Blackstone Mortgage Trust (BXMT) 10-K 13 Feb 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2017	Feb. 06, 2018	Jun. 30, 2017
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Trading Symbol	BXMT
Entity Registrant Name	BLACKSTONE MORTGAGE TRUST, INC.
Entity Central Index Key	1,061,630
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		108,194,090
Entity Public Float			$ 2.8

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Assets
Cash and cash equivalents	$ 69,654	$ 75,567
Restricted cash	32,864
Loans receivable, net	10,056,732	8,692,978
Other assets	99,575	44,070
Total Assets	10,258,825	8,812,615
Liabilities and Equity
Secured debt agreements, net	5,273,855	5,716,354
Loan participations sold, net	80,415	348,077
Securitized debt obligations, net	1,282,412	0
Convertible notes, net	563,911	166,762
Other liabilities	140,826	87,819
Total Liabilities	7,341,419	6,319,012
Commitments and contingencies
Equity
Class A common stock, $0.01 par value, 200,000,000 shares authorized, 107,883,860 and 94,540,263 shares issued and outstanding as of December 31, 2017 and 2016, respectively	1,079	945
Additional paid-in capital	3,506,861	3,089,997
Accumulated other comprehensive loss	(29,706)	(56,202)
Accumulated deficit	(567,168)	(541,137)
Total Blackstone Mortgage Trust, Inc. stockholders' equity	2,911,066	2,493,603
Non-controlling interests	6,340
Total Equity	2,917,406	2,493,603
Total Liabilities and Equity	$ 10,258,825	$ 8,812,615

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Billions	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Common stock, par value in dollars per share	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	107,883,860	94,540,263
Common stock, shares outstanding	107,883,860	94,540,263
Variable interest entity, consolidated, carrying amount, assets	$ 1.5
Variable interest entity, consolidated, carrying amount, liabilities	$ 1.3

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income from loans and other investments
Interest and related income	$ 537,915	$ 497,974	$ 410,635
Less: Interest and related expenses	234,870	184,270	152,416
Income from loans and other investments, net	303,045	313,704	258,219
Other expenses
Management and incentive fees	54,841	55,959	42,886
General and administrative expenses	29,922	27,716	36,709
Total other expenses	84,763	83,675	79,595
Gain on investments at fair value		13,420	21,967
Income from equity investment in unconsolidated subsidiary		3,187	11,798
Income before income taxes	218,282	246,636	212,389
Income tax provision	314	196	504
Net income	217,968	246,440	211,885
Net income attributable to non-controlling interests	(337)	(8,143)	(15,056)
Net income attributable to Blackstone Mortgage Trust, Inc.	$ 217,631	$ 238,297	$ 196,829
Net income per share of common stock basic and diluted	$ 2.27	$ 2.53	$ 2.41
Weighted-average shares of common stock outstanding, basic and diluted	95,963,616	94,165,351	81,740,227

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Net income	$ 217,968	$ 246,440	$ 211,885
Other comprehensive income
Unrealized gain (loss) on foreign currency translation	47,124	(49,686)	(41,616)
Realized and unrealized (loss) gain on derivative financial instruments	(20,628)	26,242	23,882
Other comprehensive income (loss)	26,496	(23,444)	(17,734)
Comprehensive income	244,464	222,996	194,151
Comprehensive income attributable to non-controlling interests	(337)	(8,143)	(15,056)
Comprehensive income attributable to Blackstone Mortgage Trust, Inc.	$ 244,127	$ 214,853	$ 179,095

Consolidated Statements of Chan

Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Class A Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Accumulated Deficit [Member]	Stockholders' Equity [Member]	Non-Controlling Interests [Member]
Balance at Dec. 31, 2014	$ 1,500,886	$ 583	$ 2,027,404	$ (15,024)	$ (547,592)	$ 1,465,371	$ 35,515
Shares of class A common stock issued, net	1,029,540	354	1,029,186			1,029,540
Restricted class A common stock earned	12,960		12,960			12,960
Dividends reinvested	16		275		(259)	16
Deferred directors' compensation	375		375			375
Other comprehensive income (loss)	(17,734)			(17,734)		(17,734)
Net income	211,885				196,829	196,829	15,056
Dividends declared on common stock	(194,769)				(194,769)	(194,769)
Distributions to non-controlling interests	(37,428)						(37,428)
Balance at Dec. 31, 2015	2,505,731	937	3,070,200	(32,758)	(545,791)	2,492,588	13,143
Shares of class A common stock issued, net	8	8				8
Restricted class A common stock earned	19,045		19,045			19,045
Dividends reinvested	27		377		(350)	27
Deferred directors' compensation	375		375			375
Other comprehensive income (loss)	(23,444)			(23,444)		(23,444)
Net income	246,440				238,297	238,297	8,143
Dividends declared on common stock	(233,293)				(233,293)	(233,293)
Distributions to non-controlling interests	(21,286)						(21,286)
Balance at Dec. 31, 2016	2,493,603	945	3,089,997	(56,202)	(541,137)	2,493,603
Shares of class A common stock issued, net	391,568	134	391,434			391,568
Restricted class A common stock earned	23,584		23,584			23,584
Issuance of convertible notes	964		964			964
Dividends reinvested	44		444		(400)	44
Deferred directors' compensation	438		438			438
Other comprehensive income (loss)	26,496			26,496		26,496
Net income	217,968				217,631	217,631	337
Dividends declared on common stock	(243,262)				(243,262)	(243,262)
Contributions from non-controlling interests	12,165						12,165
Distributions to non-controlling interests	(6,162)						(6,162)
Balance at Dec. 31, 2017	$ 2,917,406	$ 1,079	$ 3,506,861	$ (29,706)	$ (567,168)	$ 2,911,066	$ 6,340

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities
Net income	$ 217,968	$ 246,440	$ 211,885
Adjustments to reconcile net income to net cash provided by operating activities
Non-cash compensation expense	24,031	21,899	20,717
Amortization of deferred fees on loans	(38,373)	(40,345)	(36,053)
Amortization of deferred financing costs and premiums/discount on debt obligations	21,988	19,339	20,708
Gain on investments at fair value		(13,420)	(21,967)
Income from equity investment in unconsolidated subsidiary		(3,187)	(11,798)
Distributions of income from unconsolidated subsidiary		9,977	5,007
Changes in assets and liabilities, net
Other assets	(4,632)	6,069	(22,385)
Other liabilities	6,479	(10,120)	5,280
Net cash provided by operating activities	227,461	236,652	171,394
Cash flows from investing activities
Origination and fundings of loans receivable	(3,598,166)	(3,151,882)	(7,204,487)
Principal collections and sales proceeds from loans receivable and other assets	2,780,431	3,514,429	2,347,966
Origination and exit fees received on loans receivable	55,441	44,697	33,501
Receipts under derivative financial instruments	6,453	41,573
Payments under derivative financial instruments	(20,870)	(14,730)
Return of collateral deposited under derivative agreements	16,120
Collateral deposited under derivative agreements	(20,161)
Net cash (used in) provided by investing activities	(780,752)	434,087	(4,823,020)
Cash flows from financing activities
Borrowings under secured debt agreements	4,306,301	3,185,933	6,885,393
Repayments under secured debt agreements	(4,778,194)	(3,534,803)	(3,030,091)
Proceeds from issuance of collateralized loan obligations	817,500
Proceeds from sale of loan participations	80,706	54,441	256,000
Repayment of loan participations	(381,310)	(136,000)	(238,164)
Payment of deferred financing costs	(27,465)	(15,350)	(21,230)
Receipts under derivative financial instruments			17,076
Contributions from non-controlling interests	12,165
Distributions to non-controlling interests	(6,162)	(21,070)	(37,428)
Net proceeds from issuance of convertible notes	394,632
Net proceeds from issuance of class A common stock	391,558	27	1,029,540
Dividends paid on class A common stock	(234,989)	(232,775)	(166,978)
Net cash provided by (used in) financing activities	574,742	(699,597)	4,694,118
Net increase (decrease) in cash, cash equivalents, and restricted cash	21,451	(28,858)	42,492
Cash, cash equivalents, and restricted cash at beginning of year	75,567	106,006	63,401
Effects of currency translation on cash, cash equivalents, and restricted cash	5,500	(1,581)	113
Cash, cash equivalents, and restricted cash at end of year	102,518	75,567	106,006
Supplemental disclosure of cash flows information
Payments of interest	(206,966)	(164,905)	(127,429)
Payments of income taxes	(296)	(286)	(125)
Supplemental disclosure of non-cash investing and financing activities
Dividends declared, not paid	(66,888)	(58,615)	(58,095)
Loan principal payments held by servicer, net	15,763	$ 670	$ 118,074
Consolidation of loans receivable of a VIE	500,000
Consolidation of securitized debt obligations of a VIE	$ (474,620)

Organization

Organization	12 Months Ended
	Dec. 31, 2017
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 and Europe. 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, 42nd 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.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America, or GAAP, and include, on a consolidated basis, our accounts, the accounts of our wholly-owned subsidiaries, majority-owned subsidiaries, and variable interest entities, or VIEs, of which we are the primary beneficiary. All intercompany balances and transactions have been eliminated in consolidation. Principles of Consolidation We consolidate all entities that we control through either majority ownership or voting rights. In addition, we consolidate all VIEs of which we are considered the primary beneficiary. VIEs are defined as entities in which equity investors (i) do not have the characteristics of a controlling financial interest and/or (ii) do not have sufficient equity at risk for the entity to finance its activities without additional subordinated financial support from other parties. The entity that consolidates a VIE is known as its primary beneficiary and is generally the entity with (i) the power to direct the activities that most significantly affect the VIE’s economic performance and (ii) the right to receive benefits from the VIE or the obligation to absorb losses of the VIE that could be significant to the VIE. Refer to Note 16 for additional discussion of our consolidated VIE. In April 2017, we entered into a joint venture, or our Multifamily Joint Venture, with Walker & Dunlop Inc. to originate, hold, and finance multifamily bridge loans. Pursuant to the terms of the agreements governing the joint venture, Walker & Dunlop contributed 15% of the venture’s equity capital and we contributed 85%. We consolidate the Multifamily Joint Venture as we have a controlling financial interest. The non-controlling interests included on our consolidated balance sheets represent the equity interests in our Multifamily Joint Venture that are owned by Walker & Dunlop. A portion of our Multifamily Joint Venture’s consolidated equity and results of operations are allocated to these non-controlling interests based on Walker & Dunlop’s pro rata ownership of our Multifamily Joint Venture. Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results may ultimately differ from those estimates. Revenue Recognition Interest income from our loans receivable portfolio is recognized over the life of each investment using the effective interest method and is recorded on the accrual basis. Recognition of fees, premiums, and discounts associated with these investments is deferred until the loan is advanced and is then recorded over the term of the loan as an adjustment to yield. Income accrual is generally suspended for loans at the earlier of the date at which payments become 90 days past due or when, in the opinion of our Manager, recovery of income and principal becomes doubtful. Income is then recorded on the basis of cash received until accrual is resumed when the loan becomes contractually current and performance is demonstrated to be resumed. In addition, for loans we originate, the related origination expenses are deferred and recognized as a component of interest income, however expenses related to loans we acquire are included in general and administrative expenses as incurred. Cash, Cash Equivalents, and Restricted Cash Cash and cash equivalents represent cash held in banks, cash on hand, and liquid investments with original maturities of three months or less. We may have bank balances in excess of federally insured amounts; however, we deposit our cash and cash equivalents with high credit-quality institutions to minimize credit risk exposure. We have not experienced, and do not expect, any losses on our cash or cash equivalents. Restricted cash represents cash held in a segregated bank account related to a letter of credit. The following table provides a reconciliation of cash, cash equivalents, and restricted cash in our consolidated balance sheets to the total amount shown in our consolidated statements of cash flows ($ in thousands): December 31, December 31, Cash and cash equivalents $ 69,654 $ 75,567 Restricted cash 32,864 — Total cash, cash equivalents, and restricted cash shown in our consolidated statements of cash flows $ 102,518 $ 75,567 Loans Receivable and Provision for Loan Losses We originate and purchase commercial real estate debt and related instruments generally to be held as long-term investments at amortized cost. We are required to periodically evaluate each of these loans for possible impairment. Impairment is indicated when it is deemed probable that we will not be able to collect all amounts due to us pursuant to the contractual terms of the loan. If a loan is determined to be impaired, we write down the loan through a charge to the provision for loan losses. Impairment of these loans, which are collateral dependent, is measured by comparing the estimated fair value of the underlying collateral, less costs to sell, to the book value of the respective loan. These valuations require significant judgments, which include assumptions regarding capitalization rates, leasing, creditworthiness of major tenants, occupancy rates, availability of financing, exit plan, loan sponsorship, actions of other lenders, and other factors deemed necessary by our Manager. Actual losses, if any, could ultimately differ from these estimates. Our Manager performs a quarterly review of our portfolio of loans. In conjunction with this review, our Manager assesses the risk factors of each loan, and assigns a risk rating based on a variety of factors, including, without limitation, loan-to-value ratio, or LTV, debt yield, property type, geographic and local market dynamics, physical condition, cash flow volatility, leasing and tenant profile, loan structure and exit plan, and project sponsorship. Based on a 5-point scale, our loans are rated “1” through “5,” from less risk to greater risk, which ratings are defined as follows: 1 – Very Low Risk 2 – Low Risk 3 – Medium Risk 4 – High Risk/Potential for Loss: 5 – Impaired/Loss Likely: During the second quarter of 2015, we acquired a portfolio of loans from General Electric Capital Corporation and certain of its affiliates, or the GE portfolio, for a total purchase price of $4.7 billion. We allocated the aggregate purchase price between each loan based on its fair value relative to the overall portfolio, which allocation resulted in purchase discounts or premiums determined on an asset-by-asset basis. Each loan accretes from its allocated purchase price to its expected collection value over the life of the loan, consistent with the other loans in our portfolio. Equity Investment in Unconsolidated Subsidiary Our carried interest in CT Opportunity Partners I, LP, or CTOPI, was accounted for using the equity method. CTOPI’s assets and liabilities were not consolidated into our financial statements due to our determination that (i) it was not a VIE and (ii) the other investors in CTOPI had sufficient rights to preclude consolidation by us. As such, we reported our allocable percentage of the net assets of CTOPI on our consolidated balance sheets. The investment was fully realized as of December 31, 2016 and we no longer have any equity investments in unconsolidated subsidiaries in our consolidated financial statements. Derivative Financial Instruments We classify all derivative financial instruments as either other assets or other liabilities on our consolidated balance sheets at fair value. On the date we enter into a derivative contract, we designate each contract as (i) a hedge of a net investment in a foreign operation, or net investment hedge, (ii) a hedge of a forecasted transaction or of the variability of cash flows to be received or paid related to a recognized asset or liability, or cash flow hedge, (iii) a hedge of a recognized asset or liability, or fair value hedge, or (iv) a derivative instrument not to be designated as a hedging derivative, or non-designated hedge. For all derivatives other than those designated as non-designated hedges, we formally document our hedge relationships and designation at the contract’s inception. This documentation includes the identification of the hedging instruments and the hedged items, its risk management objectives, strategy for undertaking the hedge transaction and our evaluation of the effectiveness of its hedged transaction. On a quarterly basis, we also formally assess whether the derivative we designated in each hedging relationship is expected to be, and has been, highly effective in offsetting changes in the value or cash flows of the hedged items. If it is determined that a derivative is not highly effective at hedging the designated exposure, hedge accounting is discontinued and the changes in fair value of the instrument are included in net income prospectively. Changes in the fair value of our derivative instruments that qualify as hedges are reported as a component of accumulated other comprehensive income (loss) on our consolidated financial statements. Deferred gains and losses are reclassified out of accumulated other comprehensive income (loss) and into net income in the same period or periods during which the hedged transaction affects earnings, and are presented in the same line item as the earnings effect of the hedged item. For cash flow hedges, this is typically when the periodic swap settlements are made, while for net investment hedges, this occurs when the hedged item is sold or substantially liquidated. To the extent a derivative does not qualify for hedge accounting and is deemed a non-designated hedge, the changes in its fair value are included in net income concurrently. Secured Debt Agreements Where applicable, we record investments financed with repurchase agreements as separate assets and the related borrowings under any repurchase agreements are recorded as separate liabilities on our consolidated balance sheets. Interest income earned on the investments and interest expense incurred on the repurchase agreements are reported separately on our consolidated statements of operations. Senior Loan Participations In certain instances, we finance our loans through the non-recourse syndication of a senior loan interest to a third-party. Depending on the particular structure of the syndication, the senior loan interest may remain on our GAAP balance sheet or, in other cases, the sale will be recognized and the senior loan interest will no longer be included in our consolidated financial statements. When these sales are not recognized under GAAP we reflect the transaction by recording a loan participations sold liability on our consolidated balance sheet, however this gross presentation does not impact stockholders’ equity or net income. When the sales are recognized, our balance sheet only includes our remaining subordinate loan and not the non-consolidated senior interest we sold. Convertible Notes The “Debt with Conversion and Other Options” Topic of the Financial Accounting Standards Board, or FASB, Accounting Standards Codification, or ASC, requires the liability and equity components of convertible debt instruments that may be settled in cash upon conversion, including partial cash settlement, to be separately accounted for in a manner that reflects the issuer’s nonconvertible debt borrowing rate. The initial proceeds from the sale of convertible notes are allocated between a liability component and an equity component in a manner that reflects interest expense at the rate of similar nonconvertible debt that could have been issued at such time. The equity component represents the excess initial proceeds received over the fair value of the liability component of the notes as of the date of issuance. We measured the estimated fair value of the debt component of our convertible notes as of the respective issuance dates based on our nonconvertible debt borrowing rate. The equity component of each series of our convertible notes is reflected within additional paid-in capital on our consolidated balance sheet, and the resulting debt discount is amortized over the period during which such convertible notes are expected to be outstanding (through the maturity date) as additional non-cash interest expense. The additional non-cash interest expense attributable to such convertible notes will increase in subsequent periods through the maturity date as the notes accrete to their par value over the same period. Deferred Financing Costs The deferred financing costs that are included as a reduction in the net book value of the related liability on our consolidated balance sheets include issuance and other costs related to our debt obligations. These costs are amortized as interest expense using the effective interest method over the life of the related obligations. Fair Value of Financial Instruments The “Fair Value Measurements and Disclosures” Topic, or ASC 820, defines fair value, establishes a framework for measuring fair value, and requires certain disclosures about fair value measurements under GAAP. Specifically, this guidance defines fair value based on exit price, or the price that would be received upon the sale of an asset or the transfer of a liability in an orderly transaction between market participants at the measurement date. ASC 820 also establishes a fair value hierarchy that prioritizes and ranks the level of market price observability used in measuring financial instruments. Market price observability is affected by a number of factors, including the type of financial instrument, the characteristics specific to the financial instrument, and the state of the marketplace, including the existence and transparency of transactions between market participants. Financial instruments with readily available quoted prices in active markets generally will have a higher degree of market price observability and a lesser degree of judgment used in measuring fair value. Financial instruments measured and reported at fair value are classified and disclosed based on the observability of inputs used in the determination, as follows: • Level 1: Generally includes only unadjusted quoted prices that are available in active markets for identical financial instruments as of the reporting date. • Level 2: Pricing inputs include quoted prices in active markets for similar instruments, quoted prices in less active or inactive markets for identical or similar instruments where multiple price quotes can be obtained, and other observable inputs, such as interest rates, yield curves, credit risks, and default rates. • Level 3: Pricing inputs are unobservable for the financial instruments and include situations where there is little, if any, market activity for the financial instrument. These inputs require significant judgment or estimation by management of third-parties when determining fair value and generally represent anything that does not meet the criteria of Levels 1 and 2. The estimated value of each asset reported at fair value using Level 3 inputs is determined by an internal committee composed of members of senior management of our Manager, including our Chief Executive Officer, Chief Financial Officer, and other senior officers. Certain of our other assets are reported at fair value either (i) on a recurring basis, as of each quarter-end, or (ii) on a nonrecurring basis, as a result of impairment or other events. Our assets that are recorded at fair value are discussed further in Note 15. We generally value our assets recorded at fair value by either (i) discounting expected cash flows based on assumptions regarding the collection of principal and interest and estimated market rates, or (ii) obtaining assessments from third-party dealers. For collateral-dependent loans that are identified as impaired, we measure impairment by comparing our Manager’s estimation of the fair value of the underlying collateral, less costs to sell, to the book value of the respective loan. These valuations may require significant judgments, which include assumptions regarding capitalization rates, leasing, creditworthiness of major tenants, occupancy rates, availability of financing, exit plan, loan sponsorship, actions of other lenders, and other factors deemed necessary by our Manager. We are also required by GAAP to disclose fair value information about financial instruments, that are not otherwise reported at fair value in our consolidated balance sheet, to the extent it is practicable to estimate a fair value for those instruments. These disclosure requirements exclude certain financial instruments and all non-financial instruments. The following methods and assumptions are used to estimate the fair value of each class of financial instruments, for which it is practicable to estimate that value: • Cash and cash equivalents: The carrying amount of cash and cash equivalents approximates fair value. • Restricted cash: The carrying amount of restricted cash approximates fair value. • Loans receivable, net: The fair values of these loans were estimated by our Manager based on a discounted cash flow methodology, taking into consideration various factors including capitalization rates, discount rates, leasing, occupancy rates, availability and cost of financing, exit plan, sponsorship, actions of other lenders, and indications of market value from other market participants. • Derivative financial instruments: The fair value of our foreign currency and interest rate contracts was estimated using advice from a third-party derivative specialist, based on contractual cash flows and observable inputs comprising foreign currency rates and credit spreads. • Secured debt agreements, net: The fair value of these instruments was estimated based on the rate at which a similar credit facility would currently be priced. • Loan participations sold, net: The fair value of these instruments was estimated based on the value of the related loan receivable asset. • Securitized debt obligations, net: The fair value of these instruments was estimated by utilizing third-party pricing service providers. In determining the value of a particular investment, pricing service providers may use broker-dealer quotations, reported trades, or valuation estimates from their internal pricing models to determine the reported price. • Convertible notes, net: Each series of the convertible notes is actively traded and their fair values were obtained using quoted market prices. Income Taxes Our financial results generally do not reflect provisions for current or deferred income taxes on our REIT taxable income. We believe that we operate in a manner that will continue to allow us to be taxed as a REIT and, as a result, we generally do not expect to pay substantial corporate level taxes other than those payable by our taxable REIT subsidiaries. If we were to fail to meet these requirements, we may be subject to federal, state, and local income tax on current and past income, and penalties. Refer to Note 13 for additional information. Stock-Based Compensation Our stock-based compensation consists of awards issued to our Manager and certain individuals employed by an affiliate of our Manager that vest over the life of the awards, as well as deferred stock units issued to certain members of our Board of Directors. Stock-based compensation expense is recognized for these awards in net income on a variable basis over the applicable vesting period of the awards, based on the value of our class A common stock. Refer to Note 14 for additional information. Earnings per Share Basic earnings per share, or Basic EPS, is computed in accordance with the two-class method and is based on the net earnings allocable to our class A common stock, including restricted class A common stock and deferred stock units, divided by the weighted-average number of shares of our class A common stock, including restricted class A common stock and deferred stock units outstanding during the period. Our restricted class A common stock is considered a participating security, as defined by GAAP, and has been included in our Basic EPS under the two- class method as these restricted shares have the same rights as our other shares of class A common stock, including participating in any gains or losses. Diluted earnings per share, or Diluted EPS, is determined using the treasury stock method, and is based on the net earnings allocable to our class A common stock, including restricted class A common stock and deferred stock units, divided by the weighted-average number of shares of our class A common stock, including restricted class A common stock and deferred stock units. Refer to Note 11 for additional discussion of earnings per share. Foreign Currency In the normal course of business, we enter into transactions not denominated in United States, or U.S., dollars. Foreign exchange gains and losses arising on such transactions are recorded as a gain or loss in our consolidated statements of operations. In addition, we consolidate entities that have a non-U.S. dollar functional currency. Non-U.S. dollar denominated assets and liabilities are translated to U.S. dollars at the exchange rate prevailing at the reporting date and income, expenses, gains, and losses are translated at the average exchange rate over the applicable period. Cumulative translation adjustments arising from the translation of non-U.S. dollar denominated subsidiaries are recorded in other comprehensive income (loss). Underwriting Commissions and Offering Costs Underwriting commissions and offering costs incurred in connection with common stock offerings are reflected as a reduction of additional paid-in capital. Costs incurred that are not directly associated with the completion of a common stock offering are expensed when incurred. Recent Accounting Pronouncements In August 2017, the FASB issued ASU 2017-12 “Derivatives and Hedging Topic 815: Targeted Improvements to Accounting for Hedging Activities,” or ASU 2017-12. ASU 2017-12 is intended to better align an entity’s financial reporting for hedging activities with the economic objectives of those activities. Upon adoption of ASU 2017-12, the cumulative ineffectiveness that has previously been recognized on existing cash flow and net investment hedges will be adjusted and removed from beginning retained earnings and placed in accumulated other comprehensive income (loss). We adopted ASU 2017-12 in the third quarter of 2017, which did not have an impact on our financial statements as we had not previously recognized any hedge ineffectiveness related to our existing cash flow and net investment hedges. In future periods, for hedges that are deemed effective, we will no longer need to bifurcate hedges into an effective and ineffective portion, and all gains or losses on effective hedges will be recognized in other comprehensive income (loss). In November 2016, the FASB issued ASU 2016-18 “Statement of Cash Flows (Topic 230): Restricted Cash,” or ASU 2016-18. ASU 2016-18 is intended to clarify how entities present restricted cash in the statement of cash flows. The guidance requires entities to show the changes in the total of cash and cash equivalents and restricted cash in the statement of cash flows. As a result, entities will no longer present transfers between cash and cash equivalents and restricted cash in the statement of cash flows. We adopted ASU 2016-18 in the second quarter of 2017 and applied the guidance retrospectively to our prior period consolidated statement of cash flows. In June 2016, the FASB issued ASU 2016-13 “Financial Instruments – Credit Losses – Measurement of Credit Losses on Financial Instruments (Topic 326),” or ASU 2016-13. ASU 2016-13 significantly changes how entities will measure credit losses for most financial assets and certain other instruments that are not measured at fair value through net income. ASU 2016-13 will replace the “incurred loss” model under existing guidance with an “expected loss” model for instruments measured at amortized cost, and require entities to record allowances for available-for-sale debt securities rather than reduce the carrying amount, as they do today under the other-than-temporary impairment model. It also simplifies the accounting model for purchased credit-impaired debt securities and loans. ASU 2016-13 is effective for fiscal years beginning after December 15, 2019 and is to be adopted through a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective. While we are currently evaluating the impact ASU 2016-13 will have on our consolidated financial statements, we expect that the adoption will result in an increased amount of provisions for potential loan losses as well as the recognition of such provisions earlier in the lending cycle. We currently do not have any provision for loan losses on our consolidated financial statements. In May 2014, the FASB issued ASU 2014-09, “Revenue from Contracts with Customers (Topic 606) ,

