Fair Value (Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Detail) (USD $) In Millions, unless otherwise specified	Jan. 26, 2013	Jul. 28, 2012
Fair Value, Inputs, Level 1 [Member]
Assets, Fair Value Disclosure, Recurring	$ 6,621	$ 4,126
Fair Value, Inputs, Level 2 [Member]
Assets, Fair Value Disclosure, Recurring	37,665	37,560
Liabilities, Fair Value Disclosure	57	42
Fair Value, Inputs, Level 2 [Member] | Derivative Assets [Member]
Assets, Fair Value Disclosure, Recurring	244	263
Fair Value, Inputs, Level 2 [Member] | Derivative Liabilities [Member]
Liabilities, Fair Value Disclosure	57	42
Fair Value, Inputs, Level 3 [Member]
Assets, Fair Value Disclosure, Recurring	0	1
Fair Value, Inputs, Level 3 [Member] | Derivative Assets [Member]
Assets, Fair Value Disclosure, Recurring	0	1
Total Balance Fair Value Measurements [Member]
Assets, Fair Value Disclosure, Recurring	44,286	41,687
Liabilities, Fair Value Disclosure	57	42
Total Balance Fair Value Measurements [Member] | Derivative Assets [Member]
Assets, Fair Value Disclosure, Recurring	244	264
Total Balance Fair Value Measurements [Member] | Derivative Liabilities [Member]
Liabilities, Fair Value Disclosure	57	42
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, Fair Value Disclosure, Recurring	4,513	2,506
Cash and Cash Equivalents [Member] | Total Balance Fair Value Measurements [Member]
Assets, Fair Value Disclosure, Recurring	4,513	2,506
Available-for-sale Securities [Member] | US Treasury and Government [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, Fair Value Disclosure, Recurring	25,177	24,241
Available-for-sale Securities [Member] | US Treasury and Government [Member] | Total Balance Fair Value Measurements [Member]
Assets, Fair Value Disclosure, Recurring	25,177	24,241
Available-for-sale Securities [Member] | US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, Fair Value Disclosure, Recurring	3,790	5,388
Available-for-sale Securities [Member] | US Government Agencies Debt Securities [Member] | Total Balance Fair Value Measurements [Member]
Assets, Fair Value Disclosure, Recurring	3,790	5,388
Available-for-sale Securities [Member] | Foreign Government Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, Fair Value Disclosure, Recurring	1,336	1,638
Available-for-sale Securities [Member] | Foreign Government Debt Securities [Member] | Total Balance Fair Value Measurements [Member]
Assets, Fair Value Disclosure, Recurring	1,336	1,638
Available-for-sale Securities [Member] | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, Fair Value Disclosure, Recurring	7,118	6,030
Available-for-sale Securities [Member] | Corporate Debt Securities [Member] | Total Balance Fair Value Measurements [Member]
Assets, Fair Value Disclosure, Recurring	7,118	6,030
Available-for-sale Securities [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, Fair Value Disclosure, Recurring	2,108	1,620
Equity Securities [Member] | Total Balance Fair Value Measurements [Member] | Available-for-sale Securities [Member]
Assets, Fair Value Disclosure, Recurring	$ 2,108	$ 1,620