Dispositions, Real Property Held for Sale and Impairment - Summary of Real Property Disposition Activity (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Real estate dispositions:
Total dispositions			$ 339,066	$ 1,549,401
Gain (loss) on real estate dispositions, net	$ 44,668	$ 155,863	103,748	418,687
Net other assets/liabilities disposed			3,866	29,999
Proceeds from real estate dispositions			446,680	1,998,087
Seniors Housing Operating
Real estate dispositions:
Total dispositions			112,809	706,964
Triple-net
Real estate dispositions:
Total dispositions			88,367	33,445
Outpatient Medical
Real estate dispositions:
Total dispositions			$ 137,890	$ 808,992