Dispositions, Real Property Held for Sale and Impairment - Summary of Real Property Disposition Activity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Real estate dispositions:
Total dispositions	$ 212,216	$ 528,448
Gain (loss) on real estate dispositions, net	59,080	262,824
Net other assets/liabilities disposed	2,912	10,120
Proceeds from real estate dispositions	274,208	801,392
Seniors Housing Operating
Real estate dispositions:
Total dispositions	74,326	0
Triple-net
Real estate dispositions:
Total dispositions	0	33,445
Outpatient Medical
Real estate dispositions:
Total dispositions	$ 137,890	$ 495,003