Loans Receivable and Other Lending Investments, net - Credit Characteristics by Payment Status (Details) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2020 USD ($) loan	Dec. 31, 2019 USD ($)
Recorded investment in loans, aged by payment status and presented by class
Current	$ 692,129	$ 665,460
Total Past Due	37,517	37,820
Total	729,646	703,280
Less Than and Equal to 90 Days
Recorded investment in loans, aged by payment status and presented by class
Total Past Due	0	0
Greater Than 90 Days
Recorded investment in loans, aged by payment status and presented by class
Total Past Due	$ 37,517	$ 37,820
Financing receivable, number of loans greater than 90 days past due \| loan	1
Financing receivables, past due time period	10 years 9 months 18 days	10 years 6 months
Commercial Portfolio Segment \| Senior mortgages
Recorded investment in loans, aged by payment status and presented by class
Current	$ 558,043	$ 534,765
Total Past Due	37,517	37,820
Total	595,560	572,585
Commercial Portfolio Segment \| Senior mortgages \| Less Than and Equal to 90 Days
Recorded investment in loans, aged by payment status and presented by class
Total Past Due		0
Commercial Portfolio Segment \| Senior mortgages \| Greater Than 90 Days
Recorded investment in loans, aged by payment status and presented by class
Total Past Due	37,517	37,820
Commercial Portfolio Segment \| Corporate/Partnership loans
Recorded investment in loans, aged by payment status and presented by class
Current	123,023	119,818
Total Past Due	0	0
Total	123,023	119,818
Commercial Portfolio Segment \| Corporate/Partnership loans \| Less Than and Equal to 90 Days
Recorded investment in loans, aged by payment status and presented by class
Total Past Due	0	0
Commercial Portfolio Segment \| Corporate/Partnership loans \| Greater Than 90 Days
Recorded investment in loans, aged by payment status and presented by class
Total Past Due	0	0
Commercial Portfolio Segment \| Subordinate mortgages
Recorded investment in loans, aged by payment status and presented by class
Current	11,063	10,877
Total Past Due	0	0
Total	11,063	10,877
Commercial Portfolio Segment \| Subordinate mortgages \| Less Than and Equal to 90 Days
Recorded investment in loans, aged by payment status and presented by class
Total Past Due	0	0
Commercial Portfolio Segment \| Subordinate mortgages \| Greater Than 90 Days
Recorded investment in loans, aged by payment status and presented by class
Total Past Due	$ 0	$ 0

Financing Receivable, Number of Loans Greater than 90 Days Past Due

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- Definition

Financing Receivables, Past Due Time Period

+ References

No definition available.

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- Definition

Amount of financing receivable not past due.

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- Definition

Amount of financing receivable past due.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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+ References

No definition available.

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- Definition

Amount, before allowance for credit loss, of financing receivable.

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