Long-Term Debt - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended			9 Months Ended
	Sep. 30, 2012	Sep. 30, 2012	Sep. 30, 2011	Aug. 21, 2012 6.25% Senior Notes Due 2017	Sep. 30, 2012 12.75% Senior Secured Notes Due 2014	Sep. 30, 2012 14 1/4% Senior Secured Notes Due 2015	Sep. 30, 2012 12.5% Senior Notes Due 2016	Sep. 30, 2012 Premium and Expenses	Sep. 30, 2012 Write Off of Unamortized Discounts
Debt Instrument [Line Items]
Senior notes				$ 210
Interest rate of the debt instruments				6.25%	12.75%	14.25%	12.50%
Maturity year of the debt instruments				2017	2014	2015	2016
Repayments of long-term debt, total		362.3
Repayments of long-term debt		388.9	462.5		186.2	25.5	150.6
Loss on debt extinguishment	$ 23.1	$ 30.6	$ 77.6					$ 26.6	$ 4.0