Gross Real Estate and Loan Activity (Parenthetical) (Detail) (USD $)
9 Months Ended
Sep. 30, 2013
Sep. 30, 2012
Investments in and Advances to Affiliates, Schedule of Investments [Abstract]    
Accumulated depreciation and amortization associated with dispositions of real estate $ 8,200,000  
Gain on debt extinguishment $ 1,028,000 $ (32,522,000)