Quarterly report pursuant to Section 13 or 15(d)

Contingencies - Additional Information (Detail)

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Contingencies - Additional Information (Detail) (USD $)
 1 Months Ended 3 Months Ended 12 Months Ended 3 Months Ended
Jan. 31, 2014
Mar. 31, 2014
Dec. 31, 2013
Dec. 31, 2009
Royalties
Sep. 30, 2010
Royalties
Mar. 31, 2014
Contingent Consideration Liabilities
Dec. 31, 2013
Contingent Consideration Liabilities
Nov. 08, 2013
Revolving Bank Credit Facility Due November 8, 2018
Mar. 31, 2014
Energy VI
Loss Contingencies [Line Items]                  
Bonds fees                 $ 900,000
Letters of credit outstanding   400,000 400,000         300,000,000  
Under payment of royalties 30,000                
Under payment percentage of total royalty payments 0.0045%                
Statutory fine payment relative to underpayment   2,300,000              
Costs incurred related to an insurance claim in dispute   46,000,000              
Allowable reductions of cash payments       5,300,000          
Notified disallowed amount in reductions taken by ONRR         4,700,000        
Liability loss contingency           $ 100,000 $ 200,000