SEGMENT REPORTING - Schedule of Segments (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2023		Dec. 31, 2022		Dec. 31, 2021
Income Statement [Abstract]
Interest income		$ 407,284		$ 293,520		$ 176,099
Interest expense		(245,097)		(195,602)		(182,949)
Net interest income (expense)		162,187		97,918		(6,850)
(Provision for) release of loan loss reserves		(25,096)		(3,711)		8,713
Net interest income (expense) after provision for (release of) loan loss reserves		137,091		94,207		1,863
Real estate operating income		96,950		108,269		101,564
Net result from mortgage loan receivables held for sale		(523)		(2,511)		8,398
Realized gain (loss) on securities		(276)		(73)		1,594
Unrealized gain (loss) on securities		29		(86)		(91)
Realized gain (loss) on sale of real estate, net		8,808		115,998		55,766
Fee and other income		9,178		15,020		11,190
Net result from derivative transactions		1,481		12,360		1,749
Earnings (loss) from investment in unconsolidated ventures		758		1,410		1,579
Gain (loss) on extinguishment of debt		10,718		685		0
Total other income (loss)		127,123		251,072		181,749
Compensation and employee benefits		(63,618)		(75,836)		(38,347)
Operating expenses		(19,503)		(20,716)		(17,672)
Real estate operating expenses		(37,587)		(38,605)		(26,161)
Investment related expenses		(8,847)		(7,235)		(5,810)
Depreciation and amortization		(29,914)		(32,673)		(37,801)
Total costs and expenses		(159,469)		(175,065)		(125,791)
Income tax (expense) benefit		(4,244)		(4,909)		(928)
Net income (loss)		100,501		165,305		56,893
Total assets		5,512,677	[1]	5,951,173	[1]	5,851,252
Investment in unconsolidated ventures	[1]	6,877		6,219
Investment in FHLB stock		5,200		9,600
Operating Segment
Income Statement [Abstract]
Investment in unconsolidated ventures		6,900		6,200
Operating Segment | Loans
Income Statement [Abstract]
Interest income		341,840		269,629		162,349
Interest expense		(122,420)		(68,158)		(53,414)
Net interest income (expense)		219,420		201,471		108,935
(Provision for) release of loan loss reserves		(25,096)		(3,711)		8,713
Net interest income (expense) after provision for (release of) loan loss reserves		194,324		197,760		117,648
Real estate operating income		0		0		0
Net result from mortgage loan receivables held for sale		(523)		(2,511)		8,398
Realized gain (loss) on securities		0		0		0
Unrealized gain (loss) on securities		0		0		0
Realized gain (loss) on sale of real estate, net		0		0		0
Fee and other income		8,237		10,149		10,507
Net result from derivative transactions		404		6,755		507
Earnings (loss) from investment in unconsolidated ventures		0		0		335
Gain (loss) on extinguishment of debt		0		0
Total other income (loss)		8,118		14,393		19,747
Compensation and employee benefits		0		0		0
Operating expenses		0		0		127
Real estate operating expenses		0		0		0
Investment related expenses		(6,310)		(2,325)		(2,341)
Depreciation and amortization		0		0		0
Total costs and expenses		(6,310)		(2,325)		(2,214)
Income tax (expense) benefit		0		0		0
Net income (loss)		196,132		209,828		135,181
Total assets		3,138,794		3,892,382		3,521,986
Operating Segment | Securities
Income Statement [Abstract]
Interest income		32,479		20,659		13,101
Interest expense		(3,177)		(4,620)		(2,403)
Net interest income (expense)		29,302		16,039		10,698
(Provision for) release of loan loss reserves		0		0
Net interest income (expense) after provision for (release of) loan loss reserves		29,302		16,039		10,698
Real estate operating income		0		0		0
Net result from mortgage loan receivables held for sale		0		0		0
Realized gain (loss) on securities		(276)		(73)		1,594
