Net Loss Per Share Attributable to Common Stockholders- Antidilutive securities excluded from computation of earnings per share (Details) - shares	12 Months Ended
	Oct. 03, 2020	Sep. 28, 2019	Sep. 29, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation (in shares)	42,728,825	46,447,646	48,504,182
Stock options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation (in shares)	33,503,698	42,300,183	48,504,182
RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation (in shares)	9,225,127	4,147,463	0