REVENUE RECOGNITION - Contract Balances (Details) - USD ($) $ in Thousands	6 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Apr. 01, 2018	Mar. 31, 2018
ASSETS:
Customer accounts receivable		$ 190,903	$ 205,299
Increase (decrease) in customer accounts receivable	$ (14,396)
Unbilled receivables		4,402	4,338
Increase (decrease) of unbilled receivables	64
Other receivables		3,287	4,996
Increase (decrease) in other receivables	(1,709)
Long-term unbilled receivables		3,754	2,254
Increase (decrease) of long-term unbilled receivables	1,500
Contract assets		202,346	216,887
Increase (decrease) in contract assets	(14,541)
LIABILITIES:
Deferred revenue		230,098	271,698	$ 301,925
Increase (decrease) in deferred revenue	(41,600)
Deferred revenue, long-term		77,135	90,157	$ 91,409
Increase (decrease) in deferred revenue, long-term	(13,022)
Contract liabilities	307,233	$ 307,233	$ 361,855
Increase (decrease) in contract liabilities	(54,622)
Changes In Contract With Customer, Liabilities [Roll Forward]
Revenue recognized in the period	(206,512)
Additions to customer deposits and contract liabilities	159,265
Reclassifications and other adjustments	594
Divestiture of the HNT tools business	(7,969)
Balance at September 30, 2018	$ 307,233