REAL ESTATE AND OTHER SECURITIES - Summary of Real Estate Securities in an Unrealized Loss Position (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2022 USD ($) security
Debt Securities, Available-for-sale [Line Items]
Outstanding Face Amount	$ 25,301,502
Weighted Average Life (Years)	1 year 3 months 18 days
Less than 12 Months
Debt Securities, Available-for-sale [Line Items]
Outstanding Face Amount	$ 384,799
Before Credit Impairment - Amortized Cost Basis	382,423
Credit Impairment - Amortized Cost Basis	(2,202)
After Credit Impairment - Amortized Cost Basis	380,220
Gross Unrealized Losses - Less than 12 Months	(13,047)
Carrying Value - Less than 12 Months	$ 367,173
Number of Securities - Less than 12 Months | security	159
Weighted Average Rating	AAA
Weighted Average Coupon	3.70%
Weighted Average Yield	3.50%
Weighted Average Life (Years)	3 years 9 months 18 days
12 or More Months
Debt Securities, Available-for-sale [Line Items]
Outstanding Face Amount	$ 18,094
Before Credit Impairment - Amortized Cost Basis	8,931
Credit Impairment - Amortized Cost Basis	(4,154)
After Credit Impairment - Amortized Cost Basis	4,777
Gross Unrealized Losses - 12 or More Months	(98)
Carrying Value - 12 or More Months	$ 4,679
Number of Securities - 12 or More Months | security	14
Weighted Average Rating	AAA
Weighted Average Coupon	1.90%
Weighted Average Yield	0.70%
Weighted Average Life (Years)	7 months 6 days
Total/Weighted Average
Debt Securities, Available-for-sale [Line Items]
Outstanding Face Amount	$ 402,893
Before Credit Impairment - Amortized Cost Basis	391,354
Credit Impairment - Amortized Cost Basis	(6,356)
After Credit Impairment - Amortized Cost Basis	384,997
Gross Unrealized Losses - Total	(13,145)
Carrying Value - Total	$ 371,852
Number of Securities - Total | security	173
Weighted Average Rating	AAA
Weighted Average Coupon	3.70%
Weighted Average Yield	3.50%
Weighted Average Life (Years)	3 years 9 months 18 days