Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2016

Fair Value Measurements

Schedule of the Company's financial assets and liabilities that have been measured at fair value on a recurring basis

Description	Total		Level 1		Level 2		Level 3
	(in thousands)
September 30, 2016
Assets:
Money market funds	$	42,490	$	42,490	$	—	$	—
Available-for-sale securities:
Certificates of deposit	33,380		33,380		—		—
U.S. treasury notes	57,085		57,085		—		—
U.S. government agency securities	122,142		—		122,142		—
Total assets at fair value	$	255,097	$	132,955	$	122,142	$	—
December 31, 2015
Assets:
Money market funds	$	31,761	$	31,761	$	—	$	—
Available-for-sale securities:
Certificates of deposit	32,003		32,003		—		—
U.S. treasury notes	35,054		35,054		—		—
U.S. government agency securities	148,183		—		148,183		—
Total assets at fair value	$	247,001	$	98,818	$	148,183	$	—