Debt (Summary of Debt) (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Debt Instrument
Deferred financing costs, net and other	$ (50,262)	$ (34,462)
Long term debt	$ 2,562,148	1,818,447
Mortgages
Debt Instrument
Interest rate, end of period (percent)	2.52%
Long-term debt, gross	$ 5,585,015	5,608,458
Deferred financing costs, net and other	(37,410)	(27,909)
Long term debt	$ 5,547,605	5,580,549
Mortgages | Fixed Rate
Debt Instrument
Interest rate, end of period (percent)	3.09%
Long-term debt, gross	$ 3,140,000	3,012,643
Mortgages | Variable Rate
Debt Instrument
Interest rate, end of period (percent)	1.78%
Long-term debt, gross	$ 2,445,015	2,595,815
Senior Unsecured Notes
Debt Instrument
Interest rate, end of period (percent)	3.02%
Long-term debt, gross	$ 1,200,000	450,000
Deferred financing costs, net and other	(10,139)	(3,315)
Long term debt	$ 1,189,861	446,685
Unsecured term loan
Debt Instrument
Interest rate, end of period (percent)	3.70%
Long-term debt, gross	$ 800,000	800,000
Deferred financing costs, net and other	(2,713)	(3,238)
Long term debt	$ 797,287	796,762
Unsecured Revolving Credit Facilities
Debt Instrument
Interest rate, end of period (percent)	1.00%
Long term debt	$ 575,000	$ 575,000