Taxation - Schedule of Unrecognized Tax Benefits (Detail)
¥ in Thousands, $ in Thousands
12 Months Ended
Dec. 31, 2017
CNY (¥)
Dec. 31, 2017
USD ($)
Dec. 31, 2016
CNY (¥)
Income Tax Disclosure [Abstract]      
Beginning balance ¥ 21,902 $ 3,366 ¥ 22,003
Additions based on tax positions related to current year 0 0 0
Decreases based on tax positions related to prior years (2,855) (439) (101)
Ending balance ¥ 19,047 $ 2,927 ¥ 21,902