Note 6- Long-Term Debt (Details) (USD $)	9 Months Ended					9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Sep. 30, 2013 Amended Agreement [Member]	Mar. 13, 2012 Previous Agreement [Member]	Sep. 30, 2013 Minimum [Member]	Sep. 30, 2013 Maximum [Member]
Note 6- Long-Term Debt (Details) [Line Items]
Credit Facility Syndication Number Of Commercial Banks	11
Line of Credit Facility, Maximum Borrowing Capacity				$ 500,000,000	$ 350,000,000
Line Of Credit Facility Stated Borrowing Period	5 years
Line of Credit Facility, Expiration Date	Mar. 14, 2017
Line Of Credit Facility, Maximum Borrowing Capacity Without Borrowing Base Requirement	400,000,000
Line Of Credit Facility, Accordion Feature, Additional Revolving Credit Commitments Under Existing Loan Facility	100,000,000
Debt Issuance Cost		2,000,000
Line Of Credit Facility, Fixed Charge Coverage Ratio, Covenant						1.25
Line Of Credit Facility, Leverage Ratio Covenant							3.75
Line of Credit Facility, Interest Rate During Period						1.43%	1.46%
Long-term Debt, Excluding Current Maturities	64,064,000		105,000,000
Letters of Credit Outstanding, Amount	3,000,000
Line of Credit Facility, Remaining Borrowing Capacity	332,900,000
Line of Credit Facility, Current Borrowing Capacity	$ 295,600,000