Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Statement [Abstract]
Net income	$ 422,273	$ 140,414	$ 307,393
Other comprehensive (loss) income
Unrealized (loss) gain on foreign currency translation	(84,470)	87,113	23,920
Realized and unrealized gain (loss) on derivative financial instruments	81,608	(59,710)	(5,931)
Other comprehensive (loss) income	(2,862)	27,403	17,989
Comprehensive income	419,411	167,817	325,382
Comprehensive income attributable to non-controlling interests	(3,080)	(2,744)	(1,826)
Comprehensive income attributable to Blackstone Mortgage Trust, Inc.	$ 416,331	$ 165,073	$ 323,556