Financial Instruments and Risk - Additional Information (Detail) |
12 Months Ended |
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Dec. 31, 2017 | |
| Schedule Of Cost Method Investments [Line Items] | |
| Average days to maturity of Company's portfolio of cash equivalents and marketable securities | 0 days |
| Maximum [Member] | |
| Schedule Of Cost Method Investments [Line Items] | |
| Maturity period of securities | 1 year |
| X | ||||||||||
- Definition Average period to maturity for portfolio of cash and marketable securities. No definition available.
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| X | ||||||||||
- Definition Maturity period of securities. No definition available.
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| X | ||||||||||
- 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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| X | ||||||||||
- Details
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