Fair Market Value of Investments with Unrealized Losses Not Deemed to be Other-Than Temporarily Impaired (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 27, 2014
Schedule of Available-for-sale Securities [Line Items]
Unrealized Loss Position, Less than 12 Months, Fair Value	$ 14,772
Unrealized Loss Position, Less than 12 Months, Gross Unrealized Losses	14
Unrealized Loss Position, Greater than 12 Months, Fair Value
Unrealized Loss Position, Greater than 12 Months, Gross Unrealized Losses
Corporate bonds and medium-term notes
Schedule of Available-for-sale Securities [Line Items]
Unrealized Loss Position, Less than 12 Months, Fair Value	11,774
Unrealized Loss Position, Less than 12 Months, Gross Unrealized Losses	11
Unrealized Loss Position, Greater than 12 Months, Fair Value
Unrealized Loss Position, Greater than 12 Months, Gross Unrealized Losses
Municipal bonds
Schedule of Available-for-sale Securities [Line Items]
Unrealized Loss Position, Less than 12 Months, Fair Value	1,000
Unrealized Loss Position, Less than 12 Months, Gross Unrealized Losses	1
Unrealized Loss Position, Greater than 12 Months, Fair Value
Unrealized Loss Position, Greater than 12 Months, Gross Unrealized Losses
U.S. treasury and agency securities
Schedule of Available-for-sale Securities [Line Items]
Unrealized Loss Position, Less than 12 Months, Fair Value	1,998
Unrealized Loss Position, Less than 12 Months, Gross Unrealized Losses	2
Unrealized Loss Position, Greater than 12 Months, Fair Value
Unrealized Loss Position, Greater than 12 Months, Gross Unrealized Losses