Investments (Tables)

12 Months Ended

Dec. 30, 2017

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 30, 2017 and December 31, 2016 (in thousands):

			Gross		Gross
	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
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
December 31, 2016
Money market investments	$	12,395	$	—	$	—	$	12,395
Asset-backed securities		4,027		3		19		4,011
Corporate bonds and direct obligations of government agencies		70,069		150		239		69,980
U.S. Treasury obligations		23,037		2		6		23,033
Total	$	109,528	$	155	$	264	$	109,419

Schedule of Unrealized Loss on Available-for-Sale Investments

For those available-for-sale investments with unrealized losses at December 30, 2017 and December 31, 2016, 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 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
December 31, 2016
Asset-backed securities	$	1,363	$	6	$	2,314	$	13	$	3,677	$	19
Corporate bonds and direct obligations of government agencies		28,809		195		1,367		44		30,176		239
U.S. Treasury obligations		12,734		6		—		—		12,734		6
Total	$	42,906	$	207	$	3,681	$	57	$	46,587	$	264