Composition of Certain Balance Sheet Captions - Composition of Certain Balance Sheet Captions (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2017
Accounts receivable, net:
Accounts receivable, Billed	$ 184,536	$ 145,626
Accounts receivable, Unbilled	85,156	119,565
Allowance for doubtful accounts	(2,027)	(1,470)
Accounts receivable, net	267,665	263,721
Inventories:
Raw materials	62,252	56,096
Work in process	47,465	25,820
Finished goods	86,590	81,285
Inventories	196,307	163,201
Prepaid expenses and other current assets:
Prepaid expenses	68,516	51,856
Other	8,619	5,980
Prepaid expenses and other current assets	77,135	57,836
Other assets:
Investment in unconsolidated affiliate	163,835	141,894
Deferred income taxes	222,274	134,764
Capitalized software costs, net	246,792	203,686
Patents, orbital slots and other licenses, net	16,100	16,500
Other	37,133	32,522
Other assets	686,134	529,366
Accrued liabilities:
Collections in excess of revenues and deferred revenues	121,439	76,682
Accrued employee compensation	46,106	41,691
Accrued vacation	39,022	33,214
Warranty reserve, current portion	5,357	7,796
Other	51,752	65,576
Accrued liabilities	263,676	224,959
Other liabilities:
Deferred revenue, long-term portion	77,831	4,617
Deferred rent, long-term portion	13,769	10,743
Warranty reserve, long-term portion	1,557	3,262
Satellite performance incentive obligation, long-term portion	18,181	19,164
Deferred income taxes, long-term	864	1,936
Other	9,038	3,000
Other liabilities	121,240	42,722
Satellites, Net [Member]
Property and equipment, net:
Property and equipment	1,613,935	1,434,824
Less accumulated depreciation and amortization	(373,948)	(326,554)
Property and equipment, net	1,239,987	1,108,270
Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	1,442,398	1,202,589
Less accumulated depreciation and amortization	(719,910)	(661,981)
Property and equipment, net	722,488	540,608
Satellites [Member] | Satellites, Net [Member]
Property and equipment, net:
Property and equipment	1,152,503	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	362,342	776,354
Construction in Progress [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	108,192	116,902
Equipment and Software [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	864,140	679,008
CPE Leased Equipment [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	298,746	271,917
Less accumulated depreciation and amortization	(129,000)	(158,200)
Furniture and Fixtures [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	35,234	30,539
Leasehold Improvements [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	111,841	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	$ 15,322	$ 14,573