Leases (Narrative) (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Operating lease term for land and office	expiring from 2022 through 2037
Weighted average remaining lease term	18 years 4 days
Weighted average discount rate	6.70%
Rental expenses incurred for operating leases of plant and equipment and office spaces		$ 2,455,509