Series C Convertible Preferred Stock - Additional Information (Detail) (Series C Convertible Preferred Stock, USD $)	1 Months Ended		2 Months Ended	3 Months Ended	9 Months Ended
	May 31, 2013	Mar. 31, 2011	Aug. 31, 2013	Mar. 31, 2013	Sep. 30, 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		$ 15.83	$ 15.83
Conversion share of convertible preference stock	650			165
Issuance of common stock related to conversion of preferred stock	418,000		432,000	105,000