Investments (Tables)

6 Months Ended

Jun. 30, 2015

Investments

Summary of the Company's cash equivalents and investments

	June 30, 2015
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(in thousands)
Cash equivalents:
Money market funds	$	50,357	$	—	$	—		$	50,357
U.S. government agency securities	3,125		—		—			3,125
Short-term investments:
Certificates of deposit	7,935		1		—			7,936
U.S. treasury notes	2,000		—		—			2,000
U.S. government agency securities	85,079		2		(22		)	85,059
Long-term investments:
Certificates of deposit	10,830		1		—			10,831
U.S. treasury notes	10,022		2		(1		)	10,023
U.S. government agency securities	68,698		5		(48		)	68,655
Total	$	238,046	$	11	$	(71	)	$	237,986

	December 31, 2014
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(in thousands)
Cash equivalents:
Money market funds	$	357	$	—	$	—		$	357
Short-term investments:
Certificates of deposit	2,934		—		—			2,934
U.S treasury notes	9,020		4		—			9,024
U.S. government agency securities	8,853		—		(8		)	8,845
Long-term investments:
Certificates of deposit	1,848		—		—			1,848
U.S. treasury notes	2,494		—		(5		)	2,489
U.S. government agency securities	31,454		—		(50		)	31,404
Total	$	56,960	$	4	$	(63	)	$	56,901