Fair Value (Assets and Liabilities Measured At Fair Value On Recurring Basis) (Details) - USD ($) $ in Millions	Jul. 29, 2017	Jul. 30, 2016
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Derivative assets	$ 149	$ 385
Total	68,824	64,664
Derivative liabilities	4	54
Total	4	54
Derivative assets
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Derivative assets	149	385
Derivative liabilities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Derivative liabilities	4	54
Cash equivalents: | Money market funds
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	9,567	6,111
Cash equivalents: | U.S. government securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	139	0
Cash equivalents: | Corporate debt securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	0	43
Cash equivalents: | Commercial paper
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	160	0
Cash equivalents: | Certificates of deposit
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	25	0
Available-for-sale investments: | U.S. government securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	19,823	26,544
Available-for-sale investments: | U.S. government agency securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	2,052	2,817
Available-for-sale investments: | Non-U.S. government and agency securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	388	1,100
Available-for-sale investments: | Corporate debt securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	31,735	24,292
Available-for-sale investments: | Mortgage-backed Securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	2,023	1,868
Available-for-sale investments: | Commercial paper
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	996	0
Available-for-sale investments: | Certificates of deposit
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	60	0
Available-for-sale investments: | Publicly traded equity securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	1,707	1,504
Level 1
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Total	11,274	7,615
Total	0	0
Level 1 | Derivative assets
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Derivative assets	0	0
Level 1 | Derivative liabilities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Derivative liabilities	0	0
Level 1 | Cash equivalents: | Money market funds
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	9,567	6,111
Level 1 | Cash equivalents: | U.S. government securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	0	0
Level 1 | Cash equivalents: | Corporate debt securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	0	0
Level 1 | Cash equivalents: | Commercial paper
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	0	0
Level 1 | Cash equivalents: | Certificates of deposit
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	0	0
Level 1 | Available-for-sale investments: | U.S. government securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	0	0
Level 1 | Available-for-sale investments: | U.S. government agency securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	0	0
Level 1 | Available-for-sale investments: | Non-U.S. government and agency securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	0	0
Level 1 | Available-for-sale investments: | Corporate debt securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	0	0
Level 1 | Available-for-sale investments: | Mortgage-backed Securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	0	0
Level 1 | Available-for-sale investments: | Commercial paper
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	0	0
Level 1 | Available-for-sale investments: | Certificates of deposit
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	0	0
Level 1 | Available-for-sale investments: | Publicly traded equity securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	1,707	1,504
Level 2
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Total	57,550	57,048
Total	4	54
Level 2 | Derivative assets
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Derivative assets	149	384
Level 2 | Derivative liabilities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Derivative liabilities	4	54
Level 2 | Cash equivalents: | Money market funds
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	0	0
Level 2 | Cash equivalents: | U.S. government securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	139	0
Level 2 | Cash equivalents: | Corporate debt securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	0	43
Level 2 | Cash equivalents: | Commercial paper
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	160	0
Level 2 | Cash equivalents: | Certificates of deposit
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	25	0
Level 2 | Available-for-sale investments: | U.S. government securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	19,823	26,544
Level 2 | Available-for-sale investments: | U.S. government agency securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	2,052	2,817
Level 2 | Available-for-sale investments: | Non-U.S. government and agency securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	388	1,100
Level 2 | Available-for-sale investments: | Corporate debt securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	31,735	24,292
Level 2 | Available-for-sale investments: | Mortgage-backed Securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	2,023	1,868
Level 2 | Available-for-sale investments: | Commercial paper
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	996	0
Level 2 | Available-for-sale investments: | Certificates of deposit
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	60	0
Level 2 | Available-for-sale investments: | Publicly traded equity securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	0	0
Level 3
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Total	0	1
Total	0	0
Level 3 | Derivative assets
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Derivative assets	0	1
Level 3 | Derivative liabilities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Derivative liabilities	0	0
Level 3 | Cash equivalents: | Money market funds
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	0	0
Level 3 | Cash equivalents: | U.S. government securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	0	0
Level 3 | Cash equivalents: | Corporate debt securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	0	0
Level 3 | Cash equivalents: | Commercial paper
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	0	0
Level 3 | Cash equivalents: | Certificates of deposit
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	0	0
Level 3 | Available-for-sale investments: | U.S. government securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	0	0
Level 3 | Available-for-sale investments: | U.S. government agency securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	0	0
Level 3 | Available-for-sale investments: | Non-U.S. government and agency securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	0	0
Level 3 | Available-for-sale investments: | Corporate debt securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	0	0
Level 3 | Available-for-sale investments: | Mortgage-backed Securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	0	0
Level 3 | Available-for-sale investments: | Commercial paper
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	0	0
Level 3 | Available-for-sale investments: | Certificates of deposit
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	0	0
Level 3 | Available-for-sale investments: | Publicly traded equity securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments	$ 0	$ 0