Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2021		Dec. 31, 2020		Dec. 31, 2019
Cash flows from operating activities:
Net income (loss)	$ 56,893,000		$ (9,458,000)		$ 137,001,000
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
(Gain) loss on extinguishment of debt	0		(22,250,000)		1,070,000
Depreciation and amortization	37,801,000		39,079,000		38,511,000
Unrealized (gain) loss on derivative instruments	(42,000)		269,000		(1,542,000)
Unrealized (gain) loss on equity securities and investment in mutual fund	0		132,000		(1,737,000)
Unrealized (gain) loss on Agency interest-only securities	91,000		(263,000)		(84,000)
Provision for (release of) loan loss reserves	(8,713,000)		18,275,000		2,600,000
Impairment of real estate	0		0		1,350,000
Amortization of equity based compensation	15,300,000		42,728,000		21,777,000
Amortization of deferred financing costs included in interest expense	21,530,000		18,730,000		10,987,000
Amortization of premium on mortgage loan financing	(1,226,000)		(1,160,000)		(1,584,000)
Amortization of above- and below-market lease intangibles	(1,888,000)		(2,234,000)		(1,359,000)
(Accretion)/amortization of discount, premium and other fees on loans	(13,832,000)		(15,530,000)		(17,845,000)
(Accretion)/amortization of discount, premium and other fees on securities	236,000		526,000		217,000
Realized (gain) loss on sale of mortgage loan receivables held for sale	(8,398,000)		(8,026,000)		(54,758,000)
Realized (gain) loss on sale of mortgage loan receivables held for investment	0		9,596,000		0
Realized (gain) loss on disposition of loan via foreclosure	26,000		(98,000)		(2,250,000)
Realized (gain) loss on securities	(1,594,000)		13,136,000		(14,911,000)
Realized (gain) loss on sale of real estate, net	(55,766,000)		(32,102,000)		(1,392,000)
Realized gain on sale of derivative instruments	0		(108,000)		84,000
(Earnings) loss from investments in unconsolidated joint ventures in excess of distributions received	(1,462,000)		(1,821,000)		(3,432,000)
Insurance proceeds for remediation work due to property damage	2,092,000		0		0
Insurance proceeds used for remediation work due to property damage	(1,888,000)		0		0
Origination of mortgage loan receivables held for sale	(220,359,000)		(212,845,000)		(946,178,000)
Purchases of mortgage loan receivables held for sale	0		0		(9,934,000)
Repayment of mortgage loan receivables held for sale	183,000		404,000		667,000
Proceeds from sales of mortgage loan receivables held for sale	259,092,000		312,273,000		1,024,357,000
Distributions from operations of investment in unconsolidated joint ventures	0		0		3,317,000
Change in deferred tax asset (liability)	271,000		94,000		4,814,000
Changes in operating assets and liabilities:
Accrued interest receivable	649,000		4,895,000		5,556,000
Other assets	5,758,000		(8,778,000)		1,502,000
Accrued expenses and other liabilities	(5,015,000)		(33,363,000)		(13,192,000)
Net cash provided by (used in) operating activities	79,739,000		111,943,000		183,207,000
Cash flows from investing activities:
Origination of mortgage loan receivables held for investment	(2,309,888,000)		(353,662,000)		(1,452,049,000)
Purchases of mortgage loan receivables held for investment	(63,600,000)		0		0
Repayment of mortgage loan receivables held for investment	1,103,614,000		891,705,000		1,639,101,000
Proceeds from sale of mortgage loan receivables held for investment	46,557,000		270,491,000		0
Purchases of real estate securities	(247,022,000)		(440,612,000)		(1,645,640,000)
Repayment of real estate securities	164,494,000		146,158,000		491,880,000
Basis recovery of interest-only securities	6,589,000		7,611,000		12,086,000
Proceeds from sales of real estate securities	438,594,000		932,158,000		855,618,000
Purchases of real estate	(20,452,000)		(7,440,000)		(20,235,000)
Capital improvements of real estate	(4,873,000)		(6,103,000)		(7,592,000)
Proceeds from sale of real estate	190,870,000		67,104,000		12,123,000
Capital contributions and advances to investment in unconsolidated joint ventures	0		0		(56,337,000)
Capital distribution from investment in unconsolidated joint ventures	24,561,000		4,002,000		48,514,000
Capitalization of interest on investment in unconsolidated joint ventures	0		0		(142,000)
Purchase of FHLB stock	0		0		(3,704,000)
