Stockholders' Equity of REIT and Partners' Capital of Operating Partnership - Schedule of Preferred Stock (Parenthetical) (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Series L Preferred Stock [Member]
Class of Stock [Line Items]
Preferred shares, liquidation preference per share	$ 25	$ 25
Preferred shares, par value	$ 0.01	$ 0.01
Preferred shares, shares issued	2,000	2,000
Preferred shares, shares outstanding	2,000	2,000
Series M Preferred Stock [Member]
Class of Stock [Line Items]
Preferred shares, liquidation preference per share	$ 25	$ 25
Preferred shares, par value	$ 0.01	$ 0.01
Preferred shares, shares issued	2,300	2,300
Preferred shares, shares outstanding	2,300	2,300
Series O Preferred Stock [Member]
Class of Stock [Line Items]
Preferred shares, liquidation preference per share	$ 25	$ 25
Preferred shares, par value	$ 0.01	$ 0.01
Preferred shares, shares issued	3,000	3,000
Preferred shares, shares outstanding	3,000	3,000
Series P Preferred Stock [Member]
Class of Stock [Line Items]
Preferred shares, liquidation preference per share	$ 25	$ 25
Preferred shares, par value	$ 0.01	$ 0.01
Preferred shares, shares issued	2,000	2,000
Preferred shares, shares outstanding	2,000	2,000
Series Q Preferred Stock [Member]
Class of Stock [Line Items]
Preferred shares, liquidation preference per share	$ 50	$ 50
Preferred shares, par value	$ 0.01	$ 0.01
Preferred shares, shares issued	2,000	2,000
Preferred shares, shares outstanding	2,000	2,000
Series R Preferred Stock [Member]
Class of Stock [Line Items]
Preferred shares, liquidation preference per share	$ 25	$ 25
Preferred shares, par value	$ 0.01	$ 0.01
Preferred shares, shares issued	5,000	5,000
Preferred shares, shares outstanding	5,000	5,000
Series S Preferred Stock [Member]
Class of Stock [Line Items]
Preferred shares, liquidation preference per share	$ 25	$ 25
Preferred shares, par value	$ 0.01	$ 0.01
Preferred shares, shares issued	5,000	5,000
Preferred shares, shares outstanding	5,000	5,000