Summary of Significant Accounting Policies - Basic and Diluted Net Loss Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended				9 Months Ended
		Sep. 30, 2015		Sep. 30, 2014		Sep. 30, 2015	Sep. 30, 2014
Numerator
Net income (loss), basic		$ (12,981)		$ (1,461)		$ (29,843)	$ 71,060
Income (loss) from discontinued operations		(1,635)		(11,364)		64,829	(41,952)
Net income (loss), diluted		$ (12,981)		$ (1,461)		$ (29,843)	$ 45,039
Denominator
Weighted average common shares outstanding, basic		22,613,000		17,630,000		20,332,000	17,513,000
Weighted average shares outstanding, diluted		22,613,000		17,630,000		20,332,000	17,909,000
Basic net income (loss), Continuing operations, usd per share	[1]	$ (0.57)		$ (0.08)		$ (1.47)	$ 4.06
Basic net income (loss), Discontinued operations, usd per share		(0.07)	[1]	(0.64)	[1]	3.19	(2.40)	[1]
Diluted net income (loss), Continuing operations, usd per share	[1]	(0.57)		(0.08)		(1.47)	2.51
Diluted net income (loss), Discontinued operations, usd per share	[1]	$ (0.07)		$ (0.64)		$ 3.19	$ (2.34)
Common stock options
Denominator
Anti-dilutive securities excluded from computation of earnings per share amount		1,786,000		7,000		471,000	1,239,000
Common stock warrants
Denominator
Anti-dilutive securities excluded from computation of earnings per share amount		32,000
Continuing Operations
Numerator
Common stock warrants		$ 0		$ 0		$ 0	$ 26,021
Equity awards		0		0		0	0
Dilutive Securities, Effect on Basic Earnings Per Share		$ 0		$ 0		$ 0	$ (26,021)
Denominator
Common stock warrants, shares		0		0		0	396,000
Non-employee stock options and restricted stock units, shares		0		0		0	0
Dilutive potential shares of common stock, shares		0		0		0	396,000
Weighted average shares outstanding, diluted		22,613,000		17,630,000		20,332,000	17,909,000
Discontinued Operations
Numerator
Common stock warrants		$ 0		$ 0		$ 0	$ 0
Equity awards		0		0		0	0
Dilutive Securities, Effect on Basic Earnings Per Share		$ 0		$ 0		$ 0	$ 0
Denominator
Common stock warrants, shares		0		0		0	396,000
Non-employee stock options and restricted stock units, shares		0		0		0	0
Dilutive potential shares of common stock, shares		0		0		0	396,000
Weighted average shares outstanding, diluted		22,613,000		17,630,000		20,332,000	17,909,000

[1] The sum of net income (loss) per share amounts may not equal the totals due to rounding.