Forward Contracts with Notional Values (Detail) (Forward Contracts) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended
	Jun. 30, 2013 British pound GBP (£)	Jun. 30, 2012 British pound GBP (£)	Jun. 30, 2013 British pound GBP (£)	Jun. 30, 2012 British pound GBP (£)	Jun. 30, 2013 Euro EUR (€)	Jun. 30, 2012 Euro EUR (€)	Jun. 30, 2013 Euro EUR (€)	Jun. 30, 2012 Euro EUR (€)
Derivative [Line Items]
Notional amount	£ 14,500	£ 11,000	£ 33,500	£ 23,000	€ 16,500	€ 16,200	€ 32,500	€ 27,200