Annual report pursuant to Section 13 and 15(d)

Long-Term Debt - Additional Information (Detail)

v2.4.0.6
Long-Term Debt - Additional Information (Detail) (USD $)
1 Months Ended 12 Months Ended 1 Months Ended 12 Months Ended 1 Months Ended 12 Months Ended
Oct. 12, 2012
Dec. 31, 2012
Dec. 31, 2011
Oct. 24, 2012
8.50% Senior Notes, due June 2019
Jun. 10, 2011
8.50% Senior Notes, due June 2019
Dec. 31, 2012
8.50% Senior Notes, due June 2019
Dec. 31, 2011
8.50% Senior Notes, due June 2019
Dec. 31, 2012
8.25% Senior Notes Due June 2014
Nov. 30, 2012
Revolving Bank Credit Facility Due May 2015
Dec. 31, 2012
Revolving Bank Credit Facility Due May 2015
Dec. 31, 2011
Revolving Bank Credit Facility Due May 2015
May 05, 2011
Revolving Bank Credit Facility Due May 2015
Debt Instrument [Line Items]                        
Long-term Debt unsecured       $ 300,000,000 $ 600,000,000 $ 900,000,000 $ 600,000,000          
Debt issuance, premium percentage       106.00%                
Senior notes interest rate       8.50% 8.50% 8.50% 8.50% 8.25%        
Senior notes maturity date       Jun. 15, 2019 Jun. 15, 2019 Jun. 15, 2019 Jun. 15, 2019 Jun. 01, 2014   May 01, 2015 May 01, 2015  
Net proceeds after fees and expenses       312,000,000 593,500,000              
Annual effective interest rate       7.73%   8.60%       5.00%    
Senior notes   1,087,611,000 [1] 717,000,000 [1]         450,000,000        
Cost related to repurchase of senior notes               22,000,000        
Senior notes payment terms           Semi-annually in arrears on June 15 and December 15 of each year            
Estimated senior notes fair value           963,000,000 612,000,000          
Revolving bank credit facility borrowing base 600,000,000                     525,000,000
Increase to borrowing base                 725,000,000      
Credit agreement expiration date                   May 05, 2015    
Restriction on payment of dividends   60,000,000                    
Common stock and senior note repurchases   100,000,000                    
One-time waiver requested and granted for cash dividends   85,000,000                    
Maximum letter of credit issued   90,000,000                    
Revolving bank credit facility interest rate description Issuance of additional Senior Notes above the $600.0 million level and provided for a reduction in the borrowing base of 25% of every $1.00 of Senior Notes above $600.0 million until such time as the borrowing base is re-determined. Borrowings under the revolving bank credit facility bear interest at the applicable LIBOR plus a margin that varies from 2.00% to 2.75% depending on the level of total borrowings under the Credit Agreement, or an alternative base rate equal to the applicable margin ranging from 1.00% to 1.75% plus the highest of the (a) Prime Rate, (b) Federal Funds Rate plus 0.50%, and (c) LIBOR plus 1.0%.                    
Unused portion of the borrowing base commitment fee   0.50%                    
Line of credit facility conditional potential additional borrowing capacity 1.00                      
Percentage of base of senior notes for potential additional borrowing capacity 25.00%                      
Unamortized debt issuance cost written off     700,000                  
Revolving bank credit facility borrowings outstanding                   170,000,000 117,000,000  
Letters of credit outstanding   $ 600,000 $ 400,000                  
[1] Aggregate annual maturities of long-term debt as of December 31, 2012 are as follows (in millions): 2013 - $0.0; 2014 - $0.0; 2015 - $170.0; 2016 - $0.0; thereafter - $900.0.