Real Property Acquisitions and Development - Construction Activity (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting Information [Line Items]
Total construction in progress conversions	$ 28,117	$ 107,761
Seniors Housing Operating
Segment Reporting Information [Line Items]
Total development projects	28,117	37,215
Triple-net
Segment Reporting Information [Line Items]
Total development projects	0	59,188
Outpatient Medical
Segment Reporting Information [Line Items]
Total development projects	$ 0	$ 11,358