Stock Based Compensation - Stock Based Compensation Expense (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Share based Compensation Allocation of Recognized Period Cost [Line Items]
Total stock based compensation	$ 1,106	$ 946	$ 2,816	$ 2,200
Cost of Sales [Member]
Share based Compensation Allocation of Recognized Period Cost [Line Items]
Total stock based compensation	108	64	270	162
Service, Rental and Maintenance [Member]
Share based Compensation Allocation of Recognized Period Cost [Line Items]
Total stock based compensation	56	59	78	99
Selling and Marketing [Member]
Share based Compensation Allocation of Recognized Period Cost [Line Items]
Total stock based compensation	151	122	413	360
General and Administrative [Member]
Share based Compensation Allocation of Recognized Period Cost [Line Items]
Total stock based compensation	$ 791	$ 701	$ 2,055	$ 1,579