Loans Receivable, Net

Loans Receivable, Net	12 Months Ended
	Dec. 31, 2017
Receivables [Abstract]
Loans Receivable, Net	3. LOANS RECEIVABLE, NET The following table details overall statistics for our loans receivable portfolio ($ in thousands): December 31, December 31, Number of loans 110 107 Principal balance $ 10,108,226 $ 8,727,218 Net book value $ 10,056,732 $ 8,692,978 Unfunded loan commitments (1) $ 1,573,107 $ 882,472 Weighted-average cash coupon (2) 5.55 % 5.01 % Weighted-average all-in yield (2) 5.95 % 5.36 % Weighted-average maximum maturity (years) (3) 3.5 3.2 (1) Unfunded commitments will primarily be funded to finance property improvements or lease-related expenditures by the borrowers. These future commitments will be funded over the term of each loan, subject in certain cases to an expiration date. (2) As of December 31, 2017, our floating rate loans were indexed to various benchmark rates, with 92% of floating rate loans by principal balance indexed to USD LIBOR. As of December 31, 2016, our floating rate loans were indexed to various benchmark rates, with 84% of floating rate loans indexed to USD LIBOR. In addition, $216.3 million of our floating rate loans earned interest based on floors that are above the applicable index, with an average floor of 1.27%, as of December 31, 2016. In addition to cash coupon, all-in yield includes the amortization of deferred origination and extension fees, loan origination costs, and purchase discounts, as well as the accrual of exit fees. Cash coupon and all-in yield assume applicable floating benchmark rates as of December 31, 2017 for weighted-average calculation. (3) Maximum maturity assumes all extension options are exercised by the borrower, however our loans may be repaid prior to such date. As of December 31, 2017, 75% of our loans by principal balance were subject to yield maintenance or other prepayment restrictions and 25% were open to repayment by the borrower without penalty. As of December 31, 2016, 64% of our loans were subject to yield maintenance or other prepayment restrictions and 36% were open to repayment by the borrower without penalty. Activity relating to our loans receivable portfolio was as follows ($ in thousands): Principal Deferred Fees / (1) Net Book December 31, 2015 $ 9,108,361 $ (31,354) $ 9,077,007 Loan fundings 3,151,882 — 3,151,882 Loan repayments (3,374,622 ) — (3,374,622 ) Unrealized (loss) gain on foreign currency translation (158,403 ) 1,466 (156,937 ) Deferred fees and other items — (44,697 ) (44,697 ) Amortization of fees and other items — 40,345 40,345 December 31, 2016 $ 8,727,218 $ (34,240 ) $ 8,692,978 Loan fundings 4,072,786 — 4,072,786 Loan repayments (2,828,610 ) — (2,828,610 ) Unrealized gain (loss) on foreign currency translation 136,832 (186 ) 136,646 Deferred fees and other items — (55,441 ) (55,441 ) Amortization of fees and other items — 38,373 38,373 December 31, 2017 $ 10,108,226 $ (51,494 ) $ 10,056,732 (1) Other items primarily consist of purchase discounts or premiums, exit fees, and deferred origination expenses. The tables below detail the property type and geographic distribution of the properties securing the loans in our portfolio ($ in thousands): December 31, 2017 Property Type Number of Net Total Loan (1) Percentage of Office 53 $ 5,773,972 $ 5,807,170 53 % Hotel 15 1,830,568 1,905,497 17 Multifamily 25 1,220,423 1,228,959 11 Retail 6 487,473 940,980 8 Condominium 2 142,342 268,751 2 Other 9 601,954 942,251 9 110 $ 10,056,732 $ 11,093,608 100 % Geographic Location Number of Net Total Loan (1) Percentage of United States Northeast 26 $ 2,857,948 $ 2,871,219 26 % West 29 2,672,069 2,816,276 24 Southeast 17 2,007,202 2,470,992 22 Midwest 9 856,559 862,578 8 Southwest 10 380,204 380,120 3 Northwest 2 283,381 286,221 3 Subtotal 93 9,057,363 9,687,406 86 International United Kingdom 6 440,317 794,789 7 Canada 7 415,893 412,343 4 Belgium 1 73,779 74,431 1 Germany 1 12,237 67,399 1 Netherlands 2 57,143 57,240 1 Subtotal 17 999,369 1,406,202 14 Total 110 $ 10,056,732 $ 11,093,608 100 % (1) In certain instances, we finance our loans through the non-recourse sale of a senior loan interest that is not included in our consolidated financial statements. See Note 2 for further discussion. Total loan exposure encompasses the entire loan we originated and financed, including $985.4 million of such non-consolidated senior interests as of December 31, 2017. December 31, 2016 Property Type Number of Net Total Loan (1) Percentage of Office 55 $ 4,800,609 $ 4,889,456 50 % Hotel 18 1,889,732 1,957,334 20 Retail 9 769,813 1,173,592 12 Multifamily 17 817,387 819,781 8 Condominium 2 66,070 258,360 3 Other 6 349,367 658,211 7 107 $ 8,692,978 $ 9,756,734 100 % Geographic Location Number of Net Total Loan (1) Percentage of United States Northeast 26 $ 2,548,257 $ 2,562,149 26 % Southeast 21 1,492,530 1,899,748 19 West 22 1,628,811 1,828,667 19 Midwest 7 695,713 698,093 7 Southwest 8 380,639 379,766 4 Northwest 3 227,747 293,564 3 Subtotal 87 6,973,697 7,661,987 78 International United Kingdom 9 977,136 1,305,816 13 Canada 8 487,835 483,923 5 Germany 1 204,241 254,644 3 Netherlands 2 50,069 50,364 1 Subtotal 20 1,719,281 2,094,747 22 Total 107 $ 8,692,978 $ 9,756,734 100 % (1) In certain instances, we finance our loans through the non-recourse sale of a senior loan interest that is not included in our consolidated financial statements. See Note 2 for further discussion. Total loan exposure encompasses the entire loan we originated and financed, including $1.0 billion of such non-consolidated senior interests as of December 31, 2016. Loan Risk Ratings As further described in Note 2, our Manager evaluates our loan portfolio on a quarterly basis. In conjunction with our quarterly loan portfolio review, our Manager assesses the risk factors of each loan, and assigns a risk rating based on several factors. Factors considered in the assessment include, but are not limited to, risk of loss, current LTV, debt yield, collateral performance, structure, exit plan, and sponsorship. Loans are rated “1” (less risk) through “5” (greater risk), which ratings are defined in Note 2. The following table allocates the principal balance and net book value of our loans receivable based on our internal risk ratings ($ in thousands): December 31, 2017 December 31, 2016 Risk Number Net Book Value Total Loan (1) Risk Number Net Book Value Total Loan (1) 1 1 $ 31,842 $ 31,890 1 8 $ 361,100 $ 361,574 2 41 3,512,709 3,521,701 2 52 4,011,992 4,083,678 3 67 6,491,617 7,519,465 3 46 4,299,026 5,290,668 4 1 20,564 20,552 4 1 20,860 20,814 5 — — — 5 — — — 110 $ 10,056,732 $ 11,093,608 107 $ 8,692,978 $ 9,756,734 (1) In certain instances, we finance our loans through the non-recourse sale of a senior loan interest that is not included in our consolidated financial statements. See Note 2 for further discussion. Total loan exposure encompasses the entire loan we originated and financed, including $985.4 million and $1.0 billion of such non-consolidated senior interests as of December 31, 2017 and December 31, 2016, respectively. The weighted-average risk rating of our total loan exposure was 2.7 and 2.5 as of December 31, 2017 and December 31, 2016, respectively. The increase in weighted-average risk rating was primarily driven by repayments of loans with lower risk ratings, and not rating downgrades in the existing portfolio. We did not have any impaired loans, nonaccrual loans, or loans in maturity default as of December 31, 2017 or 2016. Multifamily Joint Venture As discussed in Note 2, we entered into a Multifamily Joint Venture in April 2017. As of December 31, 2017, our Multifamily Joint Venture held $182.2 million of loans, which are included in the loan disclosures above. Refer to Note 2 for additional discussion of our Multifamily Joint Venture.

Equity Investment in Unconsolid

Equity Investment in Unconsolidated Subsidiary	12 Months Ended
	Dec. 31, 2017
Equity Method Investments and Joint Ventures [Abstract]
Equity Investment in Unconsolidated Subsidiary	4. EQUITY INVESTMENT IN UNCONSOLIDATED SUBSIDIARY Our equity investment in unconsolidated subsidiary consisted solely of our carried interest in CTOPI, a fund formerly sponsored and managed by an affiliate of our Manager. The investment was fully realized as of December 31, 2016 and we no longer have any investments in unconsolidated subsidiaries on our consolidated financial statements. Our carried interest in CTOPI entitled us to earn promote revenue in an amount equal to 17.7% of the fund’s profits, after a 9% preferred return and 100% return of capital to the CTOPI partners. During the years ended December 31, 2016 and 2015, we recognized $3.2 million and $11.8 million, respectively, of promote income from CTOPI in respect of our carried interest and recorded such amounts as income in our consolidated statement of operations. CTOPI Incentive Management Fee Grants In January 2011, we created a management compensation pool for employees equal to 45% of the CTOPI promote distributions received by us. During the years ended December 31, 2016 and 2015, we recognized $1.6 million and $5.4 million, respectively, of expenses under the CTOPI incentive plan. Such amounts were recognized as a component of general and administrative expenses in our consolidated statements of operations.

Other Assets and Liabilities

Other Assets and Liabilities	12 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Other Assets and Liabilities	5. OTHER ASSETS AND LIABILITIES The following table details the components of our other assets ($ in thousands): December 31, December 31, Loan portfolio payments held by servicer (1) $ 54,759 $ 5,765 Accrued interest receivable 38,573 32,871 Collateral deposited under derivative agreements 4,120 79 Derivative assets 1,214 4,086 Prepaid expenses 798 803 Prepaid taxes 31 16 Other 80 450 Total $ 99,575 $ 44,070 (1) Represents loan principal and interest payments held by our third-party loan servicer as of the balance sheet date which were remitted to us during the subsequent remittance cycle. The following table details the components of our other liabilities ($ in thousands): December 31, December 31, Accrued dividends payable $ 66,888 $ 58,615 Secured debt repayments pending servicer remittance (1) 38,456 5,372 Accrued management and incentive fees payable 14,284 12,798 Accrued interest payable 14,162 9,049 Derivative liabilities 4,911 210 Accounts payable and other liabilities 2,125 1,775 Total $ 140,826 $ 87,819 (1) Represents pending transfers from our third-party loan servicer that were remitted to our banking counterparties during the subsequent remittance cycle.

Secured Debt Agreements, Net

Secured Debt Agreements, Net	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Secured Debt Agreements, Net	6. SECURED DEBT AGREEMENTS, NET Our secured debt agreements include credit facilities, the GE portfolio acquisition facility, asset-specific financings, and a revolving credit agreement. The following table details our secured debt agreements ($ in thousands): Secured Debt Agreements Borrowings Outstanding December 31, December 31, Credit facilities $ 4,068,249 $ 3,572,837 GE portfolio acquisition facility 703,423 1,479,582 Asset-specific financings 518,864 679,207 Revolving credit agreement — — Total secured debt agreements $ 5,290,536 $ 5,731,626 Deferred financing costs (1) (16,681 ) (15,272 ) Net book value of secured debt $ 5,273,855 $ 5,716,354 (1) Costs incurred in connection with our secured debt agreements are recorded on our consolidated balance sheet when incurred and recognized as a component of interest expense over the life of each related agreement. Credit Facilities During the year ended December 31, 2017, we (i) added two new credit facilities related to our Multifamily Joint Venture, providing an aggregate additional $450.0 million of credit capacity, (ii) increased the maximum facility size of two of our existing credit facilities, providing an additional £250.0 million and €250.0 million of credit capacity, respectively, and (iii) converted one of our asset-specific financings to a $500.0 million credit facility. The following tables detail our credit facilities ($ in thousands): December 31, 2017 Maximum Facility Size (1) Collateral Assets (2) Credit Borrowings Lender Potential (3) Outstanding Available (3) Wells Fargo $ 2,000,000 $ 1,680,325 $ 1,289,135 $ 1,170,801 $ 118,334 MetLife 1,000,000 1,039,231 807,164 807,164 — Bank of America 750,000 765,049 573,542 573,542 — JP Morgan (4) 500,000 579,218 443,496 319,755 123,741 Société Générale (5) 480,200 373,181 300,871 300,871 — Deutsche Bank 500,000 399,203 295,743 295,743 — Citibank (6) 800,125 455,433 354,354 240,881 113,473 Morgan Stanley (7) 675,650 591,168 456,344 216,044 240,300 Bank of America - Multi. JV (8) 200,000 106,950 85,560 85,560 — Goldman Sachs - Multi. JV (8) 250,000 75,225 57,888 57,888 — $ 7,155,975 $ 6,064,983 $ 4,664,097 $ 4,068,249 $ 595,848 December 31, 2016 Maximum Facility Size (1) Collateral Assets (2) Credit Borrowings Lender Potential (3) Outstanding Available (3) Wells Fargo $ 2,000,000 $ 1,718,874 $ 1,339,942 $ 1,107,733 $ 232,209 MetLife 1,000,000 1,106,017 862,454 862,454 — Bank of America 750,000 794,881 617,694 617,694 — JP Morgan (4) 500,000 550,560 420,414 316,219 104,195 Morgan Stanley (7) 308,500 344,056 272,221 231,930 40,291 Citibank (6) 500,000 508,989 394,677 229,629 165,048 Société Générale (5) 420,680 274,351 207,178 207,178 — $ 5,479,180 $ 5,297,728 $ 4,114,580 $ 3,572,837 $ 541,743 (1) Maximum facility size represents the largest amount of borrowings available under a given facility once sufficient collateral assets have been approved by the lender and pledged by us. (2) Represents the principal balance of the collateral assets. (3) Potential borrowings represents the total amount we could draw under each facility based on collateral already approved and pledged. When undrawn, these amounts are immediately available to us at our sole discretion under the terms of each credit facility. (4) As of December 31, 2017 and December 31, 2016, the JP Morgan maximum facility size was composed of a general $500.0 million facility size, under which U.S. Dollars and British Pounds Sterling borrowings are contemplated. (5) As of December 31, 2017 and December 31, 2016, the Société Générale maximum facility size was composed of a €400.0 million facility size, which translated to $480.2 million and $420.7 million, respectively. Borrowings denominated in U.S. Dollars, British Pounds Sterling, and Euros are contemplated under this facility. (6) As of December 31, 2017, the Citibank maximum facility size was composed of a $500.0 million facility denominated in U.S. Dollars plus a €250.0 million facility, which translated to $300.1 million as of such date, which contemplated borrowings denominated in British Pounds Sterling and Euros. As of December 31, 2016, the maximum facility size was composed of a general $500.0 million facility. (7) As of December 31, 2017, the Morgan Stanley maximum facility size was composed of a £500.0 million facility size, which translated to $675.7 million as of such date. As of December 31, 2016, the maximum facility size was composed of a £250.0 million facility size, which translated to $308.5 million as of such date. Borrowings denominated in U.S. Dollars, British Pounds Sterling, and Euros are contemplated under this facility. (8) These facilities finance the loan investments of our consolidated Multifamily Joint Venture. Refer to Note 2 to our consolidated financial statements for additional discussion of our Multifamily Joint Venture. The weighted-average outstanding balance of our credit facilities was $4.1 billion for the year ended December 31, 2017. As of December 31, 2017, we had aggregate borrowings of $4.1 billion outstanding under our credit facilities, with a weighted-average cash coupon of LIBOR plus 1.90% per annum, a weighted-average all-in cost of credit, including associated fees and expenses, of LIBOR plus 2.12% per annum, and a weighted-average advance rate of 78.7%. As of December 31, 2017, outstanding borrowings under these facilities had a weighted-average maturity, excluding extension options and term-out provisions, of 1.5 years. The weighted-average outstanding balance of our credit facilities was $3.0 billion for the year ended December 31, 2016. As of December 31, 2016, we had aggregated borrowings of $3.6 billion outstanding under our credit facilities, with a weighted-average cash coupon of LIBOR plus 1.82% per annum, a weighted-average all-in cost of credit, including associated fees and expenses, of LIBOR plus 2.02% per annum, and a weighted-average advance rate of 79.1%. As of December 31, 2016, outstanding borrowings under these facilities had a weighted-average maturity, excluding extension options and term-out provisions, of 1.5 years. Borrowings under each facility are subject to the initial approval of eligible collateral loans by the lender and the maximum advance rate and pricing rate of individual advances are determined with reference to the attributes of the respective collateral loan. The following tables outline the key terms of our credit facilities as of December 31, 2017: Lender Currency Guarantee (1) Margin Call (2) Term/Maturity Wells Fargo $ 25 % Collateral marks only Term matched (3) MetLife $ 50 % Collateral marks only April 21, 2023 (4) Bank of America $ 50 % Collateral marks only May 21, 2021 (5) JP Morgan $ / £ 50 % Collateral marks only January 7, 2020 Société Générale $ / £ / € 25 % Collateral marks only Term matched (3) Deutsche Bank $ 35 % Collateral marks only Term matched (3) Citibank $ / £ / € 25 % Collateral marks only Term matched (3) Morgan Stanley $ / £ / € 25 % Collateral marks only March 3, 2020 Bank of America - Multi. JV (6) $ 43 % Collateral marks only July 19, 2021 Goldman Sachs - Multi. JV (6) $ 25 % Collateral marks only July 12, 2020 (1) Other than amounts guaranteed based on specific collateral asset types, borrowings under our credit facilities are non-recourse to us. (2) Margin call provisions under our credit facilities do not permit valuation adjustments based on capital markets events, and are limited to collateral-specific credit marks. (3) These credit facilities have various availability periods during which new advances can be made and which are generally subject to each lender’s discretion. Maturity dates for advances outstanding are tied to the term of each respective collateral asset. (4) Includes five one-year extension options which may be exercised at our sole discretion. (5) Includes two one-year extension options which may be exercised at our sole discretion. (6) These facilities finance the loan investments of our consolidated Multifamily Joint Venture. Refer to Note 2 for additional discussion of our Multifamily Joint Venture. Currency Outstanding Borrowings Potential Borrowings (1) Index Rate (2) Advance (3) $ $ 3,798,619 $ 4,275,789 1-month USD LIBOR L+1.87% 78.6% € € 66,144 € 87,744 3-month EURIBOR L+2.24% 80.0% £ £ 140,771 £ 209,406 3-month GBP LIBOR L+2.24% 78.6% $ 4,068,249 $ 4,664,097 L+1.90% 78.7% (1) Potential borrowings represents the total amount we could draw under each facility based on collateral already approved and pledged. When undrawn, these amounts are immediately available to us at our sole discretion under the terms of each credit facility. (2) Represents weighted-average cash coupon based on borrowings outstanding. (3) Represents weighted-average advance rate based on the outstanding principal balance of the collateral assets pledged. GE Portfolio Acquisition Facility During the second quarter of 2015, concurrently with our acquisition of the GE portfolio, we entered into an agreement with Wells Fargo to provide us with secured financing for the acquired portfolio. As of December 31, 2017, this facility provided for $816.3 million of financing, of which $703.4 million was outstanding and an additional $112.9 million was available to finance future loan fundings in the GE portfolio. The GE portfolio acquisition facility is non-revolving and consists of a single master repurchase agreement providing for asset-specific borrowings for each collateral asset. The asset-specific borrowings under the GE portfolio acquisition facility were advanced at a weighted-average rate of 80% of our purchase price of the collateral assets and are repaid pro rata from collateral asset repayment proceeds. The asset-specific borrowings are currency matched to the collateral assets and accrue interest at a rate equal to the sum of (i) the applicable base rate plus (ii) a margin of 1.75%, which will increase to 1.80% and 1.85% in year four and year five, respectively. As of December 31, 2017, those borrowings were denominated in U.S. Dollars and Canadian Dollars. The asset-specific borrowings are term matched to the underlying collateral assets with an outside maturity date of May 20, 2020, which may be extended pursuant to two one-year extension options. We guarantee obligations under the GE portfolio acquisition facility in an amount equal to the greater of (i) 25% of outstanding asset-specific borrowings, and (ii) $250.0 million. We had outstanding asset-specific borrowings under the GE portfolio acquisition facility of $703.4 million and a weighted-average all-in cost of credit, including associated fees and expenses, of LIBOR plus 1.72% per annum as of December 31, 2017, compared to $1.5 billion of outstanding asset-specific borrowings and a weighted-average all-in cost of credit, including associated fees and expenses, of LIBOR plus 1.83% per annum as of December 31, 2016. Asset-Specific Financings The following tables detail our asset-specific financings ($ in thousands): December 31, 2017 Asset-Specific Financings Count Principal Book Value Wtd. Avg. Yield/Cost (1) Guarantee (2) Wtd. Avg. (3) Collateral assets 6 $ 682,259 $ 677,296 L+4.76 % n/a Dec. 2020 Financing provided (4) 6 $ 518,864 $ 517,088 L+2.50 % $ 162,475 Dec. 2020 (1) These floating rate loans and related liabilities are indexed to the various benchmark rates relevant in each arrangement in terms of currency and payment frequency. Therefore the net exposure to each benchmark rate is in direct proportion to our net assets indexed to that rate. In addition to cash coupon, yield/cost includes the amortization of deferred origination fees / financing costs. (2) Other than amounts guaranteed on an asset-by-asset basis, borrowings under our asset-specific financings are non-recourse to us. (3) The weighted-average term is determined based on the maximum maturity of the corresponding loans, assuming all extension options are exercised by the borrower. Each of our asset-specific financings are term-matched to the corresponding collateral loans. (4) Borrowings of $394.8 million under these asset specific financings are cross collateralized with related credit facilities with the same lenders. December 31, 2016 Asset-Specific Financings Count Principal Book Value Wtd. Avg. Yield/Cost (1) Guarantee (2) Wtd. Avg. (3) Collateral assets 7 $ 876,083 $ 869,417 L+4.84 % n/a Aug. 2020 Financing provided (4) 7 $ 679,207 $ 676,333 L+2.60 % $ 231,585 Aug. 2020 (1) These floating rate loans and related liabilities are indexed to the various benchmark rates relevant in each arrangement in terms of currency and payment frequency. Therefore the net exposure to each benchmark rate is in direct proportion to our net assets indexed to that rate. In addition to cash coupon, yield/cost includes the amortization of deferred origination fees / financing costs. (2) Other than amounts guaranteed on an asset-by-asset basis, borrowings under our asset-specific financings are non-recourse to us. (3) The weighted-average term is determined based on the maximum maturity of the corresponding loans, assuming all extension options are exercised by the borrower. Each of our asset-specific financings are term-matched to the corresponding collateral loans. (4) Borrowings of $392.3 million under these asset specific financings are cross collateralized with related credit facilities with the same lenders. The weighted-average outstanding balance of our asset-specific financings was $576.4 million for the year ended December 31, 2017 and $584.7 million for the year ended December 31, 2016. Revolving Credit Agreement During the second quarter of 2017, we increased the borrowing capacity under our secured revolving credit agreement with Barclays by $125.0 million to $250.0 million. This full recourse facility is designed to finance first mortgage originations for up to six months as a bridge to term financing or syndication. Advances under the agreement are subject to availability under a specified borrowing base and accrue interest at a per annum pricing rate equal to the sum of (i) an applicable base rate or Eurodollar rate and (ii) an applicable margin, in each case, dependent on the applicable type of loan collateral. The maturity date of the facility is April 4, 2020. During the year ended December 31, 2017, the weighted-average outstanding borrowings under the revolving credit agreement were $30.7 million and we recorded interest expense of $3.0 million, including $829,000 of amortization of deferred fees and expenses. As of December 31, 2017, we had no outstanding borrowings under the agreement. During the year ended December 31, 2016, the weighted-average outstanding borrowings under the revolving credit agreement were $31.6 million and we recorded interest expense of $1.4 million, including $376,000 of amortization of deferred fees and expenses. As of December 31, 2016 we had no outstanding borrowings under the agreement. Debt Covenants Each of the guarantees related to our secured debt agreements contain the following uniform financial covenants: (i) our ratio of earnings before interest, taxes, depreciation, and amortization, or EBITDA, to fixed charges, as defined in the agreements, shall be not less than 1.4 to 1.0; (ii) our tangible net worth, as defined in the agreements, shall not be less than $2.2 billion as of each measurement date plus 75% of the net cash proceeds of future equity issuances subsequent to December 31, 2017; (iii) cash liquidity shall not be less than the greater of (x) $10.0 million or (y) 5% of our recourse indebtedness; and (iv) our indebtedness shall not exceed 83.33% of our total assets. As of December 31, 2017 and December 31, 2016, we were in compliance with these covenants.

Loan Participations Sold, Net

Loan Participations Sold, Net	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Loan Participations Sold, Net	7. LOAN PARTICIPATIONS SOLD, NET The financing of a loan by the non-recourse sale of a senior interest in the loan through a participation agreement generally does not qualify as a sale under GAAP. Therefore, in the instance of such sales, we present the whole loan as an asset and the loan participation sold as a liability on our consolidated balance sheet until the loan is repaid. The obligation to pay principal and interest on these liabilities is generally based on the performance of the related loan obligation. The gross presentation of loan participations sold does not impact stockholders’ equity or net income. The following tables detail our loan participations sold ($ in thousands): December 31, 2017 Loan Participations Sold Count Principal Book Value Yield/Cost (1) Guarantee (2) Term Total loan 1 $ 141,119 $ 138,907 L+5.94 % n/a Feb. 2022 Senior participation (3) 1 80,706 80,415 L+4.14 % n/a Feb. 2022 December 31, 2016 Loan Participations Sold Count Principal Book Value Yield/Cost (1) Guarantee (2) Term Total loan 1 $ 419,560 $ 416,233 L+4.48 % n/a Dec. 2019 Senior participation (3)(4) 1 349,633 348,077 L+2.72 % $ 29,616 Dec. 2019 (1) Our floating rate loans and related liabilities are indexed to the various benchmark rates relevant in each arrangement in terms of currency and payment frequency. Therefore the net exposure to each benchmark rate is in direct proportion to our net assets indexed to that rate. In addition to cash coupon, yield/cost includes the amortization of deferred fees / financing costs. (2) As of December 31, 2017, our loan participation sold was non-recourse to us. As of December 31, 2016, our loan participation was subject to a related guarantee agreement for £24.0 million ($29.6 million as of December 31, 2016). (3) During the years ended December 31, 2017 and 2016, we recorded $10.1 million and $13.7 million, respectively, of interest expense related to our loan participations sold, of which $8.4 million and $13.1 million was paid in cash. (4) The difference between principal balance and book value of loan participations sold is due to deferred financing costs of $291,000 and $1.6 million as of December 31, 2017 and December 31, 2016, respectively.

Securitized Debt Obligations, N

Securitized Debt Obligations, Net	12 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Securitized Debt Obligations, Net	8. SECURITIZED DEBT OBLIGATIONS, NET In the fourth quarter of 2017, we financed a pool of our loans through a collateralized loan obligation, or the CLO, which is consolidated in our financial statements. In the second quarter of 2017, we financed one of our loans through a single asset securitization vehicle, or the Single Asset Securitization, which is also consolidated in our financial statements. The CLO and the Single Asset Securitization have issued securitized debt obligations that are non-recourse to us. Refer to Note 16 for further discussion of our CLO and Single Asset Securitization. The following table details our securitized debt obligations ($ in thousands): December 31, 2017 Securitized Debt Obligations Count Principal Book Value Wtd. Avg. (1) Term (2) Collateralized Loan Obligation Collateral assets 31 $ 1,000,000 $ 1,000,000 5.16 % Nov. 2021 Financing provided 1 817,500 808,083 L+1.76 % June 2035 Single Asset Securitization Collateral assets (3) 1 656,406 652,880 L+3.60 % June 2023 Financing provided 1 474,620 474,328 L+1.94 % June 2033 Total Collateral assets 32 $ 1,656,406 $ 1,652,880 5.17 % Financing provided (4) 2 $ 1,292,120 $ 1,282,411 L+1.83 % (1) As of December 31, 2017, 98% of our loans financed by securitized debt obligations earned a floating rate of interest. In addition to cash coupon, all-in yield includes the amortization of deferred origination and extension fees, loan origination costs, purchase discounts, and accrual of exit fees. All-in yield for the total portfolio assume applicable floating benchmark rates for weighted-average calculation. (2) Loan term represents final maturity, assuming all extension options are exercised by the borrower. Repayments of securitized debt obligations are tied to timing of the related collateral loan asset repayments. The term of these obligations represents the rated final distribution date of the securitizations. (3) The collateral assets for the Single Asset Securitization include the total loan amount, of which we securitized $500.0 million. (4) During the year ended December 31, 2017, we recorded $8.5 million of interest expense related to our securitized debt obligations. We did not have any securitized debt obligations as of December 31, 2016.

