Summary of Unaudited Quarterly Results of Operations (Detail) - USD ($)
$ / shares in Units, $ in Thousands
 3 Months Ended 12 Months Ended
Mar. 31, 2020
Dec. 31, 2019
Sep. 30, 2019
Jun. 30, 2019
Mar. 31, 2019
Dec. 31, 2018
Sep. 30, 2018
Jun. 30, 2018
Mar. 31, 2020
Mar. 31, 2019
Mar. 31, 2018
Disclosure Unaudited Quarterly Financial Information [Abstract]                      
Revenue $ 206,658 $ 221,584 $ 204,974 $ 207,666 $ 207,081 $ 200,563 $ 181,778 $ 180,010 $ 840,883 $ 769,432 $ 593,749
Cost of revenue 39,369 39,996 34,867 37,073 34,848 34,023 29,846 30,850 151,305 129,567 98,581
Other operating expenses 109,237 111,329 109,925 109,868 106,844 104,185 101,612 102,412 440,359 415,053  
Other income (loss) (18,739) [1] 26,757 [1] (42,824) [1] 42,413 [1] 33,141 [1] 2,155 [1] 1,513 [1] 1,739 [1] 7,606 [1] 38,548 [1] 3,300
Income before income taxes 39,313 97,016 17,358 103,138 98,530 64,510 51,833 48,487 256,825 263,360 160,437
Income tax provision (benefit) 7,515 [2] 27,799 [2] 4,287 [2] 14,215 [2] 24,569 [2] 19,648 [2] 1,706 [2] (41,579) [2] 53,816 [2] 4,344 [2] 48,267
Net income $ 31,798 $ 69,217 $ 13,071 $ 88,923 $ 73,961 $ 44,862 $ 50,127 $ 90,066 $ 203,009 $ 259,016 $ 112,170
Basic net income per share $ 0.71 $ 1.53 $ 0.29 $ 1.97 $ 1.64 $ 1.00 $ 1.11 $ 2.02 $ 4.49 $ 5.77 $ 2.54
Diluted net income per share $ 0.70 $ 1.51 $ 0.28 $ 1.93 $ 1.60 $ 0.97 $ 1.09 $ 1.95 $ 4.43 $ 5.61 $ 2.45
[1]

 

(1)

In fiscal 2019, the Company invested $25.0 million in medical device company Shockwave Medical. The fair value of this investment as of March 31, 2020 was $55.7 million and the Company recognized a pre-tax loss of $0.5 million for the year ended March 31, 2020 and a pre-tax gain of $32.0 million for the year ended March 31, 2019 in other (expense) income, net.
[2]

 

(2)

The income tax provision for the years ended March 31, 2020 and 2019 included excess tax benefits of $14.8 million and $69.3 million, respectively. These recognized excess tax benefits resulted from restricted stock units that vested or stock options that were exercised during the years ended March 31, 2020 and 2019.