SUMMARY OF ACCOUNTING POLICIES - Intangible Assets (Details) - USD ($)	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Components of acquired intangible assets
Investment impairments and dispositions	$ 97,691,000	$ 193,063,000	$ 21,895,000
Intangible assets residual value	0
Gross Carrying Amount	520,595,000	571,910,000
Accumulated Amortization	(258,177,000)	(240,915,000)
Total amortization expense	262,418,000	330,995,000
Total intangible asset amortization expense	64,106,000	74,396,000	$ 78,640,000
Intangible assets fully amortized and removed	43,400,000
Foreign currency translation adjustments	5,200,000
Estimated future annual amortization expense for acquired intangible assets
2021	59,798,000
2022	51,422,000
2023	43,797,000
2024	42,262,000
2025	37,343,000
Thereafter	27,796,000
Total amortization expense	262,418,000	330,995,000
Customer-related intangibles
Components of acquired intangible assets
Gross Carrying Amount	275,678,000	297,306,000
Accumulated Amortization	(128,155,000)	(113,627,000)
Total amortization expense	147,523,000	183,679,000
Estimated future annual amortization expense for acquired intangible assets
Total amortization expense	$ 147,523,000	183,679,000
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	5 years 7 months 6 days
Licenses and other intangibles
Components of acquired intangible assets
Gross Carrying Amount	$ 244,917,000	274,604,000
Accumulated Amortization	(130,022,000)	(127,288,000)
Total amortization expense	114,895,000	147,316,000
Estimated future annual amortization expense for acquired intangible assets
Total amortization expense	$ 114,895,000	$ 147,316,000
Licenses and other intangibles | Weighted-average
Components of acquired intangible assets
Useful life	4 years 8 months 12 days