Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value Measurements

Schedule of Company's assets and liabilities by level within the fair value hierarchy

	December 31, 2017
	Fair Value Measurements
	Level 1		Level 2		Level 3		Total
	(in thousands)
Assets
Cash equivalents:
Money market funds, U.S. Government Securities and Agency Investments	$	116,433	$	—	$	—	$	116,433

	December 31, 2016
	Fair Value Measurements
	Level 1		Level 2		Level 3		Total
	(in thousands)
Assets
Cash equivalents:
Money market funds	$	54,170	$	—	$	—	$	54,170