Asset Impairment, Exit and Implementation Costs (Facilities Consolidation) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		18 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring and related costs incurred	$ 2
Restructuring charges	3	$ 27
Payments for restructuring	9
Facilities Consolidation [Member]
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges	$ 150		$ 150
Expected restructuring charges, per share (usd per share)	$ 0.05		$ 0.05
Charges expected to result in cash expenditures	$ 100
Payments for restructuring	$ 10		$ 73