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. 29, 2017	Sep. 30, 2016
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, End of Period [Abstract]
Number of Shares (in shares)	2.3	2.6
Weighted Average Remaining Contractual Term (in years)	4 years 8 months 5 days
Weighted Average Exercise Price (in dollars per share)	$ 74.08	$ 78.25
Aggregate Intrinsic Value	$ 59.5
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Number of Shares (in shares)	1.2	1.4
Weighted Average Remaining Contractual Term (in years)	3 years 7 months 25 days
Weighted Average Exercise Price (in dollars per share)	$ 71.37	$ 76.31
Aggregate Intrinsic Value	$ 34.3
Closing price (in dollars per share)	$ 100.06
$51.23 - $57.27
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)	51.23
Range of Exercise Prices, Upper (in dollars per share)	$ 57.27
Number of Shares (in shares)	0.1
Weighted Average Remaining Contractual Term (in years)	1 year 2 months 12 days
Weighted Average Exercise Price (in dollars per share)	$ 52.91
Aggregate Intrinsic Value	$ 3.7
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Number of Shares (in shares)	0.1
Weighted Average Remaining Contractual Term (in years)	1 year 2 months 12 days
Weighted Average Exercise Price (in dollars per share)	$ 52.91
Aggregate Intrinsic Value	$ 3.7
$60.91 - $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)	$ 60.91
Range of Exercise Prices, Upper (in dollars per share)	$ 67.12
Number of Shares (in shares)	0.8
Weighted Average Remaining Contractual Term (in years)	4 years 5 months 19 days
Weighted Average Exercise Price (in dollars per share)	$ 65.71
Aggregate Intrinsic Value	$ 28.2
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 10 months 17 days
Weighted Average Exercise Price (in dollars per share)	$ 64.55
Aggregate Intrinsic Value	$ 16.0
$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)	0.3
Weighted Average Remaining Contractual Term (in years)	3 years 5 months 16 days
Weighted Average Exercise Price (in dollars per share)	$ 74.28
Aggregate Intrinsic Value	$ 9.0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Number of Shares (in shares)	0.3
Weighted Average Remaining Contractual Term (in years)	3 years 4 months 21 days
Weighted Average Exercise Price (in dollars per share)	$ 74.29
Aggregate Intrinsic Value	$ 8.6
$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)	1.1
Weighted Average Remaining Contractual Term (in years)	5 years 6 months 7 days
Weighted Average Exercise Price (in dollars per share)	$ 82.18
Aggregate Intrinsic Value	$ 18.6
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Number of Shares (in shares)	0.3
Weighted Average Remaining Contractual Term (in years)	4 years 1 month 28 days
Weighted Average Exercise Price (in dollars per share)	$ 81.97
Aggregate Intrinsic Value	$ 6.0