Derivatives (Schedule of Gains (Losses) for Derivatives Designated as Fair Value Hedges) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Derivative Instruments, Gain (Loss) [Line Items]
Total gain recognized as ineffectiveness in the condensed consolidated statements of operations	$ (0.4)	$ (0.2)	$ (0.6)	$ (0.9)
Interest Rate Swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total gain recognized as ineffectiveness in the condensed consolidated statements of operations	(3.9)	(3.4)	(7.4)	(6.7)
Hedged Items [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total gain recognized as ineffectiveness in the condensed consolidated statements of operations	$ 3.5	$ 3.2	$ 6.8	$ 5.8