Comprehensive Income - Change in AOCI by Component (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 24, 2016	Sep. 26, 2015
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balances	$ 128,249	$ 119,355	$ 111,547
Total other comprehensive income/(loss)	(784)	979	(1,427)
Ending balances	134,047	128,249	119,355
Cumulative Foreign Currency Translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balances	(578)	(653)
Other comprehensive income/(loss) before reclassifications	301	67
Amounts reclassified from AOCI	0	0
Tax effect	(77)	8
Total other comprehensive income/(loss)	224	75
Ending balances	(354)	(578)	(653)
Unrealized Gains/Losses on Derivative Instruments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balances	38	772
Other comprehensive income/(loss) before reclassifications	1,793	14
Amounts reclassified from AOCI	(1,952)	(872)
Tax effect	(3)	124
Total other comprehensive income/(loss)	(162)	(734)
Ending balances	(124)	38	772
Unrealized Gains/Losses on Marketable Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balances	1,174	(464)
Other comprehensive income/(loss) before reclassifications	(1,207)	2,445
Amounts reclassified from AOCI	(99)	87
Tax effect	460	(894)
Total other comprehensive income/(loss)	(846)	1,638
Ending balances	328	1,174	(464)
Total AOCI
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balances	634	(345)	1,082
Other comprehensive income/(loss) before reclassifications	887	2,526
Amounts reclassified from AOCI	(2,051)	(785)
Tax effect	380	(762)
Total other comprehensive income/(loss)	(784)	979	(1,427)
Ending balances	$ (150)	$ 634	$ (345)