Stock Compensation - Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 232	$ 242	$ 252
COR
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	25	36	40
R&D
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	69	59	60
SG&A
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 138	$ 147	$ 152