Dispositions and Assets Held for Sale - Summary of Real Property Disposition Activity (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Real estate dispositions:
Total dispositions			$ 1,549,401	$ 451,591
Gain (loss) on real estate dispositions, net	$ 155,863	$ (1,682)	418,687	165,727
Net other assets/liabilities disposed			29,999	(498)
Proceeds from real estate dispositions			1,998,087	616,820
Seniors Housing Operating
Real estate dispositions:
Total dispositions			706,964	8,726
Triple-net
Real estate dispositions:
Total dispositions			33,445	442,865
Outpatient Medical
Real estate dispositions:
Total dispositions			$ 808,992	$ 0