Note 4 - Investments In and Advances to Real Estate Joint Ventures (Details Textual) ft² in Thousands, $ in Thousands, a in Millions		6 Months Ended
		Jun. 30, 2017 USD ($) ft² a	Jun. 30, 2016 USD ($)	Dec. 31, 2016 ft²
Business Combination, Consideration Transferred		$ 364,261
Gross Leasable Area | ft²	[1]	1,099
All Equity Method Investments [Member]
Gross Leasable Area		24.6		26,200
Kim Pru and Kim Pru II [Member]
Number Of Accounts		4
Number of Joint Ventures		4
Kim Pru [Member]
Number of Joint Ventures		3
Real Estate Joint Ventures [Member]
Business Combination, Consideration Transferred			$ 299,200
Real Estate Joint Ventures [Member] | Operating Properties [Member]
Equity Method Investment, Sales Price		$ 49,300
Equity Method Investment, Realized Gain (Loss) on Disposal		$ 100	$ 143,200
Number of Real Estate Properties, Remaining Interest Acquired		3	1
Business Combination, Consideration Transferred		$ 320,100	$ 859,000
Number of Real Estate Properties, Interest Disposed of or Transferred		6	33
Real Estate Joint Ventures [Member] | Development Properties [Member]
Number of Real Estate Properties, Remaining Interest Acquired			1

[1] Gross leasable area ("GLA")