Third Party Arrangements Related Party Disclosures - Net Transfers to Parent (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Related Party Transaction [Line Items]
Cash pooling and general financing activities	$ 0	$ 971	$ 168	$ 3,099
Cost allocations, excluding non-cash stock-based compensation		(322)	(209)	(945)
Taxes deemed settled with Merck	0	(300)	(259)	(400)
Allocated derivative and hedging (losses) gains	0	(88)	(88)	(85)
Net transfers (from) to Merck & Co., Inc. as reflected in the Condensed Consolidated Statement of Cash Flows for Continuing Operations(2)			(388)	1,669
Net transfers to (from) Merck included in Net Cash Provided by (Used in) Discontinued Operations			597	(202)
Total net transfers to Merck as included in the Condensed Consolidated Statement of Cash Flows			209	1,467
Stock-based compensation expense (includes $3 and $7 of discontinued operations for the nine months ended September 30, 2021 and 2020, respectively)			(32)	(43)
Net assets distributed to (contributed by) Merck Affiliates	0	0	(778)	(10)
Recognition of amounts in Accumulated other comprehensive loss related to employee benefit plan transfers to Merck affiliates			13	0
Net transfers (from) to Merck & Co., Inc. as reflected in the Condensed Consolidated Statement of Equity	$ 0	$ 261	(588)	1,414
Adjustment to net transfers reflected in Cash Flows from Continuing Operations			66
Discontinued Operations
Related Party Transaction [Line Items]
Stock-based compensation expense (includes $3 and $7 of discontinued operations for the nine months ended September 30, 2021 and 2020, respectively)			$ 3	$ 7