Available-for-Sale Securities and Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2016

Available for Sale Securities and Fair Value Measurements

Schedule of classification of available for sale securities in consolidated balance sheets

	December 31,
(In thousands)	2016		2015
Cash equivalents	$	323,602	$	69,126
Short-term marketable securities		156,387		59,727
Long-term marketable securities		91,565		42,860
Total	$	571,554	$	171,713

Schedule of available-for-sale securities

		December 31, 2016
(In thousands)		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
U.S. government securities	Level 1	$	69,963	$	39	$	(47	)	$	69,955
U.S. government agency securities	Level 2		60,783		9		(45	)		60,747
Corporate notes	Level 2		98,522		4		(213	)		98,313
Commercial paper	Level 2		18,937		—		—			18,937
Marketable securities			248,205		52		(305	)		247,952
Money market funds	Level 1		323,602		—		—			323,602
Total		$	571,807	$	52	$	(305	)	$	571,554

		December 31, 2015
(In thousands)		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
U.S. government securities	Level 1	$	47,068	$	4	$	(29	)	$	47,043
U.S. government agency securities	Level 2		31,502		—		(37	)		31,465
Corporate notes	Level 2		19,098		2		(11	)		19,089
Commercial paper	Level 2		4,990		—		—			4,990
Marketable securities			102,658		6		(77	)		102,587
Money market funds	Level 1		69,126		—		—			69,126
Total		$	171,784	$	6	$	(77	)	$	171,713