Note 3 - Long-Term Debt (Detail) (USD $)	3 Months Ended
	Mar. 31, 2013
Line of Credit Facility, Expiration Date	May 31, 2016
Line of Credit Facility, Amount Outstanding	$ 0
Letters of Credit Outstanding, Amount	7,400,000
Line of Credit Facility, Remaining Borrowing Capacity	42,600,000
Minimum [Member]
Line of Credit Facility, Maximum Borrowing Capacity	50,000,000
Maximum [Member]
Line of Credit Facility, Maximum Borrowing Capacity	$ 75,000,000