REVENUE RECOGNITION - Disaggregation of Revenue (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) segment	Mar. 31, 2018 USD ($)
Reconciliation of disaggregated revenue to segment revenue as well as revenue by geographical regions
Number of reportable segment | segment	1
Disaggregation of revenue	$ 93,896	$ 76,576
United States
Reconciliation of disaggregated revenue to segment revenue as well as revenue by geographical regions
Disaggregation of revenue	59,314	44,170
Europe
Reconciliation of disaggregated revenue to segment revenue as well as revenue by geographical regions
Disaggregation of revenue	34,167	31,831
Asia
Reconciliation of disaggregated revenue to segment revenue as well as revenue by geographical regions
Disaggregation of revenue	412	574
Other
Reconciliation of disaggregated revenue to segment revenue as well as revenue by geographical regions
Disaggregation of revenue	3	1
Vehicle
Reconciliation of disaggregated revenue to segment revenue as well as revenue by geographical regions
Disaggregation of revenue	33,596	32,162
Industrial
Reconciliation of disaggregated revenue to segment revenue as well as revenue by geographical regions
Disaggregation of revenue	31,311	23,892
Medical
Reconciliation of disaggregated revenue to segment revenue as well as revenue by geographical regions
Disaggregation of revenue	12,410	10,644
Aerospace & Defense
Reconciliation of disaggregated revenue to segment revenue as well as revenue by geographical regions
Disaggregation of revenue	11,253	7,811
Other
Reconciliation of disaggregated revenue to segment revenue as well as revenue by geographical regions
Disaggregation of revenue	$ 5,326	$ 2,067