Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2012

Fair Value Measurements

Schedule of financial instruments measured at fair value on recurring basis

	Actively Quoted Markets for Identical 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 agencies		—		761		—		761
Commercial paper		—		33,888		—		33,888
Corporate debt securities		—		52,102		—		52,102
Total	$	8,679	$	86,751	$	—	$	95,430

	Actively Quoted Markets for Identical Assets Level 1		Significant Other Observable Inputs Level 2		Significant Unobservable Inputs Level 3		Balance at December 31, 2011
	(In thousands)
As of December 31, 2011:
Assets
Money market deposits	$	7,377	$	—	$	—	$	7,377
Debt securities of U.S. government-sponsored agencies		—		19,350		—		19,350
Commercial paper		—		19,999		—		19,999
Corporate debt securities		—		29,005		—		29,005
Total	$	7,377	$	68,354	$	—	$	75,731

Summary of available-for-sale marketable securities

	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

	December 31, 2011
	Amortized Cost		Unrealized Gains		Unrealized Losses			Estimated Fair Value
	(In thousands)
Debt securities of U.S. government-sponsored entities	$	19,351	$	2	$	(2	)	$	19,351
Commercial paper		19,232		17		—			19,249
Corporate debt securities		29,052		5		(52	)		29,005
Total	$	67,635	$	24	$	(54	)	$	67,605

Schedule of the breakdown of available-for-sale marketable securities with unrealized losses

	In a Loss Position for Less Than 12 Months
As of December 31, 2012:	Gross Unrealized Losses			Estimated Fair Value
	(In thousands)
Corporate debt securities	$	(23	)	$	40,499
Total	$	(23	)	$	40,499