Collaboration Agreements, License Agreement and Revenues - Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations along with Associated Deferred Revenue (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Astellas Agreement [Member] \| Japan [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	$ 116,977
Deferred Revenue	0
Total Consideration	116,977
Astellas Agreement [Member] \| Japan [Member] \| Development Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	16,630
Deferred Revenue	0
Total Consideration	16,630
Astellas Agreement [Member] \| Japan [Member] \| License Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	100,347
Deferred Revenue	0
Total Consideration	100,347
Astellas Agreement [Member] \| Europe [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	894,764
Deferred Revenue	0
Total Consideration	894,764
Astellas Agreement [Member] \| Europe [Member] \| Development Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	275,789
Deferred Revenue	0
Total Consideration	275,789
Astellas Agreement [Member] \| Europe [Member] \| License Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	618,975
Deferred Revenue	0
Total Consideration	618,975
AstraZeneca Agreements [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Deferred Revenue	171,238	$ 171,516
AstraZeneca Agreements [Member] \| U.S./RoW and China [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	1,002,573
Deferred Revenue	171,238
Total Consideration	1,173,811
AstraZeneca Agreements [Member] \| U.S./RoW and China [Member] \| License Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	341,844
Deferred Revenue	0
Total Consideration	341,844
AstraZeneca Agreements [Member] \| U.S./RoW and China [Member] \| Co-development, information sharing & committee services [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	608,938
Deferred Revenue	0
Total Consideration	608,938
AstraZeneca Agreements [Member] \| U.S./RoW and China [Member] \| China performance obligation [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	51,791
Deferred Revenue	171,238
Total Consideration	$ 223,029

Collaboration Agreements, License Agreement and Revenues - Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations along with Associated Deferred Revenue (Detail) - USD ($)
$ in Thousands