Composition of Certain Balance Sheet Captions - Composition of Certain Balance Sheet Captions (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Mar. 31, 2016
Accounts receivable, net:
Accounts receivable, Billed	$ 145,626	$ 146,309
Accounts receivable, Unbilled	119,565	141,568
Allowance for doubtful accounts	(1,470)	(1,153)
Accounts receivable, net	263,721	286,724
Inventories:
Raw materials	56,096	46,757
Work in process	25,820	27,200
Finished goods	81,285	71,204
Inventories	163,201	145,161
Prepaid expenses and other current assets:
Prepaid expenses	51,856	41,784
Other	5,980	5,799
Prepaid expenses and other current assets	57,836	47,583
Other assets:
Investment in unconsolidated affiliate	141,894
Deferred income taxes	134,764	134,721
Capitalized software costs, net	203,686	163,061
Patents, orbital slots and other licenses, net	16,500	16,900
Other	32,522	25,323
Other assets	529,366	340,005
Accrued liabilities:
Collections in excess of revenues and deferred revenues	76,682	64,624
Accrued employee compensation	41,691	35,056
Accrued vacation	33,214	28,646
Warranty reserve, current portion	7,796	7,867
Current portion of other long-term debt	288	274
Other	65,576	47,877
Accrued liabilities	225,247	184,344
Other liabilities:
Deferred revenue, long-term portion	4,617	5,470
Deferred rent, long-term portion	10,743	8,808
Warranty reserve, long-term portion	3,262	3,567
Satellite performance incentives obligation, long-term portion	19,164	19,514
Deferred income taxes, long-term	1,936	12
Other	3,000
Other liabilities	42,722	37,371
Satellites, Net [Member]
Property and equipment, net:
Property and equipment	1,434,824	1,173,880
Less accumulated depreciation and amortization	(326,554)	(275,683)
Property and equipment, net	1,108,270	898,197
Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	1,202,589	1,050,886
Less accumulated depreciation and amortization	(661,981)	(563,976)
Property and equipment, net	540,608	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	776,354	515,696
Construction in Progress [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	116,902	73,535
Equipment and Software [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	679,008	568,663
CPE Leased Equipment [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	271,917	260,409
Less accumulated depreciation and amortization	(158,200)	(136,400)
Furniture and Fixtures [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	30,539	25,501
Leasehold Improvements [Member] | Property and Equipment, Net [Member]
Property and equipment, net:
Property and equipment	80,727	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	$ 14,573	$ 41,960