Segment Information - Segment Revenues, Expenses and Operating Profits (Losses) (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Revenues:
Total revenues		$ 1,140,893	$ 1,122,262	$ 2,311,947	$ 2,248,722
Operating Expenses [Abstract]
Depreciation				510,371	522,601
Stock-based compensation expense				34,829	41,965
Total expenses		1,040,049	1,080,916	2,098,690	2,081,426
Operating profits (losses):
Amortization of acquired intangible assets		(65,069)	(66,024)	(130,810)	(132,239)
Interest income		12,525	23,896	26,815	46,688
Interest expense		(93,487)	(115,340)	(193,844)	(221,116)
(Loss) gain on extinguishment of debt, net			(3,200)	(288)	(3,200)
Other income (expense), net				(5,164)
Income (loss) before income taxes		(45,187)	(119,322)	(90,034)	(142,571)
Income (loss) from operations		35,775	(24,678)	82,447	35,057
Product [Member]
Revenues:
Total revenues		319,383	323,948	664,067	629,687
Service [Member]
Revenues:
Total revenues		821,510	798,314	1,647,880	1,619,035
Operating Segments [Member]
Operating profits (losses):
Income (loss) from operations		100,844	41,346	213,257	167,296
Operating Segments [Member] | Communication Services [Member]
Revenues:
Total revenues		836,655	826,385	1,664,026	1,653,172
Operating Expenses [Abstract]
Depreciation		240,219	261,070	486,968	499,463
Stock-based compensation expense		12,490	13,483	20,802	25,578
Other than acquired intangible assets amortization	[1]	4,739	10,969	18,748	21,709
Acquisition and transaction related expenses		3,480	29,685	11,354	31,471
Other segment items	[2]	504,342	511,645	1,013,893	1,033,479
Total expenses	[3]	765,270	826,852	1,551,765	1,611,700
Operating profits (losses):
Income (loss) from operations		71,385	(467)	112,261	41,472
Operating Segments [Member] | Communication Services [Member] | Government Satcom Services [Member]
Revenues:
Total revenues		195,800	179,875	387,568	363,748
Operating Segments [Member] | Communication Services [Member] | Aviation Services [Member]
Revenues:
Total revenues		300,732	261,987	593,624	519,142
Operating Segments [Member] | Communication Services [Member] | Maritime Services [Member]
Revenues:
Total revenues		117,594	121,179	235,395	245,126
Operating Segments [Member] | Communication Services [Member] | Fixed Services and Other Services [Member]
Revenues:
Total revenues		155,691	184,853	330,428	386,489
Operating Segments [Member] | Communication Services [Member] | Product [Member]
Revenues:
Total revenues		66,838	78,491	117,011	138,667
Operating Segments [Member] | Communication Services [Member] | Service [Member]
Revenues:
Total revenues		769,817	747,894	1,547,015	1,514,505
Operating Segments [Member] | Defense and Advanced Technologies [Member]
Revenues:
Total revenues		304,238	295,877	647,921	595,550
Operating Expenses [Abstract]
Depreciation		12,451	11,731	23,403	23,138
Stock-based compensation expense		7,632	9,300	14,027	16,387
Other than acquired intangible assets amortization	[1]	6,650	4,872	11,543	9,321
Acquisition and transaction related expenses		1,600	4,865	3,451	5,380
Other segment items	[2]	246,446	223,296	494,501	415,500
Total expenses	[3]	274,779	254,064	546,925	469,726
Operating profits (losses):
Income (loss) from operations		29,459	41,813	100,996	125,824
Operating Segments [Member] | Defense and Advanced Technologies [Member] | Information Security and Cyber Defense Products [Member]
Revenues:
Total revenues		94,928	83,548	197,076	139,055
Operating Segments [Member] | Defense and Advanced Technologies [Member] | Space and Mission Systems Products [Member]
Revenues:
Total revenues		78,231	78,782	166,204	152,088
Operating Segments [Member] | Defense and Advanced Technologies [Member] | Tactical Networking Products [Member]
Revenues:
Total revenues		74,193	80,034	142,472	151,444
Operating Segments [Member] | Defense and Advanced Technologies [Member] | Advanced Technologies and Other Products [Member]
Revenues:
Total revenues		5,193	3,093	41,304	48,433
Operating Segments [Member] | Defense and Advanced Technologies [Member] | Product [Member]
Revenues:
Total revenues		252,545	245,457	547,056	491,020
Operating Segments [Member] | Defense and Advanced Technologies [Member] | Service [Member]
Revenues:
Total revenues		51,693	50,420	100,865	104,530
Corporate, Non-Segment [Member]
Operating profits (losses):
Amortization of acquired intangible assets		(65,069)	(66,024)	(130,810)	(132,239)
Interest income		12,525	23,896	26,815	46,688
Interest expense		$ (93,487)	(115,340)	(193,844)	(221,116)
(Loss) gain on extinguishment of debt, net			(3,200)	(288)	(3,200)
Other income (expense), net			$ 0	$ (5,164)	$ 0

[1] Including amortization of capitalized cloud computing implementation costs.

[2] 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.

[3] For the three and six months ended September 30, 2025, IR&D expense and related activities, including allocable depreciation, stock-based compensation and other expenses were $21.7 million and $40.8 million, respectively, for the communication services segment, and $20.6 million and $35.6 million, respectively, for the defense and advanced technologies segment. For the three and six months ended September 30, 2024, IR&D expense and related activities, including allocable depreciation, stock-based compensation and other expenses were $19.7 million and $45.5 million, respectively, for the communication services segment, and $13.7 million and $26.5 million, respectively, for the defense and advanced technologies segment.