Financial Instruments - Cash, Cash Equivalents and Marketable Securities (Details) - USD ($) $ in Millions	Apr. 01, 2017	Sep. 24, 2016	Mar. 26, 2016	Sep. 26, 2015
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	$ 257,129	$ 235,810
Unrealized Gains	880	2,186
Unrealized Losses	(1,168)	(411)
Fair Value	256,841	237,585
Cash and Cash Equivalents	15,157	20,484	$ 21,514	$ 21,120
Short-Term Marketable Securities	51,944	46,671
Long-Term Marketable Securities	189,740	170,430
Cash
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	7,600	8,601
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	7,600	8,601
Cash and Cash Equivalents	7,600	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	3,739	5,073
Unrealized Gains	0	0
Unrealized Losses	(120)	(146)
Fair Value	3,619	4,927
Cash and Cash Equivalents	2,742	3,666
Short-Term Marketable Securities	877	1,261
Long-Term Marketable Securities	0	0
Level 1 \| Money market funds
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	2,742	3,666
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	2,742	3,666
Cash and Cash Equivalents	2,742	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	997	1,407
Unrealized Gains	0	0
Unrealized Losses	(120)	(146)
Fair Value	877	1,261
Cash and Cash Equivalents	0	0
Short-Term Marketable Securities	877	1,261
Long-Term Marketable Securities	0	0
Level 2
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	245,790	222,136
Unrealized Gains	880	2,186
Unrealized Losses	(1,048)	(265)
Fair Value	245,622	224,057
Cash and Cash Equivalents	4,815	8,217
Short-Term Marketable Securities	51,067	45,410
Long-Term Marketable Securities	189,740	170,430
Level 2 \| U.S. Treasury securities
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	53,365	41,697
Unrealized Gains	65	319
Unrealized Losses	(300)	(4)
Fair Value	53,130	42,012
Cash and Cash Equivalents	2,280	1,527
Short-Term Marketable Securities	16,067	13,492
Long-Term Marketable Securities	34,783	26,993
Level 2 \| U.S. agency securities
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	5,680	7,543
Unrealized Gains	3	16
Unrealized Losses	(10)	0
Fair Value	5,673	7,559
Cash and Cash Equivalents	687	2,762
Short-Term Marketable Securities	3,687	2,441
Long-Term Marketable Securities	1,299	2,356
Level 2 \| Non-U.S. government securities
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	7,151	7,609
Unrealized Gains	135	259
Unrealized Losses	(67)	(27)
Fair Value	7,219	7,841
Cash and Cash Equivalents	0	110
Short-Term Marketable Securities	193	818
Long-Term Marketable Securities	7,026	6,913
Level 2 \| Certificates of deposit and time deposits
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	6,386	6,598
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	6,386	6,598
Cash and Cash Equivalents	921	1,108
Short-Term Marketable Securities	4,665	3,897
Long-Term Marketable Securities	800	1,593
Level 2 \| Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	3,233	7,433
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	3,233	7,433
Cash and Cash Equivalents	877	2,468
Short-Term Marketable Securities	2,356	4,965
Long-Term Marketable Securities	0	0
Level 2 \| Corporate securities
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	147,939	131,166
Unrealized Gains	643	1,409
Unrealized Losses	(449)	(206)
Fair Value	148,133	132,369
Cash and Cash Equivalents	50	242
Short-Term Marketable Securities	23,992	19,599
Long-Term Marketable Securities	124,091	112,528
Level 2 \| Municipal securities
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	950	956
Unrealized Gains	3	5
Unrealized Losses	(3)	0
Fair Value	950	961
Cash and Cash Equivalents	0	0
Short-Term Marketable Securities	77	167
Long-Term Marketable Securities	873	794
Level 2 \| Mortgage- and asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Adjusted Cost	21,086	19,134
Unrealized Gains	31	178
Unrealized Losses	(219)	(28)
Fair Value	20,898	19,284
Cash and Cash Equivalents	0	0
Short-Term Marketable Securities	30	31
Long-Term Marketable Securities	$ 20,868	$ 19,253

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

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