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Equity - Additional Information (Detail) ADSs in Millions | 12 Months Ended
--- | ---
Dec. 31, 2017 ADSs $ / shares shares
Disclosure of classes of share capital [Line Items] |
Common stock par value | $ / shares | $ 10
Percentage of American Depositary Shares as common stock outstanding | 3.36%
Percentage of net income allocation toward legal reserve | 10.00%
Bottom of range [Member] |
Disclosure of classes of share capital [Line Items] |
Percentage of retained earnings distributed as dividend | 50.00%
Dividend distributed per share threshold in the form of common stocks | $ / shares | $ 0.10
Percentage of legal reserve on additional paid in capital | 25.00%
American Depositary Shares [Member] |
Disclosure of classes of share capital [Line Items] |
Number of common stocks represented by 1 ADS | shares | 10
Number of common stock outstanding | shares | 261
Number of units | ADSs | 26

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