Real Property Acquisitions and Development (Construction Activity) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Development projects:
Total development projects	$ 49,123	$ 188,344	$ 350,142
Expansion projects	0	20,029	10,336
Total construction in progress conversions	49,123	208,373	360,478
Seniors Housing Operating
Development projects:
Total development projects	28,117	86,931	3,634
Triple-net
Development projects:
Total development projects	0	90,055	283,472
Outpatient Medical
Development projects:
Total development projects	$ 21,006	$ 11,358	$ 63,036