Segment Information - Segment Revenues, Expenses and Operating Profits (Losses) (Parenthetical) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Mar. 31, 2023
Segment Reporting Information [Line Items]
Independent research and development	$ 142,394	$ 150,653	$ 128,923
Communication Services [Member]
Segment Reporting Information [Line Items]
Independent research and development	83,400	105,000	99,500
Defense and Advanced Technologies [Member]
Segment Reporting Information [Line Items]
Independent research and development	$ 59,000	$ 45,700	$ 29,400