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Marketable Investments - Summary of Changes in Fair Value of Level 3 Financial Assets (Detail) (ARS [Member], Level 3 [Member], USD $) In Thousands, unless otherwise specified | 9 Months Ended
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Sep. 30, 2013 | Sep. 30, 2012
ARS [Member] | Level 3 [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items] |  |
Fair value of assets, Beginning Balance | $ 8,970 | $ 9,565
Sales |  |
Gains included in other comprehensive income | 122 | 224
Fair value of assets, Ending Balance | $ 9,092 | $ 9,789

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- Definition Amount of gain (loss) recognized in other comprehensive income (loss) for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1a) -URI http://asc.fasb.org/extlink&oid=25499696&loc=d3e19207-110258 + Details
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- Definition Amount of sale of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=25499696&loc=d3e19207-110258 + Details
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- Definition Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=25499696&loc=d3e19207-110258 + Details
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