Segments Summary of revenue by product line (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
Revenue from External Customer [Line Items]
Total revenue	$ 25,968	$ 20,401	$ 73,965	$ 57,797
Products
Revenue from External Customer [Line Items]
Total revenue	16,851	13,087	47,643	36,648
Products | Devices
Revenue from External Customer [Line Items]
Total revenue	12,140	9,513	34,802	26,852
Products | Software
Revenue from External Customer [Line Items]
Total revenue	4,711	3,574	12,841	9,796
Services
Revenue from External Customer [Line Items]
Total revenue	9,117	7,314	26,322	21,149
Services | Maintenance and support
Revenue from External Customer [Line Items]
Total revenue	6,687	5,536	19,158	15,705
Services | Professional services and training
Revenue from External Customer [Line Items]
Total revenue	$ 2,430	$ 1,778	$ 7,164	$ 5,444