Marketable Securities (Tables)

6 Months Ended

Jun. 30, 2015

The following table provides the Company’s marketable securities by security type as of June 30, 2015 and December 31, 2014 (in thousands):



	As of June 30, 2015
	Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Commercial paper and corporate bonds	$	415,067	$	30	$	(546	)	$	414,551
U.S. government agency debt securities	14,501		7		(8		)	14,500
Total	$	429,568	$	37	$	(554	)	$	429,051



	As of December 31, 2014
	Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Commercial paper and corporate bonds	$	417,845	$	72	$	(791	)	$	417,126
Total	$	417,845	$	72	$	(791	)	$	417,126

Contractual maturities of marketable securities

Contractual maturities of the Company’s marketable securities as of June 30, 2015 and December 31, 2014 are summarized as follows (in thousands):



	As of June 30, 2015				As of December 31, 2014
	Cost		Estimated Fair Value		Cost		Estimated Fair Value
Due in one year or less	$	222,701	$	222,625	$	233,326	$	233,284
Due in one to five years	206,867		206,426		184,519		183,842
Total	$	429,568	$	429,051	$	417,845	$	417,126

Fair market value and gross unrealized losses of marketable securities

The following tables provide the fair market value and the gross unrealized losses of the Company's marketable securities with unrealized losses, aggregated by security type, as of June 30, 2015 and December 31, 2014 (in thousands):



	In Loss Position for Less than 12 Months
	As of June 30, 2015					As of December 31, 2014
	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
Commercial paper and corporate bonds	$	283,863	$	(501	)	$	322,938	$	(791	)
U.S. government agency debt securities	14,500		(8		)	—		—
Total	$	298,363	$	(509	)	$	322,938	$	(791	)



	In Loss Position for More than 12 Months
	As of June 30, 2015					As of December 31, 2014
	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
Commercial paper and corporate bonds	$	32,834	$	(45	)	$	—	$	—
Total	$	32,834	$	(45	)	$	—	$	—