Cash and Cash Equivalents and Investments

3 Months Ended

Mar. 31, 2015

Cash and Cash Equivalents and Investments [Abstract]

Cash and Cash Equivalents Disclosure

Cash and Cash Equivalents and Investments

The fair value of cash and cash equivalents and investments held at March 31, 2015 and December 31, 2014 are as follows:

	As of March 31, 2015
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(in thousands)
Cash and cash equivalents	$	41,960	$	—	$	—		$	41,960
Securities maturing within one year:
Certificates of deposit	552		—		—			552
U.S. treasury securities	272,562		50		(27		)	272,585
Total short-term investments	$	273,114	$	50	$	(27	)	$	273,137
Total cash and cash equivalents and investments	$	315,074	$	50	$	(27	)	$	315,097
	As of December 31, 2014
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
			(in thousands)
Cash and cash equivalents	$	137,266	$	—	$	—		$	137,266
Securities maturing within one year:
Certificates of deposit	552		—		—			552
U.S. treasury securities	201,584		3		(66		)	201,521
Total short-term investments	$	202,136	$	3	$	(66	)	$	202,073
Total cash and cash equivalents and investments	$	339,402	$	3	$	(66	)	$	339,339

There were no realized gains or losses for the three months ended March 31, 2015, and no realized gains or losses for the three months ended March 31, 2014. The cost of securities sold is based on the specific identification method.