SEGMENT, GEOGRAPHIC, MAJOR CUSTOMER AND PRODUCT INFORMATION (Summary of Revenues by Product Family) (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Jun. 30, 2016
Revenue from External Customer [Line Items]
Total revenues	$ 239,997	$ 937,237	$ 607,045	$ 489,843
Inverters [Member]
Revenue from External Customer [Line Items]
Total revenues	112,585	416,966	290,632	223,756
Optimizers [Member]
Revenue from External Customer [Line Items]
Total revenues	115,229	432,410	286,856	244,852
Other Products [Member]
Revenue from External Customer [Line Items]
Total revenues	$ 12,183	$ 87,861	$ 29,557	$ 21,235