Accounts Receivable, Net (Tables)
12 Months Ended
Dec. 31, 2017
Receivables [Abstract]  
Schedule of Accounts Receivable and Allowance for Doubtful Accounts

Accounts receivable and allowance for doubtful accounts consist of the following:

 

     December 31,  
     2016      2017  
     RMB      RMB      US$  

Accounts receivable

     1,206,436        1,895,145        291,278  

Allowance for doubtful accounts

     (512      (1,408      (216
  

 

 

    

 

 

    

 

 

 

Total

     1,205,924        1,893,737        291,062  
  

 

 

    

 

 

    

 

 

 
Schedule of Analysis of Allowance for Doubtful Accounts

An analysis of the allowance for doubtful accounts is as follows:

 

     December 31,  
     2016      2017  
     RMB      RMB      US$  

Beginning balance

     2,315        512        79  

Additions charged to bad debt expense

     2,792        1,854        284  

Reversal

     (489      (744      (114

Write off

     (4,106      (214      (33
  

 

 

    

 

 

    

 

 

 

Ending balance

     512        1,408        216