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Investments - Fair Value of Long-Term Available-for-Sale Investments (Detail) - Long-Term Investments [Member] - USD ($) $ in Thousands | Sep. 30, 2015 | Dec. 31, 2014
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Schedule of Available-for-sale Securities [Line Items] |  |
Fair value of available-for-sale investments | $ 240,908 | $ 157,201
Time Deposits and Certificates of Deposit [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Fair value of available-for-sale investments |  | 48
Asset-Backed Securities [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Fair value of available-for-sale investments | 134,917 | 75,674
Corporate Obligations [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Fair value of available-for-sale investments | 93,990 | 64,669
Municipal Bonds [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Fair value of available-for-sale investments | 3,422 | 1,254
U.S. Agency Obligations [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Fair value of available-for-sale investments | $ 8,579 | $ 15,556

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- Definition Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 25 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=51813488&loc=d3e22054-111558 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27232-111563 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=49167202&loc=d3e26610-111562 + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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