Fair Value Position of Derivatives (Detail) (Not Designated as Hedges, USD $) In Thousands, unless otherwise specified			9 Months Ended		9 Months Ended	12 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2012 Prepaid Expenses And Other Foreign currency exchange forwards	Dec. 31, 2011 Prepaid Expenses And Other Foreign currency exchange forwards	Sep. 30, 2012 Accrued expenses and other liabilities Foreign currency exchange forwards	Dec. 31, 2011 Minimum Prepaid Expenses And Other Foreign currency exchange forwards	Dec. 31, 2011 Maximum Prepaid Expenses And Other Foreign currency exchange forwards
Derivative [Line Items]
Notional Amount	$ 84,537	$ 52,373	$ 2,208	$ 52,373	$ 82,329
Maturity Dates			2012-10		2012-10	2012-01	2012-02
Fair Value	$ (517)	$ 215	$ 14	$ 215	$ (531)