Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2013

Fair Value Measurements

Schedule of financial instruments measured at fair value on recurring basis

	Actively QuotedMarkets forIdentical AssetsLevel 1		Significant OtherObservableInputsLevel 2		SignificantUnobservableInputsLevel 3		Balance atJune 30,2013
	(In thousands)
As of June 30, 2013:
Assets
Money market deposits	$	7,128	$	—	$	—	$	7,128
U.S. Treasury securities	1,259		—		—		1,259
Debt securities of U.S. government-sponsored entities	—		1,115		—		1,115
Commercial paper	—		53,685		—		53,685
Corporate debt securities	—		25,569		—		25,569
Total	$	8,387	$	80,369	$	—	$	88,756

	Actively QuotedMarkets forIdentical Assets Level 1		Significant Other Observable Inputs Level 2		Significant Unobservable Inputs Level 3		Balance at December 31, 2012
	(In thousands)
As of December 31, 2012:
Assets
Money market deposits	$	7,403	$	—	$	—	$	7,403
U.S. Treasury securities	1,276		—		—		1,276
Debt securities of U.S. government-sponsored entities	—		761		—		761
Commercial paper	—		33,888		—		33,888
Corporate debt securities	—		52,102		—		52,102
Total	$	8,679	$	86,751	$	—	$	95,430

Summary of available-for-sale marketable securities

	June 30, 2013
	AmortizedCost		UnrealizedGains		UnrealizedLosses			EstimatedFair Value
	(In thousands)
U.S. Treasury securities	$	1,258	$	1	$	—		$	1,259
Debt securities of U.S. government-sponsored entities	1,115		—		—			1,115
Commercial paper	46,451		34		—			46,485
Corporate debt securities	25,583		1		(15		)	25,569
Total	$	74,407	$	36	$	(15	)	$	74,428
	December 31, 2012
	Amortized Cost		Unrealized Gains		Unrealized Losses			Estimated Fair Value
	(In thousands)
U.S. Treasury securities	$	1,275	$	1	$	—		$	1,276
Debt securities of U.S. government-sponsored entities	761		—		—			761
Commercial paper	28,854		35		—			28,889
Corporate debt securities	50,155		2		(23		)	50,134
Total	$	81,045	$	38	$	(23	)	$	81,060