Fair Value (Assets and Liabilities Measured At Fair Value On Recurring Basis) (Details) - USD ($) $ in Millions	Jul. 28, 2018	Jul. 29, 2017
Assets:
Derivative assets	$ 2	$ 149
Total	44,506	68,824
Liabilities:
Derivative liabilities	74	4
Total	74	4
Derivative assets
Assets:
Derivative assets	2	149
Derivative liabilities
Liabilities:
Derivative liabilities	74	4
Cash equivalents: | Money market funds
Assets:
Investments	6,890	9,567
Cash equivalents: | U.S. government securities
Assets:
Investments	0	139
Cash equivalents: | Commercial paper
Assets:
Investments	0	160
Cash equivalents: | Certificates of deposit
Assets:
Investments	0	25
Available-for-sale investments: | U.S. government securities
Assets:
Investments	7,275	19,823
Available-for-sale investments: | U.S. government agency securities
Assets:
Investments	727	2,052
Available-for-sale investments: | Non-U.S. government and agency securities
Assets:
Investments	208	388
Available-for-sale investments: | Corporate debt securities
Assets:
Investments	27,364	31,735
Available-for-sale investments: | U.S. agency mortgage-backed securities
Assets:
Investments	1,435	2,023
Available-for-sale investments: | Commercial paper
Assets:
Investments	0	996
Available-for-sale investments: | Certificates of deposit
Assets:
Investments	0	60
Available-for-sale investments: | Publicly traded equity securities
Assets:
Investments	605	1,707
Level 1
Assets:
Total	7,495	11,274
Liabilities:
Total	0	0
Level 1 | Derivative assets
Assets:
Derivative assets	0	0
Level 1 | Derivative liabilities
Liabilities:
Derivative liabilities	0	0
Level 1 | Cash equivalents: | Money market funds
Assets:
Investments	6,890	9,567
Level 1 | Cash equivalents: | U.S. government securities
Assets:
Investments	0	0
Level 1 | Cash equivalents: | Commercial paper
Assets:
Investments	0	0
Level 1 | Cash equivalents: | Certificates of deposit
Assets:
Investments	0	0
Level 1 | Available-for-sale investments: | U.S. government securities
Assets:
Investments	0	0
Level 1 | Available-for-sale investments: | U.S. government agency securities
Assets:
Investments	0	0
Level 1 | Available-for-sale investments: | Non-U.S. government and agency securities
Assets:
Investments	0	0
Level 1 | Available-for-sale investments: | Corporate debt securities
Assets:
Investments	0	0
Level 1 | Available-for-sale investments: | U.S. agency mortgage-backed securities
Assets:
Investments	0	0
Level 1 | Available-for-sale investments: | Commercial paper
Assets:
Investments	0	0
Level 1 | Available-for-sale investments: | Certificates of deposit
Assets:
Investments	0	0
Level 1 | Available-for-sale investments: | Publicly traded equity securities
Assets:
Investments	605	1,707
Level 2
Assets:
Total	37,011	57,550
Liabilities:
Total	74	4
Level 2 | Derivative assets
Assets:
Derivative assets	2	149
Level 2 | Derivative liabilities
Liabilities:
Derivative liabilities	74	4
Level 2 | Cash equivalents: | Money market funds
Assets:
Investments	0	0
Level 2 | Cash equivalents: | U.S. government securities
Assets:
Investments	0	139
Level 2 | Cash equivalents: | Commercial paper
Assets:
Investments	0	160
Level 2 | Cash equivalents: | Certificates of deposit
Assets:
Investments	0	25
Level 2 | Available-for-sale investments: | U.S. government securities
Assets:
Investments	7,275	19,823
Level 2 | Available-for-sale investments: | U.S. government agency securities
Assets:
Investments	727	2,052
Level 2 | Available-for-sale investments: | Non-U.S. government and agency securities
Assets:
Investments	208	388
Level 2 | Available-for-sale investments: | Corporate debt securities
Assets:
Investments	27,364	31,735
Level 2 | Available-for-sale investments: | U.S. agency mortgage-backed securities
Assets:
Investments	1,435	2,023
Level 2 | Available-for-sale investments: | Commercial paper
Assets:
Investments	0	996
Level 2 | Available-for-sale investments: | Certificates of deposit
Assets:
Investments	0	60
Level 2 | Available-for-sale investments: | Publicly traded equity securities
Assets:
Investments	$ 0	$ 0