Certain Transactions - Other Transactions - Additional Information (Detail) - USD ($) $ in Millions			1 Months Ended			3 Months Ended				9 Months Ended	12 Months Ended
	Jan. 08, 2018	May 12, 2017	Oct. 31, 2021	Aug. 31, 2021	Sep. 30, 2016	Sep. 30, 2021	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2016	Sep. 30, 2021	Dec. 31, 2018	Dec. 31, 2017
Alder [Member]
Noncash or Part Noncash Acquisitions [Line Items]
Upfront payment	$ 25
Milestone payment								$ 25
Collaborative agreement milestone payments	$ 150
Otsuka [Member]
Noncash or Part Noncash Acquisitions [Line Items]
Upfront payment		$ 50
Milestone payment						$ 35	$ 15
Celltrion [Member]
Noncash or Part Noncash Acquisitions [Line Items]
Refundable payment						60				$ 60
Total associated cost						$ 160				160
Regeneron [Member]
Noncash or Part Noncash Acquisitions [Line Items]
Upfront payment									$ 250
Collaborative agreement milestone payments					$ 2,230						$ 120	$ 120
Research and development costs					$ 1,000
Alvotech [Member]
Noncash or Part Noncash Acquisitions [Line Items]
Collaborative agreement milestone payments										$ 450
MedinCell [Member]
Noncash or Part Noncash Acquisitions [Line Items]
Collaborative agreement milestone payments				$ 112
MODAG [Member] | Subsequent Event [Member]
Noncash or Part Noncash Acquisitions [Line Items]
License agreement potential aggregate milestone payments amount			$ 80