Real Property Acquisitions and Development (Construction Activity) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Development projects:
Total development projects	$ 211,830	$ 49,123	$ 188,344
Expansion projects	48,600	0	20,029
Total construction in progress conversions	260,430	49,123	208,373
Seniors Housing Operating
Development projects:
Total development projects	93,188	28,117	86,931
Triple-net
Development projects:
Total development projects	75,149	0	90,055
Outpatient Medical
Development projects:
Total development projects	$ 43,493	$ 21,006	$ 11,358