Summary of Notional Amounts of Outstanding Foreign Exchange Forwards, Cash Flow Hedging (Detail) (Cash Flow Hedging, Forward Contracts) In Millions, unless otherwise specified	Jun. 30, 2012 Euros USD ($)	Dec. 31, 2011 Euros USD ($)	Jun. 30, 2012 GBP USD ($)	Jun. 30, 2012 GBP EUR (€)	Dec. 31, 2011 GBP USD ($)	Dec. 31, 2011 GBP EUR (€)	Jun. 30, 2012 Other Foreign Currencies USD ($)	Jun. 30, 2012 Other Foreign Currencies EUR (€)	Dec. 31, 2011 Other Foreign Currencies USD ($)	Dec. 31, 2011 Other Foreign Currencies EUR (€)
Derivative [Line Items]
Contracts to purchase foreign currencies	$ 29.2	$ 27.5	$ 3.3	€ 1.6	$ 2.4	€ 1.6	$ 5.3	€ 12.4	$ 3.2	€ 13.6
Contracts to sell foreign currencies	$ 46.5	$ 47.7		€ 14.6	$ 17.6	€ 7.2	$ 5.7		$ 7.6