Convertible Notes, Net

Convertible Notes, Net	12 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Convertible Notes, Net	9. CONVERTIBLE NOTES, NET As of December 31, 2017, the following convertible senior notes, or Convertible Notes, were outstanding ($ in thousands): Convertible Notes Issuance Face Value Coupon Rate All-in Cost (1) Conversion Rate (2) Maturity November 2013 $ 172,500 5.25 % 5.87 % 36.1380 December 1, 2018 May 2017 402,500 4.38 % 4.85 % 28.0324 May 5, 2022 (1) Includes issuance costs that are amortized through interest expense over the life of the Convertible Notes using the effective interest method. (2) Represents the shares of class A common stock per $1,000 principal amount of Convertible Notes, which is equivalent to a conversion price of $27.67 and $35.67 per share of class A common stock, respectively, for the November 2013 and May 2017 convertible notes. As a result of exceeding the cumulative dividend threshold, as defined in the November 2013 convertible notes supplemental indenture, the conversion rate on the November 2013 convertible notes was most recently adjusted on June 28, 2017 from the prior conversion rate of 35.7236 shares of class A common stock per $1,000 principal amount of convertible notes, which was equivalent to a conversion price of $27.99 per share of class A common stock. The cumulative dividend threshold as defined in the May 2017 convertible notes supplemental indenture has not been exceeded as of December 31, 2017. In May 2017 we issued $287.5 million of convertible notes. In the third quarter of 2017, we issued an additional $115.0 million of convertible notes under the same indenture and with the same terms as the May 2017 convertible notes. Accordingly, as of December 31, 2017, the May 2017 convertible notes had an aggregate outstanding face value of $402.5 million. The Convertible Notes are convertible at the holders’ option into shares of our class A common stock, only under specific circumstances, prior to the close of business on August 31, 2018 and January 31, 2022, for the November 2013 and May 2017 convertible notes, respectively, at the applicable conversion rate in effect on the conversion date. Thereafter, the Convertible Notes are convertible at the option of the holder at any time until the second scheduled trading day immediately preceding the maturity date. We may not redeem the Convertible Notes prior to maturity. The last reported sale price of our class A common stock of $32.18 on December 29, 2017, the last trading day in the year ended December 31, 2017, was greater than the per share conversion price of the November 2013 convertible notes but less than the per share conversion price of the May 2017 convertible notes. We have the intent and ability to settle each series of the Convertible Notes in cash and, as a result, the Convertible Notes did not have any impact on our diluted earnings per share. Upon our issuance of the November 2013 convertible notes, we recorded a $9.1 million discount based on the implied value of the conversion option and an assumed effective interest rate of 6.50%, as well as $4.1 million of initial issuance costs. Including the amortization of this discount and the issuance costs, our total cost of the November 2013 convertible notes issuance is 7.16% per annum. Upon our issuance of the May 2017 convertible notes, including our additional issuance in the third quarter of 2017, we recorded a $979,000 discount based on the implied value of the conversion option and an assumed effective interest rate of 4.57%, as well as $8.4 million of initial debt discount and issuance costs. Including the amortization of the discount and issuance costs, our total cost of the May 2017 convertible notes issuance is 4.91% per annum. The following table details our interest expense related to the Convertible Notes ($ in thousands): Year Ended December 31, 2017 2016 2015 Cash coupon $ 19,259 $ 9,056 $ 9,056 Discount and issuance cost amortization 4,040 2,736 2,571 Total interest expense $ 23,299 $ 11,792 $ 11,627 The following table details the net book value of our Convertible Notes on our consolidated balance sheets ($ in thousands): December 31, December 31, Face value $ 575,000 $ 172,500 Unamortized discount (10,279 ) (5,532 ) Deferred financing costs (810 ) (206 ) Net book value $ 563,911 $ 166,762 Accrued interest payable for the Convertible Notes was $3.7 million and $755,000 as of December 31, 2017 and December 31, 2016, respectively. Refer to Note 2 for additional discussion of our accounting policies for the Convertible Notes.

Derivative Financial Instrument

Derivative Financial Instruments	12 Months Ended
	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	10. DERIVATIVE FINANCIAL INSTRUMENTS The sole objective of our use of derivative financial instruments is to minimize the risks and/or costs associated with our investments and/or financing transactions. These derivatives may or may not qualify as net investment, cash flow, or fair value hedges under the hedge accounting requirements of ASC 815 – “Derivatives and Hedging.” Derivatives not designated as hedges are not speculative and are used to manage our exposure to interest rate movements and other identified risks. For more information on the accounting for designated and non-designated hedges, refer to Note 2. The use of derivative financial instruments involves certain risks, including the risk that the counterparties to these contractual arrangements do not perform as agreed. To mitigate this risk, we only enter into derivative financial instruments with counterparties that have appropriate credit ratings and are major financial institutions with which we and our affiliates may also have other financial relationships. We do not anticipate that any of the counterparties will fail to meet their obligations. Net Investment Hedges of Foreign Currency Risk Certain of our international investments expose us to fluctuations in foreign interest rates and currency exchange rates. These fluctuations may impact the value of our cash receipts and payments in terms of our functional currency, the U.S. Dollar. We use foreign currency forward contracts to protect the value or fix the amount of certain investments or cash flows in terms of the U.S. Dollar. The following table details our outstanding foreign exchange derivatives that were designated as net investment hedges of foreign currency risk (notional amount in thousands): December 31, 2017 December 31, 2016 Foreign Currency Number of Notional Amount Foreign Currency Number of Notional Amount Sell GBP Forward 1 £ 112,700 Sell GBP Forward 2 £ 141,900 Sell CAD Forward 1 C$ 95,100 Sell CAD Forward 2 C$ 122,900 Sell EUR Forward 1 € 44,900 Cash Flow Hedges of Interest Rate Risk Certain of our financing transactions expose us to a fixed versus floating rate mismatch between our assets and liabilities. We use derivative financial instruments, which include interest rate caps and swaps, and may also include interest rate options, floors, and other interest rate derivative contracts, to hedge interest rate risk associated with our borrowings where there is potential for an index mismatch. The following tables detail our outstanding interest rate derivatives that were designated as cash flow hedges of interest rate risk (notional amount in thousands): December 31, 2017 Interest Rate Number of Notional Amount Strike Index Wtd.-Avg. Interest Rate Swaps 4 C$ 108,094 1.0 % CDOR 1.4 Interest Rate Caps 9 $ 204,248 2.4 % USD LIBOR 1.5 Interest Rate Caps 3 C$ 23,370 2.0 % CDOR 0.3 December 31, 2016 Interest Rate Number of Notional Amount Strike Index Wtd.-Avg. Interest Rate Swaps 4 C$ 108,271 1.0 % CDOR 2.4 Interest Rate Caps 21 $ 802,256 2.0 % USD LIBOR 0.4 Interest Rate Caps 5 C$ 400,035 2.0 % CDOR 0.4 Interest Rate Caps 1 £ 15,142 2.0 % GBP LIBOR 0.3 Amounts reported in accumulated other comprehensive income (loss) related to derivatives will be reclassified to interest expense as interest payments are made on our floating rate debt. During the twelve months following December 31, 2017, we estimate that an additional $619,000 will be reclassified from accumulated other comprehensive income (loss) as an increase to interest income. Non-designated Hedges During the years ended December 31, 2017, 2016, and 2015, we recorded losses of $449,000, $1.9 million, and $698,000, respectively, related to non-designated hedges that were reported as a component of interest expense in our consolidated financial statements. The following tables summarize our non-designated hedges (notional amount in thousands): December 31, 2017 Non-designated Hedges Number of Notional Buy GBP / Sell EUR Forward 1 € 12,857 December 31, 2016 Non-designated Hedges Number of Notional Amount Interest Rate Caps 3 $ 256,875 Interest Rate Caps 2 C$ 37,221 Buy GBP / Sell EUR Forward 1 € 12,857 Valuation of Derivative Instruments The following table summarizes the fair value of our derivative financial instruments ($ in thousands): Fair Value of Derivatives in an Asset (1) Fair Value of Derivatives in a Liability (2) December 31, 2017 December 31, 2016 December 31, 2017 December 31, 2016 Derivatives designated as Foreign exchange contracts $ — $ 3,268 $ 4,872 $ 210 Interest rate derivatives 1,214 331 — — Total $ 1,214 $ 3,599 $ 4,872 $ 210 Derivatives not designated as hedging instruments: Foreign exchange contracts $ — $ 487 $ 39 $ — Interest rate derivatives — — — — Total $ — $ 487 $ 39 $ — Total Derivatives $ 1,214 $ 4,086 $ 4,911 $ 210 (1) Included in other assets in our consolidated balance sheets. (2) Included in other liabilities in our consolidated balance sheets. The following table presents the effect of our derivative financial instruments on our consolidated statements of operations ($ in thousands): Derivatives in Hedging Relationships Amount of (Loss) Location of Amount of Year Ended December 31, Accumulated Year Ended December 31, 2017 2016 2015 OCI into Income 2017 2016 2015 Net Investment Hedges Foreign exchange contracts (1) $ (22,216 ) $ 25,355 $ 25,356 Interest Expense $ — $ — $ — Cash Flow Hedges Interest rate derivatives 757 89 (1,474 ) Interest Expense (2) (831 ) (798 ) (4 ) Total $ (21,459 ) $ 25,444 $ 23,882 $ (831 ) $ (798 ) $ (4 ) (1) During the year ended December 31, 2017, we paid net cash settlements of $14.2 million on our foreign currency forward contracts. During the years ended December 31, 2016 and 2015, we received net cash settlements of $26.8 million and $18.8 million, respectively, on our foreign currency forward contracts. Those amounts are included as a component of accumulated other comprehensive loss on our consolidated balance sheets. (2) During the years ended December 31, 2017, 2016, and 2015, we recorded total interest and related expenses of $234.9 million, $184.3 million, and 152.4 million, respectively, which included interest expense of $831,000, $798,000, and $4,000, respectively, related to our cash flow hedges. Credit-Risk Related Contingent Features We have entered into agreements with certain of our derivative counterparties that contain provisions where if we were to default on any of our indebtedness, including default where repayment of the indebtedness has not been accelerated by the lender, we may also be declared in default on our derivative obligations. In addition, certain of our agreements with our derivative counterparties require that we post collateral to secure net liability positions. As of December 31, 2017, we were in a net asset position with one of our derivative counterparties and in a net liability position with our other derivative counterparty, and posted collateral of $4.1 million under these derivative contracts. As of December 31, 2016, we were in a net asset position with each such derivative counterparty and posted collateral of $79,000 under these derivative contracts.

Equity

Equity	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Equity	11. EQUITY Stock and Stock Equivalents Authorized Capital As of December 31, 2017, we had the authority to issue up to 300,000,000 shares of stock, consisting of 200,000,000 shares of class A common stock and 100,000,000 shares of preferred stock. Subject to applicable NYSE listing requirements, our board of directors is authorized to cause us to issue additional shares of authorized stock without stockholder approval. In addition, to the extent not issued, currently authorized stock may be reclassified between class A common stock and preferred stock. We did not have any shares of preferred stock issued and outstanding as of December 31, 2017. Class A Common Stock and Deferred Stock Units Holders of shares of our class A common stock are entitled to vote on all matters submitted to a vote of stockholders and are entitled to receive such dividends as may be authorized by our board of directors and declared by us, in all cases subject to the rights of the holders of shares of outstanding preferred stock, if any. The following table details our issuance of class A common stock during the years ended December 31, 2017, 2016 and 2015 ($ in thousands, except share and per share data): Class A Common Stock Offerings 2017 2016 2015 (1) Shares issued 12,420,000 — 34,780,025 Share issue price (2) $ 31.57 $ — $ 29.64 Net proceeds (3) $ 391,558 $ — $ 1,029,535 (1) Consists of 23.0 million shares issued in April 2015, 11.5 million shares issued in June 2015, and 280,025 shares issued over a five-day period in May 2015 under our at-the-market program. Share issue price reflects the weighted-average of such stock offerings. (2) Represents price per share paid by the underwriters or sales agents, as applicable. (3) Net proceeds represents proceeds received from the underwriters less applicable transaction costs. We also issue restricted class A common stock under our stock-based incentive plans. Refer to Note 14 for additional discussion of these long-term incentive plans. In addition to our class A common stock, we also issue deferred stock units to certain members of our board of directors in lieu of cash compensation for services rendered. These deferred stock units are non-voting, but carry the right to receive dividends in the form of additional deferred stock units in an amount equivalent to the cash dividends paid to holders of shares of class A common stock. The following table details the movement in our outstanding shares of class A common stock, including restricted class A common stock and deferred stock units: Year Ended December 31, Common Stock Outstanding (1) 2017 2016 2015 Beginning balance 94,709,290 93,843,847 58,388,808 Issuance of class A common stock (2) 12,421,401 1,070 34,780,622 Issuance of restricted class A common stock, net 922,196 836,867 651,815 Issuance of deferred stock units 28,190 27,506 22,602 Ending balance 108,081,077 94,709,290 93,843,847 (1) Includes deferred stock units held by members of our board of directors of 197,217, 169,027, and 141,521, as of December 31, 2017, 2016, and 2015, respectively. (2) Includes 1,401, 1,070, and 597 shares issued under our dividend reinvestment program during the years ended December 31, 2017, 2016, and 2015, respectively. Dividend Reinvestment and Direct Stock Purchase Plan On March 25, 2014, we adopted a dividend reinvestment and direct stock purchase plan, under which we registered and reserved for issuance, in the aggregate, 10,000,000 shares of class A common stock. Under the dividend reinvestment component of this plan, our class A common stockholders can designate all or a portion of their cash dividends to be reinvested in additional shares of class A common stock. The direct stock purchase component allows stockholders and new investors, subject to our approval, to purchase shares of class A common stock directly from us. During the years ended December 31, 2017, 2016, and 2015 we issued 1,401 shares, 1,070 shares, and 597 shares, respectively, of class A common stock under the dividend reinvestment component of the plan. As of December 31, 2017, a total of 9,996,926 shares of class A common stock remained available for issuance under the dividend reinvestment and direct stock purchase plan. At the Market Stock Offering Program On May 9, 2014, we entered into equity distribution agreements, or ATM Agreements, pursuant to which we may sell, from time to time, up to an aggregate sales price of $200.0 million of our class A common stock. On July 29, 2016, in connection with filing a new universal shelf registration statement on Form S-3, we entered into amendments to each of the ATM Agreements. Sales of class A common stock made pursuant to the ATM Agreements may be made in negotiated transactions or transactions that are deemed to be “at the market” offerings as defined in Rule 415 under the Securities Act of 1933, as amended. Actual sales will depend on a variety of factors including market conditions, the trading price of our class A common stock, our capital needs, and our determination of the appropriate sources of funding to meet such needs. We did not sell any shares of our class A common stock under the ATM Agreements during the years ended December 31, 2017 and 2016. As of December 31, 2017, sales of our class A common stock with an aggregate sales price of $188.6 million remained available for issuance under the ATM Agreements. Dividends We generally intend to distribute substantially all of our taxable income, which does not necessarily equal net income as calculated in accordance with GAAP, to our stockholders each year to comply with the REIT provisions of the Internal Revenue Code. Our dividend policy remains subject to revision at the discretion of our board of directors. All distributions will be made at the discretion of our board of directors and will depend upon our taxable income, our financial condition, our maintenance of REIT status, applicable law, and other factors as our board of directors deems relevant. On December 14, 2017, we declared a dividend of $0.62 per share, or $66.9 million, that was paid on January 16, 2018, to stockholders of record as of December 29, 2017. The following table details our dividend activity ($ in thousands, except per share data): Year Ended December 31, 2017 2016 2015 Dividends declared per share of common stock $ 2.48 $ 2.48 $ 2.28 Percent taxable as ordinary dividends 97.20 % 92.77 % 92.36 % Percent taxable as capital gain dividends 2.80 % 7.23 % 7.64 % 100.0 % 100.0 % 100.0 % Earnings Per Share We calculate our basic and diluted earnings per share using the two-class method for all periods presented, as the unvested shares of our restricted class A common stock qualify as participating securities, as defined by GAAP. These restricted shares have the same rights as our other shares of class A common stock, including participating in any dividends, and therefore have been included in our basic and diluted net income per share calculation. Our Convertible Notes are excluded from dilutive earnings per share as we have the intent and ability to settle these instruments in cash. The following table sets forth the calculation of basic and diluted net income per share of class A common stock based on the weighted-average of both restricted and unrestricted class A common stock outstanding ($ in thousands, except per share data): Year Ended December 31, 2017 2016 2015 Net income (1) $ 217,631 $ 238,297 $ 196,829 Weighted-average shares outstanding, basic and diluted 95,963,616 94,165,351 81,740,227 Per share amount, basic and diluted $ 2.27 $ 2.53 $ 2.41 (1) Represents net income attributable to Blackstone Mortgage Trust, Inc. Other Balance Sheet Items Accumulated Other Comprehensive Loss As of December 31, 2017, total accumulated other comprehensive loss was $29.7 million, primarily representing (i) $60.3 million of cumulative unrealized currency translation adjustments on assets and liabilities denominated in foreign currencies and (ii) an offsetting $30.6 million of net realized and unrealized gains related to changes in the fair value of derivative instruments. As of December 31, 2016, total accumulated other comprehensive loss was $56.2 million, primarily representing (i) $107.5 million of cumulative unrealized currency translation adjustments on assets and liabilities denominated in foreign currencies and (ii) an offsetting $51.3 million of net realized and unrealized gains related to changes in the fair value of derivative instruments. Non-Controlling Interests The non-controlling interests included on our consolidated balance sheets represent the equity interests in our Multifamily Joint Venture that are not owned by us. A portion of our Multifamily Joint Venture’s consolidated equity and results of operations are allocated to these non-controlling interests based on their pro rata ownership of our Multifamily Joint Venture. As of December 31, 2017, our Multifamily Joint Venture’s total equity was $42.3 million, of which $36.0 million was owned by us, and $6.3 million was allocated to non-controlling interests. As of December 31, 2016, we did not have any non-controlling interests on our consolidated financial statements.

Other Expenses

Other Expenses	12 Months Ended
	Dec. 31, 2017
Other Income and Expenses [Abstract]
Other Expenses	12. OTHER EXPENSES Our other expenses consist of the management and incentive fees we pay to our Manager and our general and administrative expenses. Management and Incentive Fees Pursuant to our Management Agreement, our Manager earns a base management fee in an amount equal to 1.50% per annum multiplied by our outstanding equity balance, as defined in the Management Agreement. In addition, our Manager is entitled to an incentive fee in an amount equal to the product of (i) 20% and (ii) the excess of (a) our Core Earnings (as defined in our Management Agreement) for the previous 12-month period over (b) an amount equal to 7.00% per annum multiplied by our outstanding Equity, provided that our Core Earnings over the prior three-year period is greater than zero. Core Earnings, as defined in our Management Agreement, is generally equal to our net income (loss) prepared in accordance with GAAP, excluding (i) certain non-cash items (ii) the net income (loss) related to our legacy portfolio and (iii) incentive management fees. During the years ended December 31, 2017, 2016, and 2015, we incurred $38.6 million, $38.0 million, and $32.2 million, respectively, of management fees payable to our Manager. In addition, during the years ended December 31, 2017, 2016, and 2015, we incurred $16.2 million, $18.0 million, and $10.7 million, respectively, of incentive fees payable to our Manager. As of December 31, 2017 and 2016, we had accrued management and incentive fees payable to our Manager of $14.3 million and $12.8 million, respectively. General and Administrative Expenses General and administrative expenses consisted of the following ($ in thousands): Year Ended December 31, 2017 2016 2015 Professional services (1) $ 3,812 $ 3,311 $ 3,156 Operating and other costs (1) 1,903 2,147 2,709 GE transaction costs — — 9,623 Subtotal 5,715 5,458 15,488 Non-cash and CT Legacy Portfolio compensation expenses Management incentive awards plan - CTOPI (2) — 1,568 5,370 Management incentive awards plan - CT Legacy Partners (3) — 1,094 2,177 Restricted class A common stock earned 23,593 19,052 12,966 Director stock-based compensation 438 375 375 Subtotal 24,031 22,089 20,888 Total BXMT expenses 29,746 27,547 36,376 Other expenses 176 169 333 Total general and administrative expenses $ 29,922 $ 27,716 $ 36,709 (1) During the year ended December 31, 2017, we recognized an aggregate $232,000 of expenses related to our Multifamily Joint Venture. (2) Represents the portion of CTOPI promote revenue recorded under compensation awards. See Note 4 for further discussion. (3) Represents the amounts recorded under the CT Legacy Partners management incentive awards during the period. See below for discussion of the CT Legacy Partners management incentive awards plan. CT Legacy Partners Management Incentive Awards Plan In conjunction with our March 2011 restructuring, we created an employee pool for up to 6.75% of the distributions paid to the common equity holders of our subsidiary, CT Legacy Partners (subject to certain caps and priority distributions). During the years ended December 31, 2016 and 2015, we recognized $1.1 million and $2.2 million, respectively, of expenses under the CT Legacy Partners incentive plan. Our investment in CT Legacy Partners was substantially realized as of December 31, 2016.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	13. INCOME TAXES We elected to be taxed as a REIT, effective January 1, 2003, 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, 2017 and 2016, we were in compliance with all REIT requirements. During the years ended December 31, 2017, 2016, and 2015, we recorded a current income tax provision of $314,000, $196,000, and $504,000, 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, 2017 or 2016. Effective January 1, 2018, under recent 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, 2017, 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, 2017, tax years 2014 through 2017 remain subject to examination by taxing authorities.

Stock-Based Incentive Plans

Stock-Based Incentive Plans	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Incentive Plans	14. STOCK-BASED INCENTIVE PLANS We are externally managed by our Manager and do not currently have any employees. However, as of December 31, 2017, our Manager, certain individuals employed by an affiliate of our Manager, and certain members of our board of directors were compensated, in part, through the issuance of stock-based instruments. We had stock-based incentive awards outstanding under seven benefit plans as of December 31, 2017: (i) our amended and restated 1997 non-employee director stock plan, or 1997 Plan; (ii) our 2007 long-term incentive plan, or 2007 Plan; (iii) our 2011 long-term incentive plan, or 2011 Plan; (iv) our 2013 stock incentive plan, or 2013 Plan; (v) our 2013 manager incentive plan, or 2013 Manager Plan; (vi) our 2016 stock incentive plan, or 2016 Plan; and (vii) our 2016 manager incentive plan, or 2016 Manager Plan. We refer to our 1997 Plan, our 2007 Plan, our 2011 Plan, our 2013 Plan, and our 2013 Manager Plan, collectively, as our Expired Plans and we refer to our 2016 Plan and 2016 Manager Plan, collectively, as our Current Plans. Our Expired Plans have expired and no new awards may be issued under them. Under our Current Plans, a maximum of 2,400,000 shares of our class A common stock may be issued to our Manager, our directors and officers, and certain employees of affiliates of our Manager. As of December 31, 2017, there were 805,799 shares available under the Current Plans. The following table details the movement in our outstanding shares of restricted class A common stock and the weighted-average grant date fair value per share: Restricted Class A Weighted-Average Balance as of December 31, 2015 1,114,908 $ 27.64 Granted 872,294 28.88 Vested (641,780 ) 27.21 Forfeited (35,427 ) 27.49 Balance as of December 31, 2016 1,309,995 $ 28.68 Granted 925,319 31.78 Vested (748,016 ) 28.69 Forfeited (3,123 ) 27.37 Balance as of December 31, 2017 1,484,175 $ 30.61 These shares generally vest in installments over a three-year period, pursuant to the terms of the respective award agreements and the terms of the Current Plans. The 1,484,175 shares of restricted class A common stock outstanding as of December 31, 2017 will vest as follows: 754,597 shares will vest in 2018; 517,026 shares will vest in 2019; and 212,552 shares will vest in 2020. As of December 31, 2017, total unrecognized compensation cost relating to nonvested share-based compensation arrangements was $45.6 million based on the closing price of our class A common stock of $32.18 on December 29, 2017, the last trading day in the quarter ended December 31, 2017. This cost is expected to be recognized over a weighted average period of 1.2 years from December 31, 2017.

Fair Values

Fair Values	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Values	15. FAIR VALUES Assets and Liabilities Measured at Fair Value The following table summarizes our assets and liabilities measured at fair value on a recurring basis ($ in thousands): December 31, 2017 December 31, 2016 Level 1 Level 2 Level 3 Fair Value Level 1 Level 2 Level 3 Fair Value Assets Derivatives $ — $ 1,214 $ — $ 1,214 $ — $ 4,086 $ — $ 4,086 Liabilities Derivatives $ — $ 4,911 $ — $ 4,911 $ — $ 210 $ — $ 210 The following table reconciles the beginning and ending balances of assets measured at fair value on a recurring basis using Level 3 inputs ($ in thousands): Year Ended December 31, 2017 2016 (1) January 1, $ — $ 12,561 Proceeds from investment realizations — (3,609 ) Transfers out of level 3 (2) — (20,745 ) Adjustments to fair value included in earnings Gain on investments at fair value — 11,793 December 31, $ — $ — (1) All assets measured at fair value on a recurring basis using Level 3 inputs were included as a component of other assets in the consolidated Balance Sheets. (2) During the second quarter of 2016, $20.7 million of collateralized debt obligations, or CDOs, were transferred out of Level 3 and into Level 1 as a result of a binding agreement to sell the underlying collateral assets of the CDO to an independent third-party. These investments were realized in the third quarter of 2016. Refer to Note 2 for further discussion regarding fair value measurement. Fair Value of Financial Instruments As discussed in Note 2, GAAP requires disclosure of fair value information about financial instruments, whether or not recognized in the statement of financial position, for which it is practicable to estimate that value. The following table details the carrying amount, face amount, and fair value of the financial instruments described in Note 2 ($ in thousands): December 31, 2017 December 31, 2016 Carrying Face Amount Fair Value Carrying Face Fair Value Financial assets Cash and cash equivalents $ 69,654 $ 69,654 $ 69,654 $ 75,567 $ 75,567 $ 75,567 Restricted cash 32,864 32,864 32,864 — — — Loans receivable, net 10,056,732 10,108,226 10,112,331 8,692,978 8,727,218 8,733,784 Financial liabilities Secured debt agreements, net 5,273,855 5,290,536 5,290,536 5,716,354 5,731,626 5,731,626 Loan participations sold, net 80,415 80,706 80,706 348,077 349,633 349,633 Securitized debt obligations, net 1,282,412 1,292,120 1,292,589 — — — Convertible notes, net 563,911 575,000 610,201 166,762 172,500 191,763 Estimates of fair value for cash and cash equivalents, restricted cash, and convertible notes are measured using observable, quoted market prices, or Level 1 inputs. Estimates of fair value for securitized debt obligations are measured using observable, quoted market prices, in inactive markets, or Level 2 inputs. All other fair value significant estimates are measured using unobservable inputs, or Level 3 inputs. See Note 2 for further discussion regarding fair value measurement of certain of our assets and liabilities.

Variable Interest Entities

Variable Interest Entities	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Variable Interest Entities	16. VARIABLE INTEREST ENTITIES We have financed a portion of our loans through the CLO and the Single Asset Securitization, both of which are VIEs. We are the primary beneficiary and consolidate the CLO and the Single Asset Securitization on our balance sheet as we (i) control the relevant interests of the CLO and the Single Asset Securitization that give us power to direct the activities that most significantly affect the CLO and the Single Asset Securitization, and (ii) have the right to receive benefits and obligation to absorb losses of the CLO and the Single Asset Securitization through the subordinate interests we own. The following table details the assets and liabilities of our consolidated CLO and Single Asset Securitization VIEs ($ in thousands): December 31, 2017 December 31, 2016 Assets: Loans receivable, net $ 1,500,000 $ — Other assets 2,407 — Total assets $ 1,502,407 $ — Liabilities: Securitized debt obligations, net $ 1,282,412 $ — Other liabilities 1,379 — Total liabilities $ 1,283,791 $ — Assets held by these VIEs are restricted and can be used only to settle obligations of these VIEs, including the subordinate interests owned by us. The liabilities of these VIEs are non-recourse to us and can only be satisfied from the assets of these VIEs. The consolidation of these VIEs results in an increase in our gross assets, liabilities, interest income and interest expense, however it does not affect our stockholders’ equity or net income. We are not obligated to provide, have not provided, and do not intend to provide financial support to these VIEs.

