Derivative Instruments - Effect of Derivative Instruments in Consolidated Statements of Comprehensive Loss (Detail) (Interest Expense [Member], USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Derivatives designated as hedging instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (gain) or loss reclassified from AOCL into net loss (effective portion)	$ 0	$ 3.9
Derivatives not designated as hedging instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net Periodic Cash Settlements and Accrued Interest	(43.4)	(42.2)
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$ (8.4)	$ (21.2)