Stockholders' Equity - Summary of Preferred Shares Outstanding (Detail) (USD $)	Dec. 31, 2012	Dec. 31, 2011
Series F Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Shares Outstanding	500	500
Liquidation Preference	$ 50,000	$ 50,000
Series G Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Shares Outstanding	250	250
Liquidation Preference	25,000	25,000
Series J Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Shares Outstanding	400	600
Liquidation Preference	100,000	150,000
Series K Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Shares Outstanding	200	200
Liquidation Preference	$ 50,000	$ 50,000