Taxation - Income before Income/(Loss) Tax Expenses (Detail)
¥ in Thousands, $ in Thousands
12 Months Ended
Dec. 31, 2017
CNY (¥)
Dec. 31, 2017
USD ($)
Dec. 31, 2016
CNY (¥)
Dec. 31, 2015
CNY (¥)
Income/(Loss) from Domestic and Foreign Components Before Income Tax Expenses [Abstract]        
PRC ¥ 2,266,075 $ 348,289 ¥ 1,263,223 ¥ 1,292,104
Non PRC (4,534) (697) (14,371) (15,913)
Income before income taxes ¥ 2,261,541 $ 347,592 ¥ 1,248,852 ¥ 1,276,191