Basis of Presentation - Summary of Disaggregation of Revenue by Segment and Products and Services (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Disaggregation Of Revenue [Line Items]
Total revenues	$ 1,140,893	$ 1,122,262	$ 2,311,947	$ 2,248,722
Service [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	821,510	798,314	1,647,880	1,619,035
Product [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	319,383	323,948	664,067	629,687
Operating Segments [Member] | Communication Services [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	836,655	826,385	1,664,026	1,653,172
Operating Segments [Member] | Communication Services [Member] | Service [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	769,817	747,894	1,547,015	1,514,505
Operating Segments [Member] | Communication Services [Member] | Product [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	66,838	78,491	117,011	138,667
Operating Segments [Member] | Defense and Advanced Technologies [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	304,238	295,877	647,921	595,550
Operating Segments [Member] | Defense and Advanced Technologies [Member] | Service [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	51,693	50,420	100,865	104,530
Operating Segments [Member] | Defense and Advanced Technologies [Member] | Product [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	$ 252,545	$ 245,457	$ 547,056	$ 491,020