Note 6 - Long-Term Debt (Details) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2012	Dec. 31, 2013
Note 6 - Long-Term Debt (Details) [Line Items]
Credit Facility Syndication Number Of Commercial Banks	11
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
Long-term Debt, Excluding Current Maturities	127,208,000		40,000,000
Letters of Credit Outstanding, Amount	1,900,000
Line of Credit Facility, Remaining Borrowing Capacity	270,900,000
Line of Credit Facility, Current Borrowing Capacity	270,900,000
Amended Agreement [Member]
Note 6 - Long-Term Debt (Details) [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	500,000,000
Previous Agreement [Member]
Note 6 - Long-Term Debt (Details) [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 350,000,000
Minimum [Member]
Note 6 - Long-Term Debt (Details) [Line Items]
Line Of Credit Facility, Fixed Charge Coverage Ratio, Covenant	1.25
Line of Credit Facility, Interest Rate During Period	1.40%
Maximum [Member]
Note 6 - Long-Term Debt (Details) [Line Items]
Line Of Credit Facility, Leverage Ratio Covenant	3.75
Line of Credit Facility, Interest Rate During Period	1.42%