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, 2025	Dec. 31, 2024	Dec. 31, 2025	Dec. 31, 2024
Disaggregation Of Revenue [Line Items]
Total revenues	$ 1,157,045	$ 1,123,767	$ 3,468,992	$ 3,372,489
Service [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	822,818	809,370	2,470,698	2,428,405
Product [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	334,227	314,397	998,294	944,084
Operating Segments [Member] | Communication Services [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	825,342	820,347	2,489,368	2,473,519
Operating Segments [Member] | Communication Services [Member] | Service [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	765,576	758,985	2,312,591	2,273,490
Operating Segments [Member] | Communication Services [Member] | Product [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	59,766	61,362	176,777	200,029
Operating Segments [Member] | Defense and Advanced Technologies [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	331,703	303,420	979,624	898,970
Operating Segments [Member] | Defense and Advanced Technologies [Member] | Service [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	57,242	50,385	158,107	154,915
Operating Segments [Member] | Defense and Advanced Technologies [Member] | Product [Member]
Disaggregation Of Revenue [Line Items]
Total revenues	$ 274,461	$ 253,035	$ 821,517	$ 744,055