Marketable Securities (Tables)

9 Months Ended

Sep. 30, 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)
As of September 30, 2015
Cash and cash equivalents:
Cash and money market funds	$	707,141	$	—	$	—		$	707,141
Commercial paper	$	25,109	$	—	$	—		$	25,109
Corporate debt securities	$	24,000	$	—	$	—		$	24,000
Total cash and cash equivalents	$	756,250	$	—	$	—		$	756,250
Marketable securities:
Commercial paper (due within 1 year)	$	140,131	$	114	$	—		$	140,245
Corporate debt securities (due within 1 year)	109,386		28		(79		)	109,335
Total marketable securities	$	249,517	$	142	$	(79	)	$	249,580
Total cash, cash equivalents and marketable securities	$	1,005,767	$	142	$	(79	)	$	1,005,830
As of 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