Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2012

Schedule of changes in the allowance for doubtful accounts

Changes in the allowance for doubtful accounts are as follows (in thousands):



	Year ended December 31,
	2012			2011			2010
Balance, beginning of year	$	571		$	262		$	948
Charged to provision for doubtful accounts	512			661			94
Write-offs	(369		)	(352		)	(780		)
Balance, end of year	$	714		$	571		$	262

Schedule of depreciation or amortization of property and equipment

Depreciation or amortization of property and equipment, including assets held under capital leases, is calculated using the straight-line method over the asset’s estimated useful life:



Buildings and leasehold
improvements	2-30 years
Machinery, equipment and rental
tools	7-10 years
Furniture and fixtures	3 years
Transportation equipment	2-5 years
Computer equipment and software	3-7 years

Property and equipment are as follows (in thousands):



	December 31
	2012			2011
Land	$	1,442		$	1,220
Buildings and leasehold improvements	18,520			18,401
Machinery, equipment and rental tools	54,279			44,364
Equipment in progress	9,382			4,048
Furniture and fixtures	1,358			1,288
Transportation equipment	5,136			4,853
Computer equipment and software	6,743			1,900
Property and equipment	96,860			76,074
Less accumulated depreciation	(40,361		)	(32,160		)
Property and equipment, net	$	56,499		$	43,914

- Definition

Tabular disclosure of the useful life and salvage value of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale. Examples include land, buildings, machinery and equipment, and other types of furniture and equipment including, but not limited to, office equipment, furniture and fixtures, and computer equipment and software.

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