Stockholders' Equity - Schedule of Stock Based Compensation Expense for Awards Under Equity Plans (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Share based Compensation Allocation of Recognized Period Cost [Line Items]
Total stock based compensation	$ 637	$ 443
Cost of Revenue [Member]
Share based Compensation Allocation of Recognized Period Cost [Line Items]
Total stock based compensation	49	34
Service, rental and maintenance [Member]
Share based Compensation Allocation of Recognized Period Cost [Line Items]
Total stock based compensation	52	29
Selling and Marketing [Member]
Share based Compensation Allocation of Recognized Period Cost [Line Items]
Total stock based compensation	48	51
General and Administrative [Member]
Share based Compensation Allocation of Recognized Period Cost [Line Items]
Total stock based compensation	380	236
General and Administrative [Member] | Board Of Directors [Member]
Share based Compensation Allocation of Recognized Period Cost [Line Items]
Total stock based compensation	$ 108	$ 93