Cash and cash equivalents (Tables)

12 Months Ended

Dec. 31, 2017

Statement [Line Items]

Disclosure of detailed information about cash and cash equivalents explanatory [Table Text Block]

		Dec. 31, 2017		Dec. 31, 2016
Cash on hand and demand deposits	$	356,499	$	129,850
Short-term money market instruments with maturities of three months or less at acquisition date		-		17,014
	$	356,499	$	146,864