Goodwill and Acquired Intangible Assets - Allocation of Other Acquired Intangible Assets and Related Accumulated Amortization (Detail) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life	11 years
Other acquired intangible assets, gross	$ 2,904,049	$ 2,917,299
Other acquired intangible assets, accumulated amortization	(633,272)	(372,832)
Other acquired intangible assets, net	$ 2,270,777	2,544,467
Contracts and Customer Relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life	11 years
Other acquired intangible assets, gross	$ 1,432,562	1,437,738
Other acquired intangible assets, accumulated amortization	(280,309)	(148,271)
Other acquired intangible assets, net	$ 1,152,253	1,289,467
Orbital Slots And Spectrum Assets [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life	12 years
Other acquired intangible assets, gross	$ 1,088,600	1,088,600
Other acquired intangible assets, accumulated amortization	(173,600)	(83,600)
Other acquired intangible assets, net	$ 915,000	1,005,000
Technology [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life	7 years
Other acquired intangible assets, gross	$ 247,921	251,889
Other acquired intangible assets, accumulated amortization	(131,805)	(108,414)
Other acquired intangible assets, net	$ 116,116	143,475
Trade Names [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life	8 years
Other acquired intangible assets, gross	$ 116,949	117,280
Other acquired intangible assets, accumulated amortization	(38,453)	(24,770)
Other acquired intangible assets, net	$ 78,496	92,510
Other [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life	9 years
Other acquired intangible assets, gross	$ 18,017	21,792
Other acquired intangible assets, accumulated amortization	(9,105)	(7,777)
Other acquired intangible assets, net	$ 8,912	$ 14,015