Dispositions and Assets Held for Sale - Summary of Real Property Disposition Activity (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Real estate dispositions:
Total dispositions			$ 2,521,893	$ 1,865,451
Gain (loss) on real estate dispositions, net	$ 484,304	$ 570,250	902,991	735,977
Net other assets/liabilities disposed			98,065	(357)
Proceeds from real estate dispositions			3,522,949	2,601,071
Seniors Housing Operating
Real estate dispositions:
Total dispositions			1,093,477	1,204,084
Triple-net
Real estate dispositions:
Total dispositions			33,445	660,885
Outpatient Medical
Real estate dispositions:
Total dispositions			$ 1,394,971	$ 482