Available-for-Sale Marketable Securities (Tables)

6 Months Ended

Jun. 30, 2017

Investments, Debt and Equity Securities [Abstract]

Summary of Available-for-Sale Marketable Securities by Major Type of Security

The following tables summarize the Company’s available-for-sale marketable securities by major type of security as of June 30, 2017 and December 31, 2016:

As of June 30, 2017

			Gross Unrealized					Estimated Fair Value
Type of Security	Amortized Cost		Gains		Losses
Money market funds	$	42,976	$	7	$	—		$	42,983
U.S. government agency obligations		7,999		—		(1	)		7,998
Corporate bonds		26,901		—		(12	)		26,889
Commercial paper		25,157		—		(7	)		25,150
Total available-for-sale marketable securities	$	103,033	$	7	$	(20	)	$	103,020

As of December 31, 2016

			Gross Unrealized					Estimated Fair Value
Type of Security	Amortized Cost		Gains		Losses
Money market funds	$	8,268	$	8	$	—		$	8,276
U.S. Treasury securities		2,523		—		(1	)		2,522
U.S. government agency obligations		3,501		1		—			3,502
Corporate bonds		16,683		—		(6	)		16,677
Commercial paper		15,206		3		(2	)		15,207
Total available-for-sale marketable securities	$	46,181	$	12	$	(9	)	$	46,184

Schedule of Amortized Cost and Fair Values of Marketable Debt Securities by Contractual Maturity

The Company classifies its marketable debt securities based on their contractual maturity dates. As of June 30, 2017, the Company’s marketable debt securities mature at various dates through April 2018. The amortized cost and fair values of marketable debt securities by contractual maturity were as follows. The table does not include money market funds that are classified as available-for-sale marketable securities.

	As of June 30, 2017				As of December 31, 2016
Contractual maturity	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Less than one year	$	60,057	$	60,037	$	37,913	$	37,908

Schedule of Fair Values and Continuous Unrealized Loss Positions of Available-for-Sale Marketable Securities

The following tables show the fair value of the Company’s available-for-sale marketable securities that have unrealized losses and that are deemed to be only temporarily impaired, aggregated by investment category and length of time that the individual investments have been in a continuous unrealized loss position.

As of June 30, 2017

	Less than 12 Months					12 Months or Greater				Total
	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
U.S. government agency obligations	$	4,004	$	(1	)	$	—	$	—	$	4,004	$	(1	)
Corporate bonds		24,888		(12	)		—		—		24,888		(12	)
Commercial paper		22,152		(7	)		—		—		22,152		(7	)
Total	$	51,044	$	(20	)	$	—	$	—	$	51,044	$	(20	)

As of December 31, 2016

	Less than 12 Months					12 Months or Greater				Total
	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
U.S. Treasury securities	$	2,522	$	(1	)	$	—	$	—	$	2,522	$	(1	)
Corporate bonds		9,919		(6	)		—		—		9,919		(6	)
Commercial paper		5,227		(2	)		—		—		5,227		(2	)
Total	$	17,668	$	(9	)	$	—	$	—	$	17,668	$	(9	)