REVENUE - Contract Assets (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Increase (decrease) contract assets
Outstanding at the beginning of period	[1]	$ 6,431
Outstanding at the end of period		$ 8,584
Revenue under contract manufacturing agreements (as percentage)		91.00%	91.00%
Remaining performance obligations customers upon shipment with payment terms		120 days
ASU 2014-09
Increase (decrease) contract assets
Outstanding at the beginning of period		$ 6,431
Transferred to receivables from contract assets recognized		(4,012)
Product transferred over time		6,165
Outstanding at the end of period		$ 8,584

[1] The balance sheet at December 31, 2018 has been derived from the audited financial statements at that date.