Transactions with Related Parti

Transactions with Related Parties	12 Months Ended
	Dec. 31, 2017
Related Party Transactions [Abstract]
Transactions with Related Parties	17. TRANSACTIONS WITH RELATED PARTIES We are managed by our Manager pursuant to the Management Agreement, the current term of which expires on December 19, 2018, and will be automatically renewed for a one-year term each anniversary thereafter unless earlier terminated. As of December 31, 2017 and 2016, our consolidated balance sheet included $14.3 million and $12.8 million of accrued management and incentive fees payable to our Manager, respectively. During the years ended December 31, 2017, 2016, and 2015, we paid management and incentive fees of $53.4 million, $57.5 million and $34.8 million, respectively, to our Manager. In addition, during the years ended December 31, 2017, 2016, and 2015, we reimbursed our Manager for expenses incurred on our behalf of $621,000, $462,000, and $311,000, respectively. During the years ended December 31, 2016 and 2015, CT Legacy Partners made aggregate preferred distributions of $616,000 and $1.3 million, respectively, to an affiliate of our Manager. CT Legacy Partners did not make any preferred distributions during the year ended December 31, 2017. As of December 31, 2017, our Manager held 869,058 shares of unvested restricted class A common stock, which had an aggregate grant date fair value of $26.9 million, and vest in installments over three years from the date of issuance. During the years ended December 31, 2017, 2016, and 2015, we recorded non-cash expenses related to shares held by our Manager of $11.7 million, $9.6 million, and $6.7 million, respectively. Refer to Note 14 for further details on our restricted class A common stock. During the year ended December 31, 2017, an affiliate of our Manager was named special servicer of the CLO. This affiliate did not earn any special servicing fees related to the CLO during the year ended December 31, 2017. During the year ended December 31, 2017 and 2016, we originated six loans and three loans, respectively, whereby each respective borrower engaged an affiliate of our Manager to act as title insurance agent in connection with each transaction. We did not incur any expenses or receive any revenues as a result of these transactions. On June 30, 2017, in a fully subscribed offering totaling $474.6 million, certain Blackstone-advised investment vehicles purchased, in the aggregate, $72.9 million of securitized debt obligations issued by the Single Asset Securitization. These investments by the Blackstone-advised investment vehicles represented no more than a 49% participation in any individual tranche and were purchased by the Blackstone-advised investment vehicles from third-party investment banks on market terms negotiated by the majority third-party investors. Refer to Note 8 for further details on the Single Asset Securitization. In the fourth quarter of 2016, we originated a $79.0 million senior loan to a borrower to finance its purchase of a property that it acquired from an affiliate of our Manager. The purchase price of the property was fixed between the borrower and the affiliate of our Manager prior to us engaging in discussions with the borrower to act as its potential lender. On May 8, 2015, a joint venture of CT Legacy Partners, certain affiliates of our Manager, and other non-affiliated parties, which we refer to as the Three-Pack JV, sold a hotel portfolio it owned to an investment vehicle managed by an affiliate of our Manager. We consented to the sale of the hotel portfolio by the Three-Pack JV, which resulted in the ultimate liquidation of the Three-Pack JV and distribution of net sale proceeds to CT Legacy Partners in respect of its investment therein. An aggregate of $41.3 million of net sales proceeds was paid to CT Legacy Partners, of which $37.3 million was received during 2015, and the remaining $3.6 million was received during 2016. As a result of the sale transaction, employees of our Manager, including certain of our executive officers, received incentive compensation payments totaling $2.8 million under the CT Legacy Partners Management Incentive Awards Plan, of which $2.5 million was paid during 2015, and the remaining $244,000 was paid during 2016. See Note 12 for further discussion of the CT Legacy Partners Management Incentive Awards Plan. In conjunction with our April 2015 stock offering, affiliates of our Manager, including certain of our executive officers and directors, purchased 1,885,245 shares of our class A common stock at the same $30.50 per share price offered to the public. We did not, however, pay the underwriters any fees for these affiliate share purchases. An affiliate of our Manager acted as co-manager of the offering, for which it was compensated $761,000 on terms consistent with those for other non-affiliated underwriters. During the years ended December 31, 2017, 2016, and 2015, we incurred $411,000, $385,000, and $372,000, respectively, of expenses for various administrative, compliance, and capital market data services to third-party service providers that are affiliates of our Manager. On April 10, 2015, we entered into a memorandum of designation and understanding, or Designation Agreement, with GE and certain affiliates of our Manager to acquire a $4.6 billion portfolio of commercial mortgage loans from GE. Pursuant to the terms of the Designation Agreement, we were designated as the purchaser of this loan portfolio by an affiliate of our Manager that entered into a purchase and sale agreement dated as of April 10, 2015 with GE to acquire the majority of GE’s global real estate debt and equity business for an aggregate purchase price of approximately $23.0 billion. Certain transaction-related expenses incurred by us in connection with the acquisition of this loan portfolio represent an allocation of transaction expenses paid by affiliates of our Manager in connection with the overall acquisition transaction with GE. In August 2015, we paid an aggregate $53,000 to certain independent members of our board of directors for special committee services related to the GE portfolio acquisition. On June 20, 2014, CT Legacy Partners, CTOPI, our previously consolidated CT CDO I subsidiary, and other affiliates of our Manager entered into a deed-in-lieu of foreclosure transaction that resulted in a restructuring of the loan interests held by each entity. The interests held by CT Legacy Partners and CT CDO I had a principal balance of $8.0 million and $27.0 million, respectively, and a carrying value of zero and $27.0 million, respectively, at the time of the transaction. During the fourth quarter of 2015, the collateral property securing the interests held by these entities was sold, with no net proceeds to our investments in CT Legacy Partners and CT CDO I. As a result of the collateral sale transaction, an affiliate of our Manager earned a $1.1 million special servicing fee, which fee was not paid by us.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	18. COMMITMENTS AND CONTINGENCIES Unfunded Commitments Under Loans Receivable As of December 31, 2017, we had unfunded commitments of $1.6 billion related to 74 of our loans receivable, which amounts will generally be funded to finance lease-related or capital expenditures by our borrowers. These future commitments will expire variously over the next four years. Litigation From time to time, we may be involved in various claims and legal actions arising in the ordinary course of business. As of December 31, 2017, we were not involved in any material legal proceedings. Board of Directors’ Compensation In April 2017, our board of directors approved changes to the compensation of our five independent directors which were effective as of the beginning of the third quarter of 2017. The other three board members, including our chairman and our chief executive officer, will continue to serve as directors without compensation for such service. These changes increased the annual compensation of our independent directors from $125,000 to $175,000, $75,000 of which will be paid in the form of cash and $100,000 in the form of deferred stock units. In addition, (i) the chair of our audit committee received an increase in the additional annual cash compensation from $12,000 to $20,000, (ii) the other members of our audit committee received additional annual cash compensation of $10,000, and (iii) the chairs of each of our compensation and corporate governance committees received additional annual cash compensation of $10,000.

Summary of Quarterly Results of

Summary of Quarterly Results of Operations	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Summary of Quarterly Results of Operations	19. SUMMARY OF QUARTERLY RESULTS OF OPERATIONS (UNAUDITED) The following is a summary of the unaudited quarterly results of operations for the years ended December 31, 2017 and 2016 ($ in thousands except per share data): March 31 June 30 September 30 December 31 2017 Income from loans and other investments, net $ 71,843 $ 72,473 $ 78,555 $ 80,174 Net income $ 51,405 $ 50,613 $ 57,810 $ 58,140 Net income attributable to Blackstone Mortgage Trust, Inc. $ 51,405 $ 50,613 $ 57,722 $ 57,891 Net income per share of class A common stock: Basic and diluted $ 0.54 $ 0.53 $ 0.61 $ 0.59 2016 Income from loans and other investments, net $ 77,644 $ 81,406 $ 82,817 $ 71,837 Net income $ 57,199 $ 69,450 $ 66,392 $ 53,399 Net income attributable to Blackstone Mortgage Trust, Inc. $ 57,047 $ 63,081 $ 64,794 $ 53,375 Net income per share of class A common stock: Basic and diluted $ 0.61 $ 0.67 $ 0.69 $ 0.57 Basic and diluted earnings per share are computed independently based on the weighted-average shares of common stock and stock units outstanding for each period. Accordingly, the sum of the quarterly earnings per share amounts may not agree to the total for the year.

Schedule IV - Mortgage Loans on

Schedule IV - Mortgage Loans on Real Estate	12 Months Ended
	Dec. 31, 2017
Mortgage Loans on Real Estate [Abstract]
Schedule IV - Mortgage Loans on Real Estate	Schedule IV – Mortgage Loans on Real Estate As of December 31, 2017 (in thousands) Type of Loan/Borrower Description / Location Interest Payment Rates Maximum (2) Periodic (3) Prior (4) Face Amount Carrying (5) Senior Mortgage Loans (1) Senior loans in excess of 3% of the carrying amount of total loans Borrower A Office / Southeast L+3.40% 2023 I/O $ — $ 656,406 $ 652,880 Senior loans less than 3% of the carrying amount of total loans Senior mortgage loans Office / Diversified L+3.00% – 5.75% 2018 – 2023 I/O & P/I — 5,357,888 5,327,333 Fixed 2.30 % – 5.29% Senior mortgage loans Hotel / Diversified L+3.25% – 5.16% 2018 – 2022 I/O & P/I — 1,843,143 1,837,222 Senior mortgage loans Multifamily / Diversified L+2.80% – 5.25% 2018 – 2023 I/O & P/I — 1,122,532 1,114,353 Senior mortgage loans Retail / Diversified L+3.10% – 4.25% 2019 – 2021 I/O & P/I — 319,223 318,789 Fixed 5.14% Senior mortgage loans Condo / Northeast L+4.15% 2021 I/O — 66,451 65,775 Senior mortgage loans Other / Diversified L+3.10% – 5.00% 2018 – 2022 I/O & P/I — 527,962 526,736 Fixed 4.63% – 5.20% — 9,237,199 9,190,208 Total senior mortgage loans $ — $ 9,893,605 $ 9,843,088 Subordinate Loans (6) Subordinate loans less than 3% of the carrying amount of total loans Subordinate loans Various / Diversified L+10.75% - 12.83% 2020 - 2022 I/O & P/I 985,382 214,621 213,644 Fixed 12.22% Total subordinate loans 985,382 214,621 213,644 Total loans $ 985,382 $ 10,108,226 $ 10,056,732 (1) Includes senior mortgages and similar credit quality loans, including related contiguous subordinate loans, and pari passu participations in senior mortgage loans. (2) Maximum maturity date assumes all extension options are exercised. (3) I/O = interest only, P/I = principal and interest. (4) Represents only third party liens. (5) The tax basis of the loans included above is $9.5 billion as of December 31, 2017. (6) Includes subordinate interests in mortgages and mezzanine loans. Blackstone Mortgage Trust, Inc. Notes to Schedule IV As of December 31, 2017 (in thousands) 1. Reconciliation of Mortgage Loans on Real Estate: The following table reconciles mortgage loans on real estate for the years ended: 2017 2016 2015 Balance at January 1, $ 8,692,978 $ 9,077,007 $ 4,428,500 Additions during period: Loan fundings 4,072,786 3,151,882 7,203,145 Amortization of deferred fees and expenses 38,373 40,345 36,052 Deductions during period: Collections of principal (2,828,610 ) (3,351,042 ) (2,407,920 ) Unrealized gain (loss) on foreign currency translation 136,646 (156,937 ) (149,269 ) Deferred origination fees and expenses (55,441 ) (44,697 ) (33,501 ) Loans sold — (23,580 ) — Balance at December 31, $ 10,056,732 $ 8,692,978 $ 9,077,007

Summary of Significant Accoun28

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America, or GAAP, and include, on a consolidated basis, our accounts, the accounts of our wholly-owned subsidiaries, majority-owned subsidiaries, and variable interest entities, or VIEs, of which we are the primary beneficiary. All intercompany balances and transactions have been eliminated in consolidation.
Principles of Consolidation	Principles of Consolidation We consolidate all entities that we control through either majority ownership or voting rights. In addition, we consolidate all VIEs of which we are considered the primary beneficiary. VIEs are defined as entities in which equity investors (i) do not have the characteristics of a controlling financial interest and/or (ii) do not have sufficient equity at risk for the entity to finance its activities without additional subordinated financial support from other parties. The entity that consolidates a VIE is known as its primary beneficiary and is generally the entity with (i) the power to direct the activities that most significantly affect the VIE’s economic performance and (ii) the right to receive benefits from the VIE or the obligation to absorb losses of the VIE that could be significant to the VIE. Refer to Note 16 for additional discussion of our consolidated VIE. In April 2017, we entered into a joint venture, or our Multifamily Joint Venture, with Walker & Dunlop Inc. to originate, hold, and finance multifamily bridge loans. Pursuant to the terms of the agreements governing the joint venture, Walker & Dunlop contributed 15% of the venture’s equity capital and we contributed 85%. We consolidate the Multifamily Joint Venture as we have a controlling financial interest. The non-controlling interests included on our consolidated balance sheets represent the equity interests in our Multifamily Joint Venture that are owned by Walker & Dunlop. A portion of our Multifamily Joint Venture’s consolidated equity and results of operations are allocated to these non-controlling interests based on Walker & Dunlop’s pro rata ownership of our Multifamily Joint Venture.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results may ultimately differ from those estimates.
Revenue Recognition	Revenue Recognition Interest income from our loans receivable portfolio is recognized over the life of each investment using the effective interest method and is recorded on the accrual basis. Recognition of fees, premiums, and discounts associated with these investments is deferred until the loan is advanced and is then recorded over the term of the loan as an adjustment to yield. Income accrual is generally suspended for loans at the earlier of the date at which payments become 90 days past due or when, in the opinion of our Manager, recovery of income and principal becomes doubtful. Income is then recorded on the basis of cash received until accrual is resumed when the loan becomes contractually current and performance is demonstrated to be resumed. In addition, for loans we originate, the related origination expenses are deferred and recognized as a component of interest income, however expenses related to loans we acquire are included in general and administrative expenses as incurred.
Cash, Cash Equivalents, and Restricted Cash	Cash, Cash Equivalents, and Restricted Cash Cash and cash equivalents represent cash held in banks, cash on hand, and liquid investments with original maturities of three months or less. We may have bank balances in excess of federally insured amounts; however, we deposit our cash and cash equivalents with high credit-quality institutions to minimize credit risk exposure. We have not experienced, and do not expect, any losses on our cash or cash equivalents. Restricted cash represents cash held in a segregated bank account related to a letter of credit. The following table provides a reconciliation of cash, cash equivalents, and restricted cash in our consolidated balance sheets to the total amount shown in our consolidated statements of cash flows ($ in thousands): December 31, December 31, Cash and cash equivalents $ 69,654 $ 75,567 Restricted cash 32,864 — Total cash, cash equivalents, and restricted cash shown in our consolidated statements of cash flows $ 102,518 $ 75,567
Loans Receivable and Provision for Loan Losses	Loans Receivable and Provision for Loan Losses We originate and purchase commercial real estate debt and related instruments generally to be held as long-term investments at amortized cost. We are required to periodically evaluate each of these loans for possible impairment. Impairment is indicated when it is deemed probable that we will not be able to collect all amounts due to us pursuant to the contractual terms of the loan. If a loan is determined to be impaired, we write down the loan through a charge to the provision for loan losses. Impairment of these loans, which are collateral dependent, is measured by comparing the estimated fair value of the underlying collateral, less costs to sell, to the book value of the respective loan. These valuations require significant judgments, which include assumptions regarding capitalization rates, leasing, creditworthiness of major tenants, occupancy rates, availability of financing, exit plan, loan sponsorship, actions of other lenders, and other factors deemed necessary by our Manager. Actual losses, if any, could ultimately differ from these estimates. Our Manager performs a quarterly review of our portfolio of loans. In conjunction with this review, our Manager assesses the risk factors of each loan, and assigns a risk rating based on a variety of factors, including, without limitation, loan-to-value ratio, or LTV, debt yield, property type, geographic and local market dynamics, physical condition, cash flow volatility, leasing and tenant profile, loan structure and exit plan, and project sponsorship. Based on a 5-point scale, our loans are rated “1” through “5,” from less risk to greater risk, which ratings are defined as follows: 1 – Very Low Risk 2 – Low Risk 3 – Medium Risk 4 – High Risk/Potential for Loss: 5 – Impaired/Loss Likely: During the second quarter of 2015, we acquired a portfolio of loans from General Electric Capital Corporation and certain of its affiliates, or the GE portfolio, for a total purchase price of $4.7 billion. We allocated the aggregate purchase price between each loan based on its fair value relative to the overall portfolio, which allocation resulted in purchase discounts or premiums determined on an asset-by-asset basis. Each loan accretes from its allocated purchase price to its expected collection value over the life of the loan, consistent with the other loans in our portfolio.
Equity Investment in Unconsolidated Subsidiary	Equity Investment in Unconsolidated Subsidiary Our carried interest in CT Opportunity Partners I, LP, or CTOPI, was accounted for using the equity method. CTOPI’s assets and liabilities were not consolidated into our financial statements due to our determination that (i) it was not a VIE and (ii) the other investors in CTOPI had sufficient rights to preclude consolidation by us. As such, we reported our allocable percentage of the net assets of CTOPI on our consolidated balance sheets. The investment was fully realized as of December 31, 2016 and we no longer have any equity investments in unconsolidated subsidiaries in our consolidated financial statements.
Derivative Financial Instruments	Derivative Financial Instruments We classify all derivative financial instruments as either other assets or other liabilities on our consolidated balance sheets at fair value. On the date we enter into a derivative contract, we designate each contract as (i) a hedge of a net investment in a foreign operation, or net investment hedge, (ii) a hedge of a forecasted transaction or of the variability of cash flows to be received or paid related to a recognized asset or liability, or cash flow hedge, (iii) a hedge of a recognized asset or liability, or fair value hedge, or (iv) a derivative instrument not to be designated as a hedging derivative, or non-designated non-designated On a quarterly basis, we also formally assess whether the derivative we designated in each hedging relationship is expected to be, and has been, highly effective in offsetting changes in the value or cash flows of the hedged items. If it is determined that a derivative is not highly effective at hedging the designated exposure, hedge accounting is discontinued and the changes in fair value of the instrument are included in net income prospectively. Changes in the fair value of our derivative instruments that qualify as hedges are reported as a component of accumulated other comprehensive income (loss) on our consolidated financial statements. Deferred gains and losses are reclassified out of accumulated other comprehensive income (loss) and into net income in the same period or periods during which the hedged transaction affects earnings, and are presented in the same line item as the earnings effect of the hedged item. For cash flow hedges, this is typically when the periodic swap settlements are made, while for net investment hedges, this occurs when the hedged item is sold or substantially liquidated. To the extent a derivative does not qualify for hedge accounting and is deemed a non-designated
Secured Debt Agreements	Secured Debt Agreements Where applicable, we record investments financed with repurchase agreements as separate assets and the related borrowings under any repurchase agreements are recorded as separate liabilities on our consolidated balance sheets. Interest income earned on the investments and interest expense incurred on the repurchase agreements are reported separately on our consolidated statements of operations.
Senior Loan Participations	Senior Loan Participations In certain instances, we finance our loans through the non-recourse syndication of a senior loan interest to a third-party. Depending on the particular structure of the syndication, the senior loan interest may remain on our GAAP balance sheet or, in other cases, the sale will be recognized and the senior loan interest will no longer be included in our consolidated financial statements. When these sales are not recognized under GAAP we reflect the transaction by recording a loan participations sold liability on our consolidated balance sheet, however this gross presentation does not impact stockholders’ equity or net income. When the sales are recognized, our balance sheet only includes our remaining subordinate loan and not the non-consolidated senior interest we sold.
Convertible Notes	Convertible Notes The “Debt with Conversion and Other Options” Topic of the Financial Accounting Standards Board, or FASB, Accounting Standards Codification, or ASC, requires the liability and equity components of convertible debt instruments that may be settled in cash upon conversion, including partial cash settlement, to be separately accounted for in a manner that reflects the issuer’s nonconvertible debt borrowing rate. The initial proceeds from the sale of convertible notes are allocated between a liability component and an equity component in a manner that reflects interest expense at the rate of similar nonconvertible debt that could have been issued at such time. The equity component represents the excess initial proceeds received over the fair value of the liability component of the notes as of the date of issuance. We measured the estimated fair value of the debt component of our convertible notes as of the respective issuance dates based on our nonconvertible debt borrowing rate. The equity component of each series of our convertible notes is reflected within additional paid-in capital on our consolidated balance sheet, and the resulting debt discount is amortized over the period during which such convertible notes are expected to be outstanding (through the maturity date) as additional non-cash interest expense. The additional non-cash interest expense attributable to such convertible notes will increase in subsequent periods through the maturity date as the notes accrete to their par value over the same period.
Deferred Financing Costs	Deferred Financing Costs The deferred financing costs that are included as a reduction in the net book value of the related liability on our consolidated balance sheets include issuance and other costs related to our debt obligations. These costs are amortized as interest expense using the effective interest method over the life of the related obligations.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The “Fair Value Measurements and Disclosures” Topic, or ASC 820, defines fair value, establishes a framework for measuring fair value, and requires certain disclosures about fair value measurements under GAAP. Specifically, this guidance defines fair value based on exit price, or the price that would be received upon the sale of an asset or the transfer of a liability in an orderly transaction between market participants at the measurement date. ASC 820 also establishes a fair value hierarchy that prioritizes and ranks the level of market price observability used in measuring financial instruments. Market price observability is affected by a number of factors, including the type of financial instrument, the characteristics specific to the financial instrument, and the state of the marketplace, including the existence and transparency of transactions between market participants. Financial instruments with readily available quoted prices in active markets generally will have a higher degree of market price observability and a lesser degree of judgment used in measuring fair value. Financial instruments measured and reported at fair value are classified and disclosed based on the observability of inputs used in the determination, as follows: • Level 1: Generally includes only unadjusted quoted prices that are available in active markets for identical financial instruments as of the reporting date. • Level 2: Pricing inputs include quoted prices in active markets for similar instruments, quoted prices in less active or inactive markets for identical or similar instruments where multiple price quotes can be obtained, and other observable inputs, such as interest rates, yield curves, credit risks, and default rates. • Level 3: Pricing inputs are unobservable for the financial instruments and include situations where there is little, if any, market activity for the financial instrument. These inputs require significant judgment or estimation by management of third-parties when determining fair value and generally represent anything that does not meet the criteria of Levels 1 and 2. The estimated value of each asset reported at fair value using Level 3 inputs is determined by an internal committee composed of members of senior management of our Manager, including our Chief Executive Officer, Chief Financial Officer, and other senior officers. Certain of our other assets are reported at fair value either (i) on a recurring basis, as of each quarter-end, or (ii) on a nonrecurring basis, as a result of impairment or other events. Our assets that are recorded at fair value are discussed further in Note 15. We generally value our assets recorded at fair value by either (i) discounting expected cash flows based on assumptions regarding the collection of principal and interest and estimated market rates, or (ii) obtaining assessments from third-party dealers. For collateral-dependent loans that are identified as impaired, we measure impairment by comparing our Manager’s estimation of the fair value of the underlying collateral, less costs to sell, to the book value of the respective loan. These valuations may require significant judgments, which include assumptions regarding capitalization rates, leasing, creditworthiness of major tenants, occupancy rates, availability of financing, exit plan, loan sponsorship, actions of other lenders, and other factors deemed necessary by our Manager. We are also required by GAAP to disclose fair value information about financial instruments, that are not otherwise reported at fair value in our consolidated balance sheet, to the extent it is practicable to estimate a fair value for those instruments. These disclosure requirements exclude certain financial instruments and all non-financial instruments. The following methods and assumptions are used to estimate the fair value of each class of financial instruments, for which it is practicable to estimate that value: • Cash and cash equivalents: The carrying amount of cash and cash equivalents approximates fair value. • Restricted cash: The carrying amount of restricted cash approximates fair value. • Loans receivable, net: The fair values of these loans were estimated by our Manager based on a discounted cash flow methodology, taking into consideration various factors including capitalization rates, discount rates, leasing, occupancy rates, availability and cost of financing, exit plan, sponsorship, actions of other lenders, and indications of market value from other market participants. • Derivative financial instruments: The fair value of our foreign currency and interest rate contracts was estimated using advice from a third-party derivative specialist, based on contractual cash flows and observable inputs comprising foreign currency rates and credit spreads. • Secured debt agreements, net: The fair value of these instruments was estimated based on the rate at which a similar credit facility would currently be priced. • Loan participations sold, net: The fair value of these instruments was estimated based on the value of the related loan receivable asset. • Securitized debt obligations, net: The fair value of these instruments was estimated by utilizing third-party pricing service providers. In determining the value of a particular investment, pricing service providers may use broker-dealer quotations, reported trades, or valuation estimates from their internal pricing models to determine the reported price. • Convertible notes, net: Each series of the convertible notes is actively traded and their fair values were obtained using quoted market prices.
Income Taxes	Income Taxes Our financial results generally do not reflect provisions for current or deferred income taxes on our REIT taxable income. We believe that we operate in a manner that will continue to allow us to be taxed as a REIT and, as a result, we generally do not expect to pay substantial corporate level taxes other than those payable by our taxable REIT subsidiaries. If we were to fail to meet these requirements, we may be subject to federal, state, and local income tax on current and past income, and penalties. Refer to Note 13 for additional information.
Stock-Based Compensation	Stock-Based Compensation Our stock-based compensation consists of awards issued to our Manager and certain individuals employed by an affiliate of our Manager that vest over the life of the awards, as well as deferred stock units issued to certain members of our Board of Directors. Stock-based compensation expense is recognized for these awards in net income on a variable basis over the applicable vesting period of the awards, based on the value of our class A common stock. Refer to Note 14 for additional information.
Earnings per Share	Earnings per Share Basic earnings per share, or Basic EPS, is computed in accordance with the two-class method and is based on the net earnings allocable to our class A common stock, including restricted class A common stock and deferred stock units, divided by the weighted-average number of shares of our class A common stock, including restricted class A common stock and deferred stock units outstanding during the period. Our restricted class A common stock is considered a participating security, as defined by GAAP, and has been included in our Basic EPS under the two- class method as these restricted shares have the same rights as our other shares of class A common stock, including participating in any gains or losses. Diluted earnings per share, or Diluted EPS, is determined using the treasury stock method, and is based on the net earnings allocable to our class A common stock, including restricted class A common stock and deferred stock units, divided by the weighted-average number of shares of our class A common stock, including restricted class A common stock and deferred stock units. Refer to Note 11 for additional discussion of earnings per share.
Foreign Currency	Foreign Currency In the normal course of business, we enter into transactions not denominated in United States, or U.S., dollars. Foreign exchange gains and losses arising on such transactions are recorded as a gain or loss in our consolidated statements of operations. In addition, we consolidate entities that have a non-U.S. Non-U.S. non-U.S.
Underwriting Commissions and Offering Costs	Underwriting Commissions and Offering Costs Underwriting commissions and offering costs incurred in connection with common stock offerings are reflected as a reduction of additional paid-in
Recent Accounting Pronouncements	Recent Accounting Pronouncements In August 2017, the FASB issued ASU 2017-12 “Derivatives and Hedging Topic 815: Targeted Improvements to Accounting for Hedging Activities,” or ASU 2017-12. ASU 2017-12 is intended to better align an entity’s financial reporting for hedging activities with the economic objectives of those activities. Upon adoption of ASU 2017-12, the cumulative ineffectiveness that has previously been recognized on existing cash flow and net investment hedges will be adjusted and removed from beginning retained earnings and placed in accumulated other comprehensive income (loss). We adopted ASU 2017-12 in the third quarter of 2017, which did not have an impact on our financial statements as we had not previously recognized any hedge ineffectiveness related to our existing cash flow and net investment hedges. In future periods, for hedges that are deemed effective, we will no longer need to bifurcate hedges into an effective and ineffective portion, and all gains or losses on effective hedges will be recognized in other comprehensive income (loss). In November 2016, the FASB issued ASU 2016-18 “Statement of Cash Flows (Topic 230): Restricted Cash,” or ASU 2016-18. ASU 2016-18 is intended to clarify how entities present restricted cash in the statement of cash flows. The guidance requires entities to show the changes in the total of cash and cash equivalents and restricted cash in the statement of cash flows. As a result, entities will no longer present transfers between cash and cash equivalents and restricted cash in the statement of cash flows. We adopted ASU 2016-18 in the second quarter of 2017 and applied the guidance retrospectively to our prior period consolidated statement of cash flows. In June 2016, the FASB issued ASU 2016-13 “Financial Instruments – Credit Losses – Measurement of Credit Losses on Financial Instruments (Topic 326),” or ASU 2016-13. ASU 2016-13 significantly changes how entities will measure credit losses for most financial assets and certain other instruments that are not measured at fair value through net income. ASU 2016-13 will replace the “incurred loss” model under existing guidance with an “expected loss” model for instruments measured at amortized cost, and require entities to record allowances for available-for-sale debt securities rather than reduce the carrying amount, as they do today under the other-than-temporary impairment model. It also simplifies the accounting model for purchased credit-impaired debt securities and loans. ASU 2016-13 is effective for fiscal years beginning after December 15, 2019 and is to be adopted through a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective. While we are currently evaluating the impact ASU 2016-13 will have on our consolidated financial statements, we expect that the adoption will result in an increased amount of provisions for potential loan losses as well as the recognition of such provisions earlier in the lending cycle. We currently do not have any provision for loan losses on our consolidated financial statements. In May 2014, the FASB issued ASU 2014-09, “Revenue from Contracts with Customers (Topic 606) ,

Summary of Significant Accoun29

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Schedule of Reconciliation of Cash, Cash Equivalents, and Restricted Cash	The following table provides a reconciliation of cash, cash equivalents, and restricted cash in our consolidated balance sheets to the total amount shown in our consolidated statements of cash flows ($ in thousands): December 31, December 31, Cash and cash equivalents $ 69,654 $ 75,567 Restricted cash 32,864 — Total cash, cash equivalents, and restricted cash shown in our consolidated statements of cash flows $ 102,518 $ 75,567

Loans Receivable, Net (Tables)

