Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 27, 2019	Sep. 28, 2018	Sep. 29, 2017
Accumulated Other Comprehensive Income (Loss), Net of Tax.
Balance at the beginning of fiscal year	$ (306)
Other comprehensive income (loss)	(197)	$ (108)	$ 382
Balance at the end of fiscal year	(503)	(306)
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax.
Balance at the beginning of fiscal year	236	353	316
Other comprehensive income (loss) before reclassifications	(115)	(117)	38
Amounts reclassified from accumulated other comprehensive income (loss)	67		(1)
Other comprehensive income (loss)	(48)	(117)	37
Balance at the end of fiscal year	188	236	353
Unrecognized Pension and Postretirement Benefit Costs
Accumulated Other Comprehensive Income (Loss), Net of Tax.
Balance at the beginning of fiscal year	(452)	(496)	(826)
Other comprehensive income (loss) before reclassifications	(295)	64	378
Amounts reclassified from accumulated other comprehensive income (loss)	34	40	74
Income tax (expense) benefit	66	(21)	(122)
Other comprehensive income (loss)	(195)	83	330
Balance at the end of fiscal year	(647)	(452)	(496)
Unrecognized Pension and Postretirement Benefit Costs | ASU 2018-02
Accumulated Other Comprehensive Income (Loss), Net of Tax.
Adoption of ASU No. 2018-02		(39)
Gains (Losses) on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax.
Balance at the beginning of fiscal year	(90)	(17)	(32)
Other comprehensive income (loss) before reclassifications	35	(60)	32
Amounts reclassified from accumulated other comprehensive income (loss)	15	(23)	(14)
Income tax (expense) benefit	(4)	9	(3)
Other comprehensive income (loss)	46	(74)	15
Balance at the end of fiscal year	(44)	(90)	(17)
Gains (Losses) on Cash Flow Hedges | ASU 2018-02
Accumulated Other Comprehensive Income (Loss), Net of Tax.
Adoption of ASU No. 2018-02		1
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss), Net of Tax.
Balance at the beginning of fiscal year	(306)	(160)	(542)
Other comprehensive income (loss) before reclassifications	(375)	(113)	448
Amounts reclassified from accumulated other comprehensive income (loss)	116	17	59
Income tax (expense) benefit	62	(12)	(125)
Other comprehensive income (loss)	(197)	(108)	382
Balance at the end of fiscal year	$ (503)	(306)	$ (160)
Accumulated Other Comprehensive Loss | ASU 2018-02
Accumulated Other Comprehensive Income (Loss), Net of Tax.
Adoption of ASU No. 2018-02		$ (38)