Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2018

Investments, Debt and Equity Securities [Abstract]

Investments Classified as Available-For-Sale

Marketable securities classified as available-for-sale as of December 31, 2018 and 2017 were comprised of (in thousands):

	December 31, 2018									December 31, 2017
			Gross		Gross							Gross		Gross
	Amortized		Unrealized		Unrealized					Amortized		Unrealized		Unrealized
	Cost		Gains		Losses			Fair Value		Cost		Gains		Losses			Fair Value
Asset-backed securities	$	4,999	$	―	$	(2	)	$	4,997	$	13,748	$	―	$	(5	)	$	13,743
Corporate debt securities		16,986		―		(3	)		16,983		37,265		―		(12	)		37,253
Total	$	21,985	$	―	$	(5	)	$	21,980	$	51,013	$	―	$	(17	)	$	50,996