Significant Accounting Policies - Held to maturity security (Details) ¥ in Thousands, $ in Thousands	1 Months Ended	12 Months Ended
Nov. 30, 2016 USD ($)	Dec. 31, 2018 CNY (¥)	Nov. 30, 2016 CNY (¥)
Significant Accounting Policies
Held to maturity security	$ 1,000		¥ 6,884
Ownership (in percent)	6
Interest rate (in percent)	10
Amount to be received \| $	$ 1,100
Other-than-temporary impairment loss \| ¥		¥ 7,364

The amount by which the fair value of an investment is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 8A
-URI http://asc.fasb.org/extlink&oid=118954083&loc=SL6284422-111562

Name:	us-gaap_ImpairmentOfInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration