Note 3 - Property Acquisitions, Developments and Other Investments (Details Textual) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)		Dec. 31, 2015 USD ($)		Dec. 31, 2014 USD ($)
Proceeds from Delayed Tax Exempt Exchange	$ 66,000		$ 89,500
Real Estate Revenue From Acquisitions During Period	23,800		$ 112,200		$ 75,300
Business Acquisition, Percentage of Voting Interests Acquired			50.00%
Payments to Acquire Businesses, Gross	255,910	[1]	$ 712,055	[2]
Number of Land Parcels Acquired			3
Payments to Acquire Real Estate	$ 203,190		$ 661,423		$ 384,828
Land Parcels [Member]
Payments to Acquire Real Estate			30,000
Real Estate Under Development [Member]
Business Combination, Separately Recognized Transactions, Assets Recognized			8,400
Operating Real Estate [Member]
Business Combination, Separately Recognized Transactions, Assets Recognized			14,600
Property Held in Joint [Member]
Payments to Acquire Businesses, Gross			23,000
Property Held in Joint [Member] | Other Liabilities [Member]
Business Combination, Separately Recognized Transactions, Liabilities Recognized			$ 11,500

[1] The Company utilized $66.0 million associated with Internal Revenue Code 1031 sales proceeds.

[2] The Company utilized $89.5 million associated with Internal Revenue Code 1031 sales proceeds.