Annual report pursuant to Section 13 and 15(d)

Long-Term Debt - Summary of Company's Current Debt Portfolio (Parenthetical) (Detail)

v2.4.0.6
Long-Term Debt - Summary of Company's Current Debt Portfolio (Parenthetical) (Detail) (USD $)
12 Months Ended 12 Months Ended 12 Months Ended 3 Months Ended 12 Months Ended
Dec. 31, 2012
9.125% Senior Notes, due April 2018 (Issued March 22, 2010) [Member]
Dec. 31, 2011
9.125% Senior Notes, due April 2018 (Issued March 22, 2010) [Member]
Mar. 22, 2010
9.125% Senior Notes, due April 2018 (Issued March 22, 2010) [Member]
Dec. 31, 2012
9.125% Senior Notes, due April 2018 (Issued April 25, 2012) [Member]
Dec. 31, 2011
9.125% Senior Notes, due April 2018 (Issued April 25, 2012) [Member]
Apr. 25, 2012
9.125% Senior Notes, due April 2018 (Issued April 25, 2012) [Member]
Dec. 31, 2012
2.125% Convertible Senior Notes, due July 2012 [Member]
Dec. 31, 2011
2.125% Convertible Senior Notes, due July 2012 [Member]
Dec. 31, 2012
Term Note [Member]
Dec. 31, 2012
Term Note [Member]
Dec. 31, 2011
Term Note [Member]
Debt Instrument [Line Items]                      
Aggregate principal Convertible Senior Notes     $ 300,000,000     $ 125,000,000 $ 125,000,000 $ 125,000,000      
Debt Instrument Maturity Date April 2018 April 2018   April 2018 April 2018   July 2012 July 2012      
Debt Instrument issuance date March 22, 2010 March 22, 2010   April 25, 2012 April 25, 2012            
Debt Instrument Fixed Interest Rate 9.125% 9.125%   9.125% 9.125%   2.125% 2.125%      
Net unamortized discount               3,277,000      
Amortization Term Loan                 $ 6,000,000 $ 2,500,000  
LIBOR Plus                   3.21% 3.55%