Long-Term Debt--Senior Secured Revolving Credit Facility (Details) (USD $)	1 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended
	May 31, 2014 Divestiture	Sep. 30, 2014 Divestiture	Dec. 31, 2014 Divestiture	Mar. 27, 2015 Quarters	Dec. 31, 2013	Nov. 05, 2014	Jul. 18, 2014	Apr. 01, 2015	Oct. 29, 2013
Line of Credit Facility [Line Items]
Number Of Divestitures	2	2	4
Credit facility balance subject to Eurodollar rate			$ 347,000,000		$ 272,000,000
Eurodollar Rate Option [Member]
Line of Credit Facility [Line Items]
Credit facility balance subject to Eurodollar rate					347,000,000
Line of Credit [Member]
Line of Credit Facility [Line Items]
Maturity date			Nov. 01, 2017
Borrowing base amount						650,000,000	484,500,000
Number of consecutive quarters used in Consolidated Net Debt to Consolidated EBITDAX ratio calculation			4
Number of days to make election to eliminate borrowings in excess of borrowing base as the result of a redetermination			10 days
Period of time over which borrowings in excess of borrowing base can be repaid in equal monthly installments			6 months
Line of Credit [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Borrowing base amount								550,000,000
Debt Instrument, Additional Borrowing Capacity				300,000,000
Line of Credit [Member] | Election One [Member]
Line of Credit Facility [Line Items]
Number of days to eliminate borrowings in excess of borrowing base as the result of a redetermination			30 days
Line of Credit [Member] | Election Two [Member]
Line of Credit Facility [Line Items]
Number of days to eliminate borrowings in excess of borrowing base as the result of a redetermination			30 days
Line of Credit [Member] | Election Three [Member]
Line of Credit Facility [Line Items]
Number of days to eliminate borrowings in excess of borrowing base as the result of a redetermination			30 days
Line of Credit [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Commitment fee on unused portion of the borrowing base			0.375%
Current Ratio covenant			1
Line of Credit [Member] | Minimum [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Covenant Compliance, Interest Coverage Charge Ratio				2.0
Line of Credit [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Commitment fee on unused portion of the borrowing base			0.50%
Ratio Of Consolidated Net Debt To Consolidated EBITDAX covenant			4.50
Line of Credit [Member] | Maximum [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Number of consecutive quarters used in Consolidated Net Debt to Consolidated EBITDAX ratio calculation				4
Ratio of Consolidated Secured Net Debt To Consolidated EBITDAX Covenant				2.25
Line of Credit [Member] | Eurodollar Rate Option [Member]
Line of Credit Facility [Line Items]
One month interest period			1 month
Two month interest period			2 months
Three month interest period			3 months
Six month interest period			6 months
Line of Credit [Member] | Eurodollar Rate Option [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate			1.75%
Frequency of periodic interest payment on senior secured revolving credit facility			3 months
Line of Credit [Member] | Eurodollar Rate Option [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate			2.00%
Line of Credit [Member] | Federal Funds Effective Rate [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate			0.50%
Line of Credit [Member] | Adjusted LIBO Rate [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate			1.00%
Line of Credit [Member] | Post-Cabot Acquisition [Member]
Line of Credit Facility [Line Items]
Borrowing base amount									$ 600,000,000