Summary of Significant Accounting Policies - Contract Balances from Contracts with Customers - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Aug. 31, 2023	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Feb. 28, 2023	Dec. 31, 2022	Feb. 28, 2022	Dec. 31, 2021
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Contract with customer liability		$ 63,904	$ 53,811	$ 63,904	$ 53,811		$ 50,211		$ 92,068
Revenue from contract with customer		113,425	15,375	246,447	67,615
Revenue recognized, previously deferred		3,929	7,337	9,534	43,961
Current portion of deferred revenue		37,186		37,186			13,856
Deferred revenue, net of current portion		26,718		26,718			$ 36,355
License and milestone fees
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer		51	7,382	15,122	45,247
Future Technological Improvements
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer				100
Hangzhou Zhongmei Huadong Pharmaceutical Co., Ltd | License and milestone fees
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue recognized, previously deferred					28,500
Hangzhou Zhongmei Huadong Pharmaceutical Co., Ltd | Upfront payment
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
License agreement upfront payment receivable			45,000		45,000
Lilly
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
License agreement upfront payment receivable								$ 13,000
Lilly | License and milestone fees
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer					13,800
Lilly | Upfront payment
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
License agreement upfront payment receivable			$ 19,500		19,500
KADCYLA | License and milestone fees
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue recognized, previously deferred					2,900
KADCYLA | Royalty revenue
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net proceeds from sale of residual rights to receive royalty payments				9,400
Revenue recognized, previously deferred					12,500
Novartis | License and milestone fees
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue recognized, previously deferred					$ 2,800
Vertex | License and milestone fees
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer				15,000
Vertex | Upfront payment
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
License agreement upfront payment receivable						$ 15,000
Revenue from contract with customer				15,000
Takeda
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer		0
Takeda | Upfront payment
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer	$ 23,200
Deferred revenue, net of current portion		$ 23,200		$ 23,200