Investments (Tables)

12 Months Ended

Dec. 26, 2020

Amortized Cost and Fair Value of Available-for-Sale Investments

The amortized cost and fair values of available-for-sale investments are as follows at December 26, 2020 and December 28, 2019 (in thousands):    

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
December 26, 2020
Money market investments	$	17,867	$	—	$	—	$	17,867
Asset-backed securities		567		—		26		541
Corporate bonds and direct obligations of government agencies		98,241		3,551		72		101,720
U.S. Treasury obligations		2,338		125		—		2,463
Total	$	119,013	$	3,676	$	98	$	122,591
December 28, 2019
Money market investments	$	15,691	$	—	$	—	$	15,691
Asset-backed securities		572		—		1		571
Corporate bonds and direct obligations of government agencies		97,583		1,465		44		99,004
U.S. Treasury obligations		2,335		12		5		2,342
Total	$	116,181	$	1,477	$	50	$	117,608

Schedule of Unrealized Loss on Available-for-Sale Investments

For those available-for-sale investments with unrealized losses at December 26, 2020 and December 28, 2019, the following table summarizes the duration of the unrealized loss (in thousands):

	Less than 12 months				12 months or longer				Total
	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
December 26, 2020
Asset-backed securities	$	541	$	26	$	—	$	—	$	541	$	26
Corporate bonds and direct obligations of government agencies		2,681		72		—		—		2,681		72
Total	$	3,222	$	98	$	—	$	—	$	3,222	$	98
December 28, 2019
Asset-backed securities	$	571	$	1	$	—	$	—	$	571	$	1
Corporate bonds and direct obligations of government agencies		8,728		41		4,260		3		12,988		44
U.S. Treasury obligations		1,226		5		—		—		1,226		5
Total	$	10,525	$	47	$	4,260	$	3	$	14,785	$	50