Employee Stock Plans - Activity Under Employee Stock Plans (Detail) shares in Millions	12 Months Ended
	Sep. 28, 2018 $ / shares shares
Number of Shares
Beginning balance (in shares) | shares	2.3
Granted (in shares) | shares	0.7
Canceled, expired or forfeited (in shares) | shares	(0.1)
Exercised (in shares) | shares	(0.6)
Ending balance (in shares) | shares	2.3
Weighted Average Exercise Price
Beginning balance (in dollars per share) | $ / shares	$ 74.08
Granted (in dollars per share) | $ / shares	111.54
Canceled, expired or forfeited (in dollars per share) | $ / shares	84.90
Exercised (in dollars per share) | $ / shares	71.02
Ending balance (in dollars per share) | $ / shares	$ 85.82