Basis of Presentation - Summary of Disaggregation of Revenue by Segment and Products and Services (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2024	Dec. 31, 2023
Disaggregation Of Revenue [Line Items]
Total revenues	$ 1,123,767	$ 1,128,539	$ 3,372,489	$ 3,133,745
Product [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	314,397	303,073	944,084	941,174
Service [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	809,370	825,466	2,428,405	2,192,571
Operating Segments [Member] | Communication Services [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	820,347	874,858	2,473,519	2,281,675
Operating Segments [Member] | Communication Services [Member] | Product [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	61,362	102,489	200,029	244,771
Operating Segments [Member] | Communication Services [Member] | Service [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	758,985	772,369	2,273,490	2,036,904
Operating Segments [Member] | Defense and Advanced Technologies [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	303,420	253,681	898,970	852,070
Operating Segments [Member] | Defense and Advanced Technologies [Member] | Product [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	253,035	200,584	744,055	696,403
Operating Segments [Member] | Defense and Advanced Technologies [Member] | Service [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	$ 50,385	$ 53,097	$ 154,915	$ 155,667