REVENUE RECOGNITION - Disaggregation of Revenue (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($) segment	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Reconciliation of disaggregated revenue to segment revenue as well as revenue by geographical regions
Number of reportable segment | segment									1
Disaggregation of revenue	$ 73,962	$ 80,092	$ 79,981	$ 76,576	$ 65,355	$ 64,968	$ 60,335	$ 61,354	$ 310,611	$ 252,012	$ 245,893
United States
Reconciliation of disaggregated revenue to segment revenue as well as revenue by geographical regions
Disaggregation of revenue									184,507
Europe
Reconciliation of disaggregated revenue to segment revenue as well as revenue by geographical regions
Disaggregation of revenue									123,771
Asia
Reconciliation of disaggregated revenue to segment revenue as well as revenue by geographical regions
Disaggregation of revenue									2,333
Vehicle
Reconciliation of disaggregated revenue to segment revenue as well as revenue by geographical regions
Disaggregation of revenue									121,864
Industrial
Reconciliation of disaggregated revenue to segment revenue as well as revenue by geographical regions
Disaggregation of revenue									101,332
Medical
Reconciliation of disaggregated revenue to segment revenue as well as revenue by geographical regions
Disaggregation of revenue									43,239
Aerospace & Defense
Reconciliation of disaggregated revenue to segment revenue as well as revenue by geographical regions
Disaggregation of revenue									35,927
Other
Reconciliation of disaggregated revenue to segment revenue as well as revenue by geographical regions
Disaggregation of revenue									$ 8,249