Supplemental Cash Flow Information (Schedule Of Supplemental Cash Flow Information) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Supplemental Cash Flow Information [Abstract]
Interest payments	$ 1,188		$ 589		$ 622
Income tax (receipts) payments	1,523		711		(541)
Transfer of equipment from inventory to property and equipment	3,714	[1]	2,484	[1]	1,323	[1]
Transfer of equipment to inventory from property and equipment	1,068	[2]	265	[2]	915	[2]
Issuance of stock for acquisitions of business	$ 3,042		$ 5,895

[1] Inventory is transferred from inventory to property and equipment at cost when the Company requires additional machines for training, demonstration, short-term rentals and use in its on-demand parts services.

[2] In general, an asset is transferred from property and equipment into inventory at its net book value when the Company has identified a potential sale for a used machine. The machine is removed from inventory upon recognition of the sale.