Loans Receivable, Net (Tables)	12 Months Ended
	Dec. 31, 2017
Receivables [Abstract]
Overall Statistics for Loans Receivable Portfolio	The following table details overall statistics for our loans receivable portfolio ($ in thousands): December 31, December 31, Number of loans 110 107 Principal balance $ 10,108,226 $ 8,727,218 Net book value $ 10,056,732 $ 8,692,978 Unfunded loan commitments (1) $ 1,573,107 $ 882,472 Weighted-average cash coupon (2) 5.55 % 5.01 % Weighted-average all-in yield (2) 5.95 % 5.36 % Weighted-average maximum maturity (years) (3) 3.5 3.2 (1) Unfunded commitments will primarily be funded to finance property improvements or lease-related expenditures by the borrowers. These future commitments will be funded over the term of each loan, subject in certain cases to an expiration date. (2) As of December 31, 2017, our floating rate loans were indexed to various benchmark rates, with 92% of floating rate loans by principal balance indexed to USD LIBOR. As of December 31, 2016, our floating rate loans were indexed to various benchmark rates, with 84% of floating rate loans indexed to USD LIBOR. In addition, $216.3 million of our floating rate loans earned interest based on floors that are above the applicable index, with an average floor of 1.27%, as of December 31, 2016. In addition to cash coupon, all-in yield includes the amortization of deferred origination and extension fees, loan origination costs, and purchase discounts, as well as the accrual of exit fees. Cash coupon and all-in yield assume applicable floating benchmark rates as of December 31, 2017 for weighted-average calculation. (3) Maximum maturity assumes all extension options are exercised by the borrower, however our loans may be repaid prior to such date. As of December 31, 2017, 75% of our loans by principal balance were subject to yield maintenance or other prepayment restrictions and 25% were open to repayment by the borrower without penalty. As of December 31, 2016, 64% of our loans were subject to yield maintenance or other prepayment restrictions and 36% were open to repayment by the borrower without penalty.
Activity Relating to Loans Receivable Portfolio	Activity relating to our loans receivable portfolio was as follows ($ in thousands): Principal Deferred Fees / (1) Net Book December 31, 2015 $ 9,108,361 $ (31,354) $ 9,077,007 Loan fundings 3,151,882 — 3,151,882 Loan repayments (3,374,622 ) — (3,374,622 ) Unrealized (loss) gain on foreign currency translation (158,403 ) 1,466 (156,937 ) Deferred fees and other items — (44,697 ) (44,697 ) Amortization of fees and other items — 40,345 40,345 December 31, 2016 $ 8,727,218 $ (34,240 ) $ 8,692,978 Loan fundings 4,072,786 — 4,072,786 Loan repayments (2,828,610 ) — (2,828,610 ) Unrealized gain (loss) on foreign currency translation 136,832 (186 ) 136,646 Deferred fees and other items — (55,441 ) (55,441 ) Amortization of fees and other items — 38,373 38,373 December 31, 2017 $ 10,108,226 $ (51,494 ) $ 10,056,732 (1) Other items primarily consist of purchase discounts or premiums, exit fees, and deferred origination expenses.
Property Type and Geographic Distribution of Properties Securing Loans in Portfolio	The tables below detail the property type and geographic distribution of the properties securing the loans in our portfolio ($ in thousands): December 31, 2017 Property Type Number of Net Total Loan (1) Percentage of Office 53 $ 5,773,972 $ 5,807,170 53 % Hotel 15 1,830,568 1,905,497 17 Multifamily 25 1,220,423 1,228,959 11 Retail 6 487,473 940,980 8 Condominium 2 142,342 268,751 2 Other 9 601,954 942,251 9 110 $ 10,056,732 $ 11,093,608 100 % Geographic Location Number of Net Total Loan (1) Percentage of United States Northeast 26 $ 2,857,948 $ 2,871,219 26 % West 29 2,672,069 2,816,276 24 Southeast 17 2,007,202 2,470,992 22 Midwest 9 856,559 862,578 8 Southwest 10 380,204 380,120 3 Northwest 2 283,381 286,221 3 Subtotal 93 9,057,363 9,687,406 86 International United Kingdom 6 440,317 794,789 7 Canada 7 415,893 412,343 4 Belgium 1 73,779 74,431 1 Germany 1 12,237 67,399 1 Netherlands 2 57,143 57,240 1 Subtotal 17 999,369 1,406,202 14 Total 110 $ 10,056,732 $ 11,093,608 100 % (1) In certain instances, we finance our loans through the non-recourse sale of a senior loan interest that is not included in our consolidated financial statements. See Note 2 for further discussion. Total loan exposure encompasses the entire loan we originated and financed, including $985.4 million of such non-consolidated senior interests as of December 31, 2017. December 31, 2016 Property Type Number of Net Total Loan (1) Percentage of Office 55 $ 4,800,609 $ 4,889,456 50 % Hotel 18 1,889,732 1,957,334 20 Retail 9 769,813 1,173,592 12 Multifamily 17 817,387 819,781 8 Condominium 2 66,070 258,360 3 Other 6 349,367 658,211 7 107 $ 8,692,978 $ 9,756,734 100 % Geographic Location Number of Net Total Loan (1) Percentage of United States Northeast 26 $ 2,548,257 $ 2,562,149 26 % Southeast 21 1,492,530 1,899,748 19 West 22 1,628,811 1,828,667 19 Midwest 7 695,713 698,093 7 Southwest 8 380,639 379,766 4 Northwest 3 227,747 293,564 3 Subtotal 87 6,973,697 7,661,987 78 International United Kingdom 9 977,136 1,305,816 13 Canada 8 487,835 483,923 5 Germany 1 204,241 254,644 3 Netherlands 2 50,069 50,364 1 Subtotal 20 1,719,281 2,094,747 22 Total 107 $ 8,692,978 $ 9,756,734 100 % (1) In certain instances, we finance our loans through the non-recourse sale of a senior loan interest that is not included in our consolidated financial statements. See Note 2 for further discussion. Total loan exposure encompasses the entire loan we originated and financed, including $1.0 billion of such non-consolidated senior interests as of December 31, 2016.
Principal Balance and Net Book Value of Loans Receivable Based on Internal Risk Ratings	The following table allocates the principal balance and net book value of our loans receivable based on our internal risk ratings ($ in thousands): December 31, 2017 December 31, 2016 Risk Number Net Book Value Total Loan (1) Risk Number Net Book Value Total Loan (1) 1 1 $ 31,842 $ 31,890 1 8 $ 361,100 $ 361,574 2 41 3,512,709 3,521,701 2 52 4,011,992 4,083,678 3 67 6,491,617 7,519,465 3 46 4,299,026 5,290,668 4 1 20,564 20,552 4 1 20,860 20,814 5 — — — 5 — — — 110 $ 10,056,732 $ 11,093,608 107 $ 8,692,978 $ 9,756,734 (1) In certain instances, we finance our loans through the non-recourse sale of a senior loan interest that is not included in our consolidated financial statements. See Note 2 for further discussion. Total loan exposure encompasses the entire loan we originated and financed, including $985.4 million and $1.0 billion of such non-consolidated senior interests as of December 31, 2017 and December 31, 2016, respectively.

Other Assets and Liabilities (T

Other Assets and Liabilities (Tables)	12 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Summary of Components of Other Assets	The following table details the components of our other assets ($ in thousands): December 31, December 31, Loan portfolio payments held by servicer (1) $ 54,759 $ 5,765 Accrued interest receivable 38,573 32,871 Collateral deposited under derivative agreements 4,120 79 Derivative assets 1,214 4,086 Prepaid expenses 798 803 Prepaid taxes 31 16 Other 80 450 Total $ 99,575 $ 44,070 (1) Represents loan principal and interest payments held by our third-party loan servicer as of the balance sheet date which were remitted to us during the subsequent remittance cycle.
Summary of Components of Other Liabilities	The following table details the components of our other liabilities ($ in thousands): December 31, December 31, Accrued dividends payable $ 66,888 $ 58,615 Secured debt repayments pending servicer remittance (1) 38,456 5,372 Accrued management and incentive fees payable 14,284 12,798 Accrued interest payable 14,162 9,049 Derivative liabilities 4,911 210 Accounts payable and other liabilities 2,125 1,775 Total $ 140,826 $ 87,819 (1) Represents pending transfers from our third-party loan servicer that were remitted to our banking counterparties during the subsequent remittance cycle.

Secured Debt Agreements, Net (T

Secured Debt Agreements, Net (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Schedule of Secured Debt Agreements	The following table details our secured debt agreements ($ in thousands): Secured Debt Agreements Borrowings Outstanding December 31, December 31, Credit facilities $ 4,068,249 $ 3,572,837 GE portfolio acquisition facility 703,423 1,479,582 Asset-specific financings 518,864 679,207 Revolving credit agreement — — Total secured debt agreements $ 5,290,536 $ 5,731,626 Deferred financing costs (1) (16,681 ) (15,272 ) Net book value of secured debt $ 5,273,855 $ 5,716,354 (1) Costs incurred in connection with our secured debt agreements are recorded on our consolidated balance sheet when incurred and recognized as a component of interest expense over the life of each related agreement.
Credit Facilities	The following tables detail our credit facilities ($ in thousands): December 31, 2017 Maximum Facility Size (1) Collateral Assets (2) Credit Borrowings Lender Potential (3) Outstanding Available (3) Wells Fargo $ 2,000,000 $ 1,680,325 $ 1,289,135 $ 1,170,801 $ 118,334 MetLife 1,000,000 1,039,231 807,164 807,164 — Bank of America 750,000 765,049 573,542 573,542 — JP Morgan (4) 500,000 579,218 443,496 319,755 123,741 Société Générale (5) 480,200 373,181 300,871 300,871 — Deutsche Bank 500,000 399,203 295,743 295,743 — Citibank (6) 800,125 455,433 354,354 240,881 113,473 Morgan Stanley (7) 675,650 591,168 456,344 216,044 240,300 Bank of America - Multi. JV (8) 200,000 106,950 85,560 85,560 — Goldman Sachs - Multi. JV (8) 250,000 75,225 57,888 57,888 — $ 7,155,975 $ 6,064,983 $ 4,664,097 $ 4,068,249 $ 595,848 December 31, 2016 Maximum Facility Size (1) Collateral Assets (2) Credit Borrowings Lender Potential (3) Outstanding Available (3) Wells Fargo $ 2,000,000 $ 1,718,874 $ 1,339,942 $ 1,107,733 $ 232,209 MetLife 1,000,000 1,106,017 862,454 862,454 — Bank of America 750,000 794,881 617,694 617,694 — JP Morgan (4) 500,000 550,560 420,414 316,219 104,195 Morgan Stanley (7) 308,500 344,056 272,221 231,930 40,291 Citibank (6) 500,000 508,989 394,677 229,629 165,048 Société Générale (5) 420,680 274,351 207,178 207,178 — $ 5,479,180 $ 5,297,728 $ 4,114,580 $ 3,572,837 $ 541,743 (1) Maximum facility size represents the largest amount of borrowings available under a given facility once sufficient collateral assets have been approved by the lender and pledged by us. (2) Represents the principal balance of the collateral assets. (3) Potential borrowings represents the total amount we could draw under each facility based on collateral already approved and pledged. When undrawn, these amounts are immediately available to us at our sole discretion under the terms of each credit facility. (4) As of December 31, 2017 and December 31, 2016, the JP Morgan maximum facility size was composed of a general $500.0 million facility size, under which U.S. Dollars and British Pounds Sterling borrowings are contemplated. (5) As of December 31, 2017 and December 31, 2016, the Société Générale maximum facility size was composed of a €400.0 million facility size, which translated to $480.2 million and $420.7 million, respectively. Borrowings denominated in U.S. Dollars, British Pounds Sterling, and Euros are contemplated under this facility. (6) As of December 31, 2017, the Citibank maximum facility size was composed of a $500.0 million facility denominated in U.S. Dollars plus a €250.0 million facility, which translated to $300.1 million as of such date, which contemplated borrowings denominated in British Pounds Sterling and Euros. As of December 31, 2016, the maximum facility size was composed of a general $500.0 million facility. (7) As of December 31, 2017, the Morgan Stanley maximum facility size was composed of a £500.0 million facility size, which translated to $675.7 million as of such date. As of December 31, 2016, the maximum facility size was composed of a £250.0 million facility size, which translated to $308.5 million as of such date. Borrowings denominated in U.S. Dollars, British Pounds Sterling, and Euros are contemplated under this facility. (8) These facilities finance the loan investments of our consolidated Multifamily Joint Venture. Refer to Note 2 to our consolidated financial statements for additional discussion of our Multifamily Joint Venture.
Summary of Key Terms of Credit Facilities	The following tables outline the key terms of our credit facilities as of December 31, 2017: Lender Currency Guarantee (1) Margin Call (2) Term/Maturity Wells Fargo $ 25 % Collateral marks only Term matched (3) MetLife $ 50 % Collateral marks only April 21, 2023 (4) Bank of America $ 50 % Collateral marks only May 21, 2021 (5) JP Morgan $ / £ 50 % Collateral marks only January 7, 2020 Société Générale $ / £ / € 25 % Collateral marks only Term matched (3) Deutsche Bank $ 35 % Collateral marks only Term matched (3) Citibank $ / £ / € 25 % Collateral marks only Term matched (3) Morgan Stanley $ / £ / € 25 % Collateral marks only March 3, 2020 Bank of America - Multi. JV (6) $ 43 % Collateral marks only July 19, 2021 Goldman Sachs - Multi. JV (6) $ 25 % Collateral marks only July 12, 2020 (1) Other than amounts guaranteed based on specific collateral asset types, borrowings under our credit facilities are non-recourse to us. (2) Margin call provisions under our credit facilities do not permit valuation adjustments based on capital markets events, and are limited to collateral-specific credit marks. (3) These credit facilities have various availability periods during which new advances can be made and which are generally subject to each lender’s discretion. Maturity dates for advances outstanding are tied to the term of each respective collateral asset. (4) Includes five one-year extension options which may be exercised at our sole discretion. (5) Includes two one-year extension options which may be exercised at our sole discretion. (6) These facilities finance the loan investments of our consolidated Multifamily Joint Venture. Refer to Note 2 for additional discussion of our Multifamily Joint Venture. Currency Outstanding Borrowings Potential Borrowings (1) Index Rate (2) Advance (3) $ $ 3,798,619 $ 4,275,789 1-month USD LIBOR L+1.87% 78.6% € € 66,144 € 87,744 3-month EURIBOR L+2.24% 80.0% £ £ 140,771 £ 209,406 3-month GBP LIBOR L+2.24% 78.6% $ 4,068,249 $ 4,664,097 L+1.90% 78.7% (1) Potential borrowings represents the total amount we could draw under each facility based on collateral already approved and pledged. When undrawn, these amounts are immediately available to us at our sole discretion under the terms of each credit facility. (2) Represents weighted-average cash coupon based on borrowings outstanding. (3) Represents weighted-average advance rate based on the outstanding principal balance of the collateral assets pledged.
Summary of Asset-Specific Financings	The following tables detail our asset-specific financings ($ in thousands): December 31, 2017 Asset-Specific Financings Count Principal Book Value Wtd. Avg. Yield/Cost (1) Guarantee (2) Wtd. Avg. (3) Collateral assets 6 $ 682,259 $ 677,296 L+4.76 % n/a Dec. 2020 Financing provided (4) 6 $ 518,864 $ 517,088 L+2.50 % $ 162,475 Dec. 2020 (1) These floating rate loans and related liabilities are indexed to the various benchmark rates relevant in each arrangement in terms of currency and payment frequency. Therefore the net exposure to each benchmark rate is in direct proportion to our net assets indexed to that rate. In addition to cash coupon, yield/cost includes the amortization of deferred origination fees / financing costs. (2) Other than amounts guaranteed on an asset-by-asset basis, borrowings under our asset-specific financings are non-recourse to us. (3) The weighted-average term is determined based on the maximum maturity of the corresponding loans, assuming all extension options are exercised by the borrower. Each of our asset-specific financings are term-matched to the corresponding collateral loans. (4) Borrowings of $394.8 million under these asset specific financings are cross collateralized with related credit facilities with the same lenders. December 31, 2016 Asset-Specific Financings Count Principal Book Value Wtd. Avg. Yield/Cost (1) Guarantee (2) Wtd. Avg. (3) Collateral assets 7 $ 876,083 $ 869,417 L+4.84 % n/a Aug. 2020 Financing provided (4) 7 $ 679,207 $ 676,333 L+2.60 % $ 231,585 Aug. 2020 (1) These floating rate loans and related liabilities are indexed to the various benchmark rates relevant in each arrangement in terms of currency and payment frequency. Therefore the net exposure to each benchmark rate is in direct proportion to our net assets indexed to that rate. In addition to cash coupon, yield/cost includes the amortization of deferred origination fees / financing costs. (2) Other than amounts guaranteed on an asset-by-asset basis, borrowings under our asset-specific financings are non-recourse to us. (3) The weighted-average term is determined based on the maximum maturity of the corresponding loans, assuming all extension options are exercised by the borrower. Each of our asset-specific financings are term-matched to the corresponding collateral loans. (4) Borrowings of $392.3 million under these asset specific financings are cross collateralized with related credit facilities with the same lenders.

Loan Participations Sold, Net (

Loan Participations Sold, Net (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Summary of Statistics for Loan Participations Sold	The following tables detail our loan participations sold ($ in thousands): December 31, 2017 Loan Participations Sold Count Principal Book Value Yield/Cost (1) Guarantee (2) Term Total loan 1 $ 141,119 $ 138,907 L+5.94 % n/a Feb. 2022 Senior participation (3) 1 80,706 80,415 L+4.14 % n/a Feb. 2022 December 31, 2016 Loan Participations Sold Count Principal Book Value Yield/Cost (1) Guarantee (2) Term Total loan 1 $ 419,560 $ 416,233 L+4.48 % n/a Dec. 2019 Senior participation (3)(4) 1 349,633 348,077 L+2.72 % $ 29,616 Dec. 2019 (1) Our floating rate loans and related liabilities are indexed to the various benchmark rates relevant in each arrangement in terms of currency and payment frequency. Therefore the net exposure to each benchmark rate is in direct proportion to our net assets indexed to that rate. In addition to cash coupon, yield/cost includes the amortization of deferred fees / financing costs. (2) As of December 31, 2017, our loan participation sold was non-recourse to us. As of December 31, 2016, our loan participation was subject to a related guarantee agreement for £24.0 million ($29.6 million as of December 31, 2016). (3) During the years ended December 31, 2017 and 2016, we recorded $10.1 million and $13.7 million, respectively, of interest expense related to our loan participations sold, of which $8.4 million and $13.1 million was paid in cash. (4) The difference between principal balance and book value of loan participations sold is due to deferred financing costs of $291,000 and $1.6 million as of December 31, 2017 and December 31, 2016, respectively.

Securitized Debt Obligations,34

Securitized Debt Obligations, Net (Tables)	12 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Schedule of Information on Securitized Debt Obligations	The following table details our securitized debt obligations ($ in thousands): December 31, 2017 Securitized Debt Obligations Count Principal Book Value Wtd. Avg. (1) Term (2) Collateralized Loan Obligation Collateral assets 31 $ 1,000,000 $ 1,000,000 5.16 % Nov. 2021 Financing provided 1 817,500 808,083 L+1.76 % June 2035 Single Asset Securitization Collateral assets (3) 1 656,406 652,880 L+3.60 % June 2023 Financing provided 1 474,620 474,328 L+1.94 % June 2033 Total Collateral assets 32 $ 1,656,406 $ 1,652,880 5.17 % Financing provided (4) 2 $ 1,292,120 $ 1,282,411 L+1.83 % (1) As of December 31, 2017, 98% of our loans financed by securitized debt obligations earned a floating rate of interest. In addition to cash coupon, all-in yield includes the amortization of deferred origination and extension fees, loan origination costs, purchase discounts, and accrual of exit fees. All-in yield for the total portfolio assume applicable floating benchmark rates for weighted-average calculation. (2) Loan term represents final maturity, assuming all extension options are exercised by the borrower. Repayments of securitized debt obligations are tied to timing of the related collateral loan asset repayments. The term of these obligations represents the rated final distribution date of the securitizations. (3) The collateral assets for the Single Asset Securitization include the total loan amount, of which we securitized $500.0 million. (4) During the year ended December 31, 2017, we recorded $8.5 million of interest expense related to our securitized debt obligations.

Convertible Notes, Net (Tables)

Convertible Notes, Net (Tables)	12 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Summary of Outstanding Convertible Senior Notes	As of December 31, 2017, the following convertible senior notes, or Convertible Notes, were outstanding ($ in thousands): Convertible Notes Issuance Face Value Coupon Rate All-in Cost (1) Conversion Rate (2) Maturity November 2013 $ 172,500 5.25 % 5.87 % 36.1380 December 1, 2018 May 2017 402,500 4.38 % 4.85 % 28.0324 May 5, 2022 (1) Includes issuance costs that are amortized through interest expense over the life of the Convertible Notes using the effective interest method. (2) Represents the shares of class A common stock per $1,000 principal amount of Convertible Notes, which is equivalent to a conversion price of $27.67 and $35.67 per share of class A common stock, respectively, for the November 2013 and May 2017 convertible notes. As a result of exceeding the cumulative dividend threshold, as defined in the November 2013 convertible notes supplemental indenture, the conversion rate on the November 2013 convertible notes was most recently adjusted on June 28, 2017 from the prior conversion rate of 35.7236 shares of class A common stock per $1,000 principal amount of convertible notes, which was equivalent to a conversion price of $27.99 per share of class A common stock. The cumulative dividend threshold as defined in the May 2017 convertible notes supplemental indenture has not been exceeded as of December 31, 2017.
Summary of Details about Interest Expense	The following table details our interest expense related to the Convertible Notes ($ in thousands): Year Ended December 31, 2017 2016 2015 Cash coupon $ 19,259 $ 9,056 $ 9,056 Discount and issuance cost amortization 4,040 2,736 2,571 Total interest expense $ 23,299 $ 11,792 $ 11,627
Summary of Details of Net Book Value of Convertible Note	The following table details the net book value of our Convertible Notes on our consolidated balance sheets ($ in thousands): December 31, December 31, Face value $ 575,000 $ 172,500 Unamortized discount (10,279 ) (5,532 ) Deferred financing costs (810 ) (206 ) Net book value $ 563,911 $ 166,762

Derivative Financial Instrume36

Derivative Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Summary of Outstanding Foreign Exchange Derivatives Designated as Net Investment Hedges of Foreign Currency Risk	The following table details our outstanding foreign exchange derivatives that were designated as net investment hedges of foreign currency risk (notional amount in thousands): December 31, 2017 December 31, 2016 Foreign Currency Number of Notional Amount Foreign Currency Number of Notional Amount Sell GBP Forward 1 £ 112,700 Sell GBP Forward 2 £ 141,900 Sell CAD Forward 1 C$ 95,100 Sell CAD Forward 2 C$ 122,900 Sell EUR Forward 1 € 44,900
Summary of Outstanding Interest Rate Derivatives Designated as Cash Flow Hedges of Interest Rate Risk	The following tables detail our outstanding interest rate derivatives that were designated as cash flow hedges of interest rate risk (notional amount in thousands): December 31, 2017 Interest Rate Number of Notional Amount Strike Index Wtd.-Avg. Interest Rate Swaps 4 C$ 108,094 1.0 % CDOR 1.4 Interest Rate Caps 9 $ 204,248 2.4 % USD LIBOR 1.5 Interest Rate Caps 3 C$ 23,370 2.0 % CDOR 0.3 December 31, 2016 Interest Rate Number of Notional Amount Strike Index Wtd.-Avg. Interest Rate Swaps 4 C$ 108,271 1.0 % CDOR 2.4 Interest Rate Caps 21 $ 802,256 2.0 % USD LIBOR 0.4 Interest Rate Caps 5 C$ 400,035 2.0 % CDOR 0.4 Interest Rate Caps 1 £ 15,142 2.0 % GBP LIBOR 0.3
Summary of Non-designated Hedges	The following tables summarize our non-designated hedges (notional amount in thousands): December 31, 2017 Non-designated Hedges Number of Notional Buy GBP / Sell EUR Forward 1 € 12,857 December 31, 2016 Non-designated Hedges Number of Notional Amount Interest Rate Caps 3 $ 256,875 Interest Rate Caps 2 C$ 37,221 Buy GBP / Sell EUR Forward 1 € 12,857
Summary of Fair Value of Derivative Financial Instruments	The following table summarizes the fair value of our derivative financial instruments ($ in thousands): Fair Value of Derivatives in an Asset (1) Fair Value of Derivatives in a Liability (2) December 31, 2017 December 31, 2016 December 31, 2017 December 31, 2016 Derivatives designated as Foreign exchange contracts $ — $ 3,268 $ 4,872 $ 210 Interest rate derivatives 1,214 331 — — Total $ 1,214 $ 3,599 $ 4,872 $ 210 Derivatives not designated as hedging instruments: Foreign exchange contracts $ — $ 487 $ 39 $ — Interest rate derivatives — — — — Total $ — $ 487 $ 39 $ — Total Derivatives $ 1,214 $ 4,086 $ 4,911 $ 210 (1) Included in other assets in our consolidated balance sheets. (2) Included in other liabilities in our consolidated balance sheets.
Summary of Effect of Derivative Financial Instruments on Consolidated Statements of Operations	The following table presents the effect of our derivative financial instruments on our consolidated statements of operations ($ in thousands): Derivatives in Hedging Relationships Amount of (Loss) Location of Amount of Year Ended December 31, Accumulated Year Ended December 31, 2017 2016 2015 OCI into Income 2017 2016 2015 Net Investment Hedges Foreign exchange contracts (1) $ (22,216 ) $ 25,355 $ 25,356 Interest Expense $ — $ — $ — Cash Flow Hedges Interest rate derivatives 757 89 (1,474 ) Interest Expense (2) (831 ) (798 ) (4 ) Total $ (21,459 ) $ 25,444 $ 23,882 $ (831 ) $ (798 ) $ (4 ) (1) During the year ended December 31, 2017, we paid net cash settlements of $14.2 million on our foreign currency forward contracts. During the years ended December 31, 2016 and 2015, we received net cash settlements of $26.8 million and $18.8 million, respectively, on our foreign currency forward contracts. Those amounts are included as a component of accumulated other comprehensive loss on our consolidated balance sheets. (2) During the years ended December 31, 2017, 2016, and 2015, we recorded total interest and related expenses of $234.9 million, $184.3 million, and 152.4 million, respectively, which included interest expense of $831,000, $798,000, and $4,000, respectively, related to our cash flow hedges.

Equity (Tables)

Equity (Tables)	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Summary of Class A Common Stock Issuances	The following table details our issuance of class A common stock during the years ended December 31, 2017, 2016 and 2015 ($ in thousands, except share and per share data): Class A Common Stock Offerings 2017 2016 2015 (1) Shares issued 12,420,000 — 34,780,025 Share issue price (2) $ 31.57 $ — $ 29.64 Net proceeds (3) $ 391,558 $ — $ 1,029,535 (1) Consists of 23.0 million shares issued in April 2015, 11.5 million shares issued in June 2015, and 280,025 shares issued over a five-day period in May 2015 under our at-the-market program. Share issue price reflects the weighted-average of such stock offerings. (2) Represents price per share paid by the underwriters or sales agents, as applicable. (3) Net proceeds represents proceeds received from the underwriters less applicable transaction costs.
Schedule of Movement in Outstanding Shares of Class A Common Stock, Restricted Class A Common Stock and Deferred Stock Units	The following table details the movement in our outstanding shares of class A common stock, including restricted class A common stock and deferred stock units: Year Ended December 31, Common Stock Outstanding (1) 2017 2016 2015 Beginning balance 94,709,290 93,843,847 58,388,808 Issuance of class A common stock (2) 12,421,401 1,070 34,780,622 Issuance of restricted class A common stock, net 922,196 836,867 651,815 Issuance of deferred stock units 28,190 27,506 22,602 Ending balance 108,081,077 94,709,290 93,843,847 (1) Includes deferred stock units held by members of our board of directors of 197,217, 169,027, and 141,521, as of December 31, 2017, 2016, and 2015, respectively. (2) Includes 1,401, 1,070, and 597 shares issued under our dividend reinvestment program during the years ended December 31, 2017, 2016, and 2015, respectively.
Schedule of Dividend Activity	The following table details our dividend activity ($ in thousands, except per share data): Year Ended December 31, 2017 2016 2015 Dividends declared per share of common stock $ 2.48 $ 2.48 $ 2.28 Percent taxable as ordinary dividends 97.20 % 92.77 % 92.36 % Percent taxable as capital gain dividends 2.80 % 7.23 % 7.64 % 100.0 % 100.0 % 100.0 %
Schedule of Basic and Diluted Earnings Per Share, or EPS, Based on Weighted-Average of Both Restricted and Unrestricted Class A Common Stock Outstanding	The following table sets forth the calculation of basic and diluted net income per share of class A common stock based on the weighted-average of both restricted and unrestricted class A common stock outstanding ($ in thousands, except per share data): Year Ended December 31, 2017 2016 2015 Net income (1) $ 217,631 $ 238,297 $ 196,829 Weighted-average shares outstanding, basic and diluted 95,963,616 94,165,351 81,740,227 Per share amount, basic and diluted $ 2.27 $ 2.53 $ 2.41 (1) Represents net income attributable to Blackstone Mortgage Trust, Inc.

