Note 9 - Long-term Debt (Detail) (USD $)						12 Months Ended				12 Months Ended		12 Months Ended
	Dec. 31, 2012	Apr. 19, 2010	Dec. 31, 2012 Minimum [Member] Revolver [Member]	Aug. 24, 2012 Minimum [Member] Revolver [Member]	Dec. 31, 2012 Minimum [Member] Capital Lease Obligations [Member]	Dec. 31, 2012 Minimum [Member] Revolver [Member]	Dec. 31, 2013 Maximum [Member] Revolver [Member]	Dec. 31, 2012 Maximum [Member] Revolver [Member]	Dec. 31, 2012 Maximum [Member] Capital Lease Obligations [Member]	Dec. 31, 2012 Maximum [Member] Revolver [Member]	Aug. 24, 2012 Revolver [Member] Letter of Credit [Member]	Dec. 31, 2012 Revolver [Member]	Aug. 24, 2012 Revolver [Member]	Dec. 31, 2012 Letter of Credit [Member]	Apr. 19, 2010 Letter of Credit [Member]	Dec. 31, 2012 Revolver [Member]
Line of Credit Facility, Maximum Borrowing Capacity		$ 100,000,000									$ 15,000,000		$ 125,000,000		$ 25,000,000
Line of Credit Facility, Additional Borrowing Capacity		75,000,000											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	53,800,000
Book Value Of Excess Collateral	172,800,000															30,000,000
Advance Rate Factor	5.00%
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate												1.50%
Applicable Rate in Respect of Loan			2.25%					2.75%				2.50%
Payments of Debt Issuance Costs												1,500,000
Interest Rate on Overnight Borrowings												4.75%
Line of Credit Facility, Interest Rate at Period End												3.00%
Debt, Weighted Average Interest Rate												3.10%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage						0.375%				0.50%		0.50%
Line of Credit Facility, Amount Outstanding														2,800,000
Line of Credit Facility, Remaining Borrowing Capacity			18,750,000									19,900,000
Write off of Deferred Debt Issuance Cost												$ 500,000
Effective Interest Rate on Capital Leases					1.60%				4.00%