Marketable Securities (Tables)

3 Months Ended

Mar. 31, 2018

Investments Debt And Equity Securities [Abstract]

Schedule of Investments

The table below summarizes the Company’s investments (in thousands):

			Gross		Gross
	Amortized		Unrealized		Unrealized			Estimated
	Cost		Gains		(Losses)			Fair Value
March 31, 2018
Cash equivalents:
Money market funds	$	20,142	$	—	$	—			20,142
Total		20,142		—		—			20,142
Available-for-sale securities:
Commercial paper securities		126,033		8		(160	)		125,881
Corporate debt securities		75,125		—		(202	)		74,923
U.S. government-sponsored entity debt securities		3,000		—		—			3,000
Total		204,158		8		(362	)		203,804
Total cash equivalents and available-for-sale securities	$	224,300	$	8	$	(362	)	$	223,946
December 31, 2017
Cash equivalents:
Money market funds	$	24,290	$	—	$	—		$	24,290
Commercial paper securities		4,595		—		—			4,595
Total		28,885		—		—			28,885
Available-for-sale securities:
Commercial paper securities		110,365		—		(118	)		110,247
Corporate debt securities		75,886		—		(131	)		75,755
U.S. government-sponsored entity debt securities		8,498		—		(6	)		8,492
Total		194,749		—		(255	)		194,494
Total cash equivalents and available-for-sale securities	$	223,634		—	$	(255	)	$	223,379