Reconciliation of income taxes (Details) - USD ($)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Reconciliation of income taxes
(Benefit) tax at statutory rate of 25%	$ (9,868,430)	$ (4,736,660)
Stock based compensation from current and prior years		8,534
Effect of tax holiday	3,906,336	1,834,517
Other, primarily the difference in U.S. tax rates	7,815
Change in valuation allowance Reconciliation	6,031,321	3,955,022
Income tax expense Reconciliation	$ 77,042	$ 1,061,413

The amount of income tax expense or benefit for the period computed by applying the domestic federal statutory tax rates to pretax income from continuing operations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32687-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32698-109319

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 08
-Paragraph h
-Subparagraph 2
-Article 4

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