Goodwill and Acquired Intangible Assets - Allocation of Acquired Intangible Assets and Related Accumulated Amortization (Detail) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life	11 years
Other acquired intangible assets, gross	$ 2,879,053	$ 2,904,049
Other acquired intangible assets, accumulated amortization	(881,617)	(633,272)
Other acquired intangible assets, net	$ 1,997,436	2,270,777
Contracts and Customer Relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life	11 years
Other acquired intangible assets, gross	$ 1,432,934	1,432,562
Other acquired intangible assets, accumulated amortization	(413,945)	(280,309)
Other acquired intangible assets, net	$ 1,018,989	1,152,253
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	(263,600)	(173,600)
Other acquired intangible assets, net	$ 825,000	915,000
Technology [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life	7 years
Other acquired intangible assets, gross	$ 223,954	247,921
Other acquired intangible assets, accumulated amortization	(142,147)	(131,805)
Other acquired intangible assets, net	$ 81,807	116,116
Trade Names [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life	8 years
Other acquired intangible assets, gross	$ 114,570	116,949
Other acquired intangible assets, accumulated amortization	(50,811)	(38,453)
Other acquired intangible assets, net	$ 63,759	78,496
Other [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life	9 years
Other acquired intangible assets, gross	$ 18,995	18,017
Other acquired intangible assets, accumulated amortization	(11,114)	(9,105)
Other acquired intangible assets, net	$ 7,881	$ 8,912