Goodwill and Acquired Intangible Assets - Allocation of Other Acquired Intangible Assets and Related Accumulated Amortization (Detail) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Acquired Finite-Lived Intangible Assets [Line Items]
Other acquired intangible assets, gross	$ 215,091	$ 197,604
Other acquired intangible assets, accumulated amortization	(173,414)	(164,000)
Other acquired intangible assets, net	$ 41,677	33,604
Technology [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life	6 years
Other acquired intangible assets, gross	$ 87,592	74,848
Other acquired intangible assets, accumulated amortization	(62,749)	(59,921)
Other acquired intangible assets, net	$ 24,843	14,927
Contracts and Customer Relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life	7 years
Other acquired intangible assets, gross	$ 103,034	99,499
Other acquired intangible assets, accumulated amortization	(89,083)	(83,928)
Other acquired intangible assets, net	$ 13,951	15,571
Satellite Co-Location Rights [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life	9 years
Other acquired intangible assets, gross	$ 8,600	8,600
Other acquired intangible assets, accumulated amortization	(6,743)	(5,818)
Other acquired intangible assets, net	$ 1,857	2,782
Trade Name [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life	3 years
Other acquired intangible assets, gross	$ 5,940	5,940
Other acquired intangible assets, accumulated amortization	$ (5,940)	(5,918)
Other acquired intangible assets, net		22
Other [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life	6 years
Other acquired intangible assets, gross	$ 9,925	8,717
Other acquired intangible assets, accumulated amortization	(8,899)	(8,415)
Other acquired intangible assets, net	$ 1,026	$ 302