Gains and Losses on Derivatives Designated as Hedging Instruments, Net Investment Hedging (Detail) (Net Investment Hedging, USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain/(Loss) Recognized in AOCI on Derivative (Effective Portion)	$ (2.2)
Amount of Gain/(Loss) Reclassified from AOCI into Income (Effective Portion)
Amount of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)
Foreign exchange forward
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain/(Loss) Recognized in AOCI on Derivative (Effective Portion)	(2.2)
Amount of Gain/(Loss) Reclassified from AOCI into Income (Effective Portion)
Amount of Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)