Note 6 - Financial Instruments and Fair Value (Details Textual)	3 Months Ended						6 Months Ended	12 Months Ended
	Mar. 31, 2017 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2011 USD ($)
Asset Impairment Charges				$ 7,718,000				$ 427,000	$ 1,000,000
Impairment of Real Estate			$ 400,000	7,100,000
Number of Real Estate Properties Sold During Period	1						4
Real Estate Held-for-sale	$ 1,000,000						$ 6,100,000
Selling, General and Administrative Expenses [Member] | Truck Segment [Member]
Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property				$ (7,100,000)
Auction Rate Securities [Member]
Available-for-sale Securities	6,231,000						6,231,000
Available-for-sale Securities, Amortized Cost Basis	$ 6,700,000						$ 6,700,000
Auction Rate Securities Redeemed		$ 200,000	$ 250,000		$ 275,000	$ 150,000
Derivative, Basis Spread on Variable Rate	2.25%