Other Expenses (Tables)

Other Expenses (Tables)	12 Months Ended
	Dec. 31, 2017
Other Income and Expenses [Abstract]
Schedule of General and Administrative Expenses	General and administrative expenses consisted of the following ($ in thousands): Year Ended December 31, 2017 2016 2015 Professional services (1) $ 3,812 $ 3,311 $ 3,156 Operating and other costs (1) 1,903 2,147 2,709 GE transaction costs — — 9,623 Subtotal 5,715 5,458 15,488 Non-cash and CT Legacy Portfolio compensation expenses Management incentive awards plan - CTOPI (2) — 1,568 5,370 Management incentive awards plan - CT Legacy Partners (3) — 1,094 2,177 Restricted class A common stock earned 23,593 19,052 12,966 Director stock-based compensation 438 375 375 Subtotal 24,031 22,089 20,888 Total BXMT expenses 29,746 27,547 36,376 Other expenses 176 169 333 Total general and administrative expenses $ 29,922 $ 27,716 $ 36,709 (1) During the year ended December 31, 2017, we recognized an aggregate $232,000 of expenses related to our Multifamily Joint Venture. (2) Represents the portion of CTOPI promote revenue recorded under compensation awards. See Note 4 for further discussion. (3) Represents the amounts recorded under the CT Legacy Partners management incentive awards during the period. See below for discussion of the CT Legacy Partners management incentive awards plan.

Stock-Based Incentive Plans (Ta

Stock-Based Incentive Plans (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Movement in Outstanding Shares of Restricted Class A Common Stock and Weighted-Average Grant Date Fair Value Per Share	The following table details the movement in our outstanding shares of restricted class A common stock and the weighted-average grant date fair value per share: Restricted Class A Weighted-Average Balance as of December 31, 2015 1,114,908 $ 27.64 Granted 872,294 28.88 Vested (641,780 ) 27.21 Forfeited (35,427 ) 27.49 Balance as of December 31, 2016 1,309,995 $ 28.68 Granted 925,319 31.78 Vested (748,016 ) 28.69 Forfeited (3,123 ) 27.37 Balance as of December 31, 2017 1,484,175 $ 30.61

Fair Values (Tables)

Fair Values (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Assets and Liabilities Measured at Fair Value on Recurring Basis	The following table summarizes our assets and liabilities measured at fair value on a recurring basis ($ in thousands): December 31, 2017 December 31, 2016 Level 1 Level 2 Level 3 Fair Value Level 1 Level 2 Level 3 Fair Value Assets Derivatives $ — $ 1,214 $ — $ 1,214 $ — $ 4,086 $ — $ 4,086 Liabilities Derivatives $ — $ 4,911 $ — $ 4,911 $ — $ 210 $ — $ 210
Reconciliation of Beginning and Ending Balances of Assets Measured at Fair Value on Recurring Basis Using Level 3 Inputs	The following table reconciles the beginning and ending balances of assets measured at fair value on a recurring basis using Level 3 inputs ($ in thousands): Year Ended December 31, 2017 2016 (1) January 1, $ — $ 12,561 Proceeds from investment realizations — (3,609 ) Transfers out of level 3 (2) — (20,745 ) Adjustments to fair value included in earnings Gain on investments at fair value — 11,793 December 31, $ — $ — (1) All assets measured at fair value on a recurring basis using Level 3 inputs were included as a component of other assets in the consolidated Balance Sheets. (2) During the second quarter of 2016, $20.7 million of collateralized debt obligations, or CDOs, were transferred out of Level 3 and into Level 1 as a result of a binding agreement to sell the underlying collateral assets of the CDO to an independent third-party. These investments were realized in the third quarter of 2016.
Schedule of Details of Carrying Amount, Face Amount, and Fair Value of Financial Instruments	The following table details the carrying amount, face amount, and fair value of the financial instruments described in Note 2 ($ in thousands): December 31, 2017 December 31, 2016 Carrying Face Amount Fair Value Carrying Face Fair Value Financial assets Cash and cash equivalents $ 69,654 $ 69,654 $ 69,654 $ 75,567 $ 75,567 $ 75,567 Restricted cash 32,864 32,864 32,864 — — — Loans receivable, net 10,056,732 10,108,226 10,112,331 8,692,978 8,727,218 8,733,784 Financial liabilities Secured debt agreements, net 5,273,855 5,290,536 5,290,536 5,716,354 5,731,626 5,731,626 Loan participations sold, net 80,415 80,706 80,706 348,077 349,633 349,633 Securitized debt obligations, net 1,282,412 1,292,120 1,292,589 — — — Convertible notes, net 563,911 575,000 610,201 166,762 172,500 191,763

Variable Interest Entities (Tab

Variable Interest Entities (Tables)	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Summary of Assets and Liabilities of Consolidated CLO and Single Asset Securitization VIE	The following table details the assets and liabilities of our consolidated CLO and Single Asset Securitization VIEs ($ in thousands): December 31, 2017 December 31, 2016 Assets: Loans receivable, net $ 1,500,000 $ — Other assets 2,407 — Total assets $ 1,502,407 $ — Liabilities: Securitized debt obligations, net $ 1,282,412 $ — Other liabilities 1,379 — Total liabilities $ 1,283,791 $ —

Summary of Quarterly Results 42

Summary of Quarterly Results of Operations (Tables)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Summary of Quarterly Results of Operations	The following is a summary of the unaudited quarterly results of operations for the years ended December 31, 2017 and 2016 ($ in thousands except per share data): March 31 June 30 September 30 December 31 2017 Income from loans and other investments, net $ 71,843 $ 72,473 $ 78,555 $ 80,174 Net income $ 51,405 $ 50,613 $ 57,810 $ 58,140 Net income attributable to Blackstone Mortgage Trust, Inc. $ 51,405 $ 50,613 $ 57,722 $ 57,891 Net income per share of class A common stock: Basic and diluted $ 0.54 $ 0.53 $ 0.61 $ 0.59 2016 Income from loans and other investments, net $ 77,644 $ 81,406 $ 82,817 $ 71,837 Net income $ 57,199 $ 69,450 $ 66,392 $ 53,399 Net income attributable to Blackstone Mortgage Trust, Inc. $ 57,047 $ 63,081 $ 64,794 $ 53,375 Net income per share of class A common stock: Basic and diluted $ 0.61 $ 0.67 $ 0.69 $ 0.57

Summary of Significant Accoun43

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Apr. 30, 2017	Jun. 30, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Joint venture capital contribution percentage		85.00%
Income accrual, description	Income accrual is generally suspended for loans at the earlier of the date at which payments become 90 days past due or when, in the opinion of our Manager, recovery of income and principal becomes doubtful.
Cash and cash equivalents, description	Cash and cash equivalents represent cash held in banks, cash on hand, and liquid investments with original maturities of three months or less.
Expected loss	$ 0
Provision for loan losses	$ 0
Walker and Dunlop [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Joint venture capital contribution percentage		15.00%
General Electrical Capital Corporation [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchase price of Loan Portfolio			$ 4,700,000,000

Summary of Significant Accoun44

Summary of Significant Accounting Policies - Schedule of Reconciliation of Cash, Cash Equivalents, and Restricted Cash (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	$ 69,654	$ 75,567
Restricted cash	32,864
Total cash, cash equivalents, and restricted cash shown in our consolidated statements of cash flows	$ 102,518	$ 75,567	$ 106,006	$ 63,401

Loans Receivable, Net - Overall

Loans Receivable, Net - Overall Statistics for Loans Receivable Portfolio (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)SecurityLoan	Dec. 31, 2016USD ($)SecurityLoan	Dec. 31, 2015USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | SecurityLoan	110	107
Net book value	$ 10,056,732	$ 8,692,978
Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | SecurityLoan	110	107
Principal balance	$ 10,108,226	$ 8,727,218	$ 9,108,361
Unfunded loan commitments	$ 1,573,107	$ 882,472
Weighted-average maximum maturity (years)	3 years 6 months	3 years 2 months 12 days
Loans Receivable [Member] | LIBOR [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted-average cash coupon, rate	5.55%	5.01%
Weighted-average all-in yield, rate	5.95%	5.36%
Net Book Value [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net book value	$ 10,056,732	$ 8,692,978	$ 9,077,007

Loans Receivable, Net - Overa46

Loans Receivable, Net - Overall Statistics for Loans Receivable Portfolio (Parenthetical) (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Floating rate loans		$ 216.3
Average floor rate		1.27%
Percentage of loans subject to yield maintenance, or other prepayment restrictions	75.00%	64.00%
Percentage of loans open to repayment by borrower without penalty	25.00%	36.00%
USD LIBOR [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of loans receivable by type	92.00%	84.00%

Loans Receivable, Net - Activit

Loans Receivable, Net - Activity Relating to Loans Receivable Portfolio (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	$ 8,692,978
Unrealized (loss) gain on foreign currency translation	47,124	$ (49,686)	$ (41,616)
Amortization of fees and other items	38,373	40,345	36,053
Ending Balance	10,056,732	8,692,978
Net Book Value [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	8,692,978	9,077,007
Loan fundings	4,072,786	3,151,882
Loan repayments	(2,828,610)	(3,374,622)
Unrealized (loss) gain on foreign currency translation	136,646	(156,937)
Deferred fees and other items	(55,441)	(44,697)
Amortization of fees and other items	38,373	40,345
Ending Balance	10,056,732	8,692,978	9,077,007
Deferred Fees/Other Items [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	(34,240)	(31,354)
Unrealized (loss) gain on foreign currency translation	(186)	1,466
Deferred fees and other items	(55,441)	(44,697)
Amortization of fees and other items	38,373	40,345
Ending Balance	(51,494)	(34,240)	(31,354)
Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	8,727,218	9,108,361
Loan fundings	4,072,786	3,151,882
Loan repayments	(2,828,610)	(3,374,622)
Unrealized (loss) gain on foreign currency translation	136,832	(158,403)
Ending Balance	$ 10,108,226	$ 8,727,218	$ 9,108,361

Loans Receivable, Net - Propert

Loans Receivable, Net - Property Type and Geographic Distribution of Properties Securing Loans in Portfolio (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)SecurityLoan	Dec. 31, 2016USD ($)SecurityLoan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | SecurityLoan	110	107
Net book value	$ 10,056,732	$ 8,692,978
Total Loan Exposure	$ 11,093,608	$ 9,756,734
Percentage of Portfolio	100.00%	100.00%
Office [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | SecurityLoan	53	55
Net book value	$ 5,773,972	$ 4,800,609
Total Loan Exposure	$ 5,807,170	$ 4,889,456
Percentage of Portfolio	53.00%	50.00%
Hotel [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | SecurityLoan	15	18
Net book value	$ 1,830,568	$ 1,889,732
Total Loan Exposure	$ 1,905,497	$ 1,957,334
Percentage of Portfolio	17.00%	20.00%
Multifamily [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | SecurityLoan	25	17
Net book value	$ 1,220,423	$ 817,387
Total Loan Exposure	$ 1,228,959	$ 819,781
Percentage of Portfolio	11.00%	8.00%
Retail [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | SecurityLoan	6	9
Net book value	$ 487,473	$ 769,813
Total Loan Exposure	$ 940,980	$ 1,173,592
Percentage of Portfolio	8.00%	12.00%
Condominium [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | SecurityLoan	2	2
Net book value	$ 142,342	$ 66,070
Total Loan Exposure	$ 268,751	$ 258,360
Percentage of Portfolio	2.00%	3.00%
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | SecurityLoan	9	6
Net book value	$ 601,954	$ 349,367
Total Loan Exposure	$ 942,251	$ 658,211
Percentage of Portfolio	9.00%	7.00%
United States Northeast [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | SecurityLoan	26	26
Net book value	$ 2,857,948	$ 2,548,257
Total Loan Exposure	$ 2,871,219	$ 2,562,149
Percentage of Portfolio	26.00%	26.00%
United States West [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | SecurityLoan	29	22
Net book value	$ 2,672,069	$ 1,628,811
Total Loan Exposure	$ 2,816,276	$ 1,828,667
Percentage of Portfolio	24.00%	19.00%
United States Southeast [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | SecurityLoan	17	21
Net book value	$ 2,007,202	$ 1,492,530
Total Loan Exposure	$ 2,470,992	$ 1,899,748
Percentage of Portfolio	22.00%	19.00%
United States Midwest [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | SecurityLoan	9	7
Net book value	$ 856,559	$ 695,713
Total Loan Exposure	$ 862,578	$ 698,093
Percentage of Portfolio	8.00%	7.00%
United States Southwest [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | SecurityLoan	10	8
Net book value	$ 380,204	$ 380,639
Total Loan Exposure	$ 380,120	$ 379,766
Percentage of Portfolio	3.00%	4.00%
United States Northwest [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | SecurityLoan	2	3
Net book value	$ 283,381	$ 227,747
Total Loan Exposure	$ 286,221	$ 293,564
Percentage of Portfolio	3.00%	3.00%
United States [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | SecurityLoan	93	87
Net book value	$ 9,057,363	$ 6,973,697
Total Loan Exposure	$ 9,687,406	$ 7,661,987
Percentage of Portfolio	86.00%	78.00%
United Kingdom [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | SecurityLoan	6	9
Net book value	$ 440,317	$ 977,136
Total Loan Exposure	$ 794,789	$ 1,305,816
Percentage of Portfolio	7.00%	13.00%
Canada [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | SecurityLoan	7	8
Net book value	$ 415,893	$ 487,835
Total Loan Exposure	$ 412,343	$ 483,923
Percentage of Portfolio	4.00%	5.00%
Belgium [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | SecurityLoan	1
Net book value	$ 73,779
Total Loan Exposure	$ 74,431
Percentage of Portfolio	1.00%
Germany [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | SecurityLoan	1	1
Net book value	$ 12,237	$ 204,241
Total Loan Exposure	$ 67,399	$ 254,644
Percentage of Portfolio	1.00%	3.00%
Netherlands [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | SecurityLoan	2	2
Net book value	$ 57,143	$ 50,069
Total Loan Exposure	$ 57,240	$ 50,364
Percentage of Portfolio	1.00%	1.00%
International [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | SecurityLoan	17	20
Net book value	$ 999,369	$ 1,719,281
Total Loan Exposure	$ 1,406,202	$ 2,094,747
Percentage of Portfolio	14.00%	22.00%

Loans Receivable, Net - Prope49

Loans Receivable, Net - Property Type and Geographic Distribution of Properties Securing Loans in Portfolio (Parenthetical) (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Receivables [Abstract]
Total loan exposure including senior interests	$ 985.4	$ 1,000

Loans Receivable, Net - Princip

Loans Receivable, Net - Principal Balance and Net Book Value of Loans Receivable Based on Internal Risk Ratings (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)SecurityLoan	Dec. 31, 2016USD ($)SecurityLoan	Dec. 31, 2015USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | SecurityLoan	110	107
Net book value	$ 10,056,732	$ 8,692,978
Total Loan Exposure	$ 11,093,608	$ 9,756,734
Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | SecurityLoan	110	107
Net Book Value [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net book value	$ 10,056,732	$ 8,692,978	$ 9,077,007
Risk Rating 1 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loan Exposure	$ 31,890	$ 361,574
Risk Rating 1 [Member] | Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | SecurityLoan	1	8
Risk Rating 1 [Member] | Net Book Value [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net book value	$ 31,842	$ 361,100
Risk Rating 2 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loan Exposure	$ 3,521,701	$ 4,083,678
Risk Rating 2 [Member] | Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | SecurityLoan	41	52
Risk Rating 2 [Member] | Net Book Value [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net book value	$ 3,512,709	$ 4,011,992
Risk Rating 3 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loan Exposure	$ 7,519,465	$ 5,290,668
Risk Rating 3 [Member] | Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | SecurityLoan	67	46
Risk Rating 3 [Member] | Net Book Value [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net book value	$ 6,491,617	$ 4,299,026
Risk Rating 4 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loan Exposure	$ 20,552	$ 20,814
Risk Rating 4 [Member] | Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | SecurityLoan	1	1
Risk Rating 4 [Member] | Net Book Value [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net book value	$ 20,564	$ 20,860

Loans Receivable, Net - Princ51

Loans Receivable, Net - Principal Balance and Net Book Value of Loans Receivable Based on Internal Risk Ratings (Parenthetical) (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Receivables [Abstract]
Total loan exposure including senior interests	$ 985.4	$ 1,000

Loans Receivable, Net - Additio

Loans Receivable, Net - Additional Information (Detail)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted-average risk rating on loan exposure	2.7	2.5
Impaired loans	$ 0	$ 0
Loans held	11,093,608,000	9,756,734,000
Multifamily [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held	1,228,959,000	$ 819,781,000
Joint Venture [Member] | Multifamily [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held	$ 182,200,000

Equity Investment in Unconsol53

Equity Investment in Unconsolidated Subsidiary - Additional Information (Detail) - CT Opportunity Partners I, LP [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 31, 2011
Schedule of Equity Method Investments [Line Items]
Carried interest revenue, percentage of fund's profit	17.70%
Preferred return	9.00%
Return of capital to partners	100.00%
Promote income recognized		$ 3.2	$ 11.8
Percentage of carried interest distributions pool for employees				45.00%
Description of incentive management fee grants to employees vesting schedule	During the years ended December 31, 2016 and 2015, we recognized $1.6 million and $5.4 million, respectively, of expenses under the CTOPI incentive plan. Such amounts were recognized as a component of general and administrative expenses in our consolidated statements of operations.
CTOPI Incentive Plan [Member]
Schedule of Equity Method Investments [Line Items]
Recognized expenses for incentive plan		$ 1.6	$ 5.4

Other Assets and Liabilities -

Other Assets and Liabilities - Summary of Components of Other Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Loan portfolio payments held by servicer	$ 54,759	$ 5,765
Accrued interest receivable	38,573	32,871
Collateral deposited under derivative agreements	4,120	79
Derivative assets	1,214	4,086
Prepaid expenses	798	803
Prepaid taxes	31	16
Other	80	450
Total	$ 99,575	$ 44,070

Other Assets and Liabilities 55

Other Assets and Liabilities - Summary of Components of Other Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Other Liabilities [Abstract]
Accrued dividends payable	$ 66,888	$ 58,615
Secured debt repayments pending servicer remittance	38,456	5,372
Accrued management and incentive fees payable	14,284	12,798
Accrued interest payable	14,162	9,049
Derivative liabilities	4,911	210
Accounts payable and other liabilities	2,125	1,775
Total	$ 140,826	$ 87,819

Secured Debt Agreements, Net -

Secured Debt Agreements, Net - Schedule of Secured Debt Agreements (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Secured debt agreements borrowings outstanding	$ 518,864	$ 679,207
Secured debt agreements borrowings outstanding	5,290,536	5,731,626
Deferred financing costs	(16,681)	(15,272)
Net book value of secured debt	5,273,855	5,716,354
Credit Facilities [Member]
Debt Instrument [Line Items]
Secured debt agreements borrowings outstanding	4,068,249	3,572,837
GE Portfolio Acquisition Facility [Member]
Debt Instrument [Line Items]
Secured debt agreements borrowings outstanding	703,423	1,479,582
Asset-Specific Financings [Member]
Debt Instrument [Line Items]
Secured debt agreements borrowings outstanding	$ 518,864	$ 679,207

Secured Debt Agreements, Net 57

Secured Debt Agreements, Net - Additional Information (Detail) € in Millions, £ in Millions	3 Months Ended		12 Months Ended
	Jun. 30, 2017USD ($)	Jun. 30, 2015USD ($)ExtensionOptions	Dec. 31, 2017USD ($)Facility	Dec. 31, 2017EUR (€)Facility	Dec. 31, 2017GBP (£)Facility	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	May 31, 2017USD ($)
Debt Instrument [Line Items]
Aggregate borrowings			$ 4,068,249,000
Basis spread on debt obligation, in percent			1.90%	1.90%	1.90%
Weighted-average advance rate			78.70%	78.70%	78.70%
Secured debt agreements borrowings outstanding			$ 5,273,855,000			$ 5,716,354,000
Interest expense			234,870,000			184,270,000	$ 152,416,000
Secured debt agreements borrowings outstanding			5,290,536,000			5,731,626,000
Covenants, minimum tangible net worth			$ 2,200,000,000
Covenants, percentage of tangible assets on cash proceeds from equity issuances			75.00%	75.00%	75.00%
Covenants, percentage of recourse indebtedness			5.00%
Maximum [Member]
Debt Instrument [Line Items]
Covenants, indebtedness to total assets, in percent			83.33%
Minimum [Member]
Debt Instrument [Line Items]
Covenants, EBITDA to fixed charges, in percent			140.00%	140.00%	140.00%
Covenants, minimum cash liquidity amount			$ 10,000,000
Asset-Specific Financings [Member]
Debt Instrument [Line Items]
Weighted-average outstanding balance			576,400,000			584,700,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Weighted-average outstanding balance			30,700,000			31,600,000
Interest expense			3,000,000			1,400,000
Amortization of deferred fees and expenses			829,000			376,000
Secured debt agreements borrowings outstanding			0			0
Revolving Credit Facility [Member] | Barclays [Member]
Debt Instrument [Line Items]
Maximum Facility Size	$ 250,000,000							$ 125,000,000
First mortgage bridge to term financing maximum period	6 months
GE Portfolio Acquisition Facility [Member]
Debt Instrument [Line Items]
Secured debt agreements borrowings outstanding			703,423,000			1,479,582,000
GE Portfolio Acquisition Facility [Member] | Wells Fargo [Member]
Debt Instrument [Line Items]
Aggregate borrowings			703,400,000
Maximum Facility Size			816,300,000
Amount available for potential future fundings of loan			$ 112,900,000
GE Portfolio Acquisition Facility [Member] | Asset Specific Borrowings [Member]
Debt Instrument [Line Items]
Weighted average rate		80.00%
Maturity date			May 20, 2020	May 20, 2020	May 20, 2020
Borrowings maturity term			The asset-specific borrowings are term matched to the underlying collateral assets with an outside maturity date of May 20, 2020, which may be extended pursuant to two one-year extension options.	The asset-specific borrowings are term matched to the underlying collateral assets with an outside maturity date of May 20, 2020, which may be extended pursuant to two one-year extension options.	The asset-specific borrowings are term matched to the underlying collateral assets with an outside maturity date of May 20, 2020, which may be extended pursuant to two one-year extension options.
Number of extension options | ExtensionOptions		2
Term of maturity date		1 year
GE Portfolio Acquisition Facility [Member] | Asset Specific Borrowings [Member] | Maximum [Member]
Debt Instrument [Line Items]
Percentage of guarantee rate		25.00%
Guarantee of outstanding borrowings		$ 250,000,000
GE Portfolio Acquisition Facility [Member] | Weighted-Average All-in Cost of Credit [Member] | Asset Specific Borrowings [Member]
Debt Instrument [Line Items]
Secured debt agreements borrowings outstanding			$ 703,400,000			1,500,000,000
Credit Facilities [Member]
Debt Instrument [Line Items]
Additional credit capacity				€ 250	£ 250
Number of revolving repurchase facilities closed | Facility			2	2	2
Weighted-average outstanding balance			$ 4,100,000,000			3,000,000,000
Aggregate borrowings			$ 4,068,249,000			$ 3,572,837,000
Weighted-average advance rate			78.70%	78.70%	78.70%	79.10%
Weighted-average initial maturity			1 year 6 months	1 year 6 months	1 year 6 months	1 year 6 months
Maximum Facility Size			$ 7,155,975,000			$ 5,479,180,000
Amount available for potential future fundings of loan			595,848,000			541,743,000
Secured debt agreements borrowings outstanding			$ 4,068,249,000			3,572,837,000
Credit Facilities [Member] | Joint Venture [Member] | Multifamily [Member]
Debt Instrument [Line Items]
Number of new credit facility | Facility			2	2	2
Additional credit capacity			$ 450,000,000
Credit Facilities [Member] | Wells Fargo [Member]
Debt Instrument [Line Items]
Aggregate borrowings			1,170,801,000			1,107,733,000
Maximum Facility Size			2,000,000,000			2,000,000,000
Amount available for potential future fundings of loan			$ 118,334,000			$ 232,209,000
Borrowings maturity term			Term matched	Term matched	Term matched
Credit Facilities [Member] | Asset-Specific Financings [Member]
Debt Instrument [Line Items]
Additional credit capacity			$ 500,000,000
Base Rate [Member] | GE Portfolio Acquisition Facility [Member] | Asset Specific Borrowings [Member] | Primary [Member]
Debt Instrument [Line Items]
Basis spread on debt obligation, in percent		1.75%
Base Rate [Member] | GE Portfolio Acquisition Facility [Member] | Asset Specific Borrowings [Member] | Year Four [Member] | Primary [Member]
Debt Instrument [Line Items]
Basis spread on debt obligation, in percent		1.80%
Base Rate [Member] | GE Portfolio Acquisition Facility [Member] | Asset Specific Borrowings [Member] | Year Five [Member] | Primary [Member]
Debt Instrument [Line Items]
Basis spread on debt obligation, in percent		1.85%
LIBOR [Member] | GE Portfolio Acquisition Facility [Member] | Weighted-Average All-in Cost of Credit [Member] | Asset Specific Borrowings [Member]
Debt Instrument [Line Items]
Basis spread on debt obligation, in percent			1.72%	1.72%	1.72%	1.83%
LIBOR [Member] | Credit Facilities [Member] | Weighted-Average Cash Coupon [Member]
Debt Instrument [Line Items]
Basis spread on debt obligation, in percent			1.90%	1.90%	1.90%	1.82%
LIBOR [Member] | Credit Facilities [Member] | Weighted-Average All-in Cost of Credit [Member]
Debt Instrument [Line Items]
Basis spread on debt obligation, in percent			2.12%	2.12%	2.12%	2.02%

Secured Debt Agreements, Net 58

Secured Debt Agreements, Net - Credit Facilities (Detail)	Dec. 31, 2017USD ($)	Dec. 31, 2017EUR (€)	Dec. 31, 2017GBP (£)	Dec. 31, 2016USD ($)	Dec. 31, 2016EUR (€)	Dec. 31, 2016GBP (£)
Line of Credit Facility [Line Items]
Potential	$ 4,664,097,000
Repurchase Borrowings Outstanding	4,068,249,000
Credit Facilities [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	7,155,975,000			$ 5,479,180,000
Collateral Assets	6,064,983,000			5,297,728,000
Potential	4,664,097,000			4,114,580,000
Repurchase Borrowings Outstanding	4,068,249,000			3,572,837,000
Available	595,848,000			541,743,000
Wells Fargo [Member] | Credit Facilities [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	2,000,000,000			2,000,000,000
Collateral Assets	1,680,325,000			1,718,874,000
Potential	1,289,135,000			1,339,942,000
Repurchase Borrowings Outstanding	1,170,801,000			1,107,733,000
Available	118,334,000			232,209,000
MetLife [Member] | Credit Facilities [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	1,000,000,000			1,000,000,000
Collateral Assets	1,039,231,000			1,106,017,000
Potential	807,164,000			862,454,000
Repurchase Borrowings Outstanding	807,164,000			862,454,000
Bank of America [Member] | Credit Facilities [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	750,000,000			750,000,000
Collateral Assets	765,049,000			794,881,000
Potential	573,542,000			617,694,000
Repurchase Borrowings Outstanding	573,542,000			617,694,000
Societe Generale [Member] | Credit Facilities [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	480,200,000	€ 400,000,000		420,680,000	€ 400,000,000
Collateral Assets	373,181,000			274,351,000
Potential	300,871,000			207,178,000
Repurchase Borrowings Outstanding	300,871,000			207,178,000
Deutsche Bank [Member] | Credit Facilities [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	500,000,000
Collateral Assets	399,203,000
Potential	295,743,000
Repurchase Borrowings Outstanding	295,743,000
Citibank [Member] | Credit Facilities [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	800,125,000			500,000,000
Collateral Assets	455,433,000			508,989,000
Potential	354,354,000			394,677,000
Repurchase Borrowings Outstanding	240,881,000			229,629,000
Available	113,473,000			165,048,000
Morgan Stanley [Member] | Credit Facilities [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	675,650,000		£ 500,000,000	308,500,000		£ 250,000,000
Collateral Assets	591,168,000			344,056,000
Potential	456,344,000			272,221,000
Repurchase Borrowings Outstanding	216,044,000			231,930,000
Available	240,300,000			40,291,000
JP Morgan [Member] | Credit Facilities [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	500,000,000			500,000,000
Collateral Assets	579,218,000			550,560,000
Potential	443,496,000			420,414,000
Repurchase Borrowings Outstanding	319,755,000			316,219,000
Available	123,741,000			$ 104,195,000
Bank of America - Multi. JV [Member] | Credit Facilities [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	200,000,000
Collateral Assets	106,950,000
Potential	85,560,000
Repurchase Borrowings Outstanding	85,560,000
Goldman Sachs - Multi. JV [Member] | Credit Facilities [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	250,000,000
Collateral Assets	75,225,000
Potential	57,888,000
Repurchase Borrowings Outstanding	$ 57,888,000

