Derivative Commodity Instruments - Commodity Contracts by Business Segment (Details) (USD $)	Mar. 31, 2014 counterparty		Dec. 31, 2013		Jun. 30, 2013 bbl	Mar. 31, 2013 bbl
Derivative [Line Items]
Number of Active Counterparties with Whom Company Holds Net Gain Positions	2
Number of Active Counterparties with Whom Company Holds Net Loss Positions	12
Fair Value as of March 31, 2014	$ 53,404,000		$ 30,302,000
Derivative assets	5,995,000		22,902,000
Barrels dedesignated					2,353,000	5,078,000
Gross Amounts Recognized	22,511,000		44,215,000
Derivative liability	(69,920,000)		(51,615,000)
Deferred tax assets (liabilities), net	(6,700,000)		(8,200,000)
Not Designated as Hedging Instrument | Oil and gas operations
Derivative [Line Items]
Gross Amounts Recognized	22,511,000		44,216,000
Derivative liability	(69,920,000)		(51,616,000)
Total derivatives	(47,409,000)		(7,400,000)
Accounts receivable | Not Designated as Hedging Instrument | Oil and gas operations
Derivative [Line Items]
Gross Amounts Recognized	17,522,000		36,224,000
Derivative liability	(14,165,000)	[1]	(18,761,000)	[1]
Long-term asset derivative instruments | Not Designated as Hedging Instrument | Oil and gas operations
Derivative [Line Items]
Gross Amounts Recognized	4,989,000		7,992,000
Derivative liability	(2,351,000)	[1]	(2,553,000)	[1]
Accounts payable | Not Designated as Hedging Instrument | Oil and gas operations
Derivative [Line Items]
Derivative liability	(52,602,000)		(30,302,000)
Other Liabilities [Member] | Not Designated as Hedging Instrument | Oil and gas operations
Derivative [Line Items]
Derivative liability	(802,000)
Cash Flow Hedging | Macquarie Bank Limited
Derivative [Line Items]
Derivative assets	$ 3,000,000

[1] Amounts classified in accordance with accounting guidance which permits offsetting fair value amounts recognized for multiple derivative instruments executed with the same counterparty under a master netting arrangement.