Income Taxes	12 Months Ended
Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	13. INCOME TAXES We have elected to be taxed as a REIT under the Internal Revenue Code for U.S. federal income tax purposes. We generally must distribute annually at least 90% of our net taxable income, subject to certain adjustments and excluding any net capital gain, in order for U.S. federal income tax not to apply to our earnings that we distribute. To the extent that we satisfy this distribution requirement, but distribute less than 100% of our net taxable income, we will be subject to U.S. federal income tax on our undistributed taxable income. In addition, we will be subject to a 4% nondeductible excise tax if the actual amount that we pay out to our stockholders in a calendar year is less than a minimum amount specified under U.S. federal tax laws. Our qualification as a REIT also depends on our ability to meet various other requirements imposed by the Internal Revenue Code, which relate to organizational structure, diversity of stock ownership, and certain restrictions with regard to the nature of our assets and the sources of our income. Even if we qualify as a REIT, we may be subject to certain U.S. federal income and excise taxes and state and local taxes on our income and assets. If we fail to maintain our qualification as a REIT for any taxable year, we may be subject to material penalties as well as federal, state, and local income tax on our taxable income at regular corporate rates and we would not be able to qualify as a REIT for the subsequent four full taxable years. As of December 31, 2018 and 2017, we were in compliance with all REIT requirements. Securitization transactions could result in the creation of taxable mortgage pools for federal income tax purposes. As a REIT, so long as we own 100% of the equity interests in a taxable mortgage pool, we generally would not be adversely affected by the characterization of the securitization as a taxable mortgage pool. Certain categories of stockholders, however, such as foreign stockholders eligible for treaty or other benefits, stockholders with net operating losses, and certain tax-exempt stockholders that are subject to unrelated business income tax, or UBTI, could be subject to increased taxes on a portion of their dividend income from us that is attributable to the taxable mortgage pool. We currently own no UBTI producing assets and we do not intend to purchase or generate assets that produce UBTI distributions in the future. During the years ended December 31, 2018, 2017, and 2016, we recorded a current income tax provision of $308,000, $314,000, and $196,000, respectively, primarily related to activities of our taxable REIT subsidiaries and various state and local taxes. We did not have any deferred tax assets or liabilities as of December 31, 2018 or 2017. Effective January 1, 2018, under legislation from the Tax Cuts and Jobs Act of 2017, the maximum U.S. federal corporate income tax rate was reduced from 35% to 21%. Accordingly, to the extent that the activities of our taxable REIT subsidiaries generate taxable income in future periods, they may be subject to lower U.S. federal income tax rates. We have net operating losses, or NOLs, generated by our predecessor business that may be carried forward and utilized in current or future periods. As a result of our issuance of 25,875,000 shares of class A common stock in May 2013, the availability of our NOLs is generally limited to $2.0 million per annum by change of control provisions promulgated by the Internal Revenue Service with respect to the ownership of Blackstone Mortgage Trust. As of December 31, 2018, we had estimated NOLs of $159.0 million that will expire in 2029, unless they are utilized by us prior to expiration. As of December 31, 2018, tax years 2015 through 2018 remain subject to examination by taxing authorities.

13. INCOME TAXES

We have elected to be taxed as a REIT under the Internal Revenue Code for U.S. federal income tax purposes. We generally must distribute annually at least 90% of our net taxable income, subject to certain adjustments and excluding any net capital gain, in order for U.S. federal income tax not to apply to our earnings that we distribute. To the extent that we satisfy this distribution requirement, but distribute less than 100% of our net taxable income, we will be subject to U.S. federal income tax on our undistributed taxable income. In addition, we will be subject to a 4% nondeductible excise tax if the actual amount that we pay out to our stockholders in a calendar year is less than a minimum amount specified under U.S. federal tax laws.

Our qualification as a REIT also depends on our ability to meet various other requirements imposed by the Internal Revenue Code, which relate to organizational structure, diversity of stock ownership, and certain restrictions with regard to the nature of our assets and the sources of our income. Even if we qualify as a REIT, we may be subject to certain U.S. federal income and excise taxes and state and local taxes on our income and assets. If we fail to maintain our qualification as a REIT for any taxable year, we may be subject to material penalties as well as federal, state, and local income tax on our taxable income at regular corporate rates and we would not be able to qualify as a REIT for the subsequent four full taxable years. As of December 31, 2018 and 2017, we were in compliance with all REIT requirements.

Securitization transactions could result in the creation of taxable mortgage pools for federal income tax purposes. As a REIT, so long as we own 100% of the equity interests in a taxable mortgage pool, we generally would not be adversely affected by the characterization of the securitization as a taxable mortgage pool. Certain categories of stockholders, however, such as foreign stockholders eligible for treaty or other benefits, stockholders with net operating losses, and certain tax-exempt stockholders that are subject to unrelated business income tax, or UBTI, could be subject to increased taxes on a portion of their dividend income from us that is attributable to the taxable mortgage pool. We currently own no UBTI producing assets and we do not intend to purchase or generate assets that produce UBTI distributions in the future.

During the years ended December 31, 2018, 2017, and 2016, we recorded a current income tax provision of $308,000, $314,000, and $196,000, respectively, primarily related to activities of our taxable REIT subsidiaries and various state and local taxes. We did not have any deferred tax assets or liabilities as of December 31, 2018 or 2017.

Effective January 1, 2018, under legislation from the Tax Cuts and Jobs Act of 2017, the maximum U.S. federal corporate income tax rate was reduced from 35% to 21%. Accordingly, to the extent that the activities of our taxable REIT subsidiaries generate taxable income in future periods, they may be subject to lower U.S. federal income tax rates.

We have net operating losses, or NOLs, generated by our predecessor business that may be carried forward and utilized in current or future periods. As a result of our issuance of 25,875,000 shares of class A common stock in May 2013, the availability of our NOLs is generally limited to $2.0 million per annum by change of control provisions promulgated by the Internal Revenue Service with respect to the ownership of Blackstone Mortgage Trust. As of December 31, 2018, we had estimated NOLs of $159.0 million that will expire in 2029, unless they are utilized by us prior to expiration.

As of December 31, 2018, tax years 2015 through 2018 remain subject to examination by taxing authorities.