Guarantees (Tables)

12 Months Ended

Dec. 31, 2012

Guarantees [Abstract]

Changes in the carrying amount of service and product warranties

Changes in the carrying amount of service and product warranties for the year ended December 31, are as follows:

	2010			2011			2012
Balance as of January 1,	$	3,383		$	3,363		$	3,618
Provision for warranties	3,510			4,344			4,163
Claims made	(3,530		)	(4,089		)	(4,145		)
Balance as of December 31,	$	3,363		$	3,618		$	3,636