Composition of Certain Balance Sheet Captions - Composition of Certain Balance Sheet Captions (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Mar. 31, 2017
Accounts receivable, net:
Accounts receivable, Billed	$ 157,903	$ 145,626
Accounts receivable, Unbilled	96,528	119,565
Allowance for doubtful accounts	(2,552)	(1,470)
Accounts receivable, net	251,879	263,721
Inventories:
Raw materials	59,008	56,096
Work in process	42,216	25,820
Finished goods	80,175	81,285
Inventories	181,399	163,201
Prepaid expenses and other current assets:
Prepaid expenses	61,841	51,856
Other	10,548	5,980
Prepaid expenses and other current assets	72,389	57,836
Other acquired intangible assets, net:
Other acquired intangible assets, gross	217,725	215,091
Less: accumulated amortization	(180,929)	(173,414)
Other acquired intangible assets, net	36,796	41,677
Other assets:
Investment in unconsolidated affiliate	153,973	141,894
Deferred income taxes	209,477	134,764
Capitalized software costs, net	225,163	203,686
Patents, orbital slots and other licenses, net	16,300	16,500
Other	37,177	32,522
Other assets	642,090	529,366
Accrued liabilities:
Collections in excess of revenues and deferred revenues	86,293	76,682
Accrued employee compensation	25,774	41,691
Accrued vacation	34,311	33,214
Warranty reserve, current portion	6,514	7,796
Other	54,108	65,576
Accrued liabilities	207,000	224,959
Other liabilities:
Deferred revenue, long-term portion	71,666	4,617
Deferred rent, long-term portion	12,219	10,743
Warranty reserve, long-term portion	2,145	3,262
Satellite performance incentives obligation, long-term portion	18,700	19,164
Deferred income taxes, long-term	566	1,936
Other	7,683	3,000
Other liabilities	112,979	42,722
Technology [Member]
Other acquired intangible assets, net:
Other acquired intangible assets, gross	89,580	87,592
Contracts and Customer Relationships [Member]
Other acquired intangible assets, net:
Other acquired intangible assets, gross	103,540	103,034
Satellite Co-Location Rights [Member]
Other acquired intangible assets, net:
Other acquired intangible assets, gross	8,600	8,600
Trade Name [Member]
Other acquired intangible assets, net:
Other acquired intangible assets, gross	5,940	5,940
Other [Member]
Other acquired intangible assets, net:
Other acquired intangible assets, gross	10,065	9,925
Satellites, Net [Member]
Property and equipment, net:
Property and equipment	1,508,537	1,434,824
Less accumulated depreciation and amortization	(345,686)	(326,554)
Property and equipment, net	1,162,851	1,108,270
Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	1,287,903	1,202,589
Less accumulated depreciation and amortization	(710,386)	(661,981)
Property and equipment, net	577,517	540,608
Satellites [Member] | Satellites, Net [Member]
Property and equipment, net:
Property and equipment	551,201	559,380
Capital Lease of Satellite Capacity - Anik F2 [Member] | Satellites, Net [Member]
Property and equipment, net:
Property and equipment	99,090	99,090
Construction in Progress [Member] | Satellites, Net [Member]
Property and equipment, net:
Property and equipment	858,246	776,354
Construction in Progress [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	140,667	116,902
Equipment and Software [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	741,635	679,008
CPE Leased Equipment [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	260,219	271,917
Less accumulated depreciation and amortization	(162,400)	(158,200)
Furniture and Fixtures [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	32,430	30,539
Leasehold Improvements [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	89,456	80,727
Building [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	8,923	8,923
Land [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	$ 14,573	$ 14,573