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Significant Concentrations - Summary of Revenue and Accounts Receivable (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Concentration Risk [Line Items]
Revenue	$ 16,839	$ 16,694	$ 19,203	$ 20,678	$ 19,469	$ 19,653	$ 18,848	$ 22,841	$ 73,414	$ 80,811
Accounts receivable	11,581				18,014				11,581	18,014
Honeywell International Inc and affiliated entities [Member] \| Customer Concentration Risk [Member]
Concentration Risk [Line Items]
Revenue									7,013	12,278
Honeywell International Inc and affiliated entities [Member] \| Credit Concentration Risk [Member]
Concentration Risk [Line Items]
Accounts receivable	$ 2,758				$ 8,659				$ 2,758	$ 8,659
Honeywell International Inc and affiliated entities [Member] \| Revenue [Member] \| Customer Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration risk, percentage									10.00%	15.00%
Honeywell International Inc and affiliated entities [Member] \| Accounts receivable [Member] \| Credit Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration risk, percentage									24.00%	48.00%