Goodwill and Acquired Intangible Assets - Allocation of Other Acquired Intangible Assets and Related Accumulated Amortization (Detail) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Acquired Finite-Lived Intangible Assets [Line Items]
Other acquired intangible assets, gross	$ 217,784	$ 219,137
Other acquired intangible assets, accumulated amortization	(195,483)	(187,275)
Other acquired intangible assets, net	$ 22,301	31,862
Technology [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life	6 years
Other acquired intangible assets, gross	$ 89,972	90,652
Other acquired intangible assets, accumulated amortization	(73,992)	(69,387)
Other acquired intangible assets, net	$ 15,980	21,265
Contracts and Customer Relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life	7 years
Other acquired intangible assets, gross	$ 103,283	103,808
Other acquired intangible assets, accumulated amortization	(96,970)	(94,584)
Other acquired intangible assets, net	$ 6,313	9,224
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	(8,592)	(7,668)
Other acquired intangible assets, net	$ 8	932
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)	(5,940)
Other [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life	6 years
Other acquired intangible assets, gross	$ 9,989	10,137
Other acquired intangible assets, accumulated amortization	$ (9,989)	(9,696)
Other acquired intangible assets, net		$ 441