Short-term Investments (Tables)

12 Months Ended

Dec. 31, 2016

Investments, Debt and Equity Securities [Abstract]

Short-Term Investments Available-for-Sale Securities

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

Type of securities as of December 31, 2016	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
Corporate debt securities	$	36,198	$	4	$	(42	)	$	36,160
U.S. government-related debt securities	17,312		1		(20		)	$	17,293
Total available-for-sale securities	$	53,510	$	5	$	(62	)	$	53,453

Type of securities as of December 31, 2015	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
Corporate debt securities	$	26,116	$	—	$	(28	)	$	26,088
U.S. government-related debt securities	1,101		—		(1		)	1,100
Total available-for-sale securities	$	27,217	$	—	$	(29	)	$	27,188

Fair Values of Available-for-Sale Securities by Contractual Maturity

The fair values of available-for-sale securities by contractual maturity at December 31 were as follows (in thousands):

	2016		2015
Maturing in one year or less	$	46,310	$	27,188
Maturing in one to three years	7,143		—
Total available-for-sale securities	$	53,453	$	27,188