compensation	206			206			206
Other comprehensive income	9,148				9,340		9,340	(192)
Consolidation of additional securitization vehicles	(4,360)				538	(4,898)	(4,360)
Net income	252,319					258,142	258,142	(5,823)
Contributions from non-controlling interests	125							125
Distributions to non-controlling interests	(2)							(2)
Balance, ending at Dec. 31, 2011	(128,939)	220	2	597,049	(40,584)	(667,111)	(110,424)	(18,515)
Issuance of class A common stock	10,000	50		9,950			10,000
Restricted class A common stock earned	997	6	(2)	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, ending at Dec. 31, 2012	153,453	293		609,002		(535,851)	73,444	80,009
Issuance of class A common stock	633,807	258		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		7	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, ending at Dec. 31, 2013	$ 756,750	$ 288	$ 7	$ 1,252,986	$ 798	$ (536,170)	$ 717,909	$ 38,841