Cash Equivalents and Investments (Tables)

12 Months Ended

Dec. 31, 2012

Cash Equivalents and Investments [Abstract]

Summary of cash and available-for-sale securities

Summary of Cash and Available-For-Sale Securities	Adjusted Cost		Unrealized Gains		Unrealized Losses			Fair Value		Cash and Cash Equivalents		Restricted Investment		Short-Term Marketable Securities		Long-Term Marketable Securities
(In thousands)
December 31, 2012
Cash	$	7,894	$	—	$	—		$	7,894	$	7,894	$	—	$	—	$	—
Money market funds	121,095		—		—			121,095		121,095		—		—		—
Certificates of deposit	26,128		—		—			26,128		2,223		20,000		3,905		—
Corporate debt securities	13,562		10		—			13,572		—		—		13,572		—
Total	$	168,679	$	10	$	—		$	168,689	$	131,212	$	20,000	$	17,477	$	—
December 31, 2011
Cash	$	3,177	$	—	$	—		$	3,177	$	3,177	$	—	$	—	$	—
Money market funds	163,368		—		—			163,368		163,368		—		—		—
Corporate debt securities	44,863		57		(43		)	44,877		—		—		27,776		17,101
Commercial paper	8,997		—		(1		)	8,996		1,999		—		6,997		—
U.S. government sponsored agency bonds	2,003		12		—			2,015		—		—		2,015		—
U.S. treasury securities	5,494		19		—			5,513		—		—		5,513		—
Total	$	227,902	$	88	$	(44	)	$	227,946	$	168,544	$	—	$	42,301	$	17,101

Investments classified by contractual maturity date

Cash and Available-For-Sale Securities by Contractual Maturity	December 31, 2012				December 31, 2011
(In thousands)	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Less than one year	$	168,679	$	168,689	$	210,807	$	210,845
Greater than one year but less than five years	—		—		17,095		17,101
Total	$	168,679	$	168,689	$	227,902	$	227,946