Accrued product warranty liability (Tables)

3 Months Ended

Mar. 31, 2018

Accrued product warranty liability [Abstract]

Product warranty liability

The following table summarizes the activity recorded in the accrued product warranty liability during the three months ended March 31, 2018 and 2017:

	Three Months Ended March 31,
	2018				2017
	(In thousands)
Balance, beginning of period		$	267			$	267
Warranties issued			80				55
Warranty settlements			(69	)			(65	)
Balance, end of period		$	278			$	257