Series C Convertible Preferred Stock - Additional Information (Detail) (Series C Convertible Preferred Stock, USD $)	1 Months Ended	3 Months Ended
	Mar. 31, 2011	Mar. 31, 2013 Installment
Series C Convertible Preferred Stock
Preferred Stock [Line Items]
Preferred shares issued	7,000
Initial stated value per preferred share	$ 10,000
Net proceeds from sale of shares	$ 64,013,000
Agent fees and offering costs	5,987,000
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
Conversion price of convertible preference stock		$ 15.83
Conversion share of convertible preference stock		165
Issuance of common stock related to conversion of preferred stock		105,000