Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2012

Fair Value Measurements [Abstract]

Schedule of financial instruments measured at fair value on a recurring basis

	June 30, 2012 Fair value measurements using
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
	(In thousands)
Assets:
U.S. Treasury securities	$	0	$	43,964	$	0	$	43,964
Money market accounts		4,638		0		0		4,638
Total assets at fair value	$	4,638	$	43,964	$	0	$	48,602

	December 31, 2011 Fair value measurements using
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
	(In thousands)
Assets:
U.S. Treasury securities	$	0	$	48,987	$	0	$	48,987
Money market accounts		3,617		0		0		3,617
Total assets at fair value	$	3,617	$	48,987	$	0	$	52,604

Schedule of short-term investments

	June 30, 2012
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses		Fair Value
	(In thousands)
U.S. Treasury securities	$	43,964	$	0	$	0	$	43,964
Total	$	43,964	$	0	$	0	$	43,964

	December 31, 2011
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses		Fair Value
	(In thousands)
U.S. Treasury securities	$	48,970	$	17	$	0	$	48,987
Total	$	48,970	$	17	$	0	$	48,987