Open Contracts (Detail) (USD $) In Thousands	9 Months Ended
Sep. 30, 2011
Derivative [Line Items]
Notional Amounts	$ 261,305
Unrealized Gain (Loss)	11,570
Cash Flow Hedging \| Foreign Exchange Contract \| Currency, Australian Dollar
Derivative [Line Items]
Notional Amounts	11,136
Unrealized Gain (Loss)	738
Cash Flow Hedging \| Foreign Exchange Contract \| Currency, Canadian Dollar
Derivative [Line Items]
Notional Amounts	246,403
Unrealized Gain (Loss)	10,786
Cash Flow Hedging \| Foreign Exchange Contract \| Currency, Swedish Krone
Derivative [Line Items]
Notional Amounts	2,327
Unrealized Gain (Loss)	80
Cash Flow Hedging \| Foreign Exchange Contract \| Currency, Euro
Derivative [Line Items]
Notional Amounts	1,439
Unrealized Gain (Loss)	$ (34)

The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of derivative instruments, including options, swaps, futures, and forward contracts, held at each balance sheet date, that was included in earnings for the period.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 28

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585

Name:	us-gaap_UnrealizedGainLossOnDerivatives
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration