Real Property Acquisitions and Development - Construction Activity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Total construction in progress conversions	$ 22,990	$ 112,557
Seniors Housing Operating
Segment Reporting Information [Line Items]
Total development projects	0	93,188
Triple-net
Segment Reporting Information [Line Items]
Total development projects	22,990	0
Outpatient Medical
Segment Reporting Information [Line Items]
Total development projects	$ 0	$ 19,369