LOSS ON FOREIGN CURRENCY FORWARD CONTRACT (Narrative) (Details)
¥ in Thousands
1 Months Ended 12 Months Ended
May 19, 2016
CNY (¥)
Dec. 31, 2017
CNY (¥)
Dec. 31, 2016
CNY (¥)
Dec. 31, 2015
CNY (¥)
Gain (Loss) on Derivative Instruments, Net, Pretax   ¥ (12,898)
Foreign Exchange Forward [Member]        
Derivative, Notional Amount ¥ 564,095      
Gain (Loss) on Derivative Instruments, Net, Pretax     ¥ 12,898  
Derivative, Inception Date Jan. 29, 2016      
Derivative, Forward Exchange Rate 6.7070      
Derivative, Maturity Date May 19, 2016