Series C Convertible Preferred Stock - Additional Information (Detail) (USD $)	12 Months Ended	0 Months Ended	12 Months Ended
	Dec. 31, 2011	Mar. 31, 2011 Series C Convertible Preferred Stock	Dec. 31, 2012 Series C Convertible Preferred Stock Installment	Dec. 31, 2012 Series C Convertible Preferred Stock [Member]	Mar. 06, 2011 Series C Convertible Preferred Stock [Member]	Mar. 03, 2011 Series C Convertible Preferred Stock [Member]
Preferred Stock [Line Items]
Preferred shares issued		7,000
Initial stated value per preferred share		$ 10,000
Net proceeds from sale of shares	$ 61,403,000	$ 64,013,000
Agent fees and offering costs		5,987,000
Redemption price premium percentage				102.50%
Fair value of redemption premium						700,000
Fair value of warrants					0	1,910,000
Percentage of dividend payable				8.00%
Number of equal quarterly installments			9
Installments start date			Sep. 01, 2011
Installments end date			Sep. 01, 2013
Preferred share plus accumulated and unpaid dividends			10,000
Market price discount				10.00%
Conversion price of convertible preference stock				$ 15.83
Preferred stock redemption rate				125.00%
Maximum indetedness under credit facility				$ 150,000,000