Fair Value of Financial Instruments - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
Sep. 30, 2012	Dec. 31, 2011
Fair Values Of Financial Assets And Liabilities Including Derivative Financial Instruments [Line Items]
Notional amount of the foreign currency derivative instruments	$ 219,055	$ 263,944
Maturities of forward contracts	12 months
Effective portion of change in fair value of foreign currency forward contracts	$ (2,123)	$ 6,009

Aggregate notional amount of foreign currency exchange rate derivatives. Notional amount refers to the number of currency units specified in the foreign currency derivative contract.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Notional Amount

-URI http://asc.fasb.org/extlink&oid=6519104

Name:	us-gaap_NotionalAmountOfForeignCurrencyDerivatives
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant