Property, plant and equipment, net (Allocated Depreciation Expense) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Property, Plant and Equipment [Line Items]
Total depreciation expense	$ 15,169,452	$ 11,276,313
Cost of revenues [Member]
Property, Plant and Equipment [Line Items]
Total depreciation expense	13,458,983	9,568,618
Selling expenses [Member]
Property, Plant and Equipment [Line Items]
Total depreciation expense	1,823	1,430
General and administrative expenses [Member]
Property, Plant and Equipment [Line Items]
Total depreciation expense	686,523	794,625
Research and development expenses [Member]
Property, Plant and Equipment [Line Items]
Total depreciation expense	$ 1,022,123	$ 911,640