Composition of Certain Balance Sheet Captions - Composition of Certain Balance Sheet Captions (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Mar. 31, 2018
Accounts receivable, net:
Accounts receivable, Billed	$ 188,915	$ 184,536
Accounts receivable, Unbilled	81,592	85,156
Allowance for doubtful accounts	(1,704)	(2,027)
Accounts receivable, net	268,803	267,665
Inventories:
Raw materials	74,995	62,252
Work in process	51,704	47,465
Finished goods	105,379	86,590
Inventories	232,078	196,307
Prepaid expenses and other current assets:
Prepaid expenses	80,984	68,516
Insurance receivable	133,020
Other	19,254	8,619
Prepaid expenses and other current assets	233,258	77,135
Other acquired intangible assets, net:
Other acquired intangible assets, gross	217,090	219,137
Less: accumulated amortization	(191,018)	(187,275)
Other acquired intangible assets, net	26,072	31,862
Other assets:
Investment in unconsolidated affiliate	160,559	163,835
Deferred income taxes	255,292	222,274
Capitalized software costs, net	244,729	246,792
Patents, orbital slots and other licenses, net	16,800	16,100
Other	67,360	37,133
Other assets	744,740	686,134
Accrued liabilities:
Collections in excess of revenues and deferred revenues	108,977	121,439
Accrued employee compensation	28,614	46,106
Accrued vacation	40,032	39,022
Warranty reserve, current portion	5,196	5,357
Other	67,588	51,752
Accrued liabilities	250,407	263,676
Other liabilities:
Deferred revenues, long-term portion	81,740	77,831
Deferred rent, long-term portion	15,378	13,769
Warranty reserve, long-term portion	1,712	1,557
Satellite performance incentive obligations, long-term portion	25,465	18,181
Other	5,971	9,902
Other liabilities	130,266	121,240
Technology [Member]
Other acquired intangible assets, net:
Other acquired intangible assets, gross	89,094	90,652
Contracts and Customer Relationships [Member]
Other acquired intangible assets, net:
Other acquired intangible assets, gross	103,421	103,808
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	10,035	10,137
Satellites, Net [Member]
Property and equipment, net:
Property and equipment	1,536,410	1,613,935
Less: accumulated depreciation and amortization	(412,336)	(373,948)
Property and equipment, net	1,124,074	1,239,987
Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	1,604,973	1,442,398
Less: accumulated depreciation and amortization	(778,674)	(719,910)
Property and equipment, net	826,299	722,488
Satellites [Member] | Satellites, Net [Member]
Property and equipment, net:
Property and equipment	978,098	1,152,503
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	459,222	362,342
Construction in Progress [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	158,173	108,192
Equipment and Software [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	939,026	864,140
CPE Leased Equipment [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	341,308	298,746
Less: accumulated depreciation and amortization	(133,200)	(129,000)
Furniture and Fixtures [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	39,952	35,234
Leasehold Improvements [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	115,300	111,841
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	$ 2,291	$ 15,322