Net Income Per Share - Schedule of Weighted-Average Shares Used for Net Income per Share Footnotes (Detail) - USD ($) $ / shares in Units, $ in Thousands	Jul. 31, 2021	Jan. 30, 2021	Sep. 30, 2019	Jun. 30, 2018
Convertible senior notes due 2020
Earnings Per Share Diluted
Principal	$ 300,000
Convertible senior notes due 2020 | Common Stock
Earnings Per Share Diluted
Conversion price per share	$ 118.13
Convertible senior notes due 2020 | Warrant
Earnings Per Share Diluted
Conversion price per share	$ 189.00
Convertible senior notes due 2023
Earnings Per Share Diluted
Principal	$ 301,819	$ 335,000		$ 335,000
Convertible senior notes due 2023 | Common Stock
Earnings Per Share Diluted
Conversion price per share	$ 193.65			$ 193.65
Convertible senior notes due 2023 | Warrant
Earnings Per Share Diluted
Conversion price per share	$ 309.84
Convertible senior notes due 2024
Earnings Per Share Diluted
Principal	$ 350,000	$ 350,000	$ 350,000
Convertible senior notes due 2024 | Common Stock
Earnings Per Share Diluted
Conversion price per share	$ 211.40		$ 211.40
Convertible senior notes due 2024 | Warrant
Earnings Per Share Diluted
Conversion price per share	$ 338.24