Fair Value Measurements Activity Between Levels of the Fair Value Hierarchy (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 28, 2014	Sep. 29, 2013
Auction Rate Securities [Member]
Activity for Marketable Securities Classified Within Level 3 of the Valuation Hierarchy [Roll Forward]
Beginning balance of Level 3	$ 83	$ 118
Total realized and unrealized gains (losses):
Included in investment income, net	0	0
Included in other comprehensive income	0	1
Purchases	0	0
Sales	0	0
Settlements	0	(36)
Transfers (out of) into Level 3	0	0
Ending balance of Level 3	83	83
Mortgage- and asset-backed securities [Member]
Activity for Marketable Securities Classified Within Level 3 of the Valuation Hierarchy [Roll Forward]
Beginning balance of Level 3	239	203
Total realized and unrealized gains (losses):
Included in investment income, net	11	8
Included in other comprehensive income	(3)	(6)
Purchases	107	163
Sales	(126)	(70)
Settlements	(40)	(77)
Transfers (out of) into Level 3	(2)	18
Ending balance of Level 3	$ 186	$ 239