Note 5 - Long-Term Debt and Credit Facility (Details) (USD $)	0 Months Ended	1 Months Ended		12 Months Ended
	Jul. 01, 2013	Jul. 31, 2013	Apr. 30, 2012	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2014	Jul. 02, 2013
Debt Instrument [Line Items]
LineOfCreditFacilityTerm	5 years
Derivative, Fixed Interest Rate		0.87%		0.87%
TermLoanTerm		5 years
Debt Instrument, Maturity Date		Jul. 01, 2018
Proceeds from line of credit			$ 18,000,000	$ 18,000,000	$ 0	$ 26,000,000
Credit Facility, Retired Amount	232,300,000
Business Combination, Consideration Paid	7,000,000
Other Long-term Debt				4,300,000	4,900,000
Other Loans Payable				100,000	100,000
Letters of Credit Outstanding, Amount				27,300,000
Long-term Debt, Fair Value				377,000,000	380,100,000
Derivative, Variable Interest Rate				2.21%
Credit Facility Maximum Consolidated Leverage Ratio				3.75
CreditFacilityMinimumConsolidatedLeverageRatio				3.50
Credit Facility Actual Consolidated Leverage Ratio				2.90
Line of Credit Facility, Remaining Borrowing Capacity				77,100,000
Credit Facility Minimum Consolidated Fixed Charge Ratio				1.25
Credit Facility Actual Consolidated Fixed Charge Ratio				1.54
2013 Credit Facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		650,000,000
Line of Credit Facility, Maximum Borrowing Capacity		300,000,000
Secured Debt		350,000,000		319,375,000	341,250,000
Line of Credit Facility, Amount Outstanding	35,500,000			45,500,000
Proceeds from line of credit				10,000,000
Debt Instrument, Description of Variable Rate Basis				one month LIBOR borrowing rate
Debt Instrument, Interest Rate at Period End				2.13%
Derivative, Amount of Hedged Item		175,000,000
2011 Credit Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Amount Outstanding					35,500,000
Minimum [Member] | 2013 Credit Facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate				1.25%
Maximum [Member] | 2013 Credit Facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate				2.25%
Bayou Wasco [Member]
Debt Instrument [Line Items]
Due from Joint Ventures							16,600,000
Wasco Energy [Member]
Debt Instrument [Line Items]
Due from Joint Ventures				8,100,000	6,900,000
Initial [Member]
Debt Instrument [Line Items]
Due from Joint Ventures				8,000,000	8,000,000
Additional [Member]
Debt Instrument [Line Items]
Due from Joint Ventures				6,200,000	6,200,000		2,600,000
BPPC [Member]
Debt Instrument [Line Items]
Due from Joint Ventures				14,200,000	14,200,000
Bayou Wasco [Member]
Debt Instrument [Line Items]
Due from Joint Ventures					14,000,000
Bayou Wasco [Member] | Initial [Member]
Debt Instrument [Line Items]
Due from Joint Ventures				14,000,000
Insurance Carriers Collateral [Member]
Debt Instrument [Line Items]
Letters of Credit Outstanding, Amount				10,200,000
Work Performance Obligations [Member]
Debt Instrument [Line Items]
Letters of Credit Outstanding, Amount				17,100,000
2013 Interest Rate Swap [Member]
Debt Instrument [Line Items]
Derivative Asset, Notional Amount		175,000,000
Brinderson LP [Member]
Debt Instrument [Line Items]
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net	$ 147,600,000			$ 146,600,000				$ 147,600,000