Strategic Actions (Details) $ / shares in Units, shares in Thousands, $ in Thousands		1 Months Ended			3 Months Ended			9 Months Ended
	Feb. 27, 2023 USD ($)	Oct. 31, 2023 USD ($) $ / shares shares	Sep. 30, 2023 USD ($) shares	Mar. 31, 2023 ft²	Sep. 30, 2023 USD ($) $ / shares shares	Sep. 30, 2022 USD ($)		Sep. 30, 2023 USD ($) $ / shares shares		Sep. 30, 2022 USD ($)
Strategic Actions
Share repurchase authorized amount	$ 75,000
Share repurchase authorized amount			$ 325,000		$ 325,000	$ 250,000		$ 325,000		$ 250,000
Consideration for repurchase								$ 166,787		94,037
Share price (in dollars per share) | $ / shares					$ 9.70			$ 10.65
Aggregate costs					$ 30,800			$ 166,400
Repurchase of ordinary shares (in shares) | shares			294,600		3,180			15,620
Remaining repurchase amount			$ 30,400		$ 30,400			$ 30,400
Percent of Employee Reduction				17
Restructuring costs					$ 0	509	[1]	2,743	[1]	12,838	[1]
Net cash proceeds from sale of R&D laboratory equipment								1,513		1,866
Research and Development Laboratory Equipment
Strategic Actions
R&D laboratory equipment carrying value								2,700
Net cash proceeds from sale of R&D laboratory equipment								1,500
Office and Laboratory Space, South San Francisco
Strategic Actions
Area of land in sublease | ft²				42,000
Severance
Strategic Actions
Employee-related separation costs								2,700		12,800
Cash charges related to modification of equity-awards for terminated and remaining employee								1,200		5,800
Non-cash charges related to modification of equity-awards for terminated and remaining employee								1,500		7,000
Selling, general and administrative
Strategic Actions
Restructuring costs						400				6,900
Research and development
Strategic Actions
Restructuring costs						$ 100		$ 2,700		$ 5,900
Subsequent Event [Member]
Strategic Actions
Share price (in dollars per share) | $ / shares		$ 9.09
Aggregate costs		$ 9,300
Repurchase of ordinary shares (in shares) | shares		1,020
Remaining repurchase amount		$ 21,100

[1] Amounts include share-based compensation expense as follows: