v3.26.1
The Company and a Summary of Its Significant Accounting Policies - Summary of Disaggregation of Revenue by Segment and Products and Services (Detail) - USD ($)
$ in Thousands
 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Disaggregation Of Revenue [Line Items]      
Total revenues $ 4,640,280 $ 4,519,571 $ 4,283,758
Product [Member]      
Disaggregation Of Revenue [Line Items]      
Total revenues 1,365,857 1,293,795 1,279,164
Service [Member]      
Disaggregation Of Revenue [Line Items]      
Total revenues 3,274,423 3,225,776 3,004,594
Operating Segments [Member] | Communication Services [Member]      
Disaggregation Of Revenue [Line Items]      
Total revenues 3,299,651 3,298,485 3,141,540
Operating Segments [Member] | Communication Services [Member] | Product [Member]      
Disaggregation Of Revenue [Line Items]      
Total revenues 242,428 276,139 343,028
Operating Segments [Member] | Communication Services [Member] | Service [Member]      
Disaggregation Of Revenue [Line Items]      
Total revenues 3,057,223 3,022,346 2,798,512
Operating Segments [Member] | Defense and Advanced Technologies [Member]      
Disaggregation Of Revenue [Line Items]      
Total revenues 1,340,629 1,221,086 1,142,218
Operating Segments [Member] | Defense and Advanced Technologies [Member] | Product [Member]      
Disaggregation Of Revenue [Line Items]      
Total revenues 1,123,429 1,017,656 936,136
Operating Segments [Member] | Defense and Advanced Technologies [Member] | Service [Member]      
Disaggregation Of Revenue [Line Items]      
Total revenues $ 217,200 $ 203,430 $ 206,082