Segment Information - Segment Revenues, Expenses and Operating Profits (Losses) (Detail) - USD ($) $ in Thousands		12 Months Ended
		Mar. 31, 2025	Mar. 31, 2024	Mar. 31, 2023
Revenues:
Total revenues		$ 4,519,571	$ 4,283,758	$ 2,556,158
Expenses:
Depreciation		1,036,467	867,641	409,564
Stock-based compensation expense		80,385	83,631	84,459
Total expenses		4,353,118	4,946,399	2,682,303
Operating profits (losses):
Income (loss) from operations		(97,480)	(889,806)	(155,956)
Amortization of acquired intangible assets		(263,933)	(227,165)	(29,811)
Interest income		83,920	96,258	19,512
Interest expense		(421,944)	(400,398)	(26,809)
(Loss) gain on extinguishment of debt, net		(99,814)
Other income (expense), net		(9,976)		1,098
Income (loss) from continuing operations before income taxes		(545,294)	(1,193,946)	(162,155)
Product [Member]
Revenues:
Total revenues		1,293,795	1,279,164	954,126
Service [Member]
Revenues:
Total revenues		3,225,776	3,004,594	1,602,032
Operating Segments [Member]
Operating profits (losses):
Income (loss) from operations		166,453	(662,641)	(126,145)
Operating Segments [Member] | Communication Services [Member]
Revenues:
Total revenues		3,298,485	3,141,540	1,704,775
Expenses:
Depreciation		988,447	825,788	350,954
Stock-based compensation expense		48,760	52,662	51,578
Other than acquired intangibles amortization		41,373	50,718	49,058
Acquisition and transaction related expenses		50,807	114,113	53,285
Other segment items	[1]	2,049,920	2,009,817	1,389,302
Total expenses	[2]	3,348,707	3,958,594	1,894,177
Operating profits (losses):
Income (loss) from operations		(50,222)	(817,054)	(189,402)
Operating Segments [Member] | Communication Services [Member] | Product [Member]
Revenues:
Total revenues		276,139	343,028	269,126
Operating Segments [Member] | Communication Services [Member] | Service [Member]
Revenues:
Total revenues		3,022,346	2,798,512	1,435,649
Operating Segments [Member] | Communication Services [Member] | Fixed services and other services [Member]
Revenues:
Total revenues		741,601	906,762	919,440
Operating Segments [Member] | Communication Services [Member] | Aviation Services [Member]
Revenues:
Total revenues		1,048,225	864,834	346,950
Operating Segments [Member] | Communication Services [Member] | Government Satcom Services [Member]
Revenues:
Total revenues		754,552	596,826	165,897
Operating Segments [Member] | Communication Services [Member] | Maritime Services [Member]
Revenues:
Total revenues		477,968	430,090	3,362
Operating Segments [Member] | Communication Services [Member] | Ground Network and Satellite [Member]
Expenses:
Ground network (FY25), satellite (FY24) impairment and related charges, net		169,400	905,496
Operating Segments [Member] | Defense and Advanced Technologies [Member]
Revenues:
Total revenues		1,221,086	1,142,218	851,383
Expenses:
Depreciation		48,020	41,853	52,701
Stock-based compensation expense		31,625	30,969	30,534
Other than acquired intangibles amortization		19,034	12,000	11,047
Acquisition and transaction related expenses		13,660	43,466	33,011
Other segment items	[1]	892,072	859,517	660,833
Total expenses	[2]	1,004,411	987,805	788,126
Operating profits (losses):
Income (loss) from operations		216,675	154,413	63,257
Operating Segments [Member] | Defense and Advanced Technologies [Member] | Product [Member]
Revenues:
Total revenues		1,017,656	936,136	685,000
Operating Segments [Member] | Defense and Advanced Technologies [Member] | Service [Member]
Revenues:
Total revenues		203,430	206,082	166,383
Operating Segments [Member] | Defense and Advanced Technologies [Member] | Advanced Technologies and Other Products [Member]
Revenues:
Total revenues		67,770	122,733	65,024
Operating Segments [Member] | Defense and Advanced Technologies [Member] | Information Security and Cyber Defense Products [Member]
Revenues:
Total revenues		325,439	302,056	181,591
Operating Segments [Member] | Defense and Advanced Technologies [Member] | Space and Mission Systems Products [Member]
Revenues:
Total revenues		304,870	309,253	259,286
Operating Segments [Member] | Defense and Advanced Technologies [Member] | Tactical Networking Products [Member]
Revenues:
Total revenues		319,577	202,094	179,099
Corporate, Non-Segment [Member]
Operating profits (losses):
Amortization of acquired intangible assets		(263,933)	(227,165)	(29,811)
Interest income		83,920	96,258	19,512
Interest expense		(421,944)	$ (400,398)	(26,809)
(Loss) gain on extinguishment of debt, net		(99,814)
Other income (expense), net		$ (9,976)		$ 1,098

[1] Other segment items include operating expenses such as cost of service and product revenues, selling, general and administrative expenses, IR&D expenses and related activities excluding allocable portion of depreciation, other than acquired intangibles amortization, stock-based compensation, and certain significant items that are disclosed under each segment.

[2] For fiscal years 2025, 2024, and 2023, IR&D expense and related activities, including allocable depreciation, stock-based compensation and other expenses were $83.4 million, $105.0 million and $99.5 million, respectively, for the communication services segment, and $59.0 million, $45.7 million and $29.4 million, respectively, for the defense and advanced technologies segment.