LOANS RECEIVABLE AND INVESTMENTS (Details) - USD ($) $ in Thousands	1 Months Ended
	Oct. 31, 2021	Sep. 30, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable
Debt Securities, Held-to-maturity, Allowance for Credit Loss		$ (5,629)	$ (26,469)
Debt securities, available-for-sale, unrealized gain		2,996	27,638
Debt securities, available-for-sale, carrying value		0	237,553
Non-mortgage loans receivable, net		63,989	57,077
Total loans receivable and investments, net, amortized cost		597,060	899,028
Total loans receivable and investments, net, carrying amount		594,428	900,197
Total loans receivable and investments, net, fair value		582,900	852,996
Non-mortgage loans receivable, net
Accounts, Notes, Loans and Financing Receivable
Debt Securities, Held-to-maturity, Allowance for Credit Loss		(5,629)	(17,623)
Non-mortgage loans receivable, amortized cost		69,618	74,700
Non-mortgage loans receivable, net, unrealized gain		0	0
Non-mortgage loans receivable, net		63,989	57,077
Non-mortgage loans receivable, fair value		64,346	57,009
Non-mortgage loans receivable, net | Brookdale Senior Living | Subsequent Event
Accounts, Notes, Loans and Financing Receivable
Proceeds From Collection Of Debt Securities, Held-to-maturity	$ 45,000
Secured/mortgage loans and other, net
Accounts, Notes, Loans and Financing Receivable
Debt securities, held-to-maturity		488,999	555,840
Debt Securities, Held-to-maturity, Allowance for Credit Loss		0	0
Debt securities, held-to-maturity, accumulated unrecognized gain		0	0
Debt securities, held-to-maturity, fair value		477,114	508,707
Government-sponsored pooled loan investments, net
Accounts, Notes, Loans and Financing Receivable
Debt Securities, Held-to-maturity, Allowance for Credit Loss		0	(8,846)
Debt securities, available-for-sale, amortized cost		38,443	55,154
Debt securities, available-for-sale, unrealized gain		2,996	3,419
Debt securities, available-for-sale, carrying value		41,440	49,727
Total investments reported as secured loans receivable and investments, net
Accounts, Notes, Loans and Financing Receivable
Debt Securities, Held-to-maturity, Allowance for Credit Loss		0	(8,846)
Debt securities, available-for-sale, unrealized gain		2,996	3,419
Debt securities, available-for-sale and held-to-maturity, amortized cost		527,442	610,994
Debt Securities, Available-for-sale and Held-to-maturity		530,439	605,567
Debt securities, Available-for-Sale and Held-to-Maturity, fair value		$ 518,554	558,434
Marketable debt securities
Accounts, Notes, Loans and Financing Receivable
Debt Securities, Held-to-maturity, Allowance for Credit Loss			0
Debt securities, available-for-sale, amortized cost			213,334
Debt securities, available-for-sale, unrealized gain			24,219
Debt securities, available-for-sale, carrying value			$ 237,553