Series B Cumulative Convertible Preferred Stock - Additional Information (Detail) (USD $)			9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013 Series B Preferred Stock Item Director	Sep. 30, 2013 Series B Preferred Stock Minimum	Sep. 30, 2013 Series A Preferred Stock
Conversion Of Stock [Line Items]
Series B Cumulative Convertible Preferred Stock, par value	$ 0.01	$ 0.01
Series B Cumulative Convertible Preferred Stock, liquidating preference per share	$ 25	$ 25
Preferred Stock, dividend rate			6.25%		8.625%
Preferred Stock, conversion start date			Jan. 25, 2012
Number of consecutive trading days used in conversion analysis			30 days	20 days
Percentage of common stock price to then-prevailing conversion price in order to exercise conversion option				130.00%
Minimum number of quarters with failure to pay dividends, which triggers voting rights for preferred stock, quarters			6
Number of Board Of Directors that Preferred Stock owners are entitled to vote to elect when there is a failure to pay quarterly dividends for a set period			2
Minimum ratio of votes required to materially and adversely change the terms of preferred stock			0.667