SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) - CNY (¥)
¥ in Thousands |
12 Months Ended |
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
| Significant Accounting Policies [Line Items] |
|
|
|
| Short-term investment |
¥ 1,970,000
|
¥ 1,937,000
|
¥ 945,000
|
| Investment income |
19,314
|
12,676
|
5,961
|
| Advertising costs |
237,340
|
201,298
|
151,533
|
| Government grants |
7,435
|
3,199
|
5,851
|
| Contributions to employee benefits |
117,798
|
85,325
|
¥ 69,370
|
| PRC [Member] | RMB Denominated Bank Deposits [Member] |
|
|
|
| Significant Accounting Policies [Line Items] |
|
|
|
| Cash, cash equivalents, time deposits and restricted time deposits |
910,804
|
867,811
|
|
| PRC [Member] | US Dollar Denominated Bank Deposits [Member] |
|
|
|
| Significant Accounting Policies [Line Items] |
|
|
|
| Cash, cash equivalents, time deposits and restricted time deposits |
135,686
|
152,792
|
|
| HK SAR [Member] |
|
|
|
| Significant Accounting Policies [Line Items] |
|
|
|
| Cash, cash equivalents, time deposits and restricted time deposits |
4,387
|
3,535
|
|
| HK SAR [Member] | RMB Denominated Bank Deposits [Member] |
|
|
|
| Significant Accounting Policies [Line Items] |
|
|
|
| Cash, cash equivalents, time deposits and restricted time deposits |
21
|
3
|
|
| HK SAR [Member] | HK Dollar Denominated Bank Deposits [Member] |
|
|
|
| Significant Accounting Policies [Line Items] |
|
|
|
| Cash, cash equivalents, time deposits and restricted time deposits |
1
|
1
|
|
| US [Member] | US Dollar Denominated Bank Deposits [Member] |
|
|
|
| Significant Accounting Policies [Line Items] |
|
|
|
| Cash, cash equivalents, time deposits and restricted time deposits |
¥ 68,795
|
¥ 261,913
|
|
| Office buildings [Member] |
|
|
|
| Significant Accounting Policies [Line Items] |
|
|
|
| Useful life |
45 years
|
|
|
| Furniture [Member] |
|
|
|
| Significant Accounting Policies [Line Items] |
|
|
|
| Useful life |
5 years
|
|
|
| Minimum [Member] |
|
|
|
| Significant Accounting Policies [Line Items] |
|
|
|
| Operating lease term |
1 year
|
|
|
| Contributions to employee benefits, percentage of salary |
24.30%
|
|
|
| Loan Referral Service Revenue, Percentage |
|
4.00%
|
|
| Minimum [Member] | Office equipment [Member] |
|
|
|
| Significant Accounting Policies [Line Items] |
|
|
|
| Useful life |
3 years
|
|
|
| Maximum [Member] |
|
|
|
| Significant Accounting Policies [Line Items] |
|
|
|
| Operating lease term |
10 years
|
|
|
| Contributions to employee benefits, percentage of salary |
53.10%
|
|
|
| Loan Referral Service Revenue, Percentage |
|
8.00%
|
|
| Maximum [Member] | Office equipment [Member] |
|
|
|
| Significant Accounting Policies [Line Items] |
|
|
|
| Useful life |
4 years
|
|
|