Calculation of Loss Per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended		301 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012
Earnings Per Share Disclosure [Line Items]
Net loss	$ (4,583)	$ (3,960)	$ (10,123)	$ (9,759)	$ (201,858)
Average common shares outstanding	15,422	12,315	14,746	11,840
Basic and diluted loss per share	$ (0.30)	$ (0.32)	$ (0.69)	$ (0.82)