Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Income Statement [Abstract]
Net income	$ 103,919	$ 84,404	$ 298,047	$ 297,412
Other comprehensive loss
Unrealized loss on foreign currency translation	(158,097)	(46,952)	(333,526)	(66,356)
Realized and unrealized gain on derivative financial instruments	154,849	46,083	329,048	65,059
Other comprehensive loss	(3,248)	(869)	(4,478)	(1,297)
Comprehensive income	100,671	83,535	293,569	296,115
Comprehensive income attributable to non-controlling interests	(673)	(647)	(1,864)	(2,158)
Comprehensive income attributable to Blackstone Mortgage Trust, Inc.	$ 99,998	$ 82,888	$ 291,705	$ 293,957