Quarterly Financial Information (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2012

Quarterly Financial Information (Unaudited) [Abstract]

Quarterly Information

	Quarter Ended
	March 31			June 30			September 30			December 31
	(in thousands, except per share data)
2012:
Revenue	$	4,642		$	7,103		$	5,765		$	4,567
Net loss	$	(7,336	)	$	(5,920	)	$	(7,217	)	$	(8,035	)
Net loss per share	$	(0.06	)	$	(0.05	)	$	(0.05	)	$	(0.06	)

	Quarter Ended
	March 31			June 30			September 30			December 31
	(in thousands, except per share data)
2011:
Revenue	$	834		$	3,001		$	5,008		$	5,845
Net loss	$	(7,453	)	$	(4,993	)	$	(3,212	)	$	(3,705	)
Net loss per share	$	(0.07	)	$	(0.04	)	$	(0.03	)	$	(0.03	)