Composition of Certain Balance Sheet Captions - Composition of Certain Balance Sheet Captions (Detail) - USD ($) $ in Thousands	Sep. 30, 2024	Mar. 31, 2024	Sep. 30, 2023
Accounts receivable, net:
Accounts receivable, Billed	$ 554,229	$ 545,081
Accounts receivable, Unbilled	189,040	156,322
Allowance for doubtful accounts	(26,019)	(23,193)
Accounts receivable, net	717,250	678,210
Inventories:
Raw materials	113,526	89,778
Work in process	23,090	31,884
Finished goods	190,392	196,216
Inventories	327,008	317,878
Prepaid expenses and other current assets:
Insurance receivable	64,000	261,500
Prepaid expenses	249,562	185,892
Other	173,497	134,391
Prepaid expenses and other current assets	487,059	581,783
Property, equipment and satellites, net:
Property, equipment and satellites, gross	11,063,641	10,651,781
Less: accumulated depreciation and amortization	(3,577,296)	(3,094,575)
Property and equipment, net	7,486,345	7,557,206
Other acquired intangible assets, net:
Other acquired intangible assets, gross	2,916,679	2,917,299
Less: accumulated amortization	(505,827)	(372,832)
Other acquired intangible assets, net	2,410,852	2,544,467
Other assets:
Deferred income taxes	162,123	163,590
Capitalized software costs, net	248,970	240,597
Patents, orbital slots and other licenses, net	117,132	112,535
Other	231,436	217,225
Other assets	759,661	733,947
Accrued and other liabilities:
Collections in excess of revenues and deferred revenues	294,388	260,264
Accrued employee compensation	131,860	177,854
Accrued vacation	48,993	48,636
Operating lease liabilities	$ 69,174	$ 71,561
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Accrued and other liabilities	Accrued and other liabilities
Interest payable	$ 113,147	$ 127,098
Other	241,353	265,208
Accrued and other liabilities	898,915	950,621
Other liabilities:
Deferred revenues, long-term portion	859,783	896,402
Deferred income taxes, long-term	1,222,982	1,228,270
Other	322,978	327,428
Other liabilities	2,405,743	2,452,100
Contracts and Customer Relationships [Member]
Other acquired intangible assets, net:
Other acquired intangible assets, gross	1,438,162	1,437,738
Orbital Slots And Spectrum Assets [Member]
Other acquired intangible assets, net:
Other acquired intangible assets, gross	1,088,600	1,088,600
Technology [Member]
Other acquired intangible assets, net:
Other acquired intangible assets, gross	250,791	251,889
Trade Name [Member]
Other acquired intangible assets, net:
Other acquired intangible assets, gross	117,086	117,280
Other [Member]
Other acquired intangible assets, net:
Other acquired intangible assets, gross	22,040	21,792
Satellites [Member]
Prepaid expenses and other current assets:
Insurance receivable			$ 770,000
Property, equipment and satellites, net:
Property, equipment and satellites, gross	3,407,736	3,324,458
Satellites under Construction [Member]
Property, equipment and satellites, net:
Property, equipment and satellites, gross	2,084,077	1,976,469
Equipment and Software [Member]
Property, equipment and satellites, net:
Property, equipment and satellites, gross	3,586,067	2,992,325
CPE Leased Equipment [Member]
Property, equipment and satellites, net:
Property, equipment and satellites, cost	540,784	567,548
Satellite Ka-band Capacity Obtained under Finance Leases [Member]
Property, equipment and satellites, net:
Property, equipment and satellites, gross	177,576	177,576
Furniture and Fixtures [Member]
Property, equipment and satellites, net:
Property, equipment and satellites, gross	65,426	65,433
Leasehold Improvements [Member]
Property, equipment and satellites, net:
Property, equipment and satellites, gross	284,406	209,162
Buildings [Member]
Property, equipment and satellites, net:
Property, equipment and satellites, gross	16,725	16,647
Land [Member]
Property, equipment and satellites, net:
Property, equipment and satellites, gross	20,857	20,787
Construction in Progress [Member]
Property, equipment and satellites, net:
Property, equipment and satellites, gross	$ 879,987	$ 1,301,376