Fair Value - Assets and Liabilities Measured At Fair Value On Recurring Basis (Details) - USD ($) $ in Millions	Jul. 25, 2020	Jul. 27, 2019
Assets:
Available-for-sale debt investments	$ 17,610	$ 21,660
Marketable equity securities	0	3
U.S. government securities
Assets:
Available-for-sale debt investments	2,685	808
U.S. government agency securities
Assets:
Available-for-sale debt investments	110	169
Corporate debt securities
Assets:
Available-for-sale debt investments	11,877	19,262
Commercial paper
Assets:
Available-for-sale debt investments	727
Certificates of deposit
Assets:
Available-for-sale debt investments	176
Recurring
Assets:
Marketable equity securities	0	3
Derivative assets	191	89
Total	27,833	31,835
Liabilities:
Derivative liabilities	10	15
Total	10	15
Recurring \| U.S. government securities
Assets:
Available-for-sale debt investments	2,685	808
Recurring \| U.S. government agency securities
Assets:
Available-for-sale debt investments	110	169
Recurring \| Corporate debt securities
Assets:
Available-for-sale debt investments	11,877	19,262
Recurring \| U.S. agency mortgage-backed securities
Assets:
Available-for-sale debt investments	2,035	1,421
Recurring \| Commercial paper
Assets:
Available-for-sale debt investments	727	0
Recurring \| Certificates of deposit
Assets:
Available-for-sale debt investments	176	0
Recurring \| Money market funds
Assets:
Cash equivalents	10,024	10,083
Recurring \| Corporate debt securities
Assets:
Cash equivalents	8	0
Recurring \| Level 1
Assets:
Marketable equity securities	0	3
Derivative assets	0	0
Total	10,024	10,086
Liabilities:
Derivative liabilities	0	0
Total	0	0
Recurring \| Level 1 \| U.S. government securities
Assets:
Available-for-sale debt investments	0	0
Recurring \| Level 1 \| U.S. government agency securities
Assets:
Available-for-sale debt investments	0	0
Recurring \| Level 1 \| Corporate debt securities
Assets:
Available-for-sale debt investments	0	0
Recurring \| Level 1 \| U.S. agency mortgage-backed securities
Assets:
Available-for-sale debt investments	0	0
Recurring \| Level 1 \| Commercial paper
Assets:
Available-for-sale debt investments	0	0
Recurring \| Level 1 \| Certificates of deposit
Assets:
Available-for-sale debt investments	0	0
Recurring \| Level 1 \| Money market funds
Assets:
Cash equivalents	10,024	10,083
Recurring \| Level 1 \| Corporate debt securities
Assets:
Cash equivalents	0	0
Recurring \| Level 2
Assets:
Marketable equity securities	0	0
Derivative assets	190	89
Total	17,808	21,749
Liabilities:
Derivative liabilities	10	15
Total	10	15
Recurring \| Level 2 \| U.S. government securities
Assets:
Available-for-sale debt investments	2,685	808
Recurring \| Level 2 \| U.S. government agency securities
Assets:
Available-for-sale debt investments	110	169
Recurring \| Level 2 \| Corporate debt securities
Assets:
Available-for-sale debt investments	11,877	19,262
Recurring \| Level 2 \| U.S. agency mortgage-backed securities
Assets:
Available-for-sale debt investments	2,035	1,421
Recurring \| Level 2 \| Commercial paper
Assets:
Available-for-sale debt investments	727	0
Recurring \| Level 2 \| Certificates of deposit
Assets:
Available-for-sale debt investments	176	0
Recurring \| Level 2 \| Money market funds
Assets:
Cash equivalents	0	0
Recurring \| Level 2 \| Corporate debt securities
Assets:
Cash equivalents	8	$ 0
Recurring \| Level 3
Assets:
Marketable equity securities	0
Derivative assets	1
Total	1
Liabilities:
Derivative liabilities	0
Total	0
Recurring \| Level 3 \| U.S. government securities
Assets:
Available-for-sale debt investments	0
Recurring \| Level 3 \| U.S. government agency securities
Assets:
Available-for-sale debt investments	0
Recurring \| Level 3 \| Corporate debt securities
Assets:
Available-for-sale debt investments	0
Recurring \| Level 3 \| U.S. agency mortgage-backed securities
Assets:
Available-for-sale debt investments	0
Recurring \| Level 3 \| Commercial paper
Assets:
Available-for-sale debt investments	0
Recurring \| Level 3 \| Certificates of deposit
Assets:
Available-for-sale debt investments	0
Recurring \| Level 3 \| Money market funds
Assets:
Cash equivalents	0
Recurring \| Level 3 \| Corporate debt securities
Assets:
Cash equivalents	$ 0

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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