REVENUE RECOGNITION - Disaggregation of Revenue (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020 USD ($)	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2020 USD ($) segment	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Reconciliation of disaggregated revenue to segment revenue as well as revenue by geographical regions
Number of reportable segment | segment									1
Revenues	$ 92,998	$ 94,653	$ 86,661	$ 92,382	$ 87,925	$ 96,633	$ 92,630	$ 93,896	$ 366,694	$ 371,084	$ 310,611
United States
Reconciliation of disaggregated revenue to segment revenue as well as revenue by geographical regions
Revenues									214,203	244,347
Europe
Reconciliation of disaggregated revenue to segment revenue as well as revenue by geographical regions
Revenues									126,985	124,914
Asia-Pacific
Reconciliation of disaggregated revenue to segment revenue as well as revenue by geographical regions
Revenues									25,506	1,823
Vehicle
Reconciliation of disaggregated revenue to segment revenue as well as revenue by geographical regions
Revenues									110,365	126,811
Industrial
Reconciliation of disaggregated revenue to segment revenue as well as revenue by geographical regions
Revenues									114,143	124,196
Medical
Reconciliation of disaggregated revenue to segment revenue as well as revenue by geographical regions
Revenues									83,191	51,586
Aerospace & Defense
Reconciliation of disaggregated revenue to segment revenue as well as revenue by geographical regions
Revenues									39,711	47,748
Other
Reconciliation of disaggregated revenue to segment revenue as well as revenue by geographical regions
Revenues									$ 19,284	$ 20,743