Preferred Stock - Additional Information (Detail) (USD $)	1 Months Ended	12 Months Ended
	Nov. 21, 2008	Dec. 31, 2012	Dec. 31, 2011
Partners Capital And Distributions [Line Items]
Preferred shares sold	52,000	28,000	28,000
Common stock purchased	679,443
Proceeds from preferred stock and warrant		$ 52,000,000
Fair value allocated to preferred stock		48,980,000
Fair value allocated to warrant		3,020,000
Cumulative dividends		5.00%
Cumulative dividends payment term		First five years
Cumulative dividends		9.00%
Redeemed price of preferred stock		$ 1,000
Repurchase of warrant		2,670,000
Preferred stock outstanding		52,000	52,000
Warrant [Member]
Partners Capital And Distributions [Line Items]
Repurchase of warrant		$ 2,670,000
PREFERRED STOCK [Member]
Partners Capital And Distributions [Line Items]
Repurchase of preferred stock		24,000
Preferred stock outstanding		28,000