Investments - Neumora Therapeutics, Inc. (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]
Unrealized gain (loss) on equity method investment			$ 98	$ (165)	$ 161
Neumora Therapeutics, Inc.
Schedule of Equity Method Investments [Line Items]
Ownership percentage	25.90%		23.20%	24.90%
Payments to acquire equity method investments, cash		$ 30
Carrying and fair value of investment			$ 603	$ 335
Unrealized gain (loss) on equity method investment			$ 238	$ 105	$ (37)
Neumora Therapeutics, Inc.
Schedule of Equity Method Investments [Line Items]
Equity method investment, aggregate cost	$ 257
Payments to acquire equity method investments, cash	100
Payments to acquire equity method investments, noncash	$ 157