Note 11 - Long-term Debt (Detail) (USD $)									3 Months Ended	24 Months Ended		48 Months Ended				61 Months Ended				3 Months Ended
	Mar. 31, 2013	Aug. 24, 2012	May 31, 2012	Mar. 31, 2013 Maximum [Member] Revolver [Member]	Mar. 31, 2013 Maximum [Member] Capital Lease Obligations [Member]	Mar. 31, 2013 Minimum [Member] Revolver [Member]	Mar. 31, 2013 Minimum [Member] Capital Lease Obligations [Member]	Mar. 31, 2013 Minimum [Member] Revolver [Member]	Mar. 31, 2013 Revolver [Member]	May 31, 2014 Hardware Purchase Agreement [Member]	Mar. 31, 2013 Hardware Purchase Agreement [Member]	Jan. 31, 2017 Hardware Purchase Agreement 2 [Member]	Mar. 31, 2013 Hardware Purchase Agreement 2 [Member]	Jan. 31, 2013 Hardware Purchase Agreement 2 [Member]	Mar. 31, 2013 Hardware Purchase Agreement 1 & 2 [Member]	May 31, 2018 Hardware Purchase Agreement 3 [Member]	Apr. 30, 2013 Hardware Purchase Agreement 3 [Member]	Mar. 31, 2013 Letter of Credit [Member]	Aug. 24, 2012 Letter of Credit [Member]	Mar. 31, 2013 Revolver [Member]
Line of Credit Facility, Maximum Borrowing Capacity		$ 125,000,000																	$ 15,000,000
Line of Credit Facility, Increase, Additional Borrowings									50,000,000
Line of Credit Facility, Current Borrowing Capacity				18,750,000
Line of Credit Facility, Capacity Available for Specific Purpose Other than for Trade Purchases				71,000,000
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate									1.50%
				2.75%		2.25%			2.50%
Payments of Debt Issuance Costs																				1,500,000
Interest Rate on Overnight Borrowings									4.80%
Line of Credit Facility, Interest Rate at Period End									2.90%
Debt, Weighted Average Interest Rate									3.10%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage									0.50%
Book Value of Revenue Equipment Pledged as Collateral for Credit Agreements	164,200,000
Line of Credit Facility, Amount Outstanding																		3,000,000
Line of Credit Facility, Remaining Borrowing Capacity								18,750,000												15,200,000
Capital Lease Obligations	55,900,000
Debt Instrument, Interest Rate, Stated Percentage					4.00%		1.60%
Purchase Obligation			360,000											295,000			300,000
Debt Instrument, Periodic Payment										122,000		63,000				5,600
Debt Instrument, Interest Rate, Effective Percentage										3.16%		3.05%				4.492%
Long-term Debt											240,000		234,000
Long-term Debt, Current Maturities															$ 174,000