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FAIR VALUE MEASUREMENTS - SECURITIES WITH UNREALIZED LOSSES (Details) - USD ($) $ in Thousands | Dec. 31, 2016 | Dec. 31, 2015
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Available for sale securities with unrealized losses |  |
Less Than 12 Months - Estimated Fair Value | $ 66,534 | $ 101,501
Less Than 12 Months - Gross Unrealized Losses | (97) | (256)
More Than 12 Months - Estimated Fair Value | 6,944 | 6,301
More Than 12 Months - Gross Unrealized Losses | (10) | (7)
Total - Estimated Fair Value | 73,478 | 107,802
Total - Gross Unrealized Losses | (107) | (263)
Government-sponsored enterprise securities (due in less than one year) |  |
Available for sale securities with unrealized losses |  |
Less Than 12 Months - Estimated Fair Value | 4,997 |
Less Than 12 Months - Gross Unrealized Losses | (3) |
Total - Estimated Fair Value | 4,997 |
Total - Gross Unrealized Losses | (3) |
Government-sponsored enterprise securities (due in one to two years) |  |
Available for sale securities with unrealized losses |  |
Less Than 12 Months - Estimated Fair Value | 12,458 | 9,950
Less Than 12 Months - Gross Unrealized Losses | (42) | (57)
Total - Estimated Fair Value | 12,458 | 9,950
Total - Gross Unrealized Losses | (42) | (57)
Commercial paper (due in less than one year) |  |
Available for sale securities with unrealized losses |  |
Less Than 12 Months - Estimated Fair Value | 8,365 | 7,834
Less Than 12 Months - Gross Unrealized Losses | (5) | (2)
Total - Estimated Fair Value | 8,365 | 7,834
Total - Gross Unrealized Losses | (5) | (2)
Corporate notes (due in less than one year) |  |
Available for sale securities with unrealized losses |  |
Less Than 12 Months - Estimated Fair Value | 39,218 | 61,006
Less Than 12 Months - Gross Unrealized Losses | (37) | (71)
More Than 12 Months - Estimated Fair Value | 6,944 | 6,301
More Than 12 Months - Gross Unrealized Losses | (10) | (7)
Total - Estimated Fair Value | 46,162 | 67,307
Total - Gross Unrealized Losses | (47) | (78)
Corporate notes (due in one to two years) |  |
Available for sale securities with unrealized losses |  |
Less Than 12 Months - Estimated Fair Value | 1,496 | 22,711
Less Than 12 Months - Gross Unrealized Losses | (10) | (126)
Total - Estimated Fair Value | 1,496 | 22,711
Total - Gross Unrealized Losses | $ (10) | $ (126)

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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. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27290-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27337-111563 + Details
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