FAIR VALUE OF FINANCIAL INSTRUMENTS - Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Mar. 31, 2026	Dec. 31, 2025	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024
Assets:
Fair Value	$ 1,863,797		$ 2,079,720
Liabilities:
Allowance for credit losses	(47,095)	$ (47,109)	(47,137)	$ (52,166)	$ (52,208)	$ (52,323)
CMBS interest-only
Assets:
Principal Amount	172,725		347,200
Mortgage loan receivables held for investment, net, at amortized cost \| Discounted Cash Flow
Liabilities:
Allowance for credit losses	(47,100)		(47,100)
Unsecured Delayed Draw Term Loan Facility (Term Loan Facility)
Liabilities:
Principal Amount	275,000
Repurchase agreements - long-term
Liabilities:
Principal Amount	107,228
Fair Value	107,228
Portion at Other than Fair Value Measurement
Assets:
Fair Value	2,825,550		2,251,822
Liabilities:
Fair Value	4,022,465		3,557,888
Portion at Other than Fair Value Measurement \| Repurchase agreements - short-term
Liabilities:
Principal Amount	825,936		627,012
Fair Value	825,937		627,012
Portion at Other than Fair Value Measurement \| Unsecured Revolving Credit Facility
Liabilities:
Principal Amount	202,000		280,000
Fair Value	202,000		280,000
Portion at Other than Fair Value Measurement \| Unsecured Revolving Credit Facility \| Unsecured Delayed Draw Term Loan Facility (Term Loan Facility)
Liabilities:
Fair Value	275,000
Portion at Other than Fair Value Measurement \| Mortgage loan financing
Liabilities:
Principal Amount	386,017		386,543
Fair Value	382,848		385,460
Portion at Other than Fair Value Measurement \| Senior unsecured notes
Liabilities:
Principal Amount	2,222,993		2,233,409
Fair Value	2,229,452		2,265,416
Level 1
Assets:
Fair Value	11,697		12,963
Level 1 \| Repurchase agreements - long-term
Liabilities:
Fair Value	0
Level 1 \| Portion at Other than Fair Value Measurement
Assets:
Fair Value	0		0
Liabilities:
Fair Value	0		0
Level 1 \| Portion at Other than Fair Value Measurement \| Repurchase agreements - short-term
Liabilities:
Fair Value	0		0
Level 1 \| Portion at Other than Fair Value Measurement \| Unsecured Revolving Credit Facility
Liabilities:
Fair Value	0		0
Level 1 \| Portion at Other than Fair Value Measurement \| Unsecured Revolving Credit Facility \| Unsecured Delayed Draw Term Loan Facility (Term Loan Facility)
Liabilities:
Fair Value	0
Level 1 \| Portion at Other than Fair Value Measurement \| Mortgage loan financing
Liabilities:
Fair Value	0		0
Level 1 \| Portion at Other than Fair Value Measurement \| Senior unsecured notes
Liabilities:
Fair Value	0		0
Level 2
Assets:
Fair Value	1,852,100		2,066,757
Level 2 \| Repurchase agreements - long-term
Liabilities:
Fair Value	107,228
Level 2 \| Portion at Other than Fair Value Measurement
Assets:
Fair Value	8,778		8,849
Liabilities:
Fair Value	3,162,617		2,892,428
Level 2 \| Portion at Other than Fair Value Measurement \| Repurchase agreements - short-term
Liabilities:
Fair Value	825,937		627,012
Level 2 \| Portion at Other than Fair Value Measurement \| Unsecured Revolving Credit Facility
Liabilities:
Fair Value	0		0
Level 2 \| Portion at Other than Fair Value Measurement \| Unsecured Revolving Credit Facility \| Unsecured Delayed Draw Term Loan Facility (Term Loan Facility)
Liabilities:
Fair Value	0
Level 2 \| Portion at Other than Fair Value Measurement \| Mortgage loan financing
Liabilities:
Fair Value	0		0
Level 2 \| Portion at Other than Fair Value Measurement \| Senior unsecured notes
Liabilities:
Fair Value	2,229,452		2,265,416
Level 3
Assets:
Fair Value	0		0
Level 3 \| Repurchase agreements - long-term
Liabilities:
Fair Value	0
Level 3 \| Portion at Other than Fair Value Measurement
Assets:
Fair Value	2,816,772		2,242,973
Liabilities:
Fair Value	859,848		665,460
Level 3 \| Portion at Other than Fair Value Measurement \| Repurchase agreements - short-term
Liabilities:
Fair Value	0		0
Level 3 \| Portion at Other than Fair Value Measurement \| Unsecured Revolving Credit Facility
