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Other Current Monetary Assets - Annual Yield Rates of Time Deposits and Negotiable Certificates of Deposits with Maturities of more Than Three Months (Detail) | Dec. 31, 2017 | Dec. 31, 2016
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Bottom of range [Member] |  |
Disclosure of annual yield rates of other current monetary assets [Line Items] |  |
Time deposits and negotiable certificates of deposit with maturities of more than three months | 0.06% | 0.11%
Top of range [Member] |  |
Disclosure of annual yield rates of other current monetary assets [Line Items] |  |
Time deposits and negotiable certificates of deposit with maturities of more than three months | 4.15% | 1.95%

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