Stock Compensation - Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 242	$ 252	$ 286
COR
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	36	40	47
R&D
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	59	60	60
SG&A
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	147	152	169
Acquisition charges
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 0	$ 0	$ 10