Marketable Securities (Tables)

3 Months Ended

Mar. 31, 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 March 31, 2016
Cash and cash equivalents:
Cash and money market funds	$	590,688	$	—	$	—		$	590,688
Corporate debt securities	13,557		—		—			13,557
Total cash and cash equivalents	$	604,245	$	—	$	—		$	604,245
Marketable securities:
U.S. Treasury securities (due within 1 year)	$	33,108	$	—	$	(4	)	$	33,104
Government-sponsored enterprise securities (due within 1 year)	126,461		17		—			126,478
Commercial paper (due within 1 year)	141,243		319		—			141,562
Corporate debt securities (due within 1 year)	120,206		23		—			120,229
Total marketable securities	$	421,018	$	359	$	(4	)	$	421,373
Total cash, cash equivalents and marketable securities	$	1,025,263	$	359	$	(4	)	$	1,025,618
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