Net Income Per Share Attributable to Common Stockholders - Antidilutive Securities (Details) - shares	3 Months Ended
	Jan. 02, 2021	Dec. 28, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially antidilutive securities (in shares)	22,564,357	33,907,179
Stock options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially antidilutive securities (in shares)	17,074,467	29,628,623
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially antidilutive securities (in shares)	5,489,890	4,278,556