Annual report pursuant to Section 13 and 15(d)

Commitments - Additional Information (Detail)

v2.4.0.8
Commitments - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Commitments [Line Items]      
Minimum future lease payments due under noncancelable operating leases, 2014 $ 1.3    
Minimum future lease payments due under noncancelable operating leases, 2015 1.3    
Minimum future lease payments due under noncancelable operating leases, 2016 1.3    
Minimum future lease payments due under noncancelable operating leases, 2017 1.4    
Minimum future lease payments due under noncancelable operating leases, thereafter 8.0    
Total rent expense 2.6 1.7 1.9
Security amount requirement 55.0    
Additional security requirements for 2014 9.0    
Additional security requirements for 2015 9.0    
Additional security requirements for 2016 6.0    
Additional security requirements for 2017 6.0    
Additional security requirements for 2018 to 2023 18.0    
Total security requirement 103.0    
Fees related to bonds 5.0 2.9 2.6
Future estimated costs, 2014 5.5    
Future estimated costs, 2015 5.7    
Future estimated costs, 2016 5.8    
Future estimated costs, 2017 5.7    
Future estimated costs, thereafter 48.4    
Drilling Rig Commitments
      
Commitments [Line Items]      
Minimum future lease payments due under noncancelable operating leases, 2013 21.5    
Helix Well Containment Group
      
Commitments [Line Items]      
Minimum future lease payments due under noncancelable operating leases, 2014 1.9    
Minimum future lease payments due under noncancelable operating leases, 2015 1.9    
Minimum future lease payments due under noncancelable operating leases, 2016 1.9    
Other commitment
      
Commitments [Line Items]      
Security requirement minimum 74.0    
Security requirement maximum $ 94.0