WARRANTY OBLIGATIONS - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Product Warranty Liability [Line Items]
Additional warranty expense	$ 4,269	$ 1,748	$ 11,924	$ 3,425
Timing Of Cost Reduction Assumptions For Replacements Products
Product Warranty Liability [Line Items]
Additional warranty expense	2,900		2,900
Field Performance Data And Diagnostic Root-Cause Failure Analysis
Product Warranty Liability [Line Items]
Additional warranty expense	$ 1,400	$ 1,700	7,700	$ 3,400
Other Cost Assumptions Changes
Product Warranty Liability [Line Items]
Additional warranty expense			$ 1,300