Marketable Securities (Tables)

9 Months Ended

Sep. 30, 2016

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)
As of September 30, 2016
Cash and cash equivalents:
Cash and money market funds	$	719,692	$	—	$	—		$	719,692
Total cash and cash equivalents	$	719,692	$	—	$	—		$	719,692
Marketable securities:
Government-sponsored enterprise securities (due within 1 year)	130,404		29		(2		)	130,431
Commercial paper (due within 1 year)	131,099		277		—			131,376
Corporate debt securities (due within 1 year)	147,016		6		(80		)	146,942
Total marketable securities	$	408,519	$	312	$	(82	)	$	408,749
Total cash, cash equivalents and marketable securities	$	1,128,211	$	312	$	(82	)	$	1,128,441
As of 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