Goodwill In-Process Research and Development and Other Assets - Additional Information (Detail)	1 Months Ended	6 Months Ended
	Sep. 30, 2018 USD ($)	Sep. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)
Goodwill [Line Items]
Goodwill	$ 33,719,000	$ 33,719,000	$ 35,808,000
Accumulated impairment loss, goodwill	0	0
In-process research and development	15,730,000	15,730,000	16,705,000
Aggregate carrying amount of other investments	22,300,000	22,300,000	12,600,000
Other additional Investments in private medical device company		9,600,000
Manufacturing Rights and Knowledge
Goodwill [Line Items]
Milestone Payment	1,800,000
ECP Entwicklungsgesellschaft mbH
Goodwill [Line Items]
In-process research and development	$ 15,700,000	$ 15,700,000	$ 16,700,000
ECP Entwicklungsgesellschaft mbH | Discount Rate
Goodwill [Line Items]
Fair value measurement inputs	21	21