Organization	12 Months Ended
Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	1. ORGANIZATION References herein to “Blackstone Mortgage Trust,” “Company,” “we,” “us” or “our” refer to Blackstone Mortgage Trust, Inc. and its subsidiaries unless the context specifically requires otherwise. Blackstone Mortgage Trust is a real estate finance company that originates senior loans collateralized by commercial real estate in North America, Europe, and Australia. Our investment objective is to preserve and protect shareholder capital while producing attractive risk-adjusted returns primarily through dividends generated from current income from our loan portfolio. We are externally managed by BXMT Advisors L.L.C., or our Manager, a subsidiary of The Blackstone Group L.P., or Blackstone, and are a real estate investment trust, or REIT, traded on the New York Stock Exchange, or NYSE, under the symbol “BXMT.” Our principal executive offices are located at 345 Park Avenue, 42^nd Floor, New York, New York 10154. We were incorporated in Maryland in 1998, when we reorganized from a California common law business trust into a Maryland corporation. We conduct our operations as a REIT for U.S. federal income tax purposes. We generally will not be subject to U.S. federal income taxes on our taxable income to the extent that we annually distribute all of our net taxable income to stockholders and maintain our qualification as a REIT. We also operate our business in a manner that permits us to maintain an exclusion from registration under the Investment Company Act of 1940, as amended. We are organized as a holding company and conduct our business primarily through our various subsidiaries.

1. ORGANIZATION

References herein to “Blackstone Mortgage Trust,” “Company,” “we,” “us” or “our” refer to Blackstone Mortgage Trust, Inc. and its subsidiaries unless the context specifically requires otherwise.

Blackstone Mortgage Trust is a real estate finance company that originates senior loans collateralized by commercial real estate in North America, Europe, and Australia. Our investment objective is to preserve and protect shareholder capital while producing attractive risk-adjusted returns primarily through dividends generated from current income from our loan portfolio. We are externally managed by BXMT Advisors L.L.C., or our Manager, a subsidiary of The Blackstone Group L.P., or Blackstone, and are a real estate investment trust, or REIT, traded on the New York Stock Exchange, or NYSE, under the symbol “BXMT.” Our principal executive offices are located at 345 Park Avenue, 42^nd Floor, New York, New York 10154. We were incorporated in Maryland in 1998, when we reorganized from a California common law business trust into a Maryland corporation.

We conduct our operations as a REIT for U.S. federal income tax purposes. We generally will not be subject to U.S. federal income taxes on our taxable income to the extent that we annually distribute all of our net taxable income to stockholders and maintain our qualification as a REIT. We also operate our business in a manner that permits us to maintain an exclusion from registration under the Investment Company Act of 1940, as amended. We are organized as a holding company and conduct our business primarily through our various subsidiaries.