Borrowings - Schedule of Borrowings (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020 USD ($) debt_instrument property	Dec. 31, 2019 USD ($)
Debt Instrument [Line Items]
Carrying Value	$ 1,441,218
Watermark Fountains Portfolio
Debt Instrument [Line Items]
Number of healthcare real estate properties | property	14
Winterfell
Debt Instrument [Line Items]
Number of healthcare real estate properties | property	32
Mortgage notes payable, net
Debt Instrument [Line Items]
Principal Amount	$ 1,441,218	$ 1,455,413
Mortgage notes payable, net | Rochester, NY
Debt Instrument [Line Items]
Principal Amount	$ 19,900
Mortgage notes payable, net | Rochester Portfolio
Debt Instrument [Line Items]
Number of debt instruments | debt_instrument	7
Number of healthcare real estate properties | property	7
Mortgage notes payable, net | Arbors Portfolio
Debt Instrument [Line Items]
Number of debt instruments | debt_instrument	4
Number of healthcare real estate properties | property	4
Mortgage notes payable, net | Winterfell
Debt Instrument [Line Items]
Number of debt instruments | debt_instrument	32
Mortgage notes payable, net | Avamere Portfolio
Debt Instrument [Line Items]
Number of debt instruments | debt_instrument	5
Number of healthcare real estate properties | property	5
Mortgage notes payable, net | Denver, CO Non-recourse | Denver, CO
Debt Instrument [Line Items]
Principal Amount	$ 20,350	20,547
Carrying Value	$ 20,334	20,500
Mortgage notes payable, net | Denver, CO Non-recourse | Denver, CO | LIBOR
Debt Instrument [Line Items]
Interest rate (percentage)	2.92%
Mortgage notes payable, net | Frisco, TX Non-recourse | Frisco, TX
Debt Instrument [Line Items]
Principal Amount	$ 18,882	19,170
Carrying Value	$ 18,867	19,127
Mortgage notes payable, net | Frisco, TX Non-recourse | Frisco, TX | LIBOR
Debt Instrument [Line Items]
Interest rate (percentage)	3.04%
Mortgage notes payable, net | Milford, OH Non-recourse | Milford, OH
Debt Instrument [Line Items]
Principal Amount	$ 18,760	18,760
Carrying Value	$ 18,407	18,357
Mortgage notes payable, net | Milford, OH Non-recourse | Milford, OH | LIBOR
Debt Instrument [Line Items]
Interest rate (percentage)	2.68%
Mortgage notes payable, net | Rochester, NY Non-recourse, February 2025 | Rochester, NY
Debt Instrument [Line Items]
Contractual Interest Rate	4.25%
Principal Amount	$ 19,907	20,228
Carrying Value	19,824	20,131
Mortgage notes payable, net | Rochester, NY Non-recourse, August 2027 | Rochester, NY
Debt Instrument [Line Items]
Principal Amount	101,224	101,224
Carrying Value	$ 100,352	100,267
Mortgage notes payable, net | Rochester, NY Non-recourse, August 2027 | Rochester, NY | LIBOR
Debt Instrument [Line Items]
Interest rate (percentage)	2.34%
Mortgage notes payable, net | Rochester, NY Non-recourse, August 2021 | Rochester Portfolio
Debt Instrument [Line Items]
Principal Amount	$ 12,800	12,800
Carrying Value	$ 12,493	12,232
Mortgage notes payable, net | Rochester, NY Non-recourse, August 2021 | Rochester Portfolio | LIBOR
Debt Instrument [Line Items]
Interest rate (percentage)	2.90%
Mortgage notes payable, net | Non-Recourse
Debt Instrument [Line Items]
Principal Amount	$ 1,437,304	1,451,720
Carrying Value	$ 1,417,538	1,428,229
Mortgage notes payable, net | Non-Recourse | Arbors Portfolio
Debt Instrument [Line Items]
Contractual Interest Rate	3.99%
Principal Amount	$ 87,756	89,026
Carrying Value	$ 86,920	88,020
Mortgage notes payable, net | Non-Recourse | Watermark Fountains Portfolio
Debt Instrument [Line Items]
Contractual Interest Rate	3.92%
Principal Amount	$ 388,680	392,269
Carrying Value	$ 387,492	390,508
Mortgage notes payable, net | Non-Recourse | Watermark Fountains Portfolio 2
Debt Instrument [Line Items]
Contractual Interest Rate	5.56%
Principal Amount	$ 73,714	74,208
Carrying Value	$ 73,406	73,750
Number of healthcare real estate properties | property	7
Mortgage notes payable, net | Non-Recourse | Winterfell
Debt Instrument [Line Items]
Contractual Interest Rate	4.17%
Principal Amount	$ 624,513	632,024
Carrying Value	$ 609,210	614,415
Mortgage notes payable, net | Non-Recourse | Avamere Portfolio
Debt Instrument [Line Items]
Contractual Interest Rate	4.66%
Principal Amount	$ 70,718	71,464
Carrying Value	70,233	70,922
Mortgage notes payable, net | One-Month LIBOR
Debt Instrument [Line Items]
Principal Amount	172,000
Other notes payable | Non-Recourse
Debt Instrument [Line Items]
Principal Amount	3,914	3,693
Carrying Value	$ 3,915	3,693
Other notes payable | Non-Recourse | Oak Cottage
Debt Instrument [Line Items]
Contractual Interest Rate	6.00%
Principal Amount	$ 3,914	3,693
Carrying Value	3,915	3,693
Mortgages and other notes payable
Debt Instrument [Line Items]
Principal Amount	1,441,218	1,455,413
Carrying Value	$ 1,421,453	$ 1,431,922