Notes Payable and Unsecured Credit Facilities - Schedule of Debt Net of Unamortized Debt Premium (Discount) and Debt Issuance Costs (Details) - USD ($) $ in Thousands		Dec. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Long-term Debt		$ 3,718,944	$ 3,923,084
Fixed Rate Mortgage Loans [Member]
Debt Instrument [Line Items]
Long-term Debt, Maturity Date		Mar. 01, 2032
Debt, Weighted Average Contractual Interest Rate		4.00%
Debt, Weighted Average Effective Interest Rate		3.80%
Long-term Debt		$ 359,414	272,750
Unsecured Debt [Member]
Debt Instrument [Line Items]
Long-term Debt, Maturity Date		Mar. 15, 2049
Debt, Weighted Average Contractual Interest Rate		3.80%
Debt, Weighted Average Effective Interest Rate		4.00%
Long-term Debt		$ 3,243,991	3,239,609
Notes Payable to Banks [Member]
Debt Instrument [Line Items]
Long-term Debt		$ 3,718,944	3,658,405
Line of Credit [Member]
Debt Instrument [Line Items]
Long-term Debt, Maturity Date	[1]	Mar. 23, 2025
Debt, Weighted Average Contractual Interest Rate	[1]	1.00%
Debt, Weighted Average Effective Interest Rate	[1]	1.30%
Term Loan [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Contractual Interest Rate	[2]	2.00%
Debt, Weighted Average Effective Interest Rate	[2]	2.10%
Term Loan [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Total credit facilities	[2]		264,679
London Interbank Offered Rate (LIBOR) [Member] | Variable Rate Mortgage Loans [Member]
Debt Instrument [Line Items]
Long-term Debt, Maturity Date	[3]	Jun. 02, 2027
Debt, Weighted Average Contractual Interest Rate	[3]	3.20%
Debt, Weighted Average Effective Interest Rate	[3]	3.30%
Long-term Debt	[3]	$ 115,539	$ 146,046

[1] Weighted average effective rate for the Line is calculated based on a fully drawn Line balance.

[2] Weighted average contractual and effective rates for the Term Loan are as of December 31, 2020, as the entire balance was repaid during January 2021.

[3] Consists of five mortgages with interest rates that vary on LIBOR based formulas. Four of these variable rate loans have interest rate swaps in place to mitigate the interest rate fluctuation risk. The effective fixed rates of the loans range from 2.5% to 4.1