Commitments and Contingencies (Tables)

6 Months Ended

Jun. 30, 2018

Commitments and Contingencies Disclosure [Abstract]

Schedule of Product Warranty Liability [Table Text Block]

The following is a summary of the change in the Company's accrued warranty reserve (in thousands):

	Six Months Ended
	June 30,
	2018			2017
Warranty liability balance, beginning of the period	$	1,124		$	1,821
Product warranty accruals (reversals)	32			445
Utilization of accrual	(272		)	(672		)
Warranty liability balance, end of the period	$	884		$	1,594