Stock Options Outstanding (Detail) - $ / shares	12 Months Ended
	Sep. 29, 2017	Sep. 30, 2016	Oct. 02, 2015
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Options Exercisable, Shares	594,963	918,706	824,496
$23.66 - $52.00
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Prices, lower limit	$ 23.66
Range of Exercise Prices, upper limit	$ 52.00
Options Outstanding, Shares	110,575
Options Outstanding Weighted Average Remaining Life (years)	3 years 7 months 6 days
Options Outstanding, Weighted Average Price	$ 48.13
Options Exercisable, Shares	110,575
Options Exercisable, Weighted Average Price	$ 48.13
$52.01 - $65.00
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Prices, lower limit	52.01
Range of Exercise Prices, upper limit	$ 65.00
Options Outstanding, Shares	147,075
Options Outstanding Weighted Average Remaining Life (years)	3 years 1 month 6 days
Options Outstanding, Weighted Average Price	$ 62.17
Options Exercisable, Shares	147,075
Options Exercisable, Weighted Average Price	$ 62.17
$65.01 - $75.00
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Prices, lower limit	65.01
Range of Exercise Prices, upper limit	$ 75.00
Options Outstanding, Shares	113,525
Options Outstanding Weighted Average Remaining Life (years)	6 years 10 months 24 days
Options Outstanding, Weighted Average Price	$ 69.40
Options Exercisable, Shares	56,275
Options Exercisable, Weighted Average Price	$ 67.07
$75.01 - $85.00
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Prices, lower limit	75.01
Range of Exercise Prices, upper limit	$ 85.00
Options Outstanding, Shares	257,063
Options Outstanding Weighted Average Remaining Life (years)	8 years 4 months 24 days
Options Outstanding, Weighted Average Price	$ 82.34
Options Exercisable, Shares	46,363
Options Exercisable, Weighted Average Price	$ 79.38
$85.01 - $100.00
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Prices, lower limit	85.01
Range of Exercise Prices, upper limit	$ 100.00
Options Outstanding, Shares	284,750
Options Outstanding Weighted Average Remaining Life (years)	7 years
Options Outstanding, Weighted Average Price	$ 95.14
Options Exercisable, Shares	146,200
Options Exercisable, Weighted Average Price	$ 95.45
$100.01 - $118.32
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Prices, lower limit	100.01
Range of Exercise Prices, upper limit	$ 118.32
Options Outstanding, Shares	163,750
Options Outstanding Weighted Average Remaining Life (years)	6 years 10 months 24 days
Options Outstanding, Weighted Average Price	$ 109.97
Options Exercisable, Shares	88,475
Options Exercisable, Weighted Average Price	$ 110.00