SEGMENT REPORTING - Schedule of Segments (Details) - USD ($)		1 Months Ended	12 Months Ended
		Jun. 30, 2020	Dec. 31, 2022		Dec. 31, 2021		Dec. 31, 2020
Income Statement [Abstract]
Interest income			$ 293,520,000		$ 176,099,000		$ 239,849,000
Interest expense			(195,602,000)		(182,949,000)		(227,474,000)
Net interest income (expense)			97,918,000		(6,850,000)		12,375,000
(Provision for) release of loan loss reserves			(3,711,000)		8,713,000		(18,275,000)
Net interest income (expense) after provision for (release of) loan losses			94,207,000		1,863,000		(5,900,000)
Real estate operating income			108,269,000		101,564,000		100,248,000
Sale of loans, net			(2,511,000)		8,398,000		(1,571,000)
Realized gain (loss) on securities			(73,000)		1,594,000		(12,410,000)
Unrealized gain (loss) on equity securities			(41,000)		0		(132,000)
Unrealized gain (loss) on Agency interest-only securities			(45,000)		(91,000)		263,000
Realized gain (loss) on sale of real estate, net		$ 0	115,998,000		55,766,000		32,102,000
Fee and other income			15,020,000		11,190,000		12,654,000
Net result from derivative transactions			12,360,000		1,749,000		(15,270,000)
Earnings (loss) from investment in unconsolidated ventures			1,410,000		1,579,000		1,821,000
Gain (loss) on extinguishment of debt			685,000		0		22,250,000
Total other income (loss)			251,072,000		181,749,000		139,955,000
Compensation and employee benefits			(75,836,000)		(38,347,000)		(58,101,000)
Operating expenses			(20,716,000)		(17,672,000)		(20,294,000)
Real estate operating expenses			(38,605,000)		(26,161,000)		(28,584,000)
Fee expense			(7,235,000)		(5,810,000)		(7,244,000)
Depreciation and amortization			(32,673,000)		(37,801,000)		(39,079,000)
Total costs and expenses			(175,065,000)		(125,791,000)		(153,302,000)
Income tax (expense) benefit			(4,909,000)		(928,000)		9,789,000
Net income (loss)			165,305,000		56,893,000		(9,458,000)
Total assets			5,951,173,000	[1]	5,851,252,000	[1]	5,881,229,000
Investment in unconsolidated ventures	[1]		6,219,000		23,154,000
Investment in FHLB stock			9,600,000		11,800,000		31,000,000
Operating Segment
Income Statement [Abstract]
Investment in unconsolidated ventures			6,200,000		23,200,000		46,300,000
Operating Segment | Loans
Income Statement [Abstract]
Interest income			269,629,000		162,349,000		205,640,000
Interest expense			(68,158,000)		(53,414,000)		(48,084,000)
Net interest income (expense)			201,471,000		108,935,000		157,556,000
(Provision for) release of loan loss reserves			(3,711,000)		8,713,000		(18,277,000)
Net interest income (expense) after provision for (release of) loan losses			197,760,000		117,648,000		139,279,000
Real estate operating income			0		0		0
Sale of loans, net			(2,511,000)		8,398,000		(1,571,000)
Realized gain (loss) on securities			0		0		0
Unrealized gain (loss) on equity securities			0				0
Unrealized gain (loss) on Agency interest-only securities			0		0		0
Realized gain (loss) on sale of real estate, net			0		0		0
Fee and other income			10,149,000		10,507,000		9,142,000
Net result from derivative transactions			6,755,000		507,000		(11,264,000)
Earnings (loss) from investment in unconsolidated ventures			0		335,000		0
Gain (loss) on extinguishment of debt			0				0
Total other income (loss)			14,393,000		19,747,000		(3,693,000)
Compensation and employee benefits			0		0		0
Operating expenses			0		127,000		3,000
Real estate operating expenses			0		0		0
Fee expense			(2,325,000)		(2,341,000)		(6,124,000)
Depreciation and amortization			0		0		0
Total costs and expenses			(2,325,000)		(2,214,000)		(6,121,000)
Income tax (expense) benefit			0		0		0
Net income (loss)			209,828,000		135,181,000		129,465,000
Total assets			3,892,382,000		3,521,986,000		2,343,070,000
Operating Segment | Securities
Income Statement [Abstract]
Interest income			20,659,000		13,101,000		32,904,000
Interest expense			(4,620,000)		(2,403,000)		(21,554,000)
Net interest income (expense)			16,039,000		10,698,000		11,349,000
(Provision for) release of loan loss reserves			0				2,000
Net interest income (expense) after provision for (release of) loan losses			16,039,000		10,698,000		11,351,000
Real estate operating income			0		0		0
Sale of loans, net			0		0		0
