Summary of Components of Other Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Sep. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Mar. 31, 2019
Goodwill [Line Items]
Other investments	$ 62,995	$ 39,041	$ 38,741	$ 43,434	$ 31,584	$ 24,584
Operating lease right of use asset (Note 10)	10,399		11,760
Cross currency swap (Note 6)			3,786
Other	5,640		7,664
Other assets	109,813		117,655
Shockwave Medical
Goodwill [Line Items]
Fair value of investment	$ 30,779		$ 55,704