Investments (Tables)

9 Months Ended

Sep. 30, 2016

Investments

Summary of the Company's cash equivalents and investments

	September 30, 2016
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(in thousands)
Cash equivalents:
Money market funds	$	42,490	$	—	$	—		$	42,490
Short-term investments:
Certificates of deposit	23,281		3		(12		)	23,272
U.S. treasury notes	36,524		14		(3		)	36,535
U.S. government agency securities	103,122		42		(10		)	103,154
Long-term investments:
Certificates of deposit	10,121		5		(18		)	10,108
U.S. treasury notes	20,554		8		(12		)	20,550
U.S. government agency securities	18,983		11		(6		)	18,988
Total	$	255,075	$	83	$	(61	)	$	255,097

	December 31, 2015
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(in thousands)
Cash equivalents:
Money market funds	$	31,761	$	—	$	—		$	31,761
Short-term investments:
Certificates of deposit	19,774		—		(28		)	19,746
U.S treasury notes	12,620		—		(14		)	12,606
U.S. government agency securities	102,683		—		(110		)	102,573
Long-term investments:
Certificates of deposit	12,299		—		(42		)	12,257
U.S. treasury notes	22,553		—		(105		)	22,448
U.S. government agency securities	45,793		—		(183		)	45,610
Total	$	247,483	$	—	$	(482	)	$	247,001