Financial instruments - Aggregate Estimated Fair Value of Investments with Unrealized Losses (Detail) - U.S. Treasury Securities [Member] - USD ($) $ in Thousands |
Sep. 30, 2016 |
Dec. 31, 2015 |
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Schedule of Available-for-sale Securities [Line Items] | ||
Period of continuous unrealized loss, 12 months or less, Fair value | $ 38,250 | $ 71,411 |
Period of continuous unrealized loss, 12 months or less, Gross unrealized losses | (18) | (290) |
Period of continuous unrealized loss, Greater than 12 months, Fair value | 0 | 0 |
Period of continuous unrealized loss, Greater than 12 months, Gross unrealized losses | $ 0 | $ 0 |
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- Definition Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for less than twelve months. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for less than twelve months. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for twelve months or longer. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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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. No definition available.
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- Details
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