Goodwill, In-Process Research and Development and Other Assets - Additional Information (Detail) - USD ($)	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Goodwill [Line Items]
Goodwill	$ 31,969,000	$ 32,601,000	$ 35,808,000
Accumulated impairment loss, goodwill	0
In-process research and development	14,913,000	15,208,000	16,705,000
Impairment on Other Investments	4,700,000
License Manufacturing Rights to Technology
Goodwill [Line Items]
Payments to third party	4,100,000
Amortization of intangible assets	$ 200,000	200,000	$ 0
Other Intangible Assets
Goodwill [Line Items]
Intangible asset, amortized useful life	15 years
Shockwave Medical
Goodwill [Line Items]
Investment in affiliate		25,000,000.0
Fair value of investment	$ 55,704,000	56,195,000
Shockwave Medical | Other Income (Expense)
Goodwill [Line Items]
Gain (loss) recorded in other income (expense)	(500,000)	31,200,000
ECP Entwicklungsgesellschaft mbH
Goodwill [Line Items]
In-process research and development	$ 14,900,000	$ 15,200,000