Consolidated Statements of Net and Comprehensive Income (Parenthetical) - USD ($) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
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| Income Statement [Abstract] | |||
| Unrealized gains (losses) on marketable securities, tax | $ 139 | $ 197 | $ (394) |
| Foreign currency translation gain (loss), tax | $ 0 | $ 0 | $ (90) |
| X | ||||||||||
- References No definition available.
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| X | ||||||||||
- Definition Amount of tax expense (benefit), after reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
- Definition Amount of tax expense (benefit) before reclassification adjustments of unrealized holding gain (loss) on available-for-sale securities. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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