Organization, Basis of Presentation and Significant Accounting Policies (Details 3) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Management, development and other fees	$ 926	$ 1,114	$ 1,933	$ 2,252
Operating Lease, Lease Income	575,479	576,149	1,176,123	1,141,194
Total revenue	576,405	577,263	1,178,056	1,143,446
Operating Segments | Established Communities
Disaggregation of Revenue [Line Items]
Total revenue	523,531	539,505	1,071,487	1,071,335
Operating Segments | Other Stabilized Communities
Disaggregation of Revenue [Line Items]
Total revenue	34,677	25,522	70,167	47,548
Non-allocated
Disaggregation of Revenue [Line Items]
Total revenue	926	1,114	1,933	2,252
Continuing Operations
Disaggregation of Revenue [Line Items]
Management, development and other fees	3,408	3,472	6,731	6,939
Operating Lease, Lease Income	572,315	564,644	1,169,218	1,116,548
Gain on Business Interruption Insurance Recovery	103	435	103	607
Total revenue	575,826	568,551	1,176,052	1,124,094
Continuing Operations | Management, development and other fees
Disaggregation of Revenue [Line Items]
Management, development and other fees	926	1,114	1,933	2,252
Continuing Operations | Rental and non-rental related income
Disaggregation of Revenue [Line Items]
Management, development and other fees	2,482	2,358	4,798	4,687
Continuing Operations | Operating Segments | Established Communities
Disaggregation of Revenue [Line Items]
Management, development and other fees	1,870	2,154	3,478	3,986
Operating Lease, Lease Income	521,558	536,916	1,067,906	1,066,742
Gain on Business Interruption Insurance Recovery	103	435	103	607
Total revenue	523,531	539,505	1,071,487	1,071,335
Continuing Operations | Operating Segments | Other Stabilized Communities
Disaggregation of Revenue [Line Items]
Management, development and other fees	317	153	793	634
Operating Lease, Lease Income	34,360	25,369	69,374	46,914
Gain on Business Interruption Insurance Recovery	0	0	0	0
Total revenue	34,677	25,522	70,167	47,548
Continuing Operations | Operating Segments | Development/ Redevelopment Communities (1)
Disaggregation of Revenue [Line Items]
Management, development and other fees	295	51	527	67
Operating Lease, Lease Income	16,397	2,359	31,938	2,892
Gain on Business Interruption Insurance Recovery	0	0	0	0
Total revenue	16,692	2,410	32,465	2,959
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 (1)
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	1,870	2,154	3,478	3,986
Continuing Operations | Operating Segments | Rental and non-rental related income | Other Stabilized Communities
Disaggregation of Revenue [Line Items]
Management, development and other fees	317	153	793	634
Continuing Operations | Operating Segments | Rental and non-rental related income | Development/ Redevelopment Communities (1)
Disaggregation of Revenue [Line Items]
Management, development and other fees	295	51	527	67
Continuing Operations | Non-allocated
Disaggregation of Revenue [Line Items]
Management, development and other fees	926	1,114	1,933	2,252
Operating Lease, Lease Income	0	0	0	0
Gain on Business Interruption Insurance Recovery	0	0	0	0
Total revenue	926	1,114	1,933	2,252
Continuing Operations | Non-allocated | Management, development and other fees
Disaggregation of Revenue [Line Items]
Management, development and other fees	926	1,114	1,933	2,252
Continuing Operations | Non-allocated | Rental and non-rental related income
Disaggregation of Revenue [Line Items]
Management, development and other fees	$ 0	$ 0	$ 0	$ 0