Third Party Arrangements Related Party Disclosures - Transactions with Merck Affiliates (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Discontinued Operations
Related Party Transaction [Line Items]
Supply sales to Merck affiliates		$ 169	$ 12	$ 467
Purchases from Merck affiliates		236	53	866
Other Merck Affiliates | Continuing Operations
Related Party Transaction [Line Items]
Supply sales to Merck affiliates	$ 0	0	143	0
Purchases from Merck affiliates	0	0	65	0
Other Merck Affiliates | Continuing Operations | Cost Reimbursements and Fees
Related Party Transaction [Line Items]
Cost reimbursements and fees from Merck affiliates	0	0	1	0
Other Merck Affiliates | Discontinued Operations
Related Party Transaction [Line Items]
Supply sales to Merck affiliates	0	169	12	467
Purchases from Merck affiliates		$ 236	$ 53	$ 866