Marketable Securities (Tables)

3 Months Ended

Mar. 31, 2017

Investments Debt And Equity Securities [Abstract]

Summary of Fair Value of Available-for-Sale Marketable Securities by Type of Security

As of March 31, 2017 and December 31, 2016 the fair value of available-for-sale marketable securities by type of security was as follows:

	March 31, 2017
(In thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
U.S. Government obligations	$	58,012	$	—	$	(26	)	$	57,986
Commercial Paper		11,521		—		—			11,521
Corporate bonds		75,153		5		(41	)		75,117
	$	144,686	$	5	$	(67	)	$	144,624

	December 31, 2016
(In thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Commercial Paper	$	7,769	$	—	$	—		$	7,769
U.S. Government obligations		75,524		5		(12	)		75,517
Corporate Bonds		96,193		1		(66	)		96,128
	$	179,486	$	6	$	(78	)	$	179,414