SUMMARY OF ACCOUNTING POLICIES - Intangible Assets (Details) - USD ($)	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Components of acquired intangible assets
Intangible assets residual value	$ 0
Gross Carrying Amount	571,910,000	$ 610,950,000
Accumulated Amortization	(240,915,000)	(186,517,000)
Total amortization expense	330,995,000	424,433,000
Total intangible asset amortization expense	74,396,000	78,640,000	$ 81,396,000
Intangible assets fully amortized and removed	9,400,000
Foreign currency translation adjustments	21,000,000
Estimated future annual amortization expense for acquired intangible assets
2019	64,917,000
2020	60,604,000
2021	52,099,000
2022	44,390,000
2023	42,830,000
Thereafter	66,155,000
Total amortization expense	330,995,000	424,433,000
Customer-related intangibles
Components of acquired intangible assets
Gross Carrying Amount	297,306,000	306,943,000
Accumulated Amortization	(113,627,000)	(79,051,000)
Total amortization expense	183,679,000	227,892,000
Estimated future annual amortization expense for acquired intangible assets
Total amortization expense	$ 183,679,000	227,892,000
Customer-related intangibles | Maximum
Components of acquired intangible assets
Useful life	10 years
Customer-related intangibles | Weighted-average
Components of acquired intangible assets
Useful life	6 years 3 months 18 days
Licenses and other intangibles
Components of acquired intangible assets
Gross Carrying Amount	$ 274,604,000	304,007,000
Accumulated Amortization	(127,288,000)	(107,466,000)
Total amortization expense	147,316,000	196,541,000
Estimated future annual amortization expense for acquired intangible assets
Total amortization expense	$ 147,316,000	$ 196,541,000
Licenses and other intangibles | Weighted-average
Components of acquired intangible assets
Useful life	5 years 6 months