Segments Summary of revenue by product line (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Revenue from External Customer [Line Items]
Total revenue	$ 24,878	$ 19,073	$ 47,997	$ 37,396
Products
Revenue from External Customer [Line Items]
Total revenue	16,155	11,925	30,792	23,561
Products | Devices
Revenue from External Customer [Line Items]
Total revenue	12,309	9,080	22,662	17,339
Products | Software
Revenue from External Customer [Line Items]
Total revenue	3,846	2,845	8,130	6,222
Services
Revenue from External Customer [Line Items]
Total revenue	8,723	7,148	17,205	13,835
Services | Maintenance and support
Revenue from External Customer [Line Items]
Total revenue	6,360	5,194	12,470	10,169
Services | Professional services and training
Revenue from External Customer [Line Items]
Total revenue	$ 2,363	$ 1,954	$ 4,735	$ 3,666