Note 4 - Investments In and Advances to Real Estate Joint Ventures (Details Textual) ft² in Thousands, $ in Thousands		3 Months Ended	9 Months Ended
		Sep. 30, 2017 USD ($) ft²	Sep. 30, 2017 USD ($) ft²	Sep. 30, 2016 USD ($)	Dec. 31, 2016 ft²
Gross Leasable Area | ft²	[1]	2,030	2,030
Business Combination, Consideration Transferred			$ 546,959
Accumulated Foreign Currency Adjustment Attributable to Noncontrolling Interest [Member] | CANADA
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax		$ (4,800)	$ (4,800)
All Equity Method Investments [Member]
Gross Leasable Area | ft²		24,600	24,600		26,200
Kim Pru and Kim Pru II [Member]
Number of Joint Ventures		4	4
Number Of Accounts		4	4
Kim Pru [Member]
Number of Joint Ventures		3	3
Real Estate Joint Ventures [Member]
Business Combination, Consideration Transferred				$ 959,200
Real Estate Joint Ventures [Member] | Operating Properties [Member]
Number of Real Estate Properties, Interest Disposed of or Transferred			6	39
Equity Method Investment, Sales Price		$ 49,300	$ 49,300
Equity Method Investment, Realized Gain (Loss) on Disposal			$ 100	$ 143,300
Number of Real Estate Properties, Remaining Interest Acquired			3	6
Business Combination, Consideration Transferred			$ 320,100	$ 486,200
Real Estate Joint Ventures [Member] | Development Properties [Member]
Number of Real Estate Properties, Remaining Interest Acquired				1

[1] Gross leasable area ("GLA")