Dispositions of Real Estate and Discontinued Operations - Schedule of Results of Discontinued Operations (Details) - Held-for-sale - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Rental and related revenues	$ 1,613	$ 24,110	$ 6,841	$ 56,481
Resident fees and services	30,273	155,771	103,270	327,496
Total revenues	31,886	179,881	110,111	383,977
Interest expense	1,177	2,727	3,853	5,412
Depreciation and amortization	0	38,797	0	102,961
Operating	33,647	138,033	105,165	276,669
Transaction costs	0	254	76	539
Impairments and loan loss reserves (recoveries), net	10,995	17,213	10,995	45,229
Total costs and expenses	45,819	197,024	120,089	430,810
Gain (loss) on sales of real estate, net	122,238	1,579	381,900	164,379
Other income (expense), net	128	2,171	6,012	2,126
Total other income (expense), net	122,366	3,750	387,912	166,505
Income (loss) before income taxes and equity income (loss) from unconsolidated joint ventures	108,433	(13,393)	377,934	119,672
Income tax benefit (expense)	302	7,452	1,124	10,628
Equity income (loss) from unconsolidated joint ventures	5,225	649	4,910	(184)
Income (loss) from discontinued operations	$ 113,960	$ (5,292)	$ 383,968	$ 130,116