Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Assets Measured at Fair Value on Recurring Basis

The Company held certain assets that are required to be measured at fair value on a recurring basis as of December 31, 2018, as follows:

			Fair Value Measurement as of December 31, 2018 Using
(in thousands)	December 31, 2018		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
U.S. Treasury and government agencies	69,270		69,270		—		—
Corporate debt	105,910		—		105,910		—
Asset-backed securities	21,175		—		21,175		—
	$	196,355	$	69,270	$	127,085	$	—

The Company held certain assets that are required to be measured at fair value on a recurring basis as of December 31, 2017, as follows:

			Fair Value Measurement as of December 31, 2017 Using
(in thousands)	December 31, 2017		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
U.S. Treasury and government agencies	$	60,618	$	60,618	$	—	$	—
Corporate debt	53,164		—		53,164		—
	$	113,782	$	60,618	$	53,164	$	—