SEGMENT REPORTING AND GEOGRAPHIC INFORMATION SEGMENT REPORTING AND GEOGRAPHIC INFORMATION - Net Revenues by Major Product Category (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Mar. 28, 2020	Dec. 28, 2019	Sep. 28, 2019	Jun. 29, 2019	Mar. 30, 2019	Dec. 29, 2018	Sep. 29, 2018	Jun. 30, 2018	Mar. 28, 2020	Mar. 28, 2020	Mar. 30, 2019	Mar. 31, 2018
Revenue from External Customer [Line Items]
Net revenues	$ 403,043	$ 384,471	$ 461,709	$ 447,767	$ 468,488	$ 501,669	$ 483,069	$ 221,309	$ 1,696,990	$ 1,696,990	$ 1,674,535	$ 856,903
Voice
Revenue from External Customer [Line Items]
Net revenues										377,059	344,586	0
Video
Revenue from External Customer [Line Items]
Net revenues										282,491	255,485	0
Service
Revenue from External Customer [Line Items]
Net revenues									$ 264,254	$ 264,254	$ 163,765	$ 0