Loans Receivable and Other Lending Investments, net (Impaired Loans) (Details) - USD ($)	3 Months Ended	12 Months Ended
Jun. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Impaired Loans
Impaired loans with allowance recorded, Recorded Investment		$ 37,820,000	$ 66,725,000
Impaired loans with allowance recorded, Unpaid Principal Balance		37,923,000	66,777,000
Impaired loans, Related Allowance		(21,701,000)	(40,395,000)
Impaired loans with no related allowance recorded, Average Recorded Investment		0	0	$ 6,582,000
Impaired loans with no related allowance recorded, Interest Income Recognized		0	301,000	1,127,000
Impaired loans with allowance recorded, Average Recorded Investment		38,556,000	106,210,000	239,505,000
Impaired loans with allowance recorded, Interest Income Recognized		0	0	0
Impaired loans, Average Recorded Investment		38,556,000	106,210,000	246,087,000
Impaired loans, Interest Income Recognized		0	301,000	1,127,000
Gross carrying value of loan		703,279,000	919,493,000
Preferred equity investment received, face value	$ 100,000,000.0
Preferred equity investment mandatory redemption period (in years)	5 years
Preferred equity investment received, recorded fair value	$ 77,000,000.0
Provision for (recovery of) loan losses		6,482,000	16,937,000	(5,828,000)
Nonperforming Financial Instruments
Impaired Loans
Impaired loans, Interest Income Recognized		0	0	0
Senior mortgages
Impaired Loans
Impaired loans with allowance recorded, Recorded Investment		37,820,000	66,725,000
Impaired loans with allowance recorded, Unpaid Principal Balance		37,923,000	66,777,000
Impaired loans, Related Allowance		(21,701,000)	(40,395,000)
Impaired loans with allowance recorded, Average Recorded Investment		38,556,000	67,041,000	82,749,000
Impaired loans with allowance recorded, Interest Income Recognized		0	0	0
Impaired loans, Average Recorded Investment		38,556,000	67,041,000	82,749,000
Impaired loans, Interest Income Recognized		0	0	0
Gross carrying value of loan		572,584,000	760,749,000
Subordinate mortgages
Impaired Loans
Impaired loans with no related allowance recorded, Average Recorded Investment		0	0	6,582,000
Impaired loans with no related allowance recorded, Interest Income Recognized		0	301,000	1,127,000
Impaired loans, Average Recorded Investment		0	0	6,582,000
Impaired loans, Interest Income Recognized		0	301,000	1,127,000
Gross carrying value of loan		10,877,000	10,161,000
Corporate/Partnership loans
Impaired Loans
Impaired loans with allowance recorded, Average Recorded Investment		0	39,169,000	156,756,000
Impaired loans with allowance recorded, Interest Income Recognized		0	0	0
Impaired loans, Average Recorded Investment		0	39,169,000	156,756,000
Impaired loans, Interest Income Recognized		0	0	$ 0
Gross carrying value of loan		$ 119,818,000	$ 148,583,000
Corporate/Partnership loans \| Nonperforming Financial Instruments
Impaired Loans
Gross carrying value of loan	145,800,000
Proceeds from collection of loan receivable	45,800,000
Provision for (recovery of) loan losses	$ 21,400,000

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Impaired Financing Receivable [Abstract]

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The interest income recognized on a cash-basis or accrual method of accounting during the time within that period that the financing receivables were impaired.

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Reflects the aggregate gross carrying amount of all categories of loans held in portfolio, after deducting deferred income, but before deducting the allowance for losses on loans.

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Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

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Amount of allowance for credit losses related to recorded investment.

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Amount of average investment of impaired financing receivables for which there is a related allowance for credit losses.

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The cash inflow associated with the collection, including prepayments, of loans receivable issued for financing of goods and services.

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Amount of credit loss expense (reversal of expense) for financing receivable.

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