Note 4 - Investments and Advances in Real Estate Joint Ventures (Details Textual) $ in Thousands		1 Months Ended	6 Months Ended
		Apr. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Dec. 31, 2015	Dec. 31, 2013 USD ($)
Kim Pru and Kim Pru II [Member]
Number of Joint Ventures			4
Number Of Accounts			4
Number of Real Estate Properties	[1],[2]		50		53
Kim Pru [Member]
Number of Joint Ventures			3
Number of Real Estate Properties				4
Impairment of Real Estate				$ 1,100
Intown [Member]
Deferred Gain on Sale of Property						$ 21,700
Gains (Losses) on Sales of Investment Real Estate				21,700
Other Joint Venture Programs [Member] | Partially Owned Properties [Member] | Various Land Parcels, Sale Pending [Member] | Joint Ventures [Member]
Impairment of Real Estate				2,600
Other Joint Venture Programs [Member] | Partially Owned Properties [Member] | Various Land Parcels, Sale Pending [Member]
Impairment of Real Estate				1,300
Other Joint Venture Programs [Member] | Partially Owned Properties [Member] | Property, Sale Pending [Member]
Impairment of Real Estate				4,100
Other Joint Venture Programs [Member]
Number of Real Estate Properties			38		40
Equity in Income of Joint Ventures, Net [Member]
Gains (Losses) on Sales of Investment Real Estate			$ 143,200	$ 62,000
CPP [Member]
Business Combination, Consideration Transferred		$ 299,200
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt		$ 100,000
Business Combination, Consideration Transferred			$ 244,750

[1] Represents four separate joint ventures, with four separate accounts managed by Prudential Real Estate Investors ("PREI"), three of these ventures are collectively referred to as KimPru and the remaining venture is referred to as KimPru II.

[2] The Company manages these joint venture investments and, where applicable, earns acquisition fees, leasing commissions, property management fees, asset management fees and construction management fees.