CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities:
Net income (loss)	$ (314,295,000)	$ (497,828,000)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Equity in (earnings) losses of unconsolidated ventures	69,889,000	(17,962,000)
Depreciation and amortization	46,766,000	82,853,000
Straight-line rental income	(3,100,000)	(5,049,000)
Amortization of above/below market lease values, net	(409,000)	(2,401,000)
Amortization of premium/accretion of discount and fees on investments and borrowings, net	(7,823,000)	(9,239,000)
Amortization of deferred financing costs	9,522,000	6,803,000
Amortization of right-of-use lease assets and operating lease liabilities	74,000	73,000
Paid-in-kind interest added to loan principal, net of interest received	3,856,000	(5,634,000)
Distributions of cumulative earnings from unconsolidated ventures	13,429,000	53,509,000
Unrealized (gain) loss on mortgage loans and obligations held in securitization trusts, net	41,589,000	(4,602,000)
Realized loss on mortgage loans and obligations held in securitization trusts, net	0	(2,772,000)
Realized loss on securities from write-down to fair value	32,606,000	0
Realized loss on sale of real estate securities, available for sale	51,889,000	0
Realized gain on sale of real estate	(9,240,000)	0
Realized loss on sale of loans receivable	1,457,000	0
Provision for loan losses	80,285,000	220,572,000
Impairment of operating real estate	33,512,000	282,846,000
Amortization of equity-based compensation	3,265,000	7,466,000
Mortgage notes above/below market value amortization	(628,000)	276,000
Deferred income tax (benefit) expense	(397,000)	(3,298,000)
Other (gain) loss, net	23,524,000	0
Changes in assets and liabilities:
Receivables, net	(30,907,000)	(1,097,000)
Deferred costs and other assets	7,169,000	718,000
Due to related party	(1,824,000)	(792,000)
Other liabilities	(5,347,000)	8,763,000
Net cash provided by operating activities	44,862,000	113,205,000
Cash flows from investing activities:
Acquisition, origination and funding of loans and preferred equity held for investment, net	(122,424,000)	(1,250,018,000)
Repayment on loans and preferred equity held for investment	334,208,000	426,438,000
Repayment on loans held for sale	137,132,000	0
Proceeds from sale of real estate	300,469,000	0
Cash and restricted cash received related to foreclosure of loans held for investment	0	3,436,000
Acquisition of and additions to real estate, related intangibles and leasing commissions	(19,749,000)	(16,773,000)
Investments in unconsolidated ventures	(47,541,000)	(28,344,000)
Proceeds from sale of investments in unconsolidated ventures	99,985,000	115,298,000
Distributions in excess of cumulative earnings from unconsolidated ventures	25,011,000	202,732,000
Repayment of real estate securities, available for sale, from sales	118,586,000	0
Repayment of real estate securities, available for sale, from cost recovery	3,020,000	0
Repayment of principal in mortgage loans held in securitization trusts	19,816,000	0
Proceeds from sale of mortgage loans held in securitization trusts	0	39,848,000
Net receipts on settlement of derivative instruments	19,637,000	27,699,000
Deposit on investments	0	(372,000)
Change in escrow deposits	(36,855,000)	20,817,000
Net cash provided (used in) by investing activities	831,295,000	(459,239,000)
Cash flows from financing activities:
Distributions paid on common stock	(51,705,000)	(167,452,000)
Distributions paid on common stock to noncontrolling interests	(922,000)	(4,020,000)
Shares canceled for tax withholding on vested stock awards	(1,768,000)	(1,576,000)
Borrowings from mortgage notes	15,026,000	85,660,000
Repayment of mortgage notes	(156,066,000)	(4,448,000)
Borrowings from credit facilities	255,128,000	1,830,412,000
Repayment of credit facilities	(745,729,000)	(1,288,773,000)
Repayment of securitization bonds	0	(81,372,000)
Repayment of mortgage obligations issued by securitization trusts	(19,816,000)	0
Payment of deferred financing costs	(6,943,000)	(7,413,000)
Contributions from noncontrolling interests	200,028,000	52,000
Distributions to noncontrolling interests	(22,893,000)	(2,702,000)
Net cash provided by (used in) financing activities	(535,660,000)	358,368,000
Effect of exchange rates on cash, cash equivalents and restricted cash	(1,132,000)	84,000
Net increase (decrease) in cash, cash equivalents and restricted cash	339,365,000	12,418,000
Cash, cash equivalents and restricted cash - beginning of period	195,684,000	187,463,000
Cash, cash equivalents and restricted cash - end of period	535,049,000	199,881,000
Reconciliation of cash, cash equivalents, and restricted cash to consolidated balance sheets
Total cash, cash equivalents and restricted cash	195,684,000	199,881,000
Supplemental disclosure of non-cash investing and financing activities:
Consolidation of securitization trust (VIE asset/liability additions)	0	59,126,000
Deconsolidation of securitization trust (VIE asset/liability reductions)	0	(1,239,627,000)
Accrual of distribution payable	(13,164,000)	19,087,000
Foreclosure of loans held for investment, net of provision for loan losses	0	127,356,000
Right-of-use lease assets and operating lease liabilities	(730,000)	26,781,000
Conversion of Class B-3 common stock to Class A common stock	$ 0	$ 444,000