Schedule of Debt Net of Unamortized Debt Premium (Discount) and Debt Issuance Costs (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Long-term Debt	$ 4,293,298	$ 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	$ 341,063	342,020
Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Contractual Interest Rate	3.80%
Debt, Weighted Average Effective Interest Rate	3.90%
Long-term Debt	$ 3,539,982	2,944,752
Total credit facilities	264,531	484,383
Notes Payable to Banks [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 4,028,767	3,435,161
Line of Credit [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Contractual Interest Rate	1.20%
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	$ 264,531	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	$ 147,722	$ 148,389