Marketable Securities

3 Months Ended

Mar. 31, 2016

Investments, Debt and Equity Securities [Abstract]

Marketable Securities

Marketable Securities

At March 31, 2016, marketable securities consisted of the following (in thousands):

	Amortized Cost		Unrealized Gains		Unrealized Losses			Aggregate Fair Value
U.S. treasury debt securities	$	4,008	$	2	$	(3	)	$	4,007
U.S. corporate debt securities	8,645		19		(6		)	8,658
Money market funds	37,419		—		—			37,419
	$	50,072	$	21	$	(9	)	$	50,084
Included in cash and cash equivalents	$	37,419	$	—	$	—		$	37,419
Included in marketable securities	$	12,653	$	21	$	(9	)	$	12,665

At December 31, 2015, marketable securities consisted of the following (in thousands):

	Amortized Cost		Unrealized Gains		Unrealized Losses			Aggregate Fair Value
U.S. treasury debt securities	$	4,805	$	—	$	(31	)	$	4,774
U.S. corporate debt securities	12,679		1		(34		)	12,646
Money market funds	53,365		—		—			53,365
	$	70,849	$	1	$	(65	)	$	70,785
Included in cash and cash equivalents	$	53,365	$	—	$	—		$	53,365
Included in marketable securities	$	17,484	$	1	$	(65	)	$	17,420

The following table presents gross unrealized losses and fair values for those marketable securities that were in an unrealized loss position as of March 31, 2016, aggregated by investment category and the length of time that individual securities have been in a continuous loss position (in thousands):

	As of March 31, 2016
	Less than 12 months					12 months or greater
	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss
U.S. treasury debt securities	$	2,407	$	(3	)	$	—	$	—
U.S. corporate debt securities	2,503		(6		)	—		—
Total	$	4,910	$	(9	)	$	—	$	—

We do not believe any of the unrealized losses represented an other-than-temporary impairment based on our evaluation of available evidence, which includes our intent as of March 31, 2016 to hold these investments until the cost basis is recovered.