Realized gain (loss) on securities			(73,000)		1,594,000		(12,410,000)
Unrealized gain (loss) on equity securities			(41,000)				(132,000)
Unrealized gain (loss) on Agency interest-only securities			(45,000)		(91,000)		263,000
Realized gain (loss) on sale of real estate, net			0		0		0
Fee and other income			55,000		0		403,000
Net result from derivative transactions			3,972,000		1,250,000		(4,006,000)
Earnings (loss) from investment in unconsolidated ventures			0		0		0
Gain (loss) on extinguishment of debt			0				0
Total other income (loss)			3,868,000		2,753,000		(15,882,000)
Compensation and employee benefits			0		0		0
Operating expenses			0		0		0
Real estate operating expenses			0		0		0
Fee expense			(277,000)		(217,000)		(236,000)
Depreciation and amortization			0		0		0
Total costs and expenses			(277,000)		(217,000)		(236,000)
Income tax (expense) benefit			0		0		0
Net income (loss)			19,630,000		13,234,000		(4,767,000)
Total assets			587,519,000		703,280,000		1,058,298,000
Operating Segment | Real Estate
Income Statement [Abstract]
Interest income			6,000		1,000		13,000
Interest expense			(36,683,000)		(36,075,000)		(39,396,000)
Net interest income (expense)			(36,677,000)		(36,074,000)		(39,383,000)
(Provision for) release of loan loss reserves			0		0		0
Net interest income (expense) after provision for (release of) loan losses			(36,677,000)		(36,074,000)		(39,383,000)
Real estate operating income			108,269,000		101,564,000		100,248,000
Sale of loans, net			0		0		0
Realized gain (loss) on securities			0		0		0
Unrealized gain (loss) on equity securities			0				0
Unrealized gain (loss) on Agency interest-only securities			0		0		0
Realized gain (loss) on sale of real estate, net			115,998,000		55,766,000		32,102,000
Fee and other income			4,355,000		50,000		25,000
Net result from derivative transactions			1,633,000		(8,000)		0
Earnings (loss) from investment in unconsolidated ventures			1,410,000		1,244,000		1,821,000
Gain (loss) on extinguishment of debt			0				0
Total other income (loss)			231,665,000		158,616,000		134,196,000
Compensation and employee benefits			0		0		0
Operating expenses			0		0		0
Real estate operating expenses			(38,605,000)		(26,161,000)		(28,584,000)
Fee expense			(954,000)		(849,000)		(884,000)
Depreciation and amortization			(32,632,000)		(37,702,000)		(38,980,000)
Total costs and expenses			(72,191,000)		(64,712,000)		(68,448,000)
Income tax (expense) benefit			0		0		0
Net income (loss)			122,797,000		57,830,000		26,365,000
Total assets			706,355,000		914,027,000		1,031,557,000
Corporate/Other
Income Statement [Abstract]
Interest income			3,226,000		648,000		1,292,000
Interest expense			(86,141,000)		(91,057,000)		(118,440,000)
Net interest income (expense)			(82,915,000)		(90,409,000)		(117,148,000)
(Provision for) release of loan loss reserves			0		0		0
Net interest income (expense) after provision for (release of) loan losses			(82,915,000)		(90,409,000)		(117,148,000)
Real estate operating income			0		0		0
Sale of loans, net			0		0		0
Realized gain (loss) on securities			0		0		0
Unrealized gain (loss) on equity securities			0				0
Unrealized gain (loss) on Agency interest-only securities			0		0		0
Realized gain (loss) on sale of real estate, net			0		0		0
Fee and other income			461,000		633,000		3,084,000
Net result from derivative transactions			0		0		0
Earnings (loss) from investment in unconsolidated ventures			0		0		0
Gain (loss) on extinguishment of debt			685,000				22,250,000
Total other income (loss)			1,146,000		633,000		25,334,000
Compensation and employee benefits			(75,836,000)		(38,347,000)		(58,101,000)
Operating expenses			(20,716,000)		(17,799,000)		(20,297,000)
Real estate operating expenses			0		0		0
Fee expense			(3,679,000)		(2,403,000)		0
Depreciation and amortization			(41,000)		(99,000)		(99,000)
Total costs and expenses			(100,272,000)		(58,648,000)		(78,497,000)
Income tax (expense) benefit			(4,909,000)		(928,000)		9,789,000
Net income (loss)			(186,950,000)		(149,352,000)		(160,523,000)
Total assets			764,917,000		711,959,000		$ 1,448,304,000
Corporate/Other | Senior Unsecured Notes
Income Statement [Abstract]
Senior notes			$ 1,600,000,000		$ 1,600,000,000

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