Restricted Net Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
China
Segment Reporting Information
Restricted net assets	$ 43,912	$ 29,920

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_SegmentReportingInformationLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration