Real Property Acquisitions and Development - Construction Activity (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Segment Reporting Information [Line Items]
Total development projects	$ 198,446	$ 195,882
Expansion projects	0	48,600
Total construction in progress conversions	198,446	244,482
Seniors Housing Operating
Segment Reporting Information [Line Items]
Total development projects	58,844	93,188
Triple-net
Segment Reporting Information [Line Items]
Total development projects	22,990	59,201
Outpatient Medical
Segment Reporting Information [Line Items]
Total development projects	$ 116,612	$ 43,493