Inventory - Additional Information (Detail) ¥ in Thousands, $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
|
Dec. 31, 2017
CNY (¥)
|
Dec. 31, 2016
CNY (¥)
|
Dec. 31, 2017
USD ($)
|
|
| Inventory Disclosure [Abstract] | |||
| Inventories, net | ¥ 0 | ¥ 95,617 | $ 0 |
| Inventory write-down | ¥ 0 | ¥ 9,201 | |