Cash and Cash Equivalents and Investments

6 Months Ended

Jun. 30, 2011

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 June 30, 2011 and December 31, 2010 are as follows:

	As of June 30, 2011
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(in thousands)
Cash and cash equivalents	$	20,328	$	—	$	—		$	20,328
Securities maturing within one year:
Certificates of deposit	545		—		—			545
U.S. treasury securities	143,870		72		(1		)	143,941
Total short-term investments	$	144,415	$	72	$	(1	)	$	144,486
Total cash and cash equivalents and investments	$	164,743	$	72	$	(1	)	$	164,814
	As of December 31, 2010
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
			(in thousands)
Cash and cash equivalents	$	47,207	$	1	$	—		$	47,208
Securities maturing within one year:
Certificates of deposit	545		—		—			545
U.S. treasury securities	163,354		10		(6		)	163,358
Total short-term investments	$	163,899	$	10	$	(6	)	$	163,903
Total cash and cash equivalents and investments	$	211,106	$	11	$	(6	)	$	211,111

There were no realized gains or losses for the three and six months ended June 30, 2011 and 2010. The cost of securities sold is based on the specific identification method.