Secured Debt Agreements, Net 59

Secured Debt Agreements, Net - Credit Facilities (Parenthetical) (Detail) - Credit Facilities [Member]	Dec. 31, 2017USD ($)	Dec. 31, 2017EUR (€)	Dec. 31, 2017GBP (£)	Dec. 31, 2016USD ($)	Dec. 31, 2016EUR (€)	Dec. 31, 2016GBP (£)
Line of Credit Facility [Line Items]
Maximum Facility Size	$ 7,155,975,000			$ 5,479,180,000
Maximum Facility Size	7,155,975,000			5,479,180,000
Maximum Facility Size	7,155,975,000			5,479,180,000
Maximum Facility Size	7,155,975,000			5,479,180,000
Societe Generale [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	480,200,000	€ 400,000,000		420,680,000	€ 400,000,000
Maximum Facility Size	480,200,000	400,000,000		420,680,000	400,000,000
Maximum Facility Size	480,200,000	400,000,000		420,680,000	400,000,000
Maximum Facility Size	480,200,000	400,000,000		420,680,000	€ 400,000,000
Citibank [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	800,125,000			500,000,000
Maximum Facility Size	800,125,000			500,000,000
Maximum Facility Size	800,125,000			500,000,000
Maximum Facility Size	800,125,000			500,000,000
Citibank [Member] | $250.0 Million Facility [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	500,000,000
Maximum Facility Size	500,000,000
Maximum Facility Size	500,000,000
Maximum Facility Size	500,000,000
Citibank [Member] | $500.0 Million Facility [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	300,100,000	250,000,000
Maximum Facility Size	300,100,000	250,000,000
Maximum Facility Size	300,100,000	250,000,000
Maximum Facility Size	300,100,000	€ 250,000,000
Citibank [Member] | UK Pound Sterling 153.0 Million ($226.7 Million) Facility [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size				500,000,000
Maximum Facility Size				500,000,000
Maximum Facility Size				500,000,000
Maximum Facility Size				500,000,000
Morgan Stanley [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	675,650,000		£ 500,000,000	308,500,000		£ 250,000,000
Maximum Facility Size	675,650,000		500,000,000	308,500,000		250,000,000
Maximum Facility Size	675,650,000		500,000,000	308,500,000		250,000,000
Maximum Facility Size	675,650,000		£ 500,000,000	308,500,000		£ 250,000,000
JP Morgan [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	500,000,000			500,000,000
Maximum Facility Size	500,000,000			500,000,000
Maximum Facility Size	500,000,000			500,000,000
Maximum Facility Size	500,000,000			500,000,000
JP Morgan [Member] | $250.0 Million Facility [Member]
Line of Credit Facility [Line Items]
Maximum Facility Size	500,000,000			500,000,000
Maximum Facility Size	500,000,000			500,000,000
Maximum Facility Size	500,000,000			500,000,000
Maximum Facility Size	$ 500,000,000			$ 500,000,000

Secured Debt Agreements, Net 60

Secured Debt Agreements, Net - Summary of Key Terms of Credit Facilities (Detail) € in Thousands, £ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2017EUR (€)	Dec. 31, 2017GBP (£)
Line of Credit Facility [Line Items]
Outstanding Borrowings	$ 4,068,249
Potential Borrowings	$ 4,664,097
Rate	1.90%
Advance Rate	78.70%
Credit Facilities [Member]
Line of Credit Facility [Line Items]
Outstanding Borrowings	$ 4,068,249	$ 3,572,837
Potential Borrowings	$ 4,664,097	$ 4,114,580
Advance Rate	78.70%	79.10%
Credit Facilities [Member] | 1-Month USD LIBOR [Member]
Line of Credit Facility [Line Items]
Outstanding Borrowings	$ 3,798,619
Potential Borrowings	$ 4,275,789
Rate	1.87%
Advance Rate	78.60%
Credit Facilities [Member] | 3-Month EURIBOR [Member]
Line of Credit Facility [Line Items]
Outstanding Borrowings | €			€ 66,144
Potential Borrowings | €			€ 87,744
Rate	2.24%
Advance Rate	80.00%
Credit Facilities [Member] | 3-Month GBP LIBOR [Member]
Line of Credit Facility [Line Items]
Outstanding Borrowings | £				£ 140,771
Potential Borrowings | £				£ 209,406
Rate	2.24%
Advance Rate	78.60%
Credit Facilities [Member] | Wells Fargo [Member]
Line of Credit Facility [Line Items]
Guarantee	25.00%
Margin Call	Collateral marks only
Term/Maturity	Term matched
Outstanding Borrowings	$ 1,170,801	$ 1,107,733
Potential Borrowings	$ 1,289,135	1,339,942
Credit Facilities [Member] | MetLife [Member]
Line of Credit Facility [Line Items]
Guarantee	50.00%
Margin Call	Collateral marks only
Term/Maturity	Apr. 21, 2023
Outstanding Borrowings	$ 807,164	862,454
Potential Borrowings	$ 807,164	862,454
Credit Facilities [Member] | Bank of America [Member]
Line of Credit Facility [Line Items]
Guarantee	50.00%
Margin Call	Collateral marks only
Term/Maturity	May 21, 2021
Outstanding Borrowings	$ 573,542	617,694
Potential Borrowings	$ 573,542	617,694
Credit Facilities [Member] | Societe Generale [Member]
Line of Credit Facility [Line Items]
Guarantee	25.00%
Margin Call	Collateral marks only
Term/Maturity	Term matched
Outstanding Borrowings	$ 300,871	207,178
Potential Borrowings	$ 300,871	207,178
Credit Facilities [Member] | Deutsche Bank [Member]
Line of Credit Facility [Line Items]
Guarantee	35.00%
Margin Call	Collateral marks only
Term/Maturity	Term matched
Outstanding Borrowings	$ 295,743
Potential Borrowings	$ 295,743
Credit Facilities [Member] | Citibank [Member]
Line of Credit Facility [Line Items]
Guarantee	25.00%
Margin Call	Collateral marks only
Term/Maturity	Term matched
Outstanding Borrowings	$ 240,881	229,629
Potential Borrowings	$ 354,354	394,677
Credit Facilities [Member] | Morgan Stanley [Member]
Line of Credit Facility [Line Items]
Guarantee	25.00%
Margin Call	Collateral marks only
Term/Maturity	Mar. 3, 2020
Outstanding Borrowings	$ 216,044	231,930
Potential Borrowings	$ 456,344	272,221
Credit Facilities [Member] | JP Morgan [Member]
Line of Credit Facility [Line Items]
Guarantee	50.00%
Margin Call	Collateral marks only
Term/Maturity	Jan. 7, 2020
Outstanding Borrowings	$ 319,755	316,219
Potential Borrowings	$ 443,496	$ 420,414
Credit Facilities [Member] | Bank of America - Multi. JV [Member]
Line of Credit Facility [Line Items]
Guarantee	43.00%
Margin Call	Collateral marks only
Term/Maturity	Jul. 19, 2021
Outstanding Borrowings	$ 85,560
Potential Borrowings	$ 85,560
Credit Facilities [Member] | Goldman Sachs - Multi. JV [Member]
Line of Credit Facility [Line Items]
Guarantee	25.00%
Margin Call	Collateral marks only
Term/Maturity	Jul. 12, 2020
Outstanding Borrowings	$ 57,888
Potential Borrowings	$ 57,888

Secured Debt Agreements, Net 61

Secured Debt Agreements, Net - Summary of Key Terms of Credit Facilities (Parenthetical) (Detail) - Credit Facilities [Member]	12 Months Ended
	Dec. 31, 2017ExtensionOptions
MetLife [Member]
Line of Credit Facility [Line Items]
Maturity period	Includes five one-year extension options which may be exercised at our sole discretion.
Number of extension options	5
Term of maturity date	1 year
Bank of America [Member]
Line of Credit Facility [Line Items]
Maturity period	Includes two one-year extension options which may be exercised at our sole discretion.
Number of extension options	2
Term of maturity date	1 year

Secured Debt Agreements, Net 62

Secured Debt Agreements, Net - Summary of Asset-Specific Financings (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)SecurityLoan	Dec. 31, 2016USD ($)SecurityLoan
Participating Mortgage Loans [Line Items]
Collateral assets, Book Value	$ 677,296	$ 869,417
Financing provided, Book Value	517,088	676,333
Collateral assets, Principal Balance	682,259	876,083
Financing provided, Principal Balance	$ 518,864	$ 679,207
Collateral Assets [Member]
Participating Mortgage Loans [Line Items]
Weighted Average Term	2020-12	2020-08
Count | SecurityLoan	6	7
LIBOR [Member] | Collateral Assets [Member]
Participating Mortgage Loans [Line Items]
Weighted Average Yield/Cost Rate	4.76%	4.84%
Asset-Specific Financings [Member]
Participating Mortgage Loans [Line Items]
Weighted Average Term	2020-12	2020-08
Guarantee	$ 162,475	$ 231,585
Financing provided, Principal Balance	$ 518,864	$ 679,207
Count | SecurityLoan	6	7
Asset-Specific Financings [Member] | LIBOR [Member]
Participating Mortgage Loans [Line Items]
Weighted Average Yield/Cost Rate	2.50%	2.60%

Secured Debt Agreements, Net 63

Secured Debt Agreements, Net - Summary of Asset-Specific Financings (Parenthetical) (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Participating Mortgage Loans [Line Items]
Borrowings	$ 518,864	$ 679,207
Asset-Specific Financings [Member]
Participating Mortgage Loans [Line Items]
Borrowings	518,864	679,207
Cross Collateral Assets [Member] | Asset-Specific Financings [Member]
Participating Mortgage Loans [Line Items]
Borrowings	$ 394,800	$ 392,300

Loan Participations Sold, Net -

Loan Participations Sold, Net - Summary of Statistics for Loan Participations Sold (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)Loans	Dec. 31, 2016USD ($)Loans
Participating Mortgage Loans [Line Items]
Count | Loans	1	1
Principal Balance	$ 141,119	$ 419,560
Book Value, Total Loan	$ 10,056,732	$ 8,692,978
Weighted Average Term	2022-02	2019-12
Book Value	$ 80,415	$ 348,077
Senior Participation [Member]
Participating Mortgage Loans [Line Items]
Count | Loans	1	1
Principal Balance	$ 80,706	$ 349,633
Guarantee		$ 29,616
Weighted Average Term	2022-02	2019-12
Book Value	$ 80,415	$ 348,077
Loan Participations Sold [Member]
Participating Mortgage Loans [Line Items]
Book Value, Total Loan	$ 138,907	$ 416,233
LIBOR [Member]
Participating Mortgage Loans [Line Items]
Weighted Average Yield/Cost	5.94%	4.48%
LIBOR [Member] | Senior Participation [Member]
Participating Mortgage Loans [Line Items]
Weighted Average Yield/Cost	4.14%	2.72%

Loan Participations Sold, Net65

Loan Participations Sold, Net - Summary of Statistics for Loan Participations Sold (Parenthetical) (Detail) £ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2017GBP (£)
Participating Mortgage Loans [Line Items]
Guarantor obligations		$ 29,600,000		£ 24
Interest paid	$ 206,966,000	164,905,000	$ 127,429,000
Deferred financing costs	16,681,000	15,272,000
Loan Participations Sold [Member]
Participating Mortgage Loans [Line Items]
Interest expense	10,100,000	13,700,000
Interest paid	8,400,000	13,100,000
Deferred financing costs	$ 291,000	$ 1,600,000

Securitized Debt Obligations,66

Securitized Debt Obligations, Net - Schedule of Information on Securitized Debt Obligations (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)Loans	Jun. 30, 2017USD ($)
Debt Instrument [Line Items]
Principal Balance		$ 474,600
Financing Provided [Member]
Debt Instrument [Line Items]
Count | Loans	2
Principal Balance	$ 1,292,120
Book Value	$ 1,282,411
Financing Provided [Member] | Collateralized Loan Obligations [Member]
Debt Instrument [Line Items]
Count | Loans	1
Principal Balance	$ 817,500
Book Value	$ 808,083
Term	2035-06
Financing Provided [Member] | Single Asset Securitization [Member]
Debt Instrument [Line Items]
Count | Loans	1
Principal Balance	$ 474,620
Book Value	$ 474,328
Term	2033-06
Collateral Assets [Member]
Debt Instrument [Line Items]
Count | Loans	32
Principal Balance	$ 1,656,406
Book Value	$ 1,652,880
Collateral Assets [Member] | Collateralized Loan Obligations [Member]
Debt Instrument [Line Items]
Count | Loans	31
Principal Balance	$ 1,000,000
Book Value	$ 1,000,000
Term	2021-10
Collateral Assets [Member] | Single Asset Securitization [Member]
Debt Instrument [Line Items]
Count | Loans	1
Principal Balance	$ 656,406
Book Value	$ 652,880
Term	2023-06
LIBOR [Member] | Financing Provided [Member]
Debt Instrument [Line Items]
Wtd.Avg.Yield/Cost	1.83%
LIBOR [Member] | Financing Provided [Member] | Collateralized Loan Obligations [Member]
Debt Instrument [Line Items]
Wtd.Avg.Yield/Cost	1.76%
LIBOR [Member] | Financing Provided [Member] | Single Asset Securitization [Member]
Debt Instrument [Line Items]
Wtd.Avg.Yield/Cost	1.94%
LIBOR [Member] | Collateral Assets [Member]
Debt Instrument [Line Items]
Wtd.Avg.Yield/Cost	5.17%
LIBOR [Member] | Collateral Assets [Member] | Collateralized Loan Obligations [Member]
Debt Instrument [Line Items]
Wtd.Avg.Yield/Cost	5.16%
LIBOR [Member] | Collateral Assets [Member] | Single Asset Securitization [Member]
Debt Instrument [Line Items]
Wtd.Avg.Yield/Cost	3.60%

Securitized Debt Obligations,67

Securitized Debt Obligations, Net - Schedule of Information on Securitized Debt Obligations (Parenthetical) (Detail) $ in Millions	Dec. 31, 2017USD ($)	Dec. 31, 2017USD ($)
Debt Instrument [Line Items]
Percentage of loans financed by securitized debt obligations earned floating rate of interest	98.00%
Interest expense on securitized debt obligations		$ 8.5
Collateral Assets [Member] | Single Asset Securitization [Member]
Debt Instrument [Line Items]
Total loan amount, securitized	$ 500	$ 500

Securitized Debt Obligations,68

Securitized Debt Obligations, Net - Additional Information (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Loans Managed, Securitized or Asset-backed Financing Arrangement [Abstract]
Securitized debt obligations	$ 1,282,412	$ 0

Convertible Notes, Net - Summar

Convertible Notes, Net - Summary of Outstanding Convertible Senior Notes (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
5.25% Convertible Senior Notes [Member]
Debt Instrument [Line Items]
Convertible Note Issuance	2013-11
Face Value	$ 172,500
Coupon Rate	5.25%
All-in Cost	5.87%
Conversion Rate	36.1380
Maturity	2018-12
4.38% Convertible Senior Notes [Member]
Debt Instrument [Line Items]
Convertible Note Issuance	2017-05
Face Value	$ 402,500
Coupon Rate	4.38%
All-in Cost	4.85%
Conversion Rate	28.0324
Maturity	2022-05

Convertible Notes, Net - Summ70

Convertible Notes, Net - Summary of Outstanding Convertible Senior Notes (Parenthetical) (Detail)	Jun. 28, 2017USD ($)$ / shares	Dec. 31, 2017USD ($)$ / shares	Dec. 29, 2017$ / shares
5.25% Convertible Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, conversion price			$ 32.18
Convertible Notes, debt conversion, common stock issued, in percent		36.1380
5.25% Convertible Senior Notes [Member] | Class A Common Stock [Member]
Debt Instrument [Line Items]
Convertible Notes, debt conversion, principal amount | $		$ 1,000
4.38% Convertible Senior Notes [Member]
Debt Instrument [Line Items]
Convertible Notes, debt conversion, common stock issued, in percent		28.0324
4.38% Convertible Senior Notes [Member] | Class A Common Stock [Member]
Debt Instrument [Line Items]
Convertible Notes, debt conversion, principal amount | $		$ 1,000
Convertible Senior Notes [Member] | Class A Common Stock [Member]
Debt Instrument [Line Items]
Convertible Notes, debt conversion, principal amount | $	$ 1,000
Debt instrument, conversion price	$ 27.99
Convertible Notes, debt conversion, common stock issued, in percent	35.7236
5.25% Convertible Senior Notes Issued in November 2013 [Member] | Class A Common Stock [Member]
Debt Instrument [Line Items]
Debt instrument, conversion price		$ 27.67
4.38% Convertible Senior Notes Issued in May 2017 [Member] | Class A Common Stock [Member]
Debt Instrument [Line Items]
Debt instrument, conversion price		$ 35.67

Convertible Notes, Net - Additi

Convertible Notes, Net - Additional Information (Detail) - USD ($)	1 Months Ended		12 Months Ended
	May 31, 2017	Nov. 30, 2013	Dec. 31, 2017	Dec. 29, 2017	Sep. 30, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Convertible notes, net			$ 563,911,000			$ 166,762,000
Accrued interest payable			14,162,000			9,049,000
5.25% Convertible Senior Notes [Member]
Debt Instrument [Line Items]
Convertible Senior Notes, Principal amount			$ 172,500,000
Description of Convertible Notes conversion			The Convertible Notes are convertible at the holders’ option into shares of our class A common stock, only under specific circumstances, prior to the close of business on August 31, 2018 and January 31, 2022, for the November 2013 and May 2017 convertible notes, respectively, at the applicable conversion rate in effect on the conversion date.
Debt instrument, conversion price				$ 32.18
Discount upon issuance of Convertible Notes		$ 9,100,000
Debt issuance costs		$ 4,100,000
Convertible Notes, assumed effective interest rate		6.50%
Convertible Senior Notes, Interest rate including amortization of discount upon issuance		7.16%
Accrued interest payable			$ 3,700,000			$ 755,000
4.38% Convertible Senior Notes [Member]
Debt Instrument [Line Items]
Convertible Senior Notes, Principal amount			402,500,000
Discount upon issuance of Convertible Notes	$ 979,000
Debt issuance costs	$ 8,400,000
Convertible Notes, assumed effective interest rate	4.57%
Convertible Senior Notes, Interest rate including amortization of discount upon issuance	4.91%
May 2017 Convertible Notes [Member]
Debt Instrument [Line Items]
Convertible Senior Notes, Principal amount	$ 287,500,000				$ 115,000,000
Convertible notes, net			$ 402,500,000

Convertible Notes, Net - Summ72

Convertible Notes, Net - Summary of Details about Interest Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Discount and issuance cost amortization	$ 21,988	$ 19,339	$ 20,708
Convertible Senior Note [Member]
Debt Instrument [Line Items]
Cash coupon	19,259	9,056	9,056
Discount and issuance cost amortization	4,040	2,736	2,571
Total interest expense	$ 23,299	$ 11,792	$ 11,627

Convertible Notes, Net - Summ73

Convertible Notes, Net - Summary of Details of Net Book Value of Convertible Note (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Deferred financing costs	$ (16,681)	$ (15,272)
Net book value	563,911	166,762
Convertible Senior Note [Member]
Debt Instrument [Line Items]
Face Value	575,000	172,500
Unamortized discount	(10,279)	(5,532)
Deferred financing costs	(810)	(206)
Net book value	$ 563,911	$ 166,762

Derivative Financial Instrume74

Derivative Financial Instruments - Summary of Outstanding Foreign Exchange Derivatives Designated as Net Investment Hedges of Foreign Currency Risk (Detail) - Sell [Member] - Designated as Hedging Instrument [Member] - Foreign Exchange Forward [Member] - Net Investment Hedges [Member] € in Thousands, £ in Thousands, CAD in Thousands	Dec. 31, 2017GBP (£)DerivativeInstrument	Dec. 31, 2017CADDerivativeInstrument	Dec. 31, 2016EUR (€)DerivativeInstrument	Dec. 31, 2016GBP (£)DerivativeInstrument	Dec. 31, 2016CADDerivativeInstrument
EUR [Member]
Derivative [Line Items]
Number of Instruments			1	1	1
Notional Amount | €			€ 44,900
GBP [Member]
Derivative [Line Items]
Number of Instruments	1	1	2	2	2
Notional Amount | £	£ 112,700			£ 141,900
CAD [Member]
Derivative [Line Items]
Number of Instruments	1	1	2	2	2
Notional Amount | CAD		CAD 95,100			CAD 122,900

Derivative Financial Instrume75

Derivative Financial Instruments - Summary of Outstanding Interest Rate Derivatives Designated as Cash Flow Hedges of Interest Rate Risk (Detail) - Cash Flow Hedges [Member] - Designated as Hedging Instrument [Member] £ in Thousands, CAD in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)DerivativeInstrument	Dec. 31, 2016USD ($)DerivativeInstrument	Dec. 31, 2017CADDerivativeInstrument	Dec. 31, 2016GBP (£)DerivativeInstrument	Dec. 31, 2016CADDerivativeInstrument
Interest Rate Caps [Member] | GBP [Member] | GBP LIBOR [Member]
Derivative [Line Items]
Number of Instruments		1		1	1
Notional Amount | £				£ 15,142
Strike		2.00%		2.00%	2.00%
Wtd. Avg. Maturity (Years)		3 months 19 days
Interest Rate Caps [Member] | USD [Member] | USD LIBOR [Member]
Derivative [Line Items]
Number of Instruments	9	21	9	21	21
Notional Amount | $	$ 204,248	$ 802,256
Strike	2.40%	2.00%	2.40%	2.00%	2.00%
Wtd. Avg. Maturity (Years)	1 year 6 months	4 months 24 days
Interest Rate Caps [Member] | CAD [Member] | CDOR [Member]
Derivative [Line Items]
Number of Instruments	3	5	3	5	5
Notional Amount | CAD			CAD 23,370		CAD 400,035
Strike	2.00%	2.00%	2.00%	2.00%	2.00%
Wtd. Avg. Maturity (Years)	3 months 19 days	4 months 24 days
Interest Rate Swaps [Member] | CAD [Member] | CDOR [Member]
Derivative [Line Items]
Number of Instruments	4	4	4	4	4
Notional Amount | CAD			CAD 108,094		CAD 108,271
Strike	1.00%	1.00%	1.00%	1.00%	1.00%
Wtd. Avg. Maturity (Years)	1 year 4 months 24 days	2 years 4 months 24 days

Derivative Financial Instrume76

Derivative Financial Instruments - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of collateral posted for the net assets/liability positions	$ 4,120,000	$ 79,000
Not Designated as Hedging Instrument [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivatives recorded losses during the period	449,000	$ 1,900,000	$ 698,000
Interest Rate Swaps/Derivatives [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Reclassification from accumulated other comprehensive income (loss) as increase to interest income	$ 619,000
Reclassification from accumulated other comprehensive income, time period	12 months

Derivative Financial Instrume77

Derivative Financial Instruments - Summary of Non-designated Hedges (Detail) - Not Designated as Hedging Instrument [Member] € in Thousands, CAD in Thousands, $ in Thousands	Dec. 31, 2017EUR (€)DerivativeInstrument	Dec. 31, 2016USD ($)DerivativeInstrument	Dec. 31, 2016EUR (€)DerivativeInstrument	Dec. 31, 2016CADDerivativeInstrument
EUR [Member] | Buy GBP / Sell EUR Forward [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Number of Instruments	1	1	1	1
Notional Amount | €	€ 12,857		€ 12,857
USD [Member] | Interest Rate Swaps/Derivatives [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Number of Instruments		3	3	3
Notional Amount | $		$ 256,875
CAD [Member] | Interest Rate Swaps/Derivatives [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Number of Instruments		2	2	2
Notional Amount | CAD				CAD 37,221

Derivative Financial Instrume78

Derivative Financial Instruments - Summary of Fair Value of Derivative Financial Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Fair Value of Derivatives in an Asset Position	$ 1,214	$ 4,086
Fair Value of Derivatives in a Liability Position	4,911	210
Designated as Hedging Instrument [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Fair Value of Derivatives in an Asset Position	1,214	3,599
Fair Value of Derivatives in a Liability Position	4,872	210
Designated as Hedging Instrument [Member] | Foreign Currency Contracts [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Fair Value of Derivatives in an Asset Position		3,268
Fair Value of Derivatives in a Liability Position	4,872	210
Designated as Hedging Instrument [Member] | Interest Rate Swaps/Derivatives [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Fair Value of Derivatives in an Asset Position	1,214	331
Not Designated as Hedging Instrument [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Fair Value of Derivatives in an Asset Position		487
Fair Value of Derivatives in a Liability Position	39
Not Designated as Hedging Instrument [Member] | Foreign Currency Contracts [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Fair Value of Derivatives in an Asset Position		$ 487
Fair Value of Derivatives in a Liability Position	$ 39

Derivative Financial Instrume79

Derivative Financial Instruments - Summary of Effect of Derivative Financial Instruments on Consolidated Statements of Operations (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of (Loss) Gain Recognized in OCI on Derivatives	$ (21,459)	$ 25,444	$ 23,882
Amount of Loss Reclassified from Accumulated OCI into Income	(831)	(798)	(4)
Net Investment [Member] | Foreign Currency Contracts [Member] | Interest Expense [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of (Loss) Gain Recognized in OCI on Derivatives	(22,216)	25,355	25,356
Cash Flow Hedges [Member] | Interest Rate Swaps/Derivatives [Member] | Interest Expense [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of (Loss) Gain Recognized in OCI on Derivatives	757	89	(1,474)
Amount of Loss Reclassified from Accumulated OCI into Income	$ (831)	$ (798)	$ (4)

Derivative Financial Instrume80

Derivative Financial Instruments - Summary of Effect of Derivative Financial Instruments on Consolidated Statements of Operations (Parenthetical) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Interest and related expenses	$ 234,870	$ 184,270	$ 152,416
Amount of Loss Reclassified from Accumulated OCI into Income	831	798	4
Foreign Currency Contracts [Member] | Net Investment Hedges [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Net cash settlements on our foreign currency forward contracts	14,200
Net cash settlements received		26,800	18,800
Interest Rate Swaps/Derivatives [Member] | Cash Flow Hedges [Member] | Interest Expense [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of Loss Reclassified from Accumulated OCI into Income	$ 831	$ 798	$ 4

Equity - Additional Information

Equity - Additional Information (Detail) - USD ($)	Jan. 16, 2018	Dec. 14, 2017	May 09, 2014	Jun. 30, 2015	May 31, 2015	Apr. 30, 2015	May 31, 2013	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Mar. 25, 2014
Class of Stock [Line Items]
Total stock, shares authorized								300,000,000
Common stock, shares authorized								200,000,000	200,000,000
Preferred stock, shares authorized								100,000,000
Preferred stock issued								0
Preferred stock outstanding								0
Plan adoption date								Mar. 25, 2014
Number of shares sold during period							25,875,000	12,421,401	1,070	34,780,622
Dividends declared per share of common stock		$ 0.62						$ 2.48	$ 2.48	$ 2.28
Date of dividend paid								Jan. 16, 2018
Date of dividend declared								Dec. 14, 2017
Record date of dividend paid								Dec. 29, 2017
Accumulated other comprehensive loss								$ 29,706,000	$ 56,202,000
Net realized and unrealized gains related to changes in fair value of derivative instruments								30,600,000	51,300,000
Cumulative unrealized currency translation adjustment on assets and liabilities denominated in foreign currencies								60,300,000	107,500,000
Multifamily [Member] | Joint Venture [Member]
Class of Stock [Line Items]
Total equity								42,300,000
Equity interests owned by Blackstone Mortgage Trust, Inc.								36,000,000
Non-controlling interests								$ 6,300,000	$ 0
Subsequent Events [Member]
Class of Stock [Line Items]
Dividends paid	$ 66,900,000
Dividends paid per common stock	$ 0.62
Dividend Reinvestment and Direct Stock Purchase Plan [Member]
Class of Stock [Line Items]
Reserved for issuance of class A common stock								9,996,926			10,000,000
Class A Common Stock [Member]
Class of Stock [Line Items]
Common stock, shares issued under dividend reinvestment program								1,401	1,070	597
Number of shares sold during period				11,500,000	280,025	23,000,000		12,420,000		34,780,025
ATM Agreements [Member]
Class of Stock [Line Items]
Aggregate sales price			$ 200,000,000
Number of shares sold during period								0	0
Aggregate sales price remaining available								$ 188,600,000

Equity - Summary of Class A Com

Equity - Summary of Class A Common Stock Issuances (Detail) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended				12 Months Ended
	Jun. 30, 2015	May 31, 2015	Apr. 30, 2015	May 31, 2013	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Class of Stock [Line Items]
Shares issued				25,875,000	12,421,401	1,070	34,780,622
Net proceeds					$ 391,558	$ 27	$ 1,029,540
Class A Common Stock [Member]
Class of Stock [Line Items]
Shares issued	11,500,000	280,025	23,000,000		12,420,000		34,780,025
Share issue price					$ 31.57		$ 29.64
Net proceeds					$ 391,558		$ 1,029,535