Proceeds from sale of FHLB stock	19,165,000		30,619,000		0
Purchase of derivative instruments	(69,000)		(196,000)		(310,000)
Sale of derivative instruments	0		430,000		100,000
Net cash provided by (used in) investing activities	(651,460,000)		1,542,265,000		(126,587,000)
Cash flows from financing activities:
Deferred financing costs paid	(3,221,000)		(18,021,000)		(6,910,000)
Proceeds from borrowings under debt obligations	4,519,064,000		10,021,156,000		14,402,852,000
Repayment of borrowings under debt obligations	(4,493,566,000)		(10,614,556,000)		(14,022,875,000)
Cash dividends paid to Class A common shareholders	(100,553,000)		(118,888,000)		(144,530,000)
Reissuance of treasury stock	(1,000)		0		0
Payment of liability assumed in exchange for shares for the minimum withholding taxes on vesting restricted stock	(4,457,000)		(17,126,000)		(9,247,000)
Purchase of treasury stock	(9,007,000)		(3,035,000)		(637,000)
Issuance of common stock	1,000		32,000,000		0
Issuance of Purchase Right	0		8,425,000		0
Net cash provided by (used in) financing activities	(91,017,000)		(725,670,000)		200,676,000
Net increase (decrease) in cash, cash equivalents and restricted cash	(662,738,000)		928,538,000		257,296,000
Cash, cash equivalents and restricted cash at beginning of period	1,284,284,000		355,746,000		98,450,000
Cash, cash equivalents and restricted cash at end of period	621,546,000		1,284,284,000		355,746,000
Supplemental information:
Cash paid for interest, net of amounts capitalized	173,128,000		202,939,000		195,061,000
Cash paid (received) for income taxes	(2,527,000)		2,197,000		885,000
Non-cash investing and financing activities:
Securities and derivatives purchased, not settled	18,000		0		0
Securities and derivatives sold, not settled	10,000		0		0
Repayment in transit of mortgage loans receivable held for investment (other assets)	26,636,000		69,649,000		0
Settlement of mortgage loan receivable held for investment by real estate, net	(81,129,000)		(28,903,000)		(44,183,000)
Transfer from mortgage loans receivable held for sale to mortgage loans receivable held for investment, net, at amortized cost	0		0		45,832,000
Real estate acquired in settlement of mortgage loan receivable held for investment, net	81,750,000		29,310,000		84,356,000
Transfer of real estate and related lease intangible, net into real estate held for sale	25,179,000	[1]	0	[1]	0
Net settlement of sale of real estate, subject to debt - real estate	(29,827,000)		(31,768,000)		(11,943,000)
Net settlement of sale of real estate, subject to debt - debt obligations	29,827,000		31,768,000		11,943,000
Exchange of noncontrolling interest for common stock	0		158,625,000		16,110,000
Mortgage loan assumed in foreclosure of real estate	0		0		(33,904,000)
Change in deferred tax asset related to exchanges of noncontrolling interest for common stock	0		223,000		394,000
Increase in amount payable pursuant to tax receivable agreement	0		0		(11,000)
Rebalancing of ownership percentage between Company and Operating Partnership	0		(978,000)		803,000
Dividends declared, not paid	27,591,000		27,537,000		38,696,000
Stock dividends	0		0		23,823,000
Cash and cash equivalents	548,744,000	[1]	1,254,432,000	[1]	58,171,000
Restricted cash	72,802,000		29,852,000		297,575,000
Total cash, cash equivalents and restricted cash shown in the consolidated statement of cash flows	621,546,000		1,284,284,000		355,746,000
Reissuance of treasury stock	(1,000)		0		0
Consolidated Joint Venture
Cash flows from financing activities:
Capital distributed to noncontrolling interests	(783,000)		(9,787,000)		(1,213,000)
Capital contributed by noncontrolling interests in consolidated joint ventures	1,506,000		860,000		498,000
Operating Partnership
Cash flows from financing activities:
Capital distributed to noncontrolling interests	0		(6,698,000)		(17,262,000)
Equity Securities
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Unrealized (gain) loss on equity securities and investment in mutual fund	0		132,000		(1,737,000)
Mutual Fund
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Unrealized (gain) loss on equity securities and investment in mutual fund	$ 0		$ (158,000)		$ (405,000)

[1] Includes amounts relating to consolidated variable interest entities. Refer to Note 2 and Note 10.