Product warranties (Tables)

6 Months Ended

Jun. 30, 2012

Product Warranties Disclosures [Abstract]

Reconciliation of the changes in warranty reserve

A reconciliation of the changes in the Company’s warranty reserve for 2010 and 2011, and the six months ended June 30, 2012 (unaudited) is as follows:  

	December 31,						June 30,
(in thousands)	2010			2011			2012
							(unaudited)
Balance at the beginning of the period	$	572		$	605		$	983
Warranty expenses accrued	1,166			1,613			611
Warranty settlements made	(1,133		)	(1,235		)	(818		)
Balance at the end of the period	$	605		$	983		$	776