SUMMARY OF ACCOUNTING POLICIES - Goodwill (Details)	12 Months Ended
Mar. 31, 2019 USD ($) segment	Mar. 31, 2018 USD ($)
Goodwill [Line Items]
Number of reportable units \| segment	4
Number of operating segments \| segment	4
Impairment charges	$ 0
Fair value above carrying value (as a percentage)	25.00%
Activity in goodwill account
Balance, beginning of the period	$ 1,121,170,000
Balance, end of the period	1,073,055,000	$ 1,121,170,000
Operating segments
Activity in goodwill account
Balance, beginning of the period	1,121,170,000	984,867,000
Additions	10,984,000	85,010,000
Divestitures	(20,628,000)	(3,475,000)
Foreign currency translation adjustments	(38,471,000)	54,768,000
Balance, end of the period	1,073,055,000	1,121,170,000
Operating segments \| HRS
Activity in goodwill account
Balance, beginning of the period	550,983,000	420,935,000
Additions	0	75,280,000
Divestitures	(5,303,000)	0
Foreign currency translation adjustments	(38,471,000)	54,768,000
Balance, end of the period	507,209,000	550,983,000
Operating segments \| IEI
Activity in goodwill account
Balance, beginning of the period	337,707,000	337,707,000
Additions	0	0
Divestitures	(4,450,000)	0
Foreign currency translation adjustments	0	0
Balance, end of the period	333,257,000	337,707,000
Operating segments \| CEC
Activity in goodwill account
Balance, beginning of the period	124,732,000	115,002,000
Additions	10,984,000	9,730,000
Divestitures	(6,391,000)	0
Foreign currency translation adjustments	0	0
Balance, end of the period	129,325,000	124,732,000
Operating segments \| CTG
Activity in goodwill account
Balance, beginning of the period	107,748,000	111,223,000
Additions	0	0
Divestitures	(4,484,000)	(3,475,000)
Foreign currency translation adjustments	0	0
Balance, end of the period	103,264,000	$ 107,748,000
Disposed of by Sale \| Wink Labs Inc \| Operating segments \| CTG
Activity in goodwill account
Divestitures	$ (20,600,000)
CTG
Goodwill [Line Items]
Fair value above carrying value (as a percentage)	22.00%

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of foreign currency translation gain (loss) which increases (decreases) an asset representing future economic benefits from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of divestiture of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

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Number of reporting units tested for impairment of goodwill. A reporting unit is an operating segment or one level below an operating segment.

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Percentage of fair value of reporting unit in excess of carrying amount.

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