Quarterly Financial Results (Unaudited) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended																9 Months Ended	12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Sep. 30, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial Information Disclosure [Abstract]
Product sales	$ 18,862		$ 20,331		$ 25,886		$ 25,216		$ 28,024		$ 24,529		$ 21,041		$ 17,083			$ 90,295	$ 90,677	$ 85,136
Service sales	20,086		19,885		17,311		14,711		11,519		14,293		10,978		9,645			71,993	46,435	27,400
Gross profit	15,390		16,527		18,026		15,769		17,090		15,490		12,451		9,943
Net income (loss)	$ (365)		$ 1,386		$ 1,549		$ 1,963		$ 2,757		$ 1,745		$ 453		$ (1,375)		$ 4,533	$ 4,533	$ 3,580	$ 860
Net (loss) income per share:
Basic (in dollars per share)	$ (0.02)	[1]	$ 0.09	[1]	$ 0.10	[1]	$ 0.13	[1]	$ 0.19	[1]	$ 0.12	[1]	$ 0.03	[1]	$ (0.09)	[1]		$ 0.30	$ 0.24	$ 0.06
Diluted (in dollars per share)	$ (0.02)	[1]	$ 0.09	[1]	$ 0.10	[1]	$ 0.13	[1]	$ 0.18	[1]	$ 0.12	[1]	$ 0.03	[1]	$ (0.09)	[1]		$ 0.30	$ 0.24	$ 0.06

[1] Net income (loss) per share is computed independently for each of the quarters. Therefore, the net income (loss) per share for the four quarters may not equal the annual net income (loss) per share data.