Investments (Tables)

9 Months Ended

Sep. 29, 2018

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 September 29, 2018 and December 30, 2017 (in thousands):    

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
September 29, 2018
Money market investments	$	12,430	$	—	$	—	$	12,430
Asset-backed securities		728		—		5		723
Corporate bonds and direct obligations of government agencies		99,833		15		1,309		98,539
Total	$	112,991	$	15	$	1,314	$	111,692
December 30, 2017
Money market investments	$	27,895	$	—	$	—	$	27,895
Asset-backed securities		2,805		—		5		2,800
Corporate bonds and direct obligations of government agencies		80,442		117		335		80,224
Total	$	111,142	$	117	$	340	$	110,919

Schedule of Unrealized Loss on Available-for-Sale Investments

For those available-for-sale investments with unrealized losses at September 29, 2018 and December 30, 2017, 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
September 29, 2018
Asset-backed securities	$	300	$	2	$	423	$	3	$	723	$	5
Corporate bonds and direct obligations of government agencies		73,890		831		20,368		478		94,258		1,309
Total	$	74,190	$	833	$	20,791	$	481	$	94,981	$	1,314
December 30, 2017
Asset-backed securities	$	1,864	$	4	$	632	$	1	$	2,496	$	5
Corporate bonds and direct obligations of government agencies		41,322		220		14,016		115		55,338		335
Total	$	43,186	$	224	$	14,648	$	116	$	57,834	$	340