Schedule of Debt Net of Unamortized Debt Premium (Discount) and Debt Issuance Costs (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Long-term Debt	$ 3,988,528	$ 3,919,544
Fixed Rate Mortgage Loans [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Contractual Interest Rate	4.40%
Debt, Weighted Average Effective Interest Rate	3.90%
Long-term Debt	$ 338,024	342,020
Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Contractual Interest Rate	3.80%
Debt, Weighted Average Effective Interest Rate	4.00%
Long-term Debt	$ 3,238,514	2,944,752
Total credit facilities	264,605	484,383
Notes Payable to Banks [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 3,723,923	3,435,161
Line of Credit [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Contractual Interest Rate	1.00%
Debt, Weighted Average Effective Interest Rate	1.40%
Line of Credit [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Total credit facilities		220,000
Term Loan [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Contractual Interest Rate	2.00%
Debt, Weighted Average Effective Interest Rate	2.10%
Term Loan [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Total credit facilities	$ 264,605	264,383
London Interbank Offered Rate (LIBOR) [Member] | Variable Rate Mortgage Loans [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Contractual Interest Rate	2.80%
Debt, Weighted Average Effective Interest Rate	2.90%
Long-term Debt	$ 147,385	$ 148,389