Short-term Investments

3 Months Ended

Mar. 31, 2019

Investments, Debt and Equity Securities [Abstract]

Short-term Investments

Short-term Investments

Short-term investments consisted of available-for-sale securities as follows (in thousands):

Type of securities as of March 31, 2019	Amortized cost		Gross unrealized gains		Gross unrealized losses		Fair value
Corporate debt securities	$	39,914	$	15	$	—	$	39,929
U.S. government-related debt securities	10,926		3		—		10,929
Asset-backed securities	7,427		3		—		7,430
Total available-for-sale securities	$	58,267	$	21	$	—	$	58,288

Type of securities as of December 31, 2018	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
Corporate debt securities	$	47,299	$	1	$	(21	)	$	47,279
U.S. government-related debt securities	14,972		—		(11		)	14,961
Asset-backed securities	7,410		—		(9		)	7,401
Total available-for-sale securities	$	69,681	$	1	$	(41	)	$	69,641

The fair values of available-for-sale securities by contractual maturity were as follows (in thousands):

	March 31, 2019		December 31, 2018
Maturing in one year or less	$	58,288	$	69,641
Maturing in one to three years	—		—
Total available-for-sale securities	$	58,288	$	69,641