Note 9 - Equity Method Investment (Details Textual) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Proceeds from Sale of Property, Plant, and Equipment, Total			$ 31,235	$ 49,302
Reversal of Deferred Gains of Sale of Property			(7)	(185)
Income (Loss) from Equity Method Investments, Total	$ 2,138	$ 2,142	7,548	5,407
Transport Enterprise Leasing LLC [Member]
Proceeds from Sale of Property, Plant, and Equipment, Total			0	100
Revenue from Related Parties			7,100	5,900
Reversal of Deferred Gains of Sale of Property			$ 100	$ 200
Equity Method Investment, Ownership Percentage	49.00%	49.00%	49.00%	49.00%
Due from Related Parties, Total	$ 1,200		$ 1,200		$ 5,100
Income (Loss) from Equity Method Investments, Total			7,500
Proceeds from Equity Method Investment, Distribution			1,200	$ 0
Equity Method Investments	32,400		32,400		$ 26,100
Transport Enterprise Leasing LLC [Member] \| Reduction in TEL Investment [Member]
Deferred Gain on Sale of Property	$ 200		$ 200

Amounts reversed from the deferred gains on sale of property.

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