Benefit Plans - Additional Information (Details) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2018 USD ($) shares	Jul. 01, 2017 USD ($)	Jun. 30, 2018 USD ($) shares	Jul. 01, 2017 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for future issuance under stock plans (in shares) | shares	280,400,000		280,400,000
Income tax benefit related to share-based compensation expense	$ 528	$ 380	$ 1,500	$ 1,300
Total unrecognized compensation cost related to RSUs and stock options	10,400		$ 10,400
Total unrecognized compensation cost related to RSUs and stock options, weighted-average recognition period			2 years 7 months
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSUs granted, vesting period			4 years
Number of shares of common stock issued per RSU upon vesting			1
Reduction in number of shares available for grant per share issued with respect to RSUs granted (in shares) | shares			2
Factor by which each RSU canceled or share withheld for taxes increases the number of shares available for grant			2
Fair value of vested RSUs as of vesting date	$ 3,300	$ 2,800	$ 6,900	$ 5,400