Organization and principal activities (Liquidity) (Details) ¥ in Thousands, $ in Thousands |
12 Months Ended | |||
|---|---|---|---|---|
|
Dec. 31, 2017
CNY (¥)
|
Dec. 31, 2017
USD ($)
|
Dec. 31, 2016
CNY (¥)
|
Dec. 31, 2015
CNY (¥)
|
|
| Debt Instrument [Line Items] | ||||
| Net Cash Provided by (Used in) Operating Activities | ¥ 2,697,317 | $ 412,800 | ¥ 1,887,849 | ¥ 198,538 |
| Working Capital | 780,100 | |||
| Cash, Cash Equivalents, and Short-term Investments | ¥ 5,000,000 | |||