Restructuring and Other Termination Costs Narrative (Details) - USD ($) $ in Millions		3 Months Ended
	Jan. 30, 2018	Mar. 31, 2018	Mar. 31, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring and other termination costs, number of positions eliminated, period percent	13.00%
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance		$ 0
Initial restructuring recognition on January 30, 2018		38	$ 0
Termination benefits paid		(11)
Restructuring reserve, ending balance		27
One-time termination benefits [Member]
Restructuring Reserve [Roll Forward]
Initial restructuring recognition on January 30, 2018	$ 38	$ 38