Note 2 - Real Estate (Details) - Components of Rental Property (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Property Subject to or Available for Operating Lease [Line Items]
Land	$ 2,072,099		$ 2,024,300
Buildings and improvements:
Buildings and improvements	6,953,427		6,825,724
	9,025,526		8,850,024
Accumulated depreciation and amortization	(1,878,681)		(1,745,462)
Total	7,146,845		7,104,562
Land [Member]
Property Subject to or Available for Operating Lease [Line Items]
Land	1,989,830		1,927,800
Undeveloped Land [Member]
Property Subject to or Available for Operating Lease [Line Items]
Land	82,269		96,500
Buildings [Member]
Buildings and improvements:
Buildings and improvements	4,572,740		4,607,931
Building Improvements [Member]
Buildings and improvements:
Buildings and improvements	1,168,959		1,091,810
Tenant Improvements [Member]
Buildings and improvements:
Buildings and improvements	725,570		708,626
Fixtures And Leasehold Improvements [Member]
Buildings and improvements:
Buildings and improvements	61,015		59,690
Other Rental Property [Member]
Buildings and improvements:
Buildings and improvements	$ 425,143	[1]	$ 357,667	[1]

[1] At December 31, 2013 and 2012, Other rental property (net of accumulated amortization of $252.8 million and $212.9 million, respectively), consisted of intangible assets including (i) $290,838 and $237,166, respectively, of in-place leases, (ii) $21,326 and $21,335, respectively, of tenant relationships, and (iii) $112,979 and $99,166, respectively, of above-market leases.