COMMITMENTS AND CONTINGENCIES - Contractual Purchase Obligations (Details) ¥ in Thousands	Dec. 31, 2017 CNY (¥)
Contractual purchase obligations
2018	¥ 11,533
Advertising Services
Contractual purchase obligations
2018	7,483
Electronic equipment
Contractual purchase obligations
2018	¥ 4,050

Minimum amount of purchase arrangement maturing in the next fiscal year following the latest fiscal year. Includes, but not limited to, recorded and unrecorded purchase obligations, long-term purchase commitments, and short-term purchase commitments.

No definition available.

Name:	us-gaap_PurchaseObligationDueInNextTwelveMonths
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant