Revenue Recognition Policy (Detail) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2015 USD ($) contract measurement unit	Dec. 31, 2014 USD ($) contract
Number of contracts in progress that were identified as a loss contract (in contracts) | contract	0	1
Loss on contract termination		$ 4
Unbilled receivables, current	$ 11,421	9,904
Billings in excess of cost, current	$ 1,106	$ 2,994
Number of units with APC technology (in units) | unit	1,000
Minimum
Contract term (in months)	8 months
Critical operational measurements (in measurements) | measurement	3
Maximum
Contract term (in months)	16 months
Critical operational measurements (in measurements) | measurement	4