Fair Value (Assets and Liabilities Measured at Fair Value on Recurring Basis) (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Millions	Oct. 27, 2018	Jul. 28, 2018
Fair Value Measurements [Line Items]
Assets:	$ 40,767	$ 44,506
Liabilities:	91	74
Fair Value, Inputs, Level 1 [Member]
Fair Value Measurements [Line Items]
Assets:	6,332	7,495
Liabilities:	0	0
Level 2
Fair Value Measurements [Line Items]
Assets:	34,435	37,011
Liabilities:	91	74
Derivative assets
Fair Value Measurements [Line Items]
Assets:	6	2
Derivative assets | Fair Value, Inputs, Level 1 [Member]
Fair Value Measurements [Line Items]
Assets:	0	0
Derivative assets | Level 2
Fair Value Measurements [Line Items]
Assets:	6	2
Derivative liabilities
Fair Value Measurements [Line Items]
Liabilities:	91	74
Derivative liabilities | Fair Value, Inputs, Level 1 [Member]
Fair Value Measurements [Line Items]
Liabilities:	0	0
Derivative liabilities | Level 2
Fair Value Measurements [Line Items]
Liabilities:	91	74
Money market funds | Cash equivalents:
Fair Value Measurements [Line Items]
Assets:	6,332	6,890
Money market funds | Cash equivalents: | Fair Value, Inputs, Level 1 [Member]
Fair Value Measurements [Line Items]
Assets:	6,332	6,890
Money market funds | Cash equivalents: | Level 2
Fair Value Measurements [Line Items]
Assets:	0	0
U.S. government securities | Available-for-sale debt investments:
Fair Value Measurements [Line Items]
Assets:	5,754	7,275
U.S. government securities | Available-for-sale debt investments: | Fair Value, Inputs, Level 1 [Member]
Fair Value Measurements [Line Items]
Assets:	0	0
U.S. government securities | Available-for-sale debt investments: | Level 2
Fair Value Measurements [Line Items]
Assets:	5,754	7,275
U.S. government agency securities | Available-for-sale debt investments:
Fair Value Measurements [Line Items]
Assets:	430	727
U.S. government agency securities | Available-for-sale debt investments: | Fair Value, Inputs, Level 1 [Member]
Fair Value Measurements [Line Items]
Assets:	0	0
U.S. government agency securities | Available-for-sale debt investments: | Level 2
Fair Value Measurements [Line Items]
Assets:	430	727
Non-U.S. government and agency securities | Available-for-sale debt investments:
Fair Value Measurements [Line Items]
Assets:	153	208
Non-U.S. government and agency securities | Available-for-sale debt investments: | Fair Value, Inputs, Level 1 [Member]
Fair Value Measurements [Line Items]
Assets:	0	0
Non-U.S. government and agency securities | Available-for-sale debt investments: | Level 2
Fair Value Measurements [Line Items]
Assets:	153	208
Corporate debt securities | Available-for-sale debt investments:
Fair Value Measurements [Line Items]
Assets:	26,031	27,364
Corporate debt securities | Available-for-sale debt investments: | Fair Value, Inputs, Level 1 [Member]
Fair Value Measurements [Line Items]
Assets:	0	0
Corporate debt securities | Available-for-sale debt investments: | Level 2
Fair Value Measurements [Line Items]
Assets:	26,031	27,364
U.S. agency mortgage-backed securities | Available-for-sale debt investments:
Fair Value Measurements [Line Items]
Assets:	1,421	1,435
U.S. agency mortgage-backed securities | Available-for-sale debt investments: | Fair Value, Inputs, Level 1 [Member]
Fair Value Measurements [Line Items]
Assets:	0	0
U.S. agency mortgage-backed securities | Available-for-sale debt investments: | Level 2
Fair Value Measurements [Line Items]
Assets:	1,421	1,435
Commercial paper | Cash equivalents:
Fair Value Measurements [Line Items]
Assets:	210	0
Commercial paper | Cash equivalents: | Fair Value, Inputs, Level 1 [Member]
Fair Value Measurements [Line Items]
Assets:	0	0
Commercial paper | Cash equivalents: | Level 2
Fair Value Measurements [Line Items]
Assets:	210	0
Commercial paper | Available-for-sale debt investments:
Fair Value Measurements [Line Items]
Assets:	309	0
Commercial paper | Available-for-sale debt investments: | Fair Value, Inputs, Level 1 [Member]
Fair Value Measurements [Line Items]
Assets:	0	0
Commercial paper | Available-for-sale debt investments: | Level 2
Fair Value Measurements [Line Items]
Assets:	309	0
Certificates of deposit | Cash equivalents:
Fair Value Measurements [Line Items]
Assets:	20	0
Certificates of deposit | Cash equivalents: | Fair Value, Inputs, Level 1 [Member]
Fair Value Measurements [Line Items]
Assets:	0	0
Certificates of deposit | Cash equivalents: | Level 2
Fair Value Measurements [Line Items]
Assets:	20	0
Certificates of deposit | Available-for-sale debt investments:
Fair Value Measurements [Line Items]
Assets:	85	0
Certificates of deposit | Available-for-sale debt investments: | Fair Value, Inputs, Level 1 [Member]
Fair Value Measurements [Line Items]
Assets:	0	0
Certificates of deposit | Available-for-sale debt investments: | Level 2
Fair Value Measurements [Line Items]
Assets:	85	0
Repurchase agreements | Cash equivalents:
Fair Value Measurements [Line Items]
Assets:	16	0
Repurchase agreements | Cash equivalents: | Fair Value, Inputs, Level 1 [Member]
Fair Value Measurements [Line Items]
Assets:	0	0
Repurchase agreements | Cash equivalents: | Level 2
Fair Value Measurements [Line Items]
Assets:	16	0
Equity securities | Available-for-sale debt investments:
Fair Value Measurements [Line Items]
Assets:	0	605
Equity securities | Available-for-sale debt investments: | Fair Value, Inputs, Level 1 [Member]
Fair Value Measurements [Line Items]
Assets:	0	605
Equity securities | Available-for-sale debt investments: | Level 2
Fair Value Measurements [Line Items]
Assets:	$ 0	$ 0