Fair Value (Assets and Liabilities Measured At Fair Value On Recurring Basis) (Details) - USD ($) $ in Millions	Apr. 30, 2016	Jul. 25, 2015
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	$ 62,143	$ 59,107
Derivative assets
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	345	218
Derivative Liabilities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Liabilities	4	12
Cash Equivalents | Money market funds
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	7,178	5,336
Cash Equivalents | Corporate debt securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	3	14
Available-for-sale Investments | Corporate debt securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	23,316	15,783
Available-for-sale Investments | U.S. government securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	24,044	29,939
Available-for-sale Investments | U.S. government agency securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	2,888	3,663
Available-for-sale Investments | Non-U.S. government and agency securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	1,065	1,128
Available-for-sale Investments | U.S. agency mortgage-backed securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	1,762	1,461
Available-for-sale Investments | Publicly traded equity securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	1,542	1,565
Level 1
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	8,720	6,901
Level 1 | Derivative assets
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 1 | Derivative Liabilities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Liabilities	0	0
Level 1 | Cash Equivalents | Money market funds
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	7,178	5,336
Level 1 | Cash Equivalents | Corporate debt securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 1 | Available-for-sale Investments | Corporate debt securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 1 | Available-for-sale Investments | U.S. government securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 1 | Available-for-sale Investments | U.S. government agency securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	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]
Assets	0	0
Level 1 | Available-for-sale Investments | U.S. agency mortgage-backed securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 1 | Available-for-sale Investments | Publicly traded equity securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	1,542	1,565
Level 2
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	53,423	52,202
Level 2 | Derivative assets
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	345	214
Level 2 | Derivative Liabilities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Liabilities	4	12
Level 2 | Cash Equivalents | Money market funds
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 2 | Cash Equivalents | Corporate debt securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	3	14
Level 2 | Available-for-sale Investments | Corporate debt securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	23,316	15,783
Level 2 | Available-for-sale Investments | U.S. government securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	24,044	29,939
Level 2 | Available-for-sale Investments | U.S. government agency securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	2,888	3,663
Level 2 | Available-for-sale Investments | Non-U.S. government and agency securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	1,065	1,128
Level 2 | Available-for-sale Investments | U.S. agency mortgage-backed securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	1,762	1,461
Level 2 | Available-for-sale Investments | Publicly traded equity securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 3
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	4
Level 3 | Derivative assets
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	4
Level 3 | Derivative Liabilities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Liabilities	0	0
Level 3 | Cash Equivalents | Money market funds
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 3 | Cash Equivalents | Corporate debt securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 3 | Available-for-sale Investments | Corporate debt securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 3 | Available-for-sale Investments | U.S. government securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 3 | Available-for-sale Investments | U.S. government agency securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	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]
Assets	0	0
Level 3 | Available-for-sale Investments | U.S. agency mortgage-backed securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	0	0
Level 3 | Available-for-sale Investments | Publicly traded equity securities
Fair Value, Assets And Liabilities Measured On Recurring Basis [Line Items]
Assets	$ 0	$ 0