Accelerated Share Repurchase Agreements (Details) - USD ($) shares in Millions, $ in Millions	1 Months Ended		2 Months Ended	6 Months Ended
	Jul. 30, 2017	Jul. 11, 2017	Jul. 30, 2017	Jul. 30, 2017	Jul. 31, 2016
Accelerated Share Repurchases [Line Items]
Repurchases of Common Stock				$ 3,921	$ 2,441
Q2 Accelerate Share Repurchase Agreement [Member]
Accelerated Share Repurchases [Line Items]
Repurchases of Common Stock			$ 1,650
Treasury Stock Shares Acquired	1.1	9.7	10.8