Note 9 - Financial Instruments and Fair Value (Details Textual)	3 Months Ended				6 Months Ended	12 Months Ended
	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2011 USD ($)
Asset Impairment Charges						$ 8,247,000			$ 1,000,000
Available-for-sale Debt Securities Gross Unrealized Gain								$ 427,000
Impairment of Real Estate						7,500,000
Number of Real Estate Properties Sold During Period					4
Real Estate Held-for-sale					$ 6,100,000	6,100,000
Auction Rate Securities [Member]
Available-for-sale Securities					6,231,000	6,231,000	6,650,000
Available-for-sale Securities, Amortized Cost Basis					$ 6,700,000	$ 6,700,000	$ 7,150,000
Auction Rate Securities Redeemed	$ 200,000	$ 250,000	$ 275,000	$ 150,000
Derivative, Basis Spread on Variable Rate					2.25%	2.25%