Notes Payable and Unsecured Credit Facilities - Schedule of Debt Net of Unamortized Debt Premium (Discount) and Debt Issuance Costs (Parentheticals) (Details) - USD ($) $ in Thousands		Jun. 30, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Long-term Debt		$ 3,737,380	$ 3,718,944
Variable Rate Mortgage Loans [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Long-term Debt	[1]	137,563	$ 115,539
Variable Rate Mortgage Loans [Member] | London Interbank Offered Rate (LIBOR) [Member] | Interest Rate Swaps [Member]
Debt Instrument [Line Items]
Long-term Debt		$ 132,600
Variable Rate Mortgage Loans [Member] | Minimum [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt instrument, effective fixed interest rate		2.50%
Variable Rate Mortgage Loans [Member] | Maximum [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt instrument, effective fixed interest rate		4.10%

[1] Five of these six variable rate loans, representing $132.6 million of debt, have interest rate swaps in place to mitigate the interest rate fluctuation risk. Based on these swap agreements, the effective fixed rates of the five loans range from 2.5% to 4.1%.