Taxes (Details 1)	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
PRC statutory rates	25.00%	25.00%	25.00%
Preferential tax rates	(9.90%)	(15.00%)	(10.00%)
R&D credits	(12.70%)	2.00%	(1.80%)
Permanent difference and others	0.30%	2.00%	0.20%
Effective tax rate	2.70%	10.00%	13.40%

Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to research tax credit.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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-SubTopic 10
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-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319

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