Commitments and Contingencies - Additional Information (Detail) - USD ($) $ / shares in Units, shares in Millions				6 Months Ended
	Jul. 28, 2020	Mar. 02, 2020	Jan. 29, 2019	Jun. 30, 2020	Sep. 30, 2021	Nov. 30, 2020
Commitments And Contingencies Disclosure [Line Items]
License agreement, expected milestone payment				$ 187,500,000
Percentage of unpaid portion of milestone payments interest rate				6.25%
Owe a success-based legal fee to the company?s legal counsel				$ 3,000,000.0
Hsingching Hsu
Commitments And Contingencies Disclosure [Line Items]
Accrued estimated losses				9,100,000
Loss contingency damages awarded percent of total claim			5.00%
Loss contingency claimed damages awarded per share			$ 87.20
Number of shares traded to claim damages			10
Legal fee, liability				0
Hsingching Hsu | Minimum
Commitments And Contingencies Disclosure [Line Items]
Percentage of stockholders sufficient to recover damages			20.00%
Amount of damages after claims			$ 9,000,000.0
Hsingching Hsu | Maximum
Commitments And Contingencies Disclosure [Line Items]
Damages awarded per share			$ 4.50
Percentage of stockholders sufficient to recover damages			40.00%
Amount of damages after claims			$ 18,000,000.0
Eshelman v. Puma Biotechnology, Inc.
Commitments And Contingencies Disclosure [Line Items]
Accrued estimated losses				22,400,000
Attorneys fees		$ 3,000,000
Total judgment value		$ 26,300,000
Stand-by letter of credit, amount				8,900,000
Eshelman v. Puma Biotechnology, Inc. | Compensatory
Commitments And Contingencies Disclosure [Line Items]
Damages awarded, value				15,900,000
Eshelman v. Puma Biotechnology, Inc. | Punitive
Commitments And Contingencies Disclosure [Line Items]
Damages awarded, value				6,500,000
Eshelman v. Puma Biotechnology, Inc. | Maximum
Commitments And Contingencies Disclosure [Line Items]
Amount of damages after claims				$ 27,200,000
CANbridge Life Sciences | Subsequent Event
Commitments And Contingencies Disclosure [Line Items]
Arbitration filed date	July 28, 2020
Forecast
Commitments And Contingencies Disclosure [Line Items]
License agreement, installment milestone payment					$ 21,900,000	$ 10,400,000