Organization, Basis of Presentation, and Significant Accounting Policies (Details 2)	12 Months Ended
	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($) community	Dec. 31, 2018 USD ($)
Accounting Policies [Abstract]
Minimum distribution of adjusted taxable income for deducting dividends from federally taxable income (as a percent)	90.00%
Minimum distribution of REIT taxable income for federal income tax exemption (as a percent)	100.00%
Accounting Policies [Line Items]
Right of use lease assets	$ 133,581,000	$ 103,063,000
Income Tax Disclosure [Abstract]
Unrecognized tax benefits	0	0
Excise and sales taxes	0	0	$ 0
Excise tax refund	0	0	0
Income Tax Expense (Benefit)	(3,247,000)	13,003,000	(160,000)
Casualty and impairment loss, net	0	0	215,000
Impairment of investment in unconsolidated entities	$ 0	$ 0	$ 0
Deferred Financing Costs
Number Of Communities Sold With Deferred Tax Obligations | community		2
Tax components of common stock dividends declared
Ordinary income (as a percent)	66.00%	96.00%	76.00%
20% capital gain (as a percent)	24.00%	3.00%	11.00%
Capital gain tax rate (as a percent)	20.00%	20.00%	20.00%
Unrecaptured 1250 gain (as a percent)	10.00%	1.00%	13.00%
Unsecured notes
Deferred Financing Costs
Accumulated amortization of deferred finance costs	$ 25,239,000	$ 25,995,000
Secured notes
Deferred Financing Costs
Accumulated amortization of deferred finance costs	2,046,000	1,784,000
Variable rate unsecured credit facility
Deferred Financing Costs
Accumulated amortization of deferred finance costs	13,501,000	11,815,000
The Park Loggia [Member]
Income Tax Disclosure [Abstract]
Income Tax Expense (Benefit)		5,782,000,000
TRS Disposed Communities [Member]
Income Tax Disclosure [Abstract]
Income Tax Expense (Benefit)		7,221,000,000
Land
Income Tax Disclosure [Abstract]
Casualty and impairment loss, net	0	0	$ 826,000
Development Communities | The Park Loggia [Member]
Income Tax Disclosure [Abstract]
Casualty and impairment loss, net	$ 0	$ 0
Minimum | Buildings and Building Improvements
Accounting Policies [Line Items]
Estimated useful life of buildings and improvements (in years)	7 years