Organization, Basis of Presentation and Significant Accounting Policies (Details 3) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Management, development and other fees	$ 1,017	$ 1,231	$ 2,950	$ 3,484
Rental and other income	566,387	586,382	1,742,509	1,727,576
Total revenue	567,404	587,613	1,745,459	1,731,060
Operating Segments | Established Communities
Disaggregation of Revenue [Line Items]
Total revenue	508,558	541,737	1,572,701	1,605,891
Operating Segments | Other Stabilized Communities
Disaggregation of Revenue [Line Items]
Total revenue	35,080	30,199	105,246	77,749
Non-allocated
Disaggregation of Revenue [Line Items]
Total revenue	1,017	1,231	2,950	3,484
Continuing Operations
Disaggregation of Revenue [Line Items]
Management, development and other fees	3,790	3,605	10,521	10,539
Rental and other income	561,883	577,607	1,728,394	1,691,491
Gain on Business Interruption Insurance Recovery	282	307	385	914
Total revenue	565,955	581,519	1,739,300	1,702,944
Continuing Operations | Management, development and other fees
Disaggregation of Revenue [Line Items]
Management, development and other fees	1,017	1,231	2,950	3,484
Continuing Operations | Rental and non-rental related income
Disaggregation of Revenue [Line Items]
Management, development and other fees	2,773	2,374	7,571	7,055
Continuing Operations | Operating Segments | Established Communities
Disaggregation of Revenue [Line Items]
Management, development and other fees	1,959	1,796	5,416	5,753
Rental and other income	506,587	539,634	1,567,170	1,599,224
Gain on Business Interruption Insurance Recovery	12	307	115	914
Total revenue	508,558	541,737	1,572,701	1,605,891
Continuing Operations | Operating Segments | Other Stabilized Communities
Disaggregation of Revenue [Line Items]
Management, development and other fees	477	445	1,271	1,078
Rental and other income	34,333	29,754	103,705	76,671
Gain on Business Interruption Insurance Recovery	270	0	270	0
Total revenue	35,080	30,199	105,246	77,749
Continuing Operations | Operating Segments | Development/ Redevelopment Communities
Disaggregation of Revenue [Line Items]
Management, development and other fees	337	133	884	224
Rental and other income	20,963	8,219	57,519	15,596
Gain on Business Interruption Insurance Recovery	0	0	0	0
Total revenue	21,300	8,352	58,403	15,820
Continuing Operations | Operating Segments | Management, development and other fees | Established Communities
Disaggregation of Revenue [Line Items]
Management, development and other fees	0	0	0	0
Continuing Operations | Operating Segments | Management, development and other fees | Other Stabilized Communities
Disaggregation of Revenue [Line Items]
Management, development and other fees	0	0	0	0
Continuing Operations | Operating Segments | Management, development and other fees | Development/ Redevelopment Communities
Disaggregation of Revenue [Line Items]
Management, development and other fees	0	0	0	0
Continuing Operations | Operating Segments | Rental and non-rental related income | Established Communities
Disaggregation of Revenue [Line Items]
Management, development and other fees	1,959	1,796	5,416	5,753
Continuing Operations | Operating Segments | Rental and non-rental related income | Other Stabilized Communities
Disaggregation of Revenue [Line Items]
Management, development and other fees	477	445	1,271	1,078
Continuing Operations | Operating Segments | Rental and non-rental related income | Development/ Redevelopment Communities
Disaggregation of Revenue [Line Items]
Management, development and other fees	337	133	884	224
Continuing Operations | Non-allocated
Disaggregation of Revenue [Line Items]
Management, development and other fees	1,017	1,231	2,950	3,484
Rental and other income	0	0	0	0
Gain on Business Interruption Insurance Recovery	0	0	0	0
Total revenue	1,017	1,231	2,950	3,484
Continuing Operations | Non-allocated | Management, development and other fees
Disaggregation of Revenue [Line Items]
Management, development and other fees	1,017	1,231	2,950	3,484
Continuing Operations | Non-allocated | Rental and non-rental related income
Disaggregation of Revenue [Line Items]
Management, development and other fees	$ 0	$ 0	$ 0	$ 0