REPORTING SEGMENTS AND RELATED INFORMATION - Major customers & products (Details) - Revenue Benchmark	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Turbochargers
Revenue from External Customer [Line Items]
Percentage of net sales	24.00%	28.00%	27.00%
Ford
Revenue from External Customer [Line Items]
Percentage of net sales	13.00%	15.00%	14.00%
Volkswagen
Revenue from External Customer [Line Items]
Percentage of net sales	11.00%	11.00%	12.00%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
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