Restricted Net assets (Details) - PRC - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Undistributed earnings in equity investees	$ 92,216,000	$ 85,400,000
Subsidiaries
Restricted net assets	$ 7,427,000	$ 7,277,000

Amount of consolidated retained earnings that represent undistributed (not yet received) earnings from 50% or less owned persons accounted for by the equity method (equity method investees).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 852
-SubTopic 20
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6462270&loc=d3e57205-112772

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