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Short Term Investments - Additional Information (Detail) - USD ($) $ in Thousands | 1 Months Ended | 12 Months Ended
--- | --- | ---
Jul. 31, 2015 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Gain (Loss) on Investments [Line Items] |  |  |  |
Realized gains on sales of short-term investments, trading securities |  | $ 3 | $ 4 | $ 4
Unrealized holding loss on short-term investment |  | $ 0 | 0 | $ 0
Gain on structured notes |  |  | $ 118 |
Senior Notes |  |  |  |
Gain (Loss) on Investments [Line Items] |  |  |  |
Senior notes coupon rate | 1.65% |  |  |
Effective interest rate | 1.65% |  |  |
Par value | $ 4,000 |  |  |
Investment maturity date | 2016-07 | 2016-07 |  |

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- Definition Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity, expected to be converted to cash, sold or exchanged within one year or the normal operating cycle. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=49167202&loc=d3e26626-111562 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 25 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=51813488&loc=d3e22054-111558 + Details
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- Definition The net realized gains or losses on investments during the period, not including gains or losses on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.3(a)) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 325 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6485959&loc=d3e22529-158502 + Details
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- Definition This item represents the gain realized during the period from the sale of trading securities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27357-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.7(c)) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Trading Securities -URI http://asc.fasb.org/extlink&oid=6526789 + Details
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