Composition of Certain Balance Sheet Captions - Composition of Certain Balance Sheet Captions (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Mar. 31, 2018
Accounts receivable, net:
Accounts receivable, Billed	$ 209,587	$ 184,536
Accounts receivable, Unbilled	87,085	85,156
Allowance for doubtful accounts	(1,347)	(2,027)
Accounts receivable, net	295,325	267,665
Inventories:
Raw materials	78,850	62,252
Work in process	52,240	47,465
Finished goods	99,032	86,590
Inventories	230,122	196,307
Prepaid expenses and other current assets:
Prepaid expenses	81,155	68,516
Insurance receivable	12,317
Other	22,372	8,619
Prepaid expenses and other current assets	115,844	77,135
Other acquired intangible assets, net:
Other acquired intangible assets, gross	217,920	219,137
Less: accumulated amortization	(193,160)	(187,275)
Other acquired intangible assets, net	24,760	31,862
Other assets:
Investment in unconsolidated affiliate	162,617	163,835
Deferred income taxes	251,992	222,274
Capitalized software costs, net	244,924	246,792
Patents, orbital slots and other licenses, net	16,700	16,100
Other	68,618	37,133
Other assets	744,851	686,134
Accrued liabilities:
Collections in excess of revenues and deferred revenues	127,286	121,439
Accrued employee compensation	55,418	46,106
Accrued vacation	39,971	39,022
Warranty reserve, current portion	5,311	5,357
Other	64,274	51,752
Accrued liabilities	292,260	263,676
Other liabilities:
Deferred revenues, long-term portion	81,877	77,831
Deferred rent, long-term portion	16,525	13,769
Warranty reserve, long-term portion	1,696	1,557
Satellite performance incentive obligations, long-term portion	25,292	18,181
Other	6,580	9,902
Other liabilities	131,970	121,240
Technology [Member]
Other acquired intangible assets, net:
Other acquired intangible assets, gross	90,046	90,652
Contracts and Customer Relationships [Member]
Other acquired intangible assets, net:
Other acquired intangible assets, gross	103,321	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	10,013	10,137
Satellites, Net [Member]
Property and equipment, net:
Property and equipment	1,620,760	1,613,935
Less: accumulated depreciation and amortization	(432,160)	(373,948)
Property and equipment, net	1,188,600	1,239,987
Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	1,671,962	1,442,398
Less: accumulated depreciation and amortization	(806,619)	(719,910)
Property and equipment, net	865,343	722,488
Satellites [Member] | Satellites, Net [Member]
Property and equipment, net:
Property and equipment	978,114	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	543,556	362,342
Construction in Progress [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	167,897	108,192
Equipment and Software [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	970,351	864,140
CPE Leased Equipment [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	354,430	298,746
Less: accumulated depreciation and amortization	(137,600)	(129,000)
Furniture and Fixtures [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	46,049	35,234
Leasehold Improvements [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	122,021	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