Note 2 - Real Estate (Details) - Components of Rental Property (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Property Subject to or Available for Operating Lease [Line Items]
Land	$ 2,365,800		$ 2,072,099
Buildings and improvements:
Buildings and improvements	7,520,095		6,953,427
	9,885,895		9,025,526
Accumulated depreciation and amortization	(1,955,406)		(1,878,681)
Total	7,930,489		7,146,845
Land [Member]
Property Subject to or Available for Operating Lease [Line Items]
Land	2,291,338		1,989,830
Undeveloped Land [Member]
Property Subject to or Available for Operating Lease [Line Items]
Land	74,462		82,269
Buildings [Member]
Buildings and improvements:
Buildings and improvements	4,909,152		4,572,740
Building Improvements [Member]
Buildings and improvements:
Buildings and improvements	1,349,028		1,168,959
Tenant Improvements [Member]
Buildings and improvements:
Buildings and improvements	658,868		725,570
Fixtures And Leasehold Improvements [Member]
Buildings and improvements:
Buildings and improvements	61,122		61,015
Other Rental Property [Member]
Buildings and improvements:
Buildings and improvements	$ 541,925	[1]	$ 425,143	[1]

[1] At December 31, 2014 and 2013, Other rental property (net of accumulated amortization of $290,748 and $252,810, respectively), consisted of intangible assets including (i) $399,293 and $290,838, respectively, of in-place leases, (ii) $20,858 and $21,326, respectively, of tenant relationships, and (iii) $121,774 and $112,979, respectively, of above-market leases.