Stock Compensation - Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation	$ 224	$ 217	$ 232
COR
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation	21	21	25
R&D
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation	68	66	69
SG&A
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation	$ 135	$ 130	$ 138