Note 3 - Long-Term Debt (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012
Line of Credit Facility, Expiration Date	May 31, 2016
Line of Credit Facility, Amount Outstanding	$ 0
Letters of Credit Outstanding, Amount	6.9
Line of Credit Facility, Remaining Borrowing Capacity	43.1
Minimum [Member]
Line of Credit Facility, Maximum Borrowing Capacity	50
Maximum [Member]
Line of Credit Facility, Maximum Borrowing Capacity	$ 75