Acquisitions and Divestitures - Additional Information (Details) (USD $)	3 Months Ended												12 Months Ended			7 Months Ended	0 Months Ended		3 Months Ended	0 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014	Jul. 11, 2013	Sep. 26, 2013	Dec. 31, 2012	May 15, 2012	Sep. 15, 2014	Sep. 14, 2014	May 20, 2014	Oct. 17, 2013	Oct. 05, 2012 Block acre
Business Acquisition [Line Items]
Goodwill, acquired during period													$ 0	$ 0	$ 0
Revenues	196,677,000	234,521,000	262,994,000	254,516,000	244,928,000	[1],[2]	244,555,000	[1],[2]	235,383,000	[1],[2]	259,222,000	[1],[2]	948,708,000	984,088,000	874,491,000
DD&A													511,102,000	451,529,000	356,232,000
Income tax expense													(4,459,000)	28,774,000	47,547,000
Net income	(33,371,000)	684,000	9,837,000	11,189,000	(11,886,000)	[1],[2]	14,194,000	[1],[2]	22,396,000	[1],[2]	26,618,000	[1],[2]	(11,661,000)	51,322,000	71,984,000
Fairway
Business Acquisition [Line Items]
Percentage of working interest																					100.00%	64.30%
Goodwill, acquired during period													0
Woodside Properties
Business Acquisition [Line Items]
Percentage of working interest																							20.00%
Goodwill, acquired during period													0
Revenues																28,400,000
Lease operating expenses																5,500,000
DD&A																11,000,000
Income tax expense																4,200,000
Net income																7,700,000
Callon Properties
Business Acquisition [Line Items]
Percentage of working interest																								15.00%
Goodwill, acquired during period														0
Revenues					5,800,000								32,500,000
Lease operating expenses					1,300,000								6,600,000
DD&A					2,400,000								16,400,000
Income tax expense					700,000								3,300,000
Net income					1,400,000								6,200,000
Adjustments to purchase price													600,000
Green Canyon Fields
Business Acquisition [Line Items]
Reversal of asset retirement obligation																	15,600,000
Proceeds from sale of properties																	4,300,000
West Delta Area Block Twenty Nine
Business Acquisition [Line Items]
Reversal of asset retirement obligation																		3,900,000
Proceeds from sale of properties																		14,700,000
West Delta Area Block Twenty Nine | Post Effective Date Repayment
Business Acquisition [Line Items]
Proceeds from sale of properties	1,700,000												1,700,000			1,700,000
Newfield Properties
Business Acquisition [Line Items]
Goodwill, acquired during period															0
Revenues													121,100,000	127,100,000					29,600,000
Lease operating expenses													23,500,000	26,700,000					5,400,000
DD&A													60,500,000	57,600,000					11,900,000
Income tax expense													13,000,000	15,000,000					4,300,000
Net income													24,100,000	27,800,000					8,000,000
Adjustments to purchase price														200,000
Number of federal offshore blocks																									78
Leasehold interest acres acquired, gross																									416,000
Leasehold interest acres acquired, net																									268,000
South Timbalier 41
Business Acquisition [Line Items]
Reversal of asset retirement obligation																				4,000,000
Proceeds from sale of properties																				$ 30,500,000
Percentage of non-operating working interest sold																				40.00%

[1] The sum of the individual quarterly earnings per share may not agree with year-to-date earnings per share because each quarterly calculation is based on the income for that quarter and the weighted average number of shares outstanding during that quarter.

[2] In January 2014, we identified that we had been receiving an erroneous million British thermal unit (“MMBtu”) conversion factor from a third party that had the effect of understating natural gas production at our Viosca Knoll 783 field (Tahoe).  The incorrect conversion factor had been used on all natural gas production from the field since we acquired it in 2011.  The use of the incorrect conversion factor did not affect revenues, operating cash flows or royalty payments to the federal government but did impact reported natural gas production and the calculation of depletion expense.  We performed an analysis of the information, assessing both quantitative and qualitative factors, and determined that the impact on our net income reported for prior annual periods, as well as the impact to our earnings trend, was not material to 2011 and 2012 results, thus the adjustment was recognized in the fourth quarter of 2013.