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Loans Receivable - Collective Pool Basis (Details) $ in Thousands	3 Months Ended
	Sep. 30, 2020 USD ($) loan	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)
Financing Receivable, Allowance for Credit Loss [Line Items]
Loan Carrying Value	$ 881,750
Allowance for Credit Loss	(84,895)	$ (68,372)	$ (68,372)	$ (68,372)
Real estate loans receivable, net of credit allowance	$ 796,855
No. of Loans \| loan	47
Deferred gains	$ 62,819
Deteriorated loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Loan Carrying Value	249,314
Allowance for Credit Loss	(76,695)
Real estate loans receivable, net of credit allowance	$ 172,619
No. of Loans \| loan	7
Collective loan pool
Financing Receivable, Allowance for Credit Loss [Line Items]
Loan Carrying Value	$ 129,949
Allowance for Credit Loss	(1,886)
Real estate loans receivable, net of credit allowance	$ 128,063
No. of Loans \| loan	15
Collective loan pool
Financing Receivable, Allowance for Credit Loss [Line Items]
Loan Carrying Value	$ 124,599
Allowance for Credit Loss	(1,612)
Real estate loans receivable, net of credit allowance	$ 122,987
No. of Loans \| loan	4
Collective loan pool
Financing Receivable, Allowance for Credit Loss [Line Items]
Loan Carrying Value	$ 124,840
Allowance for Credit Loss	(1,074)
Real estate loans receivable, net of credit allowance	$ 123,766
No. of Loans \| loan	7
Collective loan pool
Financing Receivable, Allowance for Credit Loss [Line Items]
Loan Carrying Value	$ 17,314
Allowance for Credit Loss	(251)
Real estate loans receivable, net of credit allowance	$ 17,063
No. of Loans \| loan	1
Collective loan pool
Financing Receivable, Allowance for Credit Loss [Line Items]
Loan Carrying Value	$ 49,274
Allowance for Credit Loss	(684)
Real estate loans receivable, net of credit allowance	$ 48,590
No. of Loans \| loan	7
Collective loan pool
Financing Receivable, Allowance for Credit Loss [Line Items]
Loan Carrying Value	$ 186,460
Allowance for Credit Loss	(2,693)
Real estate loans receivable, net of credit allowance	$ 183,767
No. of Loans \| loan	6
Genesis healthcare receivable
Financing Receivable, Allowance for Credit Loss [Line Items]
Loan Carrying Value	$ 62,753
No. of Loans \| loan	2