AR and Allowance for Doubtful Accounts (Tables)

12 Months Ended

Dec. 31, 2017

Accounts Receivable and Allowance for Doubtful Accounts [Abstract]

Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block]

							Exchange Rate
	Balance at		Changes		Write-Offs		Changes		Balance
	Beginning		to Costs and		Charged to		and Other		at End
	of Period		Expenses		Allowance		Adjustments		of Period
Allowance for Doubtful Accounts
Year ended December 31, 2017	$	7,220	$	137	$	(2,206)	$	306	$	5,457
Year ended December 31, 2016	$	7,818	$	1,375	$	(1,949)	$	(24)	$	7,220
Year ended December 31, 2015	$	6,498	$	1,460	$	(261)	$	121	$	7,818