Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2015

Cash and Cash Equivalents [Abstract]

Summary of cash, cash equivalents and marketable securities

A summary of the Company’s cash, cash equivalents and marketable securities is shown below:

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(in thousands)
December 31, 2015
Cash and cash equivalents:
Cash and money market funds	$	582,352	$	—	$	—		$	582,352
Government-sponsored enterprise securities	85,994		—		—			85,994
Commercial paper	34,889		—		—			34,889
Corporate debt securities	11,533		—		—			11,533
Total cash and cash equivalents	$	714,768	$	—	$	—		$	714,768
Marketable securities:
Government-sponsored enterprise securities (due within 1 year)	$	87,176	$	—	$	(14	)	$	87,162
Commercial paper (due within 1 year)	98,877		246		—			99,123
Corporate debt securities (due within 1 year)	141,515		—		(106		)	141,409
Total marketable securities	327,568		246		(120		)	327,694
Total cash, cash equivalents and marketable securities	$	1,042,336	$	246	$	(120	)	$	1,042,462
December 31, 2014
Cash and cash equivalents:
Cash and money market funds	$	625,259	$	—	$	—		$	625,259
Total cash and cash equivalents	$	625,259	$	—	$	—		$	625,259
Marketable securities:
Government-sponsored enterprise securities (due within 1 year)	$	463,788	$	14	$	(52	)	$	463,750
Commercial paper (due within 1 year)	51,674		72		—			51,746
Corporate debt securities (due within 1 year)	196,065		2		(66		)	196,001
Corporate debt securities (due after 1 year through 5 years)	50,443		—		(93		)	50,350
Total marketable securities	761,970		88		(211		)	761,847
Total cash, cash equivalents and marketable securities	$	1,387,229	$	88	$	(211	)	$	1,387,106