Schedule of Unrealized Loss on Available-for-Sale Investments (Detail) - USD ($) $ in Thousands	Sep. 25, 2021	Dec. 26, 2020
Debt Securities, Available-for-sale [Line Items]
Available-for-sale investments with unrealized losses, Less than 12 months, Fair Value	$ 62,156	$ 3,222
Available-for-sale investments with unrealized losses, Less than 12 months, Unrealized Loss	322	98
Available-for-sale investments with unrealized losses, Fair Value, Total	62,156	3,222
Available-for-sale investments with unrealized losses, Unrealized Loss, Total	322	98
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Available-for-sale investments with unrealized losses, Less than 12 months, Fair Value	12,714	541
Available-for-sale investments with unrealized losses, Less than 12 months, Unrealized Loss	63	26
Available-for-sale investments with unrealized losses, Fair Value, Total	12,714	541
Available-for-sale investments with unrealized losses, Unrealized Loss, Total	63	26
Corporate bonds and direct obligations of government agencies
Debt Securities, Available-for-sale [Line Items]
Available-for-sale investments with unrealized losses, Less than 12 months, Fair Value	49,442	2,681
Available-for-sale investments with unrealized losses, Less than 12 months, Unrealized Loss	259	72
Available-for-sale investments with unrealized losses, Fair Value, Total	49,442	2,681
Available-for-sale investments with unrealized losses, Unrealized Loss, Total	$ 259	$ 72