Schedule of Gains (Losses) for Derivatives Designated as Fair Value Hedges (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Derivative Instruments Gain Loss [Line Items]
Total gain recognized as ineffectiveness in the condensed consolidated statements of operations	$ 0.6	$ (1.0)
Interest Rate Swap
Derivative Instruments Gain Loss [Line Items]
Total gain recognized as ineffectiveness in the condensed consolidated statements of operations	4.3	5.2
Hedged Items
Derivative Instruments Gain Loss [Line Items]
Total gain recognized as ineffectiveness in the condensed consolidated statements of operations	$ (3.7)	$ (6.2)