Equity - Summary of Class A C83

Equity - Summary of Class A Common Stock Issuances (Parenthetical) (Detail) - shares	1 Months Ended				12 Months Ended
	Jun. 30, 2015	May 31, 2015	Apr. 30, 2015	May 31, 2013	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Class of Stock [Line Items]
Shares issued				25,875,000	12,421,401	1,070	34,780,622
Class A Common Stock [Member]
Class of Stock [Line Items]
Shares issued	11,500,000	280,025	23,000,000		12,420,000		34,780,025

Equity - Schedule of Movement i

Equity - Schedule of Movement in Outstanding Shares of Class A Common Stock, Restricted Class A Common Stock and Deferred Stock Units (Detail) - shares	1 Months Ended	12 Months Ended
	May 31, 2013	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Equity [Abstract]
Beginning balance		94,709,290	93,843,847	58,388,808
Issuance of class A common stock	25,875,000	12,421,401	1,070	34,780,622
Issuance of restricted class A common stock, net		922,196	836,867	651,815
Issuance of deferred stock units		28,190	27,506	22,602
Ending balance		108,081,077	94,709,290	93,843,847

Equity - Schedule of Movement85

Equity - Schedule of Movement in Outstanding Shares of Class A Common Stock, Restricted Class A Common Stock and Deferred Stock Units (Parenthetical) (Detail) - Class A Common Stock [Member] - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Class of Stock [Line Items]
Deferred stock units held by directors	197,217	169,027	141,521
Common stock, shares issued under dividend reinvestment program	1,401	1,070	597

Equity - Schedule of Dividend A

Equity - Schedule of Dividend Activity (Detail) - $ / shares	Dec. 14, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Equity [Abstract]
Dividends declared per share of common stock	$ 0.62	$ 2.48	$ 2.48	$ 2.28
Percent taxable as ordinary dividends		97.20%	92.77%	92.36%
Percent taxable as capital gain dividends		2.80%	7.23%	7.64%
Percentage of taxable dividend		100.00%	100.00%	100.00%

Equity - Schedule of Basic and

Equity - Schedule of Basic and Diluted Earnings Per Share, or EPS, Based on Weighted-Average of Both Restricted and Unrestricted Class A Common Stock Outstanding (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Net income	$ 57,891	$ 57,722	$ 50,613	$ 51,405	$ 53,375	$ 64,794	$ 63,081	$ 57,047	$ 217,631	$ 238,297	$ 196,829
Weighted-average shares outstanding, basic and diluted									95,963,616	94,165,351	81,740,227
Per share amount, basic and diluted	$ 0.59	$ 0.61	$ 0.53	$ 0.54	$ 0.57	$ 0.69	$ 0.67	$ 0.61	$ 2.27	$ 2.53	$ 2.41

Other Expenses - Additional Inf

Other Expenses - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Management fee - percent of outstanding equity balance	1.50%
Incentive fee computation-percent of the product per agreement	20.00%
Incentive fee computation-percent of outstanding Equity per annum	7.00%
Management fees description	Manager is entitled to an incentive fee in an amount equal to the product of (i) 20% and (ii) the excess of (a) our Core Earnings (as defined in our Management Agreement) for the previous 12 month period over (b) an amount equal to 7.00% per annum multiplied by our outstanding Equity, provided that our Core Earnings over the prior three-year period is greater than zero. Core Earnings, as defined in our Management Agreement, is generally equal to our net income (loss) prepared in accordance with GAAP, excluding (i) certain non-cash items (ii) the net income (loss) related to our legacy portfolio and (iii) incentive management fees.
Management fees	$ 54,841	$ 55,959	$ 42,886
Accrued management and incentive fees payable	14,284	12,798
CT Legacy Partners [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total incentive compensation payments		1,094	2,177
Manager [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Management fees	38,600	38,000	32,200
Total incentive compensation payments	16,200	18,000	10,700
Accrued management and incentive fees payable	$ 14,300	12,800
Incentive Awards Plan [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Percentage of the dividends paid to common equity holders created employee pool	6.75%
Incentive Awards Plan [Member] | CT Legacy Partners [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Recognized expenses for incentive plan		$ 1,100	$ 2,200
Incentive Awards Plan [Member] | Manager [Member] | CT Legacy Partners [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total incentive compensation payments	$ 2,800

Other Expenses - Schedule of Ge

Other Expenses - Schedule of General and Administrative Expenses (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Professional services	$ 3,812	$ 3,311	$ 3,156
Operating and other costs	1,903	2,147	2,709
Subtotal	5,715	5,458	15,488
Non-cash and CT Legacy Portfolio compensation expenses
Restricted class A common stock earned	23,593	19,052	12,966
Subtotal	24,031	22,089	20,888
Other expenses	176	169	333
General and administrative expenses	29,922	27,716	36,709
General Electrical Capital Corporation [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
GE transaction costs			9,623
General and Administrative Expense [Member]
Non-cash and CT Legacy Portfolio compensation expenses
Director stock-based compensation	438	375	375
Manager [Member]
Non-cash and CT Legacy Portfolio compensation expenses
Management incentive awards plan	16,200	18,000	10,700
General and administrative expenses	$ 29,746	27,547	36,376
CT Legacy Partners [Member]
Non-cash and CT Legacy Portfolio compensation expenses
Management incentive awards plan		1,094	2,177
CT Opportunity Partners I, LP [Member]
Non-cash and CT Legacy Portfolio compensation expenses
Management incentive awards plan		$ 1,568	$ 5,370

Other Expenses - Schedule of 90

Other Expenses - Schedule of General and Administrative Expenses (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2017USD ($)
Multifamily [Member] | Joint Venture [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Expenses related Multifamily Joint Venture.	$ 232,000

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	1 Months Ended	12 Months Ended
	May 31, 2013	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Tax Credit Carryforward [Line Items]
Annual distribution of net taxable income for U.S. federal income tax not to apply to our earnings that we distribute (percent)			90.00%
Net taxable income subject to distribution (percent)			100.00%
Excise tax rate			4.00%
Income tax provision			$ 314,000	$ 196,000	$ 504,000
Deferred tax assets			0	0
Deferred tax liabilities			$ 0	$ 0
U.S. federal corporate income tax rate			35.00%
Common stock, shares issued	25,875,000		12,421,401	1,070	34,780,622
Net operating losses carried forward			$ 159,000,000
NOLs expiration date			Dec. 31, 2029
Scenario, Forecast [Member]
Tax Credit Carryforward [Line Items]
U.S. federal corporate income tax rate		21.00%
Internal Revenue Service [Member]
Tax Credit Carryforward [Line Items]
Net operating losses limitations			The availability of our NOLs is generally limited to $2.0 million per annum
Earliest Tax Year [Member]
Tax Credit Carryforward [Line Items]
Open tax year			2,014
Latest Tax Year [Member]
Tax Credit Carryforward [Line Items]
Open tax year			2,017

Stock-Based Incentive Plans - A

Stock-Based Incentive Plans - Additional Information (Detail) $ / shares in Units, $ in Millions	Dec. 31, 2017USD ($)Plansshares	Dec. 31, 2017USD ($)Plansshares	Dec. 29, 2017$ / shares	Dec. 31, 2016shares	Dec. 31, 2015shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of benefit plans | Plans	7	7
Restricted Class A Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted shares, vesting period		3 years
Number of shares of restricted class A common stock outstanding	1,484,175	1,484,175		1,309,995	1,114,908
Unrecognized compensation cost relating to nonvested share-based compensation | $	$ 45.6	$ 45.6
Unrecognized compensation cost expected to be recognized over weighted average period	1 year 2 months 12 days
Nonvested share-based compensation, closing price | $ / shares			$ 32.18
Expired Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available under plan	0	0
Vest in 2020 [Member] | Restricted Class A Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of restricted class A common stock outstanding	212,552	212,552
Vest in 2018 [Member] | Restricted Class A Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of restricted class A common stock outstanding	754,597	754,597
Vest in 2019 [Member] | Restricted Class A Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of restricted class A common stock outstanding	517,026	517,026
Class A Common Stock [Member] | Stock Incentive Current Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available under plan	805,799	805,799
Maximum number of shares available under plan	2,400,000	2,400,000

Stock-Based Incentive Plans - M

Stock-Based Incentive Plans - Movement in Outstanding Shares of Restricted Class A Common Stock and Weighted-Average Grant Date Fair Value Per Share (Detail) - Restricted Class A Common Stock [Member] - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted Class A Common Stock, Beginning Balance	1,309,995	1,114,908
Restricted Class A Common Stock, Granted	925,319	872,294
Restricted Class A Common Stock, Vested	(748,016)	(641,780)
Restricted Class A Common Stock, Forfeited	(3,123)	(35,427)
Restricted Class A Common Stock, Ending Balance	1,484,175	1,309,995
Weighted-Average Grant Date Fair Value Per Share, Beginning Balance	$ 28.68	$ 27.64
Weighted-Average Grant Date Fair Value Per Share, Granted	31.78	28.88
Weighted-Average Grant Date Fair Value Per Share, Vested	28.69	27.21
Weighted-Average Grant Date Fair Value Per Share, Forfeited	27.37	27.49
Weighted-Average Grant Date Fair Value Per Share, Ending Balance	$ 30.61	$ 28.68

Fair Values - Assets and Liabil

Fair Values - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Assets
Derivatives	$ 1,214	$ 4,086
Liabilities
Derivatives	4,911	210
Recurring [Member]
Assets
Derivatives	1,214	4,086
Liabilities
Derivatives	4,911	210
Level 2 [Member] | Recurring [Member]
Assets
Derivatives	1,214	4,086
Liabilities
Derivatives	$ 4,911	$ 210

Fair Values - Reconciliation of

Fair Values - Reconciliation of Beginning and Ending Balances of Assets Measured at Fair Value on Recurring Basis Using Level 3 Inputs (Detail) - Level 3 [Member] - Recurring [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance, beginning	$ 12,561
Proceeds from investment realizations	(3,609)
Transfers out of level 3	(20,745)
Adjustments to fair value included in earnings
Gain on investments at fair value	$ 11,793

Fair Values - Reconciliation 96

Fair Values - Reconciliation of Beginning and Ending Balances of Assets Measured at Fair Value on Recurring Basis Using Level 3 Inputs (Parenthetical) (Detail) $ in Millions	3 Months Ended
	Jun. 30, 2016USD ($)
Level 1 [Member] | Recurring [Member] | Collateralized Debt Obligations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfer out of level 3	$ 20.7

Fair Values - Schedule of Detai

Fair Values - Schedule of Details of Carrying Amount, Face Amount, and Fair Value of Financial Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financial assets
Cash and cash equivalents, face amount	$ 69,654	$ 75,567
Restricted cash	32,864
Loans receivable, net, face amount	10,108,226	8,727,218
Financial liabilities
Secured debt agreements, net, face amount	5,290,536	5,731,626
Loan participations sold, net	80,415	348,077
Loan participations sold, net, face amount	141,119	419,560
Securitized debt obligations, net	1,282,412	0
Securitized debt obligations, net,face amount	1,292,120
Carrying Amount [Member]
Financial assets
Cash and cash equivalents	69,654	75,567
Restricted cash	32,864
Loans receivable, net	10,056,732	8,692,978
Financial liabilities
Secured debt agreements, net	5,273,855	5,716,354
Loan participations sold, net	80,415	348,077
Securitized debt obligations, net	1,282,412
Convertible notes, net	563,911	166,762
Fair Value [Member]
Financial assets
Cash and cash equivalents	69,654	75,567
Restricted cash	32,864
Loans receivable, net	10,112,331	8,733,784
Financial liabilities
Secured debt agreements, net	5,290,536	5,731,626
Loan participations sold, net	80,706	349,633
Securitized debt obligations, net	1,292,589
Convertible notes, net	610,201	191,763
Convertible Senior Note [Member]
Financial liabilities
Convertible notes, net, face amount	575,000	172,500
Senior Participation [Member]
Financial liabilities
Loan participations sold, net	80,415	348,077
Loan participations sold, net, face amount	$ 80,706	$ 349,633

Variable Interest Entities - Su

Variable Interest Entities - Summary of Assets and Liabilities of Consolidated CLO and Single Asset Securitization VIE (Detail) $ in Thousands	Dec. 31, 2017USD ($)
Assets:
Assets	$ 1,500,000
VIE [Member]
Assets:
Assets	1,502,407
Liabilities:
Liabilities	1,283,791
VIE [Member] | Loans Receivable [Member]
Assets:
Assets	1,500,000
VIE [Member] | Other Assets [Member]
Assets:
Assets	2,407
VIE [Member] | Securitized Debt Obligations, Net [Member]
Liabilities:
Liabilities	1,282,412
VIE [Member] | Other Liabilities [Member]
Liabilities:
Liabilities	$ 1,379

Transactions with Related Par99

Transactions with Related Parties - Additional Information (Detail)	1 Months Ended					3 Months Ended	12 Months Ended
	Aug. 31, 2015USD ($)	Jun. 30, 2015USD ($)shares	May 31, 2015shares	Apr. 30, 2015USD ($)$ / sharesshares	May 31, 2013shares	Dec. 31, 2015USD ($)shares	Dec. 31, 2017USD ($)SecurityLoanshares	Dec. 31, 2016USD ($)SecurityLoanshares	Dec. 31, 2015USD ($)shares	Dec. 29, 2017$ / shares	Jun. 30, 2017USD ($)	Apr. 10, 2015USD ($)	Jun. 20, 2014USD ($)
Related Party Transaction [Line Items]
Accrued management and incentive fees payable							$ 14,284,000	$ 12,798,000
Common stock value							1,079,000	945,000
Non-cash expenses							$ 24,031,000	$ 21,899,000	$ 20,717,000
Number of Loans | SecurityLoan							110	107
Fully subscribed offering costs											$ 474,600,000
Loan face amount							$ 10,108,226,000	$ 8,727,218,000
Common stock, shares issued | shares					25,875,000		12,421,401	1,070	34,780,622
CT CDO I [Member]
Related Party Transaction [Line Items]
Principal balance of loans													$ 27,000,000
Carrying value of loans													27,000,000
Net proceeds to investments from collateral property						$ 0
General Electrical Capital Corporation [Member]
Related Party Transaction [Line Items]
Purchase price of Loan Portfolio		$ 4,700,000,000
General Electrical Capital Corporation [Member] | Loan Purchase Commitments [Member] | Commercial Portfolio Segment [Member]
Related Party Transaction [Line Items]
Portfolio of loans acquired												$ 4,600,000,000
Purchase price of Loan Portfolio												$ 23,000,000,000
CT Legacy Partners [Member]
Related Party Transaction [Line Items]
Total incentive compensation payments								$ 1,094,000	$ 2,177,000
Principal balance of loans													8,000,000
Carrying value of loans													$ 0
Net proceeds to investments from collateral property						$ 0
Maximum [Member]
Related Party Transaction [Line Items]
Participation percentage in individual tranches, represented by investment vehicles							49.00%
Restricted Class A Common Stock [Member]
Related Party Transaction [Line Items]
Shares held | shares						1,114,908	1,484,175	1,309,995	1,114,908
Restricted shares, vesting period							3 years
Public offing price per share | $ / shares										$ 32.18
Class A Common Stock [Member]
Related Party Transaction [Line Items]
Common stock, shares issued | shares		11,500,000	280,025	23,000,000			12,420,000		34,780,025
Manager [Member]
Related Party Transaction [Line Items]
Management Agreement expiration date							Dec. 19, 2018
Management Agreement renewal term, description							The current term of which expires on December 19, 2018, and will be automatically renewed for a one-year term each anniversary thereafter unless earlier terminated.
Management Agreement renewal term, period							1 year
Accrued management and incentive fees payable							$ 14,300,000	$ 12,800,000
Management fees paid to Manager							53,400,000	57,500,000	$ 34,800,000
Expenses reimbursed to Manager							$ 621,000	$ 462,000	311,000
Number of Loans | SecurityLoan							6	3
Expenses incurred on insurance agency transaction of affiliate with loan borrower							$ 0	$ 0
Income received on insurance agency transaction of affiliate with loan borrower							0	0
Securitized debt obligations issued, aggregate amount											$ 72,900,000
Total incentive compensation payments							16,200,000	18,000,000	10,700,000
Manager [Member] | Senior Loan [Member]
Related Party Transaction [Line Items]
Loan face amount								79,000,000
Manager [Member] | CT Legacy Partners [Member]
Related Party Transaction [Line Items]
Net sale proceeds								41,300,000
Net sales proceeds, amount received								3,600,000	37,300,000
Manager [Member] | Incentive Awards Plan [Member] | CT Legacy Partners [Member]
Related Party Transaction [Line Items]
Total incentive compensation payments							$ 2,800,000
Incentive compensation amount paid								244,000	2,500,000
Manager [Member] | Class A Common Stock [Member] | April 2015 Stock Offering [Member]
Related Party Transaction [Line Items]
Common stock, shares issued | shares				1,885,245
Public offing price per share | $ / shares				$ 30.5
Manager [Member] | Class A Common Stock [Member] | Restricted Class A Common Stock [Member]
Related Party Transaction [Line Items]
Shares held | shares							869,058
Common stock value							$ 26,900,000
Non-cash expenses							$ 11,700,000	9,600,000	6,700,000
Manager [Member] | Class A Common Stock [Member] | Restricted Class A Common Stock [Member] | Stock Incentive Current Plan [Member]
Related Party Transaction [Line Items]
Restricted shares, vesting period							3 years
Independent Members of Board Of Directors [Member] | General Electrical Capital Corporation [Member] | Loan Purchase Commitments [Member] | Commercial Portfolio Segment [Member]
Related Party Transaction [Line Items]
Payments for special committee services	$ 53,000
Affiliate of our Manager [Member]
Related Party Transaction [Line Items]
Accrued special servicing fee payable						$ 1,100,000			1,100,000
Affiliates of Manager [Member] | Third-Party Service Provider [Member]
Related Party Transaction [Line Items]
Administrative services expenses incurred							$ 411,000	385,000	372,000
Affiliates of Manager [Member] | Class A Common Stock [Member] | April 2015 Stock Offering [Member]
Related Party Transaction [Line Items]
Compensation made to co-manager for stock offering				$ 761,000
BXMT Advisors Limited Liability Company and Affiliates [Member]
Related Party Transaction [Line Items]
Payments of preferred distributions to affiliate of our Manager							$ 0	$ 616,000	$ 1,300,000

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	1 Months Ended	12 Months Ended
	Apr. 30, 2017USD ($)	Dec. 31, 2017USD ($)LoansDirectors	Dec. 31, 2016USD ($)
Commitments And Contingencies [Line Items]
Commitments expiration period		4 years
Number of loans receivable | Loans		74
Number of independent directors entitled to annual compensation | Directors		5
Loans Receivable [Member]
Commitments And Contingencies [Line Items]
Unfunded loan commitments		$ 1,573,107,000	$ 882,472,000
Five Independent Board of Directors [Member]
Commitments And Contingencies [Line Items]
Annual cash compensation	$ 125,000	175,000
Annual cash compensation paid in cash		75,000
Annual cash compensation paid in the form of deferred stock units		100,000
Chairperson of Audit Committee [Member]
Commitments And Contingencies [Line Items]
Annual cash compensation	$ 12,000	20,000
Audit Committee Members [Member]
Commitments And Contingencies [Line Items]
Annual cash compensation		10,000
Compensation and Corporate Governance Committees [Member]
Commitments And Contingencies [Line Items]
Annual cash compensation		$ 10,000

Summary of Quarterly Results101

Summary of Quarterly Results of Operations - Summary of Quarterly Results of Operations (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Income from loans and other investments, net	$ 80,174	$ 78,555	$ 72,473	$ 71,843	$ 71,837	$ 82,817	$ 81,406	$ 77,644	$ 303,045	$ 313,704	$ 258,219
Net income	58,140	57,810	50,613	51,405	53,399	66,392	69,450	57,199	217,968	246,440	211,885
Net income attributable to Blackstone Mortgage Trust, Inc.	$ 57,891	$ 57,722	$ 50,613	$ 51,405	$ 53,375	$ 64,794	$ 63,081	$ 57,047	$ 217,631	$ 238,297	$ 196,829
Net income per share of class A common stock:
Basic and diluted	$ 0.59	$ 0.61	$ 0.53	$ 0.54	$ 0.57	$ 0.69	$ 0.67	$ 0.61	$ 2.27	$ 2.53	$ 2.41

Schedule IV - Mortgage Loans102

Schedule IV - Mortgage Loans on Real Estate (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Mortgage Loans on Real Estate [Line Items]
Interest Payment Rates	1.90%
Prior Liens	$ 985,382
Face Amount of Loans	10,108,226	$ 8,727,218
Carrying Amount of Loans	$ 10,056,732
Senior Mortgage Loans in Excess of 3% of the Carrying Amount of Total Loans [Member] | Borrower A [Member] | Office [Member]
Mortgage Loans on Real Estate [Line Items]
Location	Office / Southeast
Debt instrument variable rate basis	LIBOR
Interest Payment Rates	3.40%
Maximum Maturity Date	2,023
Periodic Payment Terms	I/O
Face Amount of Loans	$ 656,406
Carrying Amount of Loans	652,880
Senior Mortgage Loans Less Than 3% of the Carrying Amount of Total Loans [Member]
Mortgage Loans on Real Estate [Line Items]
Face Amount of Loans	9,237,199
Carrying Amount of Loans	$ 9,190,208
Senior Mortgage Loans Less Than 3% of the Carrying Amount of Total Loans [Member] | Hotel [Member]
Mortgage Loans on Real Estate [Line Items]
Location	Hotel / Diversified
Debt instrument variable rate basis	LIBOR
Periodic Payment Terms	I/O&P/I
Face Amount of Loans	$ 1,843,143
Carrying Amount of Loans	$ 1,837,222
Senior Mortgage Loans Less Than 3% of the Carrying Amount of Total Loans [Member] | Hotel [Member] | Minimum [Member]
Mortgage Loans on Real Estate [Line Items]
Interest Payment Rates	3.25%
Maximum Maturity Date	2,018
Senior Mortgage Loans Less Than 3% of the Carrying Amount of Total Loans [Member] | Hotel [Member] | Maximum [Member]
Mortgage Loans on Real Estate [Line Items]
Interest Payment Rates	5.16%
Maximum Maturity Date	2,022
Senior Mortgage Loans Less Than 3% of the Carrying Amount of Total Loans [Member] | Office [Member]
Mortgage Loans on Real Estate [Line Items]
Location	Office / Diversified
Debt instrument variable rate basis	LIBOR
Periodic Payment Terms	I/O&P/I
Face Amount of Loans	$ 5,357,888
Carrying Amount of Loans	$ 5,327,333
Senior Mortgage Loans Less Than 3% of the Carrying Amount of Total Loans [Member] | Office [Member] | Minimum [Member]
Mortgage Loans on Real Estate [Line Items]
Interest Payment Rates	3.00%
Fixed Interest Payment Rates	2.30%
Maximum Maturity Date	2,018
Senior Mortgage Loans Less Than 3% of the Carrying Amount of Total Loans [Member] | Office [Member] | Maximum [Member]
Mortgage Loans on Real Estate [Line Items]
Interest Payment Rates	5.75%
Fixed Interest Payment Rates	5.29%
Maximum Maturity Date	2,023
Senior Mortgage Loans Less Than 3% of the Carrying Amount of Total Loans [Member] | Retail [Member]
Mortgage Loans on Real Estate [Line Items]
Location	Retail / Diversified
Debt instrument variable rate basis	LIBOR
Fixed Interest Payment Rates	5.14%
Periodic Payment Terms	I/O&P/I
Face Amount of Loans	$ 319,223
Carrying Amount of Loans	$ 318,789
Senior Mortgage Loans Less Than 3% of the Carrying Amount of Total Loans [Member] | Retail [Member] | Minimum [Member]
Mortgage Loans on Real Estate [Line Items]
Interest Payment Rates	3.10%
Maximum Maturity Date	2,019
Senior Mortgage Loans Less Than 3% of the Carrying Amount of Total Loans [Member] | Retail [Member] | Maximum [Member]
Mortgage Loans on Real Estate [Line Items]
Interest Payment Rates	4.25%
Maximum Maturity Date	2,021
Senior Mortgage Loans Less Than 3% of the Carrying Amount of Total Loans [Member] | Multifamily [Member]
Mortgage Loans on Real Estate [Line Items]
Location	Multifamily / Diversified
Debt instrument variable rate basis	LIBOR
Periodic Payment Terms	I/O&P/I
Face Amount of Loans	$ 1,122,532
Carrying Amount of Loans	$ 1,114,353
Senior Mortgage Loans Less Than 3% of the Carrying Amount of Total Loans [Member] | Multifamily [Member] | Minimum [Member]
Mortgage Loans on Real Estate [Line Items]
Interest Payment Rates	2.80%
Maximum Maturity Date	2,018
Senior Mortgage Loans Less Than 3% of the Carrying Amount of Total Loans [Member] | Multifamily [Member] | Maximum [Member]
Mortgage Loans on Real Estate [Line Items]
Interest Payment Rates	5.25%
Maximum Maturity Date	2,023
Senior Mortgage Loans Less Than 3% of the Carrying Amount of Total Loans [Member] | Condo / Northeast [Member]
Mortgage Loans on Real Estate [Line Items]
Location	Condo / Northeast
Debt instrument variable rate basis	LIBOR
Interest Payment Rates	4.15%
Maximum Maturity Date	2,021
Periodic Payment Terms	I/O
Face Amount of Loans	$ 66,451
Carrying Amount of Loans	$ 65,775
Senior Mortgage Loans Less Than 3% of the Carrying Amount of Total Loans [Member] | Other [Member]
Mortgage Loans on Real Estate [Line Items]
Location	Other / Diversified
Debt instrument variable rate basis	LIBOR
Periodic Payment Terms	I/O&P/I
Face Amount of Loans	$ 527,962
Carrying Amount of Loans	$ 526,736
Senior Mortgage Loans Less Than 3% of the Carrying Amount of Total Loans [Member] | Other [Member] | Minimum [Member]
Mortgage Loans on Real Estate [Line Items]
Interest Payment Rates	3.10%
Fixed Interest Payment Rates	4.63%
Maximum Maturity Date	2,018
Senior Mortgage Loans Less Than 3% of the Carrying Amount of Total Loans [Member] | Other [Member] | Maximum [Member]
Mortgage Loans on Real Estate [Line Items]
Interest Payment Rates	5.00%
Fixed Interest Payment Rates	5.20%
Maximum Maturity Date	2,022
Senior Mortgage Loans [Member]
Mortgage Loans on Real Estate [Line Items]
Face Amount of Loans	$ 9,893,605
Carrying Amount of Loans	9,843,088
Subordinate Loans [Member]
Mortgage Loans on Real Estate [Line Items]
Prior Liens	985,382
Face Amount of Loans	214,621
Carrying Amount of Loans	$ 213,644
Subordinate Loans [Member] | Various / Diversified [Member]
Mortgage Loans on Real Estate [Line Items]
Debt instrument variable rate basis	LIBOR
Fixed Interest Payment Rates	12.22%
Periodic Payment Terms	I/O & P/I
Prior Liens	$ 985,382
Face Amount of Loans	214,621
Carrying Amount of Loans	$ 213,644
Subordinate Loans [Member] | Various / Diversified [Member] | Minimum [Member]
Mortgage Loans on Real Estate [Line Items]
Interest Payment Rates	10.75%
Maximum Maturity Date	2,020
Subordinate Loans [Member] | Various / Diversified [Member] | Maximum [Member]
Mortgage Loans on Real Estate [Line Items]
Interest Payment Rates	12.83%
Maximum Maturity Date	2,022

Schedule IV - Mortgage Loans103

Schedule IV - Mortgage Loans on Real Estate (Parenthetical) (Detail) $ in Billions	Dec. 31, 2017USD ($)
Mortgage Loans on Real Estate [Abstract]
Tax basis of mortgage loans	$ 9.5

Schedule IV - Reconciliation of

Schedule IV - Reconciliation of Mortgage Loans on Real Estate (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Mortgage Loans on Real Estate [Abstract]
Balance at January 1,	$ 8,692,978	$ 9,077,007	$ 4,428,500
Additions during period:
Loan fundings	4,072,786	3,151,882	7,203,145
Amortization of deferred fees and expenses	38,373	40,345	36,052
Deductions during period:
Collections of principal	(2,828,610)	(3,351,042)	(2,407,920)
Unrealized gain (loss) on foreign currency translation	136,646	(156,937)	(149,269)
Deferred origination fees and expenses	(55,441)	(44,697)	(33,501)
Loans sold		(23,580)
Balance at December 31,	$ 10,056,732	$ 8,692,978	$ 9,077,007