Composition of Certain Balance Sheet Captions - Composition of Certain Balance Sheet Captions (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Mar. 31, 2016
Accounts receivable, net:
Accounts receivable, Billed	$ 144,785	$ 146,309
Accounts receivable, Unbilled	133,425	141,568
Allowance for doubtful accounts	(1,713)	(1,153)
Accounts receivable, net	276,497	286,724
Inventories:
Raw materials	47,951	46,757
Work in process	30,170	27,200
Finished goods	73,510	71,204
Inventories	151,631	145,161
Prepaid expenses and other current assets:
Prepaid expenses	45,608	41,784
Other	3,694	5,799
Prepaid expenses and other current assets	49,302	47,583
Other acquired intangible assets, net:
Other acquired intangible assets, gross	196,570	197,604
Less: accumulated amortization	(167,828)	(164,000)
Other acquired intangible assets, net	28,742	33,604
Other assets:
Deferred income taxes	131,338	134,721
Capitalized software costs, net	187,424	163,061
Patents, orbital slots and other licenses, net	16,700	16,900
Other	34,334	25,323
Other assets	369,796	340,005
Accrued liabilities:
Collections in excess of revenues and deferred revenues	76,093	64,624
Accrued employee compensation	21,212	35,056
Accrued vacation	29,597	28,646
Warranty reserve, current portion	7,605	7,867
Current portion of other long-term debt	281	274
Other	51,619	47,877
Accrued liabilities	186,407	184,344
Other liabilities:
Deferred revenue, long-term portion	5,508	5,470
Deferred rent, long-term portion	10,193	8,808
Warranty reserve, long-term portion	3,761	3,567
Satellite performance incentives obligation, long-term portion	19,140	19,514
Other		12
Other liabilities	38,602	37,371
Technology-Based Intangible Assets [Member]
Other acquired intangible assets, net:
Other acquired intangible assets, gross	74,015	74,848
Contracts and Customer Relationships [Member]
Other acquired intangible assets, net:
Other acquired intangible assets, gross	99,318	99,499
Satellite Co-Location Rights [Member]
Other acquired intangible assets, net:
Other acquired intangible assets, gross	8,600	8,600
Trade Names [Member]
Other acquired intangible assets, net:
Other acquired intangible assets, gross	5,940	5,940
Other Intangible Assets [Member]
Other acquired intangible assets, net:
Other acquired intangible assets, gross	8,697	8,717
Satellites, Net [Member]
Property and equipment, net:
Property and equipment	1,315,617	1,173,880
Less: accumulated depreciation and amortization	(301,184)	(275,683)
Property and equipment, net	1,014,433	898,197
Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	1,143,156	1,050,886
Less: accumulated depreciation and amortization	(618,001)	(563,976)
Property and equipment, net	525,155	486,910
Satellites [Member] | Satellites, Net [Member]
Property and equipment, net:
Property and equipment	559,094	559,094
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	657,433	515,696
Construction in Progress [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	96,684	73,535
Equipment and Software [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	620,745	568,663
CPE Leased Equipment [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	266,811	260,409
Less: accumulated depreciation and amortization	(148,800)	(136,400)
Furniture and Fixtures [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	29,879	25,501
Leasehold Improvements [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	78,154	71,895
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	$ 41,960	$ 41,960