ACQUISITION, GOODWILL, AND ACQUIRED INTANGIBLE ASSETS - Narrative (Details) - USD ($) $ in Thousands, shares in Millions		3 Months Ended		9 Months Ended
	Jul. 02, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Mar. 31, 2019
Business Acquisition [Line Items]
Amortization of Intangible Assets		$ 46,100	$ 42,800	$ 137,400	$ 113,800
Goodwill		$ 1,279,897		1,279,897		$ 1,278,380
Triangle [Member]
Business Acquisition [Line Items]
Ownership percentage	16.00%
Polycom [Member]
Business Acquisition [Line Items]
Goodwill	$ 1,264,417
Business Combination, Consideration Transferred	$ 2,200,000
Business Combination, Consideration Transferred, Equity Interests Issued And Issuable, Shares	6.4
Business Acquisition, Equity Interest Issued or Issuable, Value Assigned	$ 500,000
Payments to Acquire Businesses, Gross	$ 1,700,000
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Deferred Tax And Tax Liabilities				45,200
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Working Capital Adjustment				8,000
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Other				1,400
Goodwill, Period Increase (Decrease)				$ 54,600
Deferred Revenue Adjustment [Member] | Polycom [Member]
Business Acquisition [Line Items]
Revenues					$ 19,300