Summary of Components of Other Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019
Goodwill [Line Items]
Fair value of investment	$ 39,041	$ 38,741	$ 38,741	$ 31,584	$ 26,584	$ 24,584
Operating lease right of use asset (Note 8)	11,021		11,760
Cross currency swap (Note 6)			3,786
Other intangible assets and other assets	10,038		7,664
Total other assets	82,594		117,655
Shockwave Medical
Goodwill [Line Items]
Investment in Shockwave Medical	$ 22,494		$ 55,704