Marketable Securities (Tables)

9 Months Ended

Sep. 30, 2014

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, 2014
Cash and cash equivalents:
Cash and money market funds	$	718,562	$	1	$	—		$	718,563
Total cash and cash equivalents	$	718,562	$	1	$	—		$	718,563
Marketable securities:
Government-sponsored enterprise securities (due within 1 year)	$	467,857	$	27	$	(16	)	$	467,868
Commercial paper (due within 1 year)	46,402		94		—			46,496
Corporate debt securities (due within 1 year)	213,352		2		—			213,354
Corporate debt securities (due after 1 year through 5 years)	31,497		—		(41		)	31,456
Total marketable securities	$	759,108	$	123	$	(57	)	$	759,174
Total cash, cash equivalents and marketable securities	$	1,477,670	$	124	$	(57	)	$	1,477,737
As of December 31, 2013
Cash and cash equivalents:
Cash and money market funds	$	569,299	$	—	$	—		$	569,299
Total cash and cash equivalents	$	569,299	$	—	$	—		$	569,299
Marketable securities:
Government-sponsored enterprise securities (due within 1 year)	$	600,496	$	7	$	(53	)	$	600,450
Commercial paper (due within 1 year)	83,384		109		—			83,493
Corporate debt securities (due within 1 year)	189,674		14		(34		)	189,654
Corporate debt securities (due after 1 year through 5 years)	22,181		6		(7		)	22,180
Total marketable securities	$	895,735	$	136	$	(94	)	$	895,777
Total cash, cash equivalents and marketable securities	$	1,465,034	$	136	$	(94	)	$	1,465,076