Summary of Significant Accounting Policies - Basic and Diluted Net Loss Per Share (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Numerator
Net loss from continuing operations	$ (10,165)	$ (4,952)
Loss from discontinued operations, net of applicable tax	(12,696)	(15,980)
Net loss, diluted	(10,165)	(13,353)
Denominator
Weighted average common shares outstanding, basic	153,362,000	139,309,000
Weighted average common shares outstanding, diluted	153,362,000	145,323,000
Continuing operations, usd per share	$ (0.07)	$ (0.04)
Discontinued operations, usd per share	$ (0.08)	$ (0.11)
Continuing operations, usd per share	$ (0.07)	$ (0.09)
Discontinued operations, usd per share	$ (0.08)	$ (0.11)
Common stock options
Denominator
Anti-dilutive securities excluded from computation of earnings per share amount	730,000	11,246,000
Common Stock Warrants
Denominator
Anti-dilutive securities excluded from computation of earnings per share amount	15,724,000	508,000
Continuing Operations
Numerator
Common stock warrants	0	8,269
Non-employee stock options and restricted stock units	0	(132)
Dilutive Securities, Effect on Basic Earnings Per Share	0	(8,401)
Denominator
Common stock warrants, shares	0	5,870,000
Non-employee stock options and restricted stock units, shares	0	144,000
Dilutive potential shares of common stock, shares	0	6,014,000
Weighted average common shares outstanding, diluted	153,362,000	145,323,000
Discontinued Operations
Numerator
Common stock warrants	0	0
Non-employee stock options and restricted stock units	0	0
Dilutive Securities, Effect on Basic Earnings Per Share	$ 0	$ 0
Denominator
Common stock warrants, shares	0	0
Non-employee stock options and restricted stock units, shares	0	0
Dilutive potential shares of common stock, shares	0	0
Weighted average common shares outstanding, diluted	153,362,000	139,309,000