Prepaid Expenses and Other Current Assets and Other Assets (Schedule Of Other Assets) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Other Assets, Noncurrent [Line Items]
Straight-line rent receivable			$ 330,660	$ 322,073
Net deferred tax assets			375,935	110,867
Total other assets	[1]		432,078	722,033
Write-off of deferred lease costs		$ 23,300
Other Assets [Member]
Other Assets, Noncurrent [Line Items]
Prepaid ground rent				263,694
Interest rate swap asset			47,583
Loan receivables			8,295	49,255
Deferred lease costs, net			4,865	27,020
Net deferred tax assets			4,342	18,330
Other			36,333	41,661
Total other assets			$ 432,078	$ 722,033

[1] On January 1, 2019, the Company adopted ASU 2016-02 which requires lessees to recognize a right-of-use asset and a lease liability. Upon adoption, certain assets and liabilities were reclassified to Right-of-use assets, net and lease liabilities in accordance with provisions of ASU 2016-02. See Note 2 for further discussion.