Dispositions, Real Property Held for Sale and Impairment - Summary of Real Property Disposition Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Real estate dispositions:
Total dispositions	$ 828,866	$ 3,097,299	$ 1,900,930
Gain (loss) on real estate dispositions, net	235,375	1,088,455	748,041
Net other assets (liabilities) disposed	6,081	114,274	1,679
Proceeds from real estate dispositions	1,070,322	4,300,028	2,650,650
Seniors Housing Operating
Real estate dispositions:
Total dispositions	112,837	1,289,769	1,232,816
Triple-net
Real estate dispositions:
Total dispositions	486,369	51,666	667,632
Outpatient Medical
Real estate dispositions:
Total dispositions	$ 229,660	$ 1,755,864	$ 482