Revenue Recognition - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Standard payment terms to customers	30 days
Losses recognized on fixed-price contracts	$ 0	$ 0
Maintenance fee revenue recognition period	1 year
Minimum [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Warranty period on fixed-price contracts	30 days
Maximum [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Warranty period on fixed-price contracts	60 days