Summary of Significant Accounting Policies - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended
	Dec. 26, 2020	Dec. 28, 2019
Numerator:
Net income	$ 28,755	$ 22,236
Denominator:
Weighted-average basic shares outstanding (in shares)	16,935,119	17,660,160
Effect of dilutive securities (in shares)	178,569	158,257
Weighted-average diluted shares (in shares)	17,113,688	17,818,417
Basic earnings per share (in dollars per share)	$ 1.70	$ 1.26
Diluted earnings per share (in dollars per share)	$ 1.68	$ 1.25