Equity - Changes in Accumulated Other Comprehensive Loss, Net of Tax (Detail) - USD ($) $ in Millions	12 Months Ended
	Oct. 03, 2015	Sep. 27, 2014	Sep. 28, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Beginning Balance	$ (1,968)	$ (1,187)	$ (3,266)
Unrealized gains (losses) arising during the period	(285)	(726)	1,876
Reclassifications of realized net (gains) losses to net income	(168)	(55)	203
AOCI, Ending Balance	$ (2,421)	(1,968)	(1,187)
Estimated tax rate	37.00%
Market Value Adjustments, Investments
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Beginning Balance	$ 100	95	3
Unrealized gains (losses) arising during the period	(37)	109	117
Reclassifications of realized net (gains) losses to net income	(50)	(104)	(25)
AOCI, Ending Balance	13	100	95
Market Value Adjustments, Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Beginning Balance	204	83	(52)
Unrealized gains (losses) arising during the period	421	169	208
Reclassifications of realized net (gains) losses to net income	(291)	(48)	(73)
AOCI, Ending Balance	334	204	83
Unrecognized Pension and Postretirement Medical Expense
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Beginning Balance	(2,196)	(1,271)	(3,234)
Unrealized gains (losses) arising during the period	(474)	(1,022)	1,668
Reclassifications of realized net (gains) losses to net income	173	97	295
AOCI, Ending Balance	(2,497)	(2,196)	(1,271)
Foreign Currency Translation and Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Beginning Balance	(76)	(94)	17
Unrealized gains (losses) arising during the period	(195)	18	(117)
Reclassifications of realized net (gains) losses to net income	0	0	6
AOCI, Ending Balance	$ (271)	$ (76)	$ (94)