SUMMARY OF ACCOUNTING POLICIES - Intangible Assets (Details) - USD ($)	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Components of acquired intangible assets
Intangible assets residual value	$ 0
Gross Carrying Amount	544,601,000	$ 508,099,000
Accumulated Amortization	(182,420,000)	(104,345,000)
Net Carrying Amount	362,181,000	403,754,000
Intangible assets fully amortized and removed	14,200,000
Total intangible asset amortization expense	81,396,000	65,965,000	$ 32,035,000
Estimated future annual amortization expense for acquired intangible assets
2018	68,472,000
2019	61,582,000
2020	52,439,000
2021	48,266,000
2022	39,714,000
Thereafter	91,708,000
Net Carrying Amount	362,181,000	403,754,000
Customer-related intangibles
Components of acquired intangible assets
Gross Carrying Amount	260,704,000	223,046,000
Accumulated Amortization	(105,912,000)	(66,473,000)
Net Carrying Amount	154,792,000	156,573,000
Estimated future annual amortization expense for acquired intangible assets
Net Carrying Amount	$ 154,792,000	156,573,000
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 7 months 6 days
Licenses and other intangibles
Components of acquired intangible assets
Gross Carrying Amount	$ 283,897,000	285,053,000
Accumulated Amortization	(76,508,000)	(37,872,000)
Net Carrying Amount	207,389,000	247,181,000
Estimated future annual amortization expense for acquired intangible assets
Net Carrying Amount	$ 207,389,000	$ 247,181,000
Licenses and other intangibles | Weighted-average
Components of acquired intangible assets
Useful life	6 years 7 months 6 days