Dispositions of Real Estate and Discontinued Operations - Schedule of Results of Discontinued Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income tax benefit (expense)	$ 10,000	$ 12,000	$ 13,000
Held-for-sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Rental and related revenues	97,877	152,576	216,887
Resident fees and services	621,253	583,653	400,557
Income from direct financing leases	0	20,815	37,926
Total revenues	719,130	757,044	655,370
Interest expense	10,538	8,007	5,062
Depreciation and amortization	143,194	224,798	144,819
Operating	550,226	474,126	326,381
Transaction costs	20,426	6,780	9,635
Impairments and loan loss reserves (recoveries), net	201,344	208,229	44,343
Total costs and expenses	925,728	921,940	530,240
Gain (loss) on sales of real estate, net	460,144	22,940	94,618
Other income (expense), net			(110)
Other income (expense), net	5,475	17,060
Total other income (expense), net	465,619	40,000	94,508
Income (loss) before income taxes and equity income (loss) from unconsolidated joint ventures	259,021	(124,896)	219,638
Income tax benefit (expense)	9,913	11,783	13,459
Equity income (loss) from unconsolidated joint ventures	(1,188)	(2,295)	3,159
Income (loss) from discontinued operations	$ 267,746	$ (115,408)	$ 236,256