Composition of Certain Balance Sheet Captions - Composition of Certain Balance Sheet Captions (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Mar. 31, 2016
Accounts receivable, net:
Accounts receivable, Billed	$ 126,592	$ 146,309
Accounts receivable, Unbilled	129,724	141,568
Allowance for doubtful accounts	(1,557)	(1,153)
Accounts receivable, net	254,759	286,724
Inventories:
Raw materials	53,756	46,757
Work in process	28,113	27,200
Finished goods	76,591	71,204
Inventories	158,460	145,161
Prepaid expenses and other current assets:
Prepaid expenses	49,589	41,784
Other	3,973	5,799
Prepaid expenses and other current assets	53,562	47,583
Other acquired intangible assets, net:
Other acquired intangible assets, gross	214,586	197,604
Less: accumulated amortization	(170,034)	(164,000)
Other acquired intangible assets, net	44,552	33,604
Other assets:
Deferred income taxes	131,808	134,721
Capitalized software costs, net	196,620	163,061
Patents, orbital slots and other licenses, net	16,600	16,900
Other	35,314	25,323
Other assets	380,342	340,005
Accrued liabilities:
Collections in excess of revenues and deferred revenues	84,430	64,624
Accrued employee compensation	39,206	35,056
Accrued vacation	29,952	28,646
Warranty reserve, current portion	7,859	7,867
Current portion of other long-term debt	284	274
Other	37,339	47,877
Accrued liabilities	199,070	184,344
Other liabilities:
Deferred revenue, long-term portion	5,123	5,470
Deferred rent, long-term portion	10,387	8,808
Warranty reserve, long-term portion	3,644	3,567
Satellite performance incentives obligation, long-term portion	19,372	19,514
Deferred income taxes, long-term	2,213	12
Other liabilities	40,739	37,371
Technology-Based Intangible Assets [Member]
Other acquired intangible assets, net:
Other acquired intangible assets, gross	87,214	74,848
Contracts and Customer Relationships [Member]
Other acquired intangible assets, net:
Other acquired intangible assets, gross	102,937	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	9,895	8,717
Satellites, Net [Member]
Property and equipment, net:
Property and equipment	1,355,169	1,173,880
Less: accumulated depreciation and amortization	(314,007)	(275,683)
Property and equipment, net	1,041,162	898,197
Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	1,179,608	1,050,886
Less: accumulated depreciation and amortization	(633,933)	(563,976)
Property and equipment, net	545,675	486,910
Satellites [Member] | Satellites, Net [Member]
Property and equipment, net:
Property and equipment	559,380	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	696,699	515,696
Construction in Progress [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	99,976	73,535
Equipment and Software [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	650,307	568,663
CPE Leased Equipment [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	268,742	260,409
Less: accumulated depreciation and amortization	(153,400)	(136,400)
Furniture and Fixtures [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	29,767	25,501
Leasehold Improvements [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	79,823	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	$ 42,070	$ 41,960