Recent Accounting Pronouncements (Details) - USD ($) $ in Millions	3 Months Ended
	Apr. 28, 2018	Jul. 29, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase in retained earnings	$ 3,709	$ 20,838
Accounting Standards Update 2018-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Effect of adoption of accounting standard	45
Accounting Standards Update 2016-16
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase in retained earnings	$ 1,300