Long-Term Debt - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Debt Instrument [Line Items]
Repayments of long-term debt, total	$ 68.5
Repayments of long-term debt	75.0	460.3
Loss on debt extinguishment	7.5	77.5
14 1/4% Senior Secured Notes Due 2015
Debt Instrument [Line Items]
Repayments of long-term debt	25.5
Interest rate of the debt instruments	14.25%
Maturity year of the debt instruments	2015
12.5% Senior Notes Due 2016
Debt Instrument [Line Items]
Repayments of long-term debt	40.0
Interest rate of the debt instruments	12.50%
Maturity year of the debt instruments	2016
12.75% Senior Secured Notes Due 2014
Debt Instrument [Line Items]
Repayments of long-term debt	3.0
Interest rate of the debt instruments	12.75%
Maturity year of the debt instruments	2014
Premium and Expenses
Debt Instrument [Line Items]
Loss on debt extinguishment	6.5
Write Off of Unamortized Discounts
Debt Instrument [Line Items]
Loss on debt extinguishment	$ 1.0