Inventories (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Changes In the Inventory Reserves
Balance at beginning of period	$ 1,737	$ 1,988	$ 1,783	$ 1,793
Provisions for losses	293	1,072	337	1,351
Write-offs and disposals	(3)	(1)	(93)	(85)
Balance at end of period	$ 2,027	$ 3,059	$ 2,027	$ 3,059