Note 9 - Leases and Commitments (Details Textual) $ in Thousands	1 Months Ended		3 Months Ended		9 Months Ended
	Sep. 30, 2015 USD ($)	Aug. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)
Capital Lease Obligations [Member] | Minimum [Member]
Debt Instrument, Interest Rate, Effective Percentage	1.88%		1.88%		1.88%
Capital Lease Obligations [Member] | Maximum [Member]
Debt Instrument, Interest Rate, Effective Percentage	3.11%		3.11%		3.11%
Financing Activities [Member]
Sale Leaseback Transaction, Deferred Gain, Net	$ 100		$ 100		$ 100
Sales Leaseback Transaction, Investing Activities #1 [Member]
Lessee Leasing Arrangements, Operating Leases, Term of Contract		4 years 300 days
Sales Leaseback Transaction, Investing Activities #2 [Member]
Lessee Leasing Arrangements, Operating Leases, Term of Contract		4 years 330 days
Investing Activities [Member]
Sale Leaseback Transaction, Deferred Gain, Net	300		300		300
Non-Revenue Equipment [Member]
Purchase Obligation	30		30		30
Revenue Equipment [Member]
Purchase Obligation	22,300		22,300		22,300
Capital Lease Obligations	23,000		23,000		23,000
Capital Lease Obligations, Current	7,200		7,200		7,200
Capital Leases, Income Statement, Amortization Expense			1,800	$ 3,100	7,000	$ 9,700
Sale Leaseback Transaction, Net Proceeds, Financing Activities	$ 3,100				3,156
Capital Lease Agreement, Term of Contract	4 years
Operating Leases, Rent Expense			$ 1,700	$ 1,400	4,500	$ 3,900
Number of Sales Leaseback Transactions, Investing Activities, Current		2
Sale Leaseback Transaction, Net Proceeds, Investing Activities		$ 8,000			$ 7,975
Number of Operating Leases, Current		2