Revenue Recognition - Schedule of Disaggregated Revenue by Major Business Line (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation Of Revenue [Table]
Total revenue	$ 209,764	$ 204,974	$ 374,614	$ 412,640
U.S.
Disaggregation Of Revenue [Table]
Total revenue	172,147	172,015	306,872	347,500
International
Disaggregation Of Revenue [Table]
Total revenue	37,617	32,959	67,742	65,140
Impella Product
Disaggregation Of Revenue [Table]
Total revenue	199,676	196,939	355,093	396,804
Service and Other
Disaggregation Of Revenue [Table]
Total revenue	$ 10,088	$ 8,035	$ 19,521	$ 15,836