Stockholders' Equity and Stock Based Compensation - Schedule of Stock Based Compensation Expense for Awards Under Equity Plans (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Share based Compensation Allocation of Recognized Period Cost [Line Items]
Total stock based compensation expense	$ 730	$ 662	$ 1,368	$ 1,104
Cost of Revenue [Member]
Share based Compensation Allocation of Recognized Period Cost [Line Items]
Total stock based compensation expense	58	34	107	67
Service, rental and maintenance [Member]
Share based Compensation Allocation of Recognized Period Cost [Line Items]
Total stock based compensation expense	63	29	116	57
Selling and Marketing [Member]
Share based Compensation Allocation of Recognized Period Cost [Line Items]
Total stock based compensation expense	75	51	123	102
General and Administrative [Member]
Share based Compensation Allocation of Recognized Period Cost [Line Items]
Total stock based compensation expense	426	455	807	693
General and Administrative [Member] | Board Of Directors [Member]
Share based Compensation Allocation of Recognized Period Cost [Line Items]
Total stock based compensation expense	$ 108	$ 93	$ 215	$ 185