Segment Information - Segment Revenues and Operating Profits (Losses) (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Revenues:
Total revenues	$ 656,683	$ 609,157	$ 1,228,117	$ 1,179,937
Operating profits (losses):
Income (loss) from operations	1,144	(24,418)	(57,363)	(38,683)
Amortization of acquired intangible assets	(7,379)	(7,399)	(14,902)	(13,328)
Product [Member]
Revenues:
Total revenues	254,861	221,055	424,106	426,697
Service [Member]
Revenues:
Total revenues	401,822	388,102	804,011	753,240
Operating Segments [Member]
Operating profits (losses):
Income (loss) from operations	8,523	(17,019)	(42,461)	(25,355)
Operating Segments [Member] | Satellite Services [Member]
Revenues:
Total revenues	300,547	300,110	612,647	574,227
Operating profits (losses):
Income (loss) from operations	(6,066)	14,313	(4,721)	24,255
Amortization of acquired intangible assets	(7,088)	(7,097)	(14,316)	(12,419)
Operating Segments [Member] | Satellite Services [Member] | Service [Member]
Revenues:
Total revenues	300,547	300,110	612,647	574,227
Operating Segments [Member] | Commercial Networks [Member]
Revenues:
Total revenues	180,027	134,806	292,811	253,402
Operating profits (losses):
Income (loss) from operations	(796)	(52,012)	(50,176)	(96,113)
Operating Segments [Member] | Commercial Networks [Member] | Product [Member]
Revenues:
Total revenues	159,831	118,935	253,406	220,466
Operating Segments [Member] | Commercial Networks [Member] | Service [Member]
Revenues:
Total revenues	20,196	15,871	39,405	32,936
Operating Segments [Member] | Government Systems [Member]
Revenues:
Total revenues	176,109	174,241	322,659	352,308
Operating profits (losses):
Income (loss) from operations	15,385	20,680	12,436	46,503
Amortization of acquired intangible assets	(291)	(302)	(586)	(909)
Operating Segments [Member] | Government Systems [Member] | Product [Member]
Revenues:
Total revenues	95,030	102,120	170,700	206,231
Operating Segments [Member] | Government Systems [Member] | Service [Member]
Revenues:
Total revenues	81,079	72,121	151,959	146,077
Material Reconciling Items [Member]
Operating profits (losses):
Amortization of acquired intangible assets	$ (7,379)	$ (7,399)	$ (14,902)	$ (13,328)