Marketable Securities

3 Months Ended

Mar. 31, 2017

Investments, Debt and Equity Securities [Abstract]

Marketable Securities

Marketable Securities

At March 31, 2017, marketable securities consisted of the following (in thousands):

	Amortized Cost		Unrealized Gains		Unrealized Losses			Aggregate Fair Value
U.S. treasury debt securities	$	3,502	$	—	$	(6	)	$	3,496
U.S. corporate debt securities	9,003		3		(4		)	9,002
Money market funds	45,230		—		—			45,230
	$	57,735	$	3	$	(10	)	$	57,728
Included in cash and cash equivalents	$	45,230	$	—	$	—		$	45,230
Included in marketable securities	$	12,505	$	3	$	(10	)	$	12,498

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

	Amortized Cost		Unrealized Gains		Unrealized Losses			Aggregate Fair Value
U.S. treasury debt securities	$	3,503	$	—	$	(5	)	$	3,498
U.S. corporate debt securities	7,943		1		(7		)	7,937
Money market funds	43,496		—		—			43,496
	$	54,942	$	1	$	(12	)	$	54,931
Included in cash and cash equivalents	$	43,496	$	—	$	—		$	43,496
Included in marketable securities	$	11,446	$	1	$	(12	)	$	11,435

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, 2017, 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, 2017
	Less than 12 months					12 months or greater
	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss
U.S. treasury debt securities	$	3,496	$	(6	)	$	—	$	—
U.S. corporate debt securities	5,036		(4		)	—		—
Total	$	8,532	$	(10	)	$	—	$	—

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, 2017 to hold these investments until the cost basis is recovered.