Summary Of Significant Accounting Policies Capital Leases Disclosures (Details) - USD ($) $ in Thousands		Dec. 31, 2018	Dec. 31, 2017
Capital Leased Assets [Line Items]
Land held for future development	[1]	$ 200,498	$ 204,925
Buildings and improvements		13,356,751	12,284,164
Construction in progress		578,796	1,269,338
2019		1,441
2020		12,682
2021		2,123
2022		1,253
2023		944
Thereafter		73,241
Total expected minimum lease payments		91,684
Interest portion		(27,497)
Present value of expected net minimum lease payments		64,187
Capital Lease Obligations [Member]
Capital Leased Assets [Line Items]
Land held for future development		12,397	0
Buildings and improvements		23,636	23,636
Construction in progress		28,962	28,962
Total		$ 64,995	$ 52,598

[1] Includes pre-development costs.