Revenue (Tables)

9 Months Ended

Sep. 30, 2012

Revenue [Abstract]

Differentiation of revenue and cost of revenue

	Three Months Ended September 30,				Nine Months Ended September 30,
	2012		2011		2012		2011
Revenue:
Product	$	56,621	$	54,841	$	170,302	$	128,508
Rental		16,374		16,632		51,420		45,590
Service		5,633		3,585		14,404		9,783
	$	78,628	$	75,058	$	236,126	$	183,881
Cost of Revenue:
Product	$	32,910	$	34,686	$	101,528	$	82,734
Rental		7,806		6,778		23,312		18,984
Service		2,271		1,302		5,665		3,554
Depreciation		1,798		1,575		5,302		4,503
	$	44,785	$	44,341	$	135,807	$	109,775