Equity - Changes in Accumulated Other Comprehensive Loss, Net of Tax (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 27, 2014	Sep. 28, 2013	Sep. 29, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Beginning Balance	$ (1,187)	$ (3,266)	$ (2,630)
Unrealized gains (losses) arising during the period	(726)	1,876	(847)
Reclassifications of realized net (gains) losses to net income	(55)	203	211
AOCI, Ending Balance	(1,968)	(1,187)	(3,266)
Estimated tax rate	37.00%
Market Value Adjustments, Investments
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Beginning Balance	95	3	6
Unrealized gains (losses) arising during the period	109	117	4
Reclassifications of realized net (gains) losses to net income	(104)	(25)	(7)
AOCI, Ending Balance	100	95	3
Market Value Adjustments, Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Beginning Balance	83	(52)	(54)
Unrealized gains (losses) arising during the period	169	208	38
Reclassifications of realized net (gains) losses to net income	(48)	(73)	(36)
AOCI, Ending Balance	204	83	(52)
Unrecognized Pension and Postretirement Medical Expense
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Beginning Balance	(1,271)	(3,234)	(2,625)
Unrealized gains (losses) arising during the period	(1,022)	1,668	(829)
Reclassifications of realized net (gains) losses to net income	97	295	220
AOCI, Ending Balance	(2,196)	(1,271)	(3,234)
Foreign Currency Translation and Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Beginning Balance	(94)	17	43
Unrealized gains (losses) arising during the period	18	(117)	(60)
Reclassifications of realized net (gains) losses to net income	0	6	34
AOCI, Ending Balance	$ (76)	$ (94)	$ 17