Liabilities:
Fair Value	202,000		280,000
Level 3 \| Portion at Other than Fair Value Measurement \| Mortgage loan financing
Liabilities:
Fair Value	382,848		385,460
Level 3 \| Portion at Other than Fair Value Measurement \| Senior unsecured notes
Liabilities:
Fair Value	0		0
CMBS
Assets:
Principal Amount	1,847,125		2,061,579
Fair Value	1,842,180		2,056,177
CMBS \| Portion at Other than Fair Value Measurement
Assets:
Principal Amount	8,836		8,913
Fair Value	8,725		8,745
CMBS \| Level 1
Assets:
Fair Value	0		0
CMBS \| Level 1 \| Portion at Other than Fair Value Measurement
Assets:
Fair Value	0		0
CMBS \| Level 2
Assets:
Fair Value	1,842,180		2,056,177
CMBS \| Level 2 \| Portion at Other than Fair Value Measurement
Assets:
Fair Value	8,725		8,745
CMBS \| Level 3
Assets:
Fair Value	0		0
CMBS \| Level 3 \| Portion at Other than Fair Value Measurement
Assets:
Fair Value	0		0
CMBS interest-only
Assets:
Principal Amount	164,844		339,241
Fair Value	573		1,171
CMBS interest-only \| Portion at Other than Fair Value Measurement
Assets:
Principal Amount	7,881		7,958
Fair Value	53		104
CMBS interest-only \| Level 1
Assets:
Fair Value	0		0
CMBS interest-only \| Level 1 \| Portion at Other than Fair Value Measurement
Assets:
Fair Value	0		0
CMBS interest-only \| Level 2
Assets:
Fair Value	573		1,171
CMBS interest-only \| Level 2 \| Portion at Other than Fair Value Measurement
Assets:
Fair Value	53		104
CMBS interest-only \| Level 3
Assets:
Fair Value	0		0
CMBS interest-only \| Level 3 \| Portion at Other than Fair Value Measurement
Assets:
Fair Value	0		0
GNMA interest-only
Assets:
Principal Amount	27,498		29,203
Fair Value	156		167
GNMA interest-only \| Level 1
Assets:
Fair Value	0		0
GNMA interest-only \| Level 2
Assets:
Fair Value	156		167
GNMA interest-only \| Level 3
Assets:
Fair Value	0		0
Agency securities
Assets:
Principal Amount			2
Fair Value			2
Agency securities \| Level 1
Assets:
Fair Value			0
Agency securities \| Level 2
Assets:
Fair Value			2
Agency securities \| Level 3
Assets:
Fair Value			0
Corporate bonds
Assets:
Principal Amount	9,250		9,250
Fair Value	9,191		9,240
Corporate bonds \| Level 1
Assets:
Fair Value	0		0
Corporate bonds \| Level 2
Assets:
Fair Value	9,191		9,240
Corporate bonds \| Level 3
Assets:
Fair Value	0		0
Equity securities
Assets:
Fair Value	11,581		12,699
Equity securities \| Level 1
Assets:
Fair Value	11,581		12,699
Equity securities \| Level 2
Assets:
Fair Value	0		0
Equity securities \| Level 3
Assets:
Fair Value	0		0
Nonhedge derivatives
Assets:
Principal Amount	101,900		113,500
Fair Value	116		264
Nonhedge derivatives \| Level 1
Assets:
Fair Value	116		264
Nonhedge derivatives \| Level 2
Assets:
Fair Value	0		0
Nonhedge derivatives \| Level 3
Assets:
Fair Value	0		0
Mortgage loan receivables held for investment, net, at amortized cost \| Portion at Other than Fair Value Measurement
Assets:
Principal Amount	2,810,014		2,234,346
Fair Value	2,789,567		2,214,987
Mortgage loan receivables held for investment, net, at amortized cost \| Level 1 \| Portion at Other than Fair Value Measurement
Assets:
Fair Value	0		0
Mortgage loan receivables held for investment, net, at amortized cost \| Level 2 \| Portion at Other than Fair Value Measurement
Assets:
Fair Value	0		0
Mortgage loan receivables held for investment, net, at amortized cost \| Level 3 \| Portion at Other than Fair Value Measurement
Assets:
Fair Value	2,789,567		2,214,987
Mortgage loan receivables held for sale \| Portion at Other than Fair Value Measurement
Assets:
Principal Amount	31,350		31,350
Fair Value	27,205		27,986
Mortgage loan receivables held for sale \| Level 1 \| Portion at Other than Fair Value Measurement
Assets:
Fair Value	0		0
Mortgage loan receivables held for sale \| Level 2 \| Portion at Other than Fair Value Measurement
Assets:
Fair Value	0		0
Mortgage loan receivables held for sale \| Level 3 \| Portion at Other than Fair Value Measurement
Assets:
Fair Value	$ 27,205		$ 27,986