Unrealized gain (loss) on securities		29		(86)		(91)
Realized gain (loss) on sale of real estate, net		0		0		0
Fee and other income		15		55		0
Net result from derivative transactions		595		3,972		1,250
Earnings (loss) from investment in unconsolidated ventures		0		0		0
Gain (loss) on extinguishment of debt		0		0
Total other income (loss)		363		3,868		2,753
Compensation and employee benefits		0		0		0
Operating expenses		0		0		0
Real estate operating expenses		0		0		0
Investment related expenses		(191)		(277)		(217)
Depreciation and amortization		0		0		0
Total costs and expenses		(191)		(277)		(217)
Income tax (expense) benefit		0		0		0
Net income (loss)		29,474		19,630		13,234
Total assets		485,533		587,519		703,280
Operating Segment | Real Estate
Income Statement [Abstract]
Interest income		12		6		1
Interest expense		(31,443)		(36,683)		(36,075)
Net interest income (expense)		(31,431)		(36,677)		(36,074)
(Provision for) release of loan loss reserves		0		0		0
Net interest income (expense) after provision for (release of) loan loss reserves		(31,431)		(36,677)		(36,074)
Real estate operating income		96,950		108,269		101,564
Net result from mortgage loan receivables held for sale		0		0		0
Realized gain (loss) on securities		0		0		0
Unrealized gain (loss) on securities		0		0		0
Realized gain (loss) on sale of real estate, net		8,808		115,998		55,766
Fee and other income		300		4,355		50
Net result from derivative transactions		482		1,633		(8)
Earnings (loss) from investment in unconsolidated ventures		758		1,410		1,244
Gain (loss) on extinguishment of debt		0		0
Total other income (loss)		107,298		231,665		158,616
Compensation and employee benefits		0		0		0
Operating expenses		0		0		0
Real estate operating expenses		(37,587)		(38,605)		(26,161)
Investment related expenses		(903)		(954)		(849)
Depreciation and amortization		(29,482)		(32,632)		(37,702)
Total costs and expenses		(67,972)		(72,191)		(64,712)
Income tax (expense) benefit		0		0		0
Net income (loss)		7,895		122,797		57,830
Total assets		733,319		706,355		914,027
Corporate/Other
Income Statement [Abstract]
Interest income		32,953		3,226		648
Interest expense		(88,057)		(86,141)		(91,057)
Net interest income (expense)		(55,104)		(82,915)		(90,409)
(Provision for) release of loan loss reserves		0		0		0
Net interest income (expense) after provision for (release of) loan loss reserves		(55,104)		(82,915)		(90,409)
Real estate operating income		0		0		0
Net result from mortgage loan receivables held for sale		0		0		0
Realized gain (loss) on securities		0		0		0
Unrealized gain (loss) on securities		0		0		0
Realized gain (loss) on sale of real estate, net		0		0		0
Fee and other income		626		461		633
Net result from derivative transactions		0		0		0
Earnings (loss) from investment in unconsolidated ventures		0		0		0
Gain (loss) on extinguishment of debt		10,718		685
Total other income (loss)		11,344		1,146		633
Compensation and employee benefits		(63,618)		(75,836)		(38,347)
Operating expenses		(19,503)		(20,716)		(17,799)
Real estate operating expenses		0		0		0
Investment related expenses		(1,443)		(3,679)		(2,403)
Depreciation and amortization		(432)		(41)		(99)
Total costs and expenses		(84,996)		(100,272)		(58,648)
Income tax (expense) benefit		(4,244)		(4,909)		(928)
Net income (loss)		(133,000)		(186,950)		(149,352)
Total assets		1,155,031		764,917		$ 711,959
Corporate/Other | Senior Unsecured Notes
Income Statement [Abstract]
Senior notes		$ 1,600,000		$ 1,600,000

[1] Includes amounts relating to consolidated variable interest entities. Refer to Note 2 and Note 9.