Quarterly report pursuant to Section 13 or 15(d)

Subsequent Event (Narrative) (Detail)

v2.4.0.6
Subsequent Event (Narrative) (Detail) (USD $)
 9 Months Ended 9 Months Ended
Sep. 30, 2012
Block
acre
Sep. 30, 2011
May 07, 2012
May 06, 2012
Dec. 31, 2011
Oct. 24, 2012
Subsequent Event [Member]
Sep. 30, 2012
Overriding Royalty Interests [Member]
Block
Sep. 30, 2012
Barracuda Properties [Member]
Subsequent Event [Line Items]                
Acquisition completion date Oct. 05, 2012              
Stated Price $ 228,000,000              
Acquisition valuing effective date Jul. 01, 2012              
Number of federal offshore blocks 78              
Number of acres 432,700              
Number of acres excluding over-riding interests 416,000              
Deepwater blocks 65           3  
Deepwater producing blocks 6           2  
Conventional shelf blocks 10              
Producing Conventional shelf blocks 4              
Expenses related to the acquisition 100,000              
Purchase price allocation 158,585,000       154,516,000     13,100,000
Incremental transaction expenses 100,000              
Assumed borrowings 207,700,000              
Assumed interest rate 7.70%              
Federal statutory rate 35.00% 35.00%            
Additional senior notes issued           300,000,000    
Senior notes rate           8.50%    
Net proceeds from issuance of senior notes 312,000,000              
Premium percentage with respect to par value 106.00%              
Borrowing base $ 650,000,000   $ 650,000,000 $ 575,000,000   $ 575,000,000