Dispositions of Real Estate and Discontinued Operations - Schedule of Results of Discontinued Operations (Details) - Held-for-sale - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Rental and related revenues	$ 5,228	$ 32,371
Resident fees and services	72,998	171,726
Total revenues	78,226	204,097
Interest expense	2,676	2,685
Depreciation and amortization	0	64,164
Operating	71,519	138,637
Transaction costs	76	285
Impairments and loan loss reserves (recoveries), net	0	28,016
Total costs and expenses	74,271	233,787
Gain (loss) on sales of real estate, net	259,662	162,800
Other income (expense), net	5,885
Other income (expense), net		(45)
Total other income (expense), net	265,547	162,755
Income (loss) before income taxes and equity income (loss) from unconsolidated joint ventures	269,502	133,065
Income tax benefit (expense)	821	3,176
Equity income (loss) from unconsolidated joint ventures	(315)	(833)
Income (loss) from discontinued operations	$ 270,008	$ 135,408