Derivatives And Risk Management (Foreign Currency Exchange Contracts) (Detail) In Thousands, unless otherwise specified	Sep. 30, 2012 USD ($) Derivative	Sep. 30, 2012 CAD	Dec. 31, 2011 USD ($) Derivative	Dec. 31, 2011 CAD
Derivatives, Fair Value [Line Items]
Number of contracts	30	30	28	28
Notional amount	$ 6,578	6,469	$ 7,033	7,192

Number of foreign currency exchange rate derivatives held by the entity at the reporting date.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1A

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5579245-113959

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1B

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5580258-113959

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 44

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

Name:	us-gaap_NumberOfForeignCurrencyDerivativesHeld
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant