Borrowings - Schedule of Borrowings (Details) $ in Thousands	1 Months Ended	6 Months Ended	12 Months Ended
	May 31, 2019 property	Jun. 30, 2019 USD ($) property Investment debt_instrument	Dec. 31, 2018 USD ($) Investment
Debt Instrument [Line Items]
Long-term debt		$ 1,466,482
Number of debt instruments | Investment		1	1
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		$ 1,466,482	$ 1,494,154
Long-term debt		$ 1,441,241	1,466,349
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 | Bonaventure Portfolio
Debt Instrument [Line Items]
Number of debt instruments | debt_instrument		5
Number of healthcare real estate properties | property		5
Mortgage notes payable, net | Rochester
Debt Instrument [Line Items]
Number of debt instruments | debt_instrument		7
Number of healthcare real estate properties | property		7
Mortgage notes payable, net | Non-Recourse
Debt Instrument [Line Items]
Principal Amount		$ 1,450,434	1,478,299
Long-term debt		1,425,193	1,450,494
Mortgage notes payable, net | Non-Recourse | Peregrine
Debt Instrument [Line Items]
Principal Amount		0	16,545
Long-term debt		$ 0	16,277
Number of properties securing debt | property	3
Mortgage notes payable, net | Non-Recourse | Peregrine | LIBOR
Debt Instrument [Line Items]
Interest rate (percentage)		3.50%
Mortgage notes payable, net | Non-Recourse | Arbors Portfolio
Debt Instrument [Line Items]
Lease obligation interest rate		3.99%
Principal Amount		$ 89,891	90,751
Long-term debt		$ 88,769	89,508
Mortgage notes payable, net | Non-Recourse | Watermark Fountains Portfolio
Debt Instrument [Line Items]
Lease obligation interest rate		3.92%
Principal Amount		$ 395,788	399,023
Long-term debt		$ 393,630	396,421
Mortgage notes payable, net | Non-Recourse | Watermark Fountains Portfolio 2
Debt Instrument [Line Items]
Lease obligation interest rate		5.56%
Principal Amount		$ 74,688	75,401
Long-term debt		$ 74,125	74,776
Number of healthcare real estate properties | property		7
Mortgage notes payable, net | Non-Recourse | Winterfell
Debt Instrument [Line Items]
Lease obligation interest rate		4.17%
Principal Amount		$ 637,510	642,954
Long-term debt		$ 618,384	622,329
Mortgage notes payable, net | Non-Recourse | Bonaventure Portfolio
Debt Instrument [Line Items]
Lease obligation interest rate		4.66%
Principal Amount		$ 71,999	72,466
Long-term debt		71,419	71,848
Mortgage notes payable, net | Denver, CO Non-recourse | Denver, CO
Debt Instrument [Line Items]
Principal Amount		20,712	20,866
Long-term debt		$ 20,642	20,774
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		$ 19,320	19,460
Long-term debt		$ 19,257	19,377
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
Long-term debt		$ 18,322	18,288
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]
Lease obligation interest rate		4.25%
Principal Amount		$ 20,542	20,849
Long-term debt		20,432	20,734
Mortgage notes payable, net | Rochester, NY Non-recourse, August 2027 | Rochester, NY
Debt Instrument [Line Items]
Principal Amount		101,224	101,224
Long-term debt		$ 100,213	100,162
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 | One-Month LIBOR
Debt Instrument [Line Items]
Principal Amount		$ 160,000
Other notes payable | Non-Recourse
Debt Instrument [Line Items]
Principal Amount		16,048	15,855
Long-term debt		$ 16,048	15,855
Other notes payable | Non-Recourse | Oak Cottage
Debt Instrument [Line Items]
Lease obligation interest rate		6.00%
Principal Amount		$ 3,693	3,500
Long-term debt		$ 3,693	3,500
Other notes payable | Non-Recourse | Rochester
Debt Instrument [Line Items]
Lease obligation interest rate		6.00%
Principal Amount		$ 12,355	12,355
Long-term debt		$ 12,355	$ 12,355