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Accounting Policies - Additional Information (Detail) | 12 Months Ended
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Dec. 31, 2017 segment
Accounting Policies [Line Items] |
Maturity period of liquid investments | 3 months
Maturity period of financial instruments | Greater than three months and less than one year
Number of operating segments | 1
Restricted Stock Unit Awards [Member] |
Accounting Policies [Line Items] |
Award vesting period | 4 years

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- Definition Accounting policies. + References No definition available. + Details
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- Definition Description of maturity period of financial instruments to be considered as short term investment. + References No definition available. + Details
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- Definition Maturity period of highly liquid investments to be considered as cash equivalent. + References No definition available. + Details
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- Definition Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues. + References No definition available. + Details
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- Definition Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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- Details
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