Employee Stock Plans - Options Outstanding and Exercisable Under Employee Stock Plans (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Sep. 28, 2018	Sep. 29, 2017
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, End of Period [Abstract]
Number of Shares (in shares)	2.3	2.3
Weighted Average Remaining Contractual Term (in years)	4 years 8 months 9 days
Weighted Average Exercise Price (in dollars per share)	$ 85.82	$ 74.08
Aggregate Intrinsic Value	$ 60.4
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Number of Shares (in shares)	1.2	1.2
Weighted Average Remaining Contractual Term (in years)	3 years 8 months 12 days
Weighted Average Exercise Price (in dollars per share)	$ 74.14	$ 71.37
Aggregate Intrinsic Value	$ 46.3
Closing price (in dollars per share)	$ 111.93
$51.23 - $67.12
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, End of Period [Abstract]
Range of Exercise Prices, Lower (in dollars per share)	51.23
Range of Exercise Prices, Upper (in dollars per share)	$ 67.12
Number of Shares (in shares)	0.6
Weighted Average Remaining Contractual Term (in years)	3 years 6 months 29 days
Weighted Average Exercise Price (in dollars per share)	$ 65.72
Aggregate Intrinsic Value	$ 28.4
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Number of Shares (in shares)	0.5
Weighted Average Remaining Contractual Term (in years)	3 years 5 months 27 days
Weighted Average Exercise Price (in dollars per share)	$ 65.43
Aggregate Intrinsic Value	$ 23.7
$71.47 - $77.49
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, End of Period [Abstract]
Range of Exercise Prices, Lower (in dollars per share)	$ 71.47
Range of Exercise Prices, Upper (in dollars per share)	$ 77.49
Number of Shares (in shares)	0.2
Weighted Average Remaining Contractual Term (in years)	2 years 7 months 10 days
Weighted Average Exercise Price (in dollars per share)	$ 74.45
Aggregate Intrinsic Value	$ 6.5
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Number of Shares (in shares)	0.2
Weighted Average Remaining Contractual Term (in years)	2 years 7 months 6 days
Weighted Average Exercise Price (in dollars per share)	$ 74.47
Aggregate Intrinsic Value	$ 6.4
$80.40 - $99.26
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, End of Period [Abstract]
Range of Exercise Prices, Lower (in dollars per share)	$ 80.40
Range of Exercise Prices, Upper (in dollars per share)	$ 99.26
Number of Shares (in shares)	0.8
Weighted Average Remaining Contractual Term (in years)	4 years 7 months 17 days
Weighted Average Exercise Price (in dollars per share)	$ 82.38
Aggregate Intrinsic Value	$ 24.8
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Number of Shares (in shares)	0.5
Weighted Average Remaining Contractual Term (in years)	4 years 2 months 27 days
Weighted Average Exercise Price (in dollars per share)	$ 82.20
Aggregate Intrinsic Value	$ 16.2
$109.03 - $118.27
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, End of Period [Abstract]
Range of Exercise Prices, Lower (in dollars per share)	$ 109.03
Range of Exercise Prices, Upper (in dollars per share)	$ 118.27
Number of Shares (in shares)	0.7
Weighted Average Remaining Contractual Term (in years)	6 years 3 months 18 days
Weighted Average Exercise Price (in dollars per share)	$ 111.51
Aggregate Intrinsic Value	$ 0.7
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Number of Shares (in shares)	0.0
Weighted Average Remaining Contractual Term (in years)	0 years
Weighted Average Exercise Price (in dollars per share)	$ 0.00
Aggregate Intrinsic Value	$ 0.0