Summary of Significant Accounting Policies - Reconciliation of Weighted Average Number of Common and Common Equivalent Shares Outstanding and Number of Awards Excluded from Diluted Earnings Per Share (Detail) - shares shares in Millions	12 Months Ended
	Sep. 30, 2017	Oct. 01, 2016	Oct. 03, 2015
Earnings Per Share [Abstract]
Weighted average number of common and common equivalent shares outstanding (basic)	1,568	1,629	1,694
Weighted average dilutive impact of Awards	10	10	15
Weighted average number of common and common equivalent shares outstanding (diluted)	1,578	1,639	1,709
Awards excluded from diluted earnings per share	10	6	3