Changes in Accumulated Other Comprehensive Loss, Net of Tax (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 28, 2015	Mar. 29, 2014	Mar. 28, 2015	Mar. 29, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Beginning Balance	$ (1,880)	$ (1,144)	$ (1,968)	$ (1,187)
Unrealized gains (losses) arising during the period	78	(7)	163	58
Reclassifications of net (gains) losses to net income	(41)	(55)	(38)	(77)
AOCI, Ending Balance	(1,843)	(1,206)	(1,843)	(1,206)
Estimated tax rate	37.00%	37.00%	37.00%	37.00%
Investments, net
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Beginning Balance	84	76	100	95
Unrealized gains (losses) arising during the period	(24)	22	(40)	40
Reclassifications of net (gains) losses to net income	(30)	(58)	(30)	(95)
AOCI, Ending Balance	30	40	30	40
Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Beginning Balance	339	114	204	83
Unrealized gains (losses) arising during the period	183	(43)	359	(2)
Reclassifications of net (gains) losses to net income	(54)	(21)	(95)	(31)
AOCI, Ending Balance	468	50	468	50
Unrecognized Pension and Postretirement Medical Expense
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Beginning Balance	(2,152)	(1,246)	(2,196)	(1,271)
Unrealized gains (losses) arising during the period	(9)	15	(9)	15
Reclassifications of net (gains) losses to net income	43	24	87	49
AOCI, Ending Balance	(2,118)	(1,207)	(2,118)	(1,207)
Foreign Currency Translation and Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Beginning Balance	(151)	(88)	(76)	(94)
Unrealized gains (losses) arising during the period	(72)	(1)	(147)	5
Reclassifications of net (gains) losses to net income	0	0	0	0
AOCI, Ending Balance	$ (223)	$ (89)	$ (223)	$ (89)