REVENUE - Schedule of Sales by Industry (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation Of Revenue [Line Items]
Revenues	$ 29,465	$ 40,981
Commercial [Member]
Disaggregation Of Revenue [Line Items]
Revenues	16,144	28,274
Healthcare [Member]
Disaggregation Of Revenue [Line Items]
Revenues	6,487	5,063
Government [Member]
Disaggregation Of Revenue [Line Items]
Revenues	4,181	3,127
Education [Member]
Disaggregation Of Revenue [Line Items]
Revenues	1,523	3,529
License Fees from Distribution Partners [Member]
Disaggregation Of Revenue [Line Items]
Revenues	207	306
Total product and transportation revenue [Member]
Disaggregation Of Revenue [Line Items]
Revenues	28,542	40,299
Installation and other services [Member]
Disaggregation Of Revenue [Line Items]
Revenues	$ 923	$ 682