Financial Instruments - Cash, Cash Equivalents and Marketable Securities (Details) - USD ($) $ in Millions	Jul. 01, 2017	Sep. 24, 2016	Jun. 25, 2016	Sep. 26, 2015
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	$ 261,259	$ 235,810
Unrealized Gains	1,155	2,186
Unrealized Losses	(898)	(411)
Fair Value	261,516	237,585
Cash and Cash Equivalents	18,571	20,484	$ 18,237	$ 21,120
Short-Term Marketable Securities	58,188	46,671
Long-Term Marketable Securities	184,757	170,430
Cash
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	8,529	8,601
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	8,529	8,601
Cash and Cash Equivalents	8,529	8,601
Short-Term Marketable Securities	0	0
Long-Term Marketable Securities	0	0
Level 1
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	4,092	5,073
Unrealized Gains	0	0
Unrealized Losses	(118)	(146)
Fair Value	3,974	4,927
Cash and Cash Equivalents	3,088	3,666
Short-Term Marketable Securities	886	1,261
Long-Term Marketable Securities	0	0
Level 1 \| Money market funds
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	3,088	3,666
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	3,088	3,666
Cash and Cash Equivalents	3,088	3,666
Short-Term Marketable Securities	0	0
Long-Term Marketable Securities	0	0
Level 1 \| Mutual funds
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	1,004	1,407
Unrealized Gains	0	0
Unrealized Losses	(118)	(146)
Fair Value	886	1,261
Cash and Cash Equivalents	0	0
Short-Term Marketable Securities	886	1,261
Long-Term Marketable Securities	0	0
Level 2
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	248,638	222,136
Unrealized Gains	1,155	2,186
Unrealized Losses	(780)	(265)
Fair Value	249,013	224,057
Cash and Cash Equivalents	6,954	8,217
Short-Term Marketable Securities	57,302	45,410
Long-Term Marketable Securities	184,757	170,430
Level 2 \| U.S. Treasury securities
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	52,616	41,697
Unrealized Gains	77	319
Unrealized Losses	(230)	(4)
Fair Value	52,463	42,012
Cash and Cash Equivalents	1,013	1,527
Short-Term Marketable Securities	20,104	13,492
Long-Term Marketable Securities	31,346	26,993
Level 2 \| U.S. agency securities
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	5,328	7,543
Unrealized Gains	3	16
Unrealized Losses	(9)	0
Fair Value	5,322	7,559
Cash and Cash Equivalents	2,255	2,762
Short-Term Marketable Securities	1,774	2,441
Long-Term Marketable Securities	1,293	2,356
Level 2 \| Non-U.S. government securities
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	6,987	7,609
Unrealized Gains	156	259
Unrealized Losses	(50)	(27)
Fair Value	7,093	7,841
Cash and Cash Equivalents	0	110
Short-Term Marketable Securities	64	818
Long-Term Marketable Securities	7,029	6,913
Level 2 \| Certificates of deposit and time deposits
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	6,731	6,598
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	6,731	6,598
Cash and Cash Equivalents	894	1,108
Short-Term Marketable Securities	5,191	3,897
Long-Term Marketable Securities	646	1,593
Level 2 \| Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	5,187	7,433
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	5,187	7,433
Cash and Cash Equivalents	2,683	2,468
Short-Term Marketable Securities	2,504	4,965
Long-Term Marketable Securities	0	0
Level 2 \| Corporate securities
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	150,089	131,166
Unrealized Gains	882	1,409
Unrealized Losses	(312)	(206)
Fair Value	150,659	132,369
Cash and Cash Equivalents	109	242
Short-Term Marketable Securities	27,522	19,599
Long-Term Marketable Securities	123,028	112,528
Level 2 \| Municipal securities
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	938	956
Unrealized Gains	3	5
Unrealized Losses	(2)	0
Fair Value	939	961
Cash and Cash Equivalents	0	0
Short-Term Marketable Securities	127	167
Long-Term Marketable Securities	812	794
Level 2 \| Mortgage- and asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	20,762	19,134
Unrealized Gains	34	178
Unrealized Losses	(177)	(28)
Fair Value	20,619	19,284
Cash and Cash Equivalents	0	0
Short-Term Marketable Securities	16	31
Long-Term Marketable Securities	$ 20,603	$ 19,253

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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