Dispositions of Real Estate and Discontinued Operations - Schedule of Results of Discontinued Operations (Details) - Held-for-sale - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Rental and related revenues	$ 694	$ 24,589	$ 7,535	$ 81,070
Resident fees and services	8,507	149,585	111,777	477,081
Total revenues	9,201	174,174	119,312	558,151
Interest expense	47	2,501	3,900	7,913
Depreciation and amortization	0	31,659	0	134,620
Operating	13,010	131,151	118,175	407,820
Transaction costs	0	602	76	1,141
Impairments and loan loss reserves (recoveries), net	21,740	36,327	32,736	81,556
Total costs and expenses	34,797	202,240	154,887	633,050
Gain (loss) on sales of real estate, net	26,758	(2,134)	408,658	162,245
Other income (expense), net	(863)	316	5,150	2,442
Total other income (expense), net	25,895	(1,818)	413,808	164,687
Income (loss) before income taxes and equity income (loss) from unconsolidated joint ventures	299	(29,884)	378,233	89,788
Income tax benefit (expense)	221	(1,204)	1,345	9,424
Equity income (loss) from unconsolidated joint ventures	81	(731)	4,991	(915)
Income (loss) from discontinued operations	$ 601	$ (31,819)	$ 384,569	$ 98,297