8.50% Senior Unsecured Convertible Notes - Additional Information (Detail)				1 Months Ended	3 Months Ended			9 Months Ended
	Jul. 16, 2015 USD ($)	Jun. 05, 2014 USD ($)	Feb. 21, 2014	Feb. 28, 2014 USD ($) d Director $ / shares	Sep. 30, 2015 USD ($)	Jun. 30, 2015 $ / shares shares	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)	[1]
Debt Instrument [Line Items]
Common stock issued for rights offering, net of costs | shares						6,688,433
Fair Value Assumptions and Methodology for Assets and Liabilities [Abstract]
Expected Volatility		40.00%
Convertible Notes, net of discount (Note 11)					$ 57,867,000			$ 57,867,000		$ 55,881,000
Debt instrument origination cost					1,907,000			1,907,000		$ 3,936,000
Interest	$ 5,200,000
Amortizing debt discounts	1,700,000
Debt issuance cost	$ 1,700,000
Change in fair value of conversion derivative liability					0		$ 0	$ 0	$ 6,759,000
8.50% Senior Unsecured Convertible Notes Due 2019
Debt Instrument [Line Items]
Debt instrument issued				$ 70,700,000
Stated interest rate				8.50%
Debt instrument, due date									2019
Debt instrument, issuance date			Feb. 21, 2014
Number of board of directors | Director				2
Debt instrument, maturity date								Feb. 15, 2019
Debt instrument, frequency of periodic payment								semi-annually in arrears on August 15 and February 15 of each year
Debt instrument, convertible, conversion rate				147.9290		151.7912
Debt Instrument, Convertible, Conversion Price | $ / shares				$ 6.76		$ 6.59
Common stock issued for rights offering, net of costs | shares						6,688,433
Debt instrument, redemption start date								Feb. 15, 2017
Debt instrument, convertible, minimum percentage of common stock price				130.00%
Debt instrument, convertible, threshold trading days | d				20
Debt instrument, convertible, threshold consecutive trading days				30 days
Debt instrument, redemption price, percentage				100.00%
Fair Value Assumptions and Methodology for Assets and Liabilities [Abstract]
Conversion derivative liability, at estimated fair value		$ 23,700,000
Convertible Notes, net of discount (Note 11)					57,900,000			$ 57,900,000
Unamortized debt discount					12,800,000			12,800,000
Debt instrument origination cost					1,900,000			1,900,000
Interest expense of notes					2,300,000		2,200,000	6,800,000	$ 5,300,000
Interest					1,500,000		1,500,000	4,500,000	3,700,000
Amortizing debt discounts					711,000		605,000	2,000,000	1,400,000
Debt issuance cost					$ 105,000		$ 90,000	$ 294,000	239,000
Change in fair value of conversion derivative liability									$ 6,800,000
8.50% Senior Unsecured Convertible Notes Due 2019 | Reclassifications to Additional Paid in Capital
Fair Value Assumptions and Methodology for Assets and Liabilities [Abstract]
Unamortized transaction costs		756,000
Deferred tax asset, conversion derivative liability		$ 8,800,000
8.50% Senior Unsecured Convertible Notes Due 2019 | Bulldog Investors Llc
Debt Instrument [Line Items]
Debt instrument issued				$ 9,200,000
Conversion derivative liability | 8.50% Senior Unsecured Convertible Notes Due 2019
Fair Value Assumptions and Methodology for Assets and Liabilities [Abstract]
Expected Term in Years		4 years 8 months 12 days
Risk Free Rate		1.50%

[1] Derived from audited consolidated financial statements.