Note 7 - Discontinued Operations and Assets Held-for-Sale (Detail) (USD $)						12 Months Ended															12 Months Ended							12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011	Dec. 31, 2010 Assets Held-for-sale [Member] Unimpaired [Member]	Dec. 31, 2012 Assets Held-for-sale [Member] Operating Properties [Member] Prior to Sales [Member] Sold [Member]	Dec. 31, 2012 Assets Held-for-sale [Member] Operating Properties [Member] Impairments [Member]	Dec. 31, 2012 Assets Held-for-sale [Member] Operating Properties [Member] Fair Value [Member]	Dec. 31, 2012 Assets Held-for-sale [Member] Operating Properties [Member] Sold [Member]	Dec. 31, 2012 Assets Held-for-sale [Member] Operating Properties [Member] Additional [Member]	Dec. 31, 2012 Assets Held-for-sale [Member] Operating Properties [Member] Remaining [Member]	Dec. 31, 2012 Assets Held-for-sale [Member] Operating Properties [Member]	Dec. 31, 2010 Assets Held-for-sale [Member] Impairments [Member]	Dec. 31, 2011 Assets Held-for-sale [Member] Additional [Member]	Dec. 31, 2011 Assets Held-for-sale [Member] Prior to Sales [Member]	Dec. 31, 2010 Assets Held-for-sale [Member] Prior to Sales [Member]	Dec. 31, 2011 Assets Held-for-sale [Member] Sold [Member]	Dec. 31, 2010 Assets Held-for-sale [Member] Sold [Member]	Dec. 31, 2011 Assets Held-for-sale [Member] Transfers [Member]	Dec. 31, 2011 Assets Held-for-sale [Member] Operating Properties [Member]	Dec. 31, 2011 Assets Held-for-sale [Member] Land Parcels [Member]	Dec. 31, 2011 Assets Held-for-sale [Member]	Dec. 31, 2010 Assets Held-for-sale [Member]	Dec. 31, 2011 Operating Properties [Member] Impairments [Member]	Dec. 31, 2012 Operating Properties [Member] Impairments [Member]	Dec. 31, 2012 Operating Properties [Member]	Dec. 31, 2012 Impairments [Member]	Dec. 31, 2011 Impairments [Member] Land Parcels [Member]	Dec. 31, 2012 Impairments [Member]	Dec. 31, 2010 Impairments [Member]	Dec. 31, 2011 Impairments [Member]	Dec. 31, 2010 Transfers [Member]
Number of Real Estate Properties	28			5	2	3		19	1		18	7	1			5	11	1	7	1	2	12	2	4	24		1		7		7
Gross Leasable Area	3,086,000	[1]	2,488,000								2,100,000										200,000	500,000
Real Estate Investment Property, Net (in Dollars)	$ 7,201,825,069		$ 7,078,167,000							$ 3,400,000	$ 73,200,000			$ 10,000,000	$ 40,500,000											$ 52,500,000				$ 5,300,000
Real Estate Investment Property, Accumulated Depreciation (in Dollars)	1,745,462,000		1,693,090,000							6,800,000	57,200,000			7,300,000							500,000	11,900,000
Impairment of Real Estate (in Dollars)						4,200,000															1,100,000	5,200,000	3,900,000					34,100,000	8,700,000
Fair Value of Real Estate (in Dollars)							102,000,000														19,700,000	66,100,000
Real Estate Held-for-sale (in Dollars)																					$ 3,800,000	$ 4,400,000

[1] Gross leasable area ("GLA")