Indebtedness (Details) $ in Thousands		3 Months Ended		9 Months Ended
	Dec. 20, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Jun. 29, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jun. 29, 2019 USD ($)
Debt Instrument [Line Items]
Unamortized Debt Issuance Expense		$ 800		$ 800
Interest Expense, Long-term Debt		28,977	$ 28,439	86,669	$ 81,579
interest expense to loan participant		0	0	0	110
Long-term Debt, Current Maturities		44,152		44,152
Long-term Debt		2,765,793		2,765,793		$ 297,800	$ 2,567,022	$ 143,800
Long-term Debt, Maturities, Repayments of Principal in Year Two		166,730		166,730
Long-term Debt, Maturities, Repayments of Principal in Year Three		105,432		105,432
Long-term Debt, Maturities, Repayments of Principal in Year Four		117,605		117,605
Long-term Debt, Maturities, Repayments of Principal after Year Five		367,421		367,421
Long-term Debt, Maturities, Repayments of Principal after Year Five		2,045,829		2,045,829
Long-term Debt		2,847,169		2,847,169
Interest Expense		29,879	28,799	90,608	83,166
Line of Credit Facility, Amount Outstanding		33,000		33,000			$ 0
Amortization of Financing Costs				5,177	4,752
interest expense credit facility		$ 902	360	$ 3,939	1,587
Short-term Debt	$ 70,000
Debt Instrument, Debt Covenant, Debt Service Coverage Ratio		1.74		1.74
Long-term Debt, Current Maturities, Line of Credit		$ 33,000		$ 33,000
London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.70%
Secured Mortgage Note [Member]
Debt Instrument [Line Items]
Initial Interest Rate		3.93%		3.93%
Spread over Initial Interest Rate option 1		200		200
Spread over Initial Interest Rate option 2		400		400
Indebtedness Weighted Average Remaining Maturity				9 years 3 months 18 days
Long-term Debt, Term		7 years		7 years
Debt, Term Of Extension				5 years
Retail Segment [Member]
Debt Instrument [Line Items]
Interest Expense, Long-term Debt		$ 6,539	6,422	$ 19,876	18,123
Office Building
Debt Instrument [Line Items]
Interest Expense, Long-term Debt		6,699	5,909	20,256	16,617
Interest Expense		6,699	5,909	20,256	16,617
Multifamily Communities
Debt Instrument [Line Items]
Interest Expense, Long-term Debt		15,739	16,108	46,537	46,729
Interest Expense		$ 15,739	$ 16,108	$ 46,537	$ 46,729