Commitments and Contingencies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified		12 Months Ended	6 Months Ended		3 Months Ended
	Jun. 30, 2014	Dec. 31, 2010 Legal Reserve	Jun. 30, 2014 Contract Drilling	Jun. 30, 2014 Maximum Contract Drilling	Jun. 30, 2014 Maximum Firm Transportation [Member]	Jun. 30, 2014 Minimum [Member] Firm Transportation [Member]	Jun. 30, 2014 Gas Gathering And Compression Services	Jun. 30, 2014 Crude Oil Gathering And Transportation Services [Member]
Commitments and Contingencies Disclosure [Line Items]
Contract term				14 months	15 years	1 year
Contract termination claims description			early termination provisions that would require us to pay penalties if we terminate the agreements prior to the end of their original terms.
Loss on contract termination for default			$ 13.3
Contractual Obligation, Due in Next Twelve Months							3.7
Contractual Obligation, Due in Second Year							4.2
Contractual Obligation, Due in Third Year							5.0
Contractual Obligation								13.7
Reserve established for contingency matters		0.9
Suspense account	2.2
Asset retirement obligations	$ 5.7