Goodwill, In-Process Research and Development and Other Assets - Additional Information (Detail)	3 Months Ended
	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2020 USD ($)
Goodwill [Line Items]
Goodwill	$ 76,783,000		$ 31,969,000
Accumulated impairment loss, goodwill	0
In-process research and development	42,223,000		14,913,000
Accumulated impairment losses on IPR&D assets	0
License Manufacturing Rghts to Technology
Goodwill [Line Items]
Payments to third party	$ 4,100,000
Other Intangible Assets
Goodwill [Line Items]
Intangible asset, amortized useful life	15 years
Shockwave Medical
Goodwill [Line Items]
Investment in Shockwave Medical	$ 79,527,000		55,704,000
Shockwave Medical | Other Income (Expense)
Goodwill [Line Items]
Gain (loss) recorded in other income (expense)	23,800,000	$ 39,700,000
ECP Entwicklungsgesellschaft mbH
Goodwill [Line Items]
In-process research and development	$ 42,200,000		$ 14,900,000
ECP Entwicklungsgesellschaft mbH | Measurement Input, Discount Rate | Maximum
Goodwill [Line Items]
Fair value inputs, discount rate	0.21
ECP Entwicklungsgesellschaft mbH | Measurement Input, Discount Rate | Minimum [Member]
Goodwill [Line Items]
Fair value inputs, discount rate	0.15