Investments (Tables)

6 Months Ended

Jun. 30, 2017

Investments, Debt and Equity Securities [Abstract]

Summary of amortized cost, unrealized gain and loss and the fair value of available-for-sale securities

The following table is a summary of amortized cost, unrealized gain and loss, and the fair value of available-for-sale securities as of June 30, 2017 and December 31, 2016 (in thousands):

	June 30, 2017
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Investments:
Corporate debt	$	43,185	$	1	$	(66	)	$	43,120
U.S. Treasury notes	68,309		—		(118		)	68,191
Total	$	111,494	$	1	$	(184	)	$	111,311
Reported as:
Short-term investments	$	94,891	$	1	$	(167	)	$	94,725
Long-term investments	16,603		—		(17		)	16,586
Total	$	111,494	$	1	$	(184	)	$	111,311

	December 31, 2016
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Investments:
Corporate debt	$	51,354	$	—	$	(121	)	$	51,233
U.S. Treasury notes	61,048		5		(77		)	60,976
Total	$	112,402	$	5	$	(198	)	$	112,209
Reported as:
Short-term investments	$	90,050	$	1	$	(134	)	$	89,917
Long-term investments	22,352		4		(64		)	22,292
Total	$	112,402	$	5	$	(198	)	$	112,209