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Treasury Stock - Additional Information (Detail) ¥ in Thousands |  | 12 Months Ended
--- | --- | ---
Mar. 16, 2016 USD ($) | Dec. 31, 2016 CNY (¥) shares
Equity, Class of Treasury Stock [Line Items] |  |
Payments for Repurchase of Common Stock | ¥ |  | ¥ 178,991
Share Repurchase Plan |  |
Equity, Class of Treasury Stock [Line Items] |  |
Stock repurchase program, authorized amount | $ | $ 100,000,000 |
Stock Repurchase Program, Period in Force | 1 year |
Payments for Repurchase of Common Stock | ¥ |  | ¥ 178,991
Share Repurchase Plan | Common Class A [Member] |  |
Equity, Class of Treasury Stock [Line Items] |  |
Repurchase of common stock | shares |  | 25,368,080
Share Repurchase Plan | ADS |  |
Equity, Class of Treasury Stock [Line Items] |  |
Repurchase of common stock | shares |  | 2,536,808

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