Notes Receivable - Principal Payments (Net of Reserves and Unamortized Discounts) and Interest Rates (Detail) (USD $)
In Millions, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2014
Receivables [Abstract]    
2015 $ 20  
2016 73  
2017 3  
2018 4  
2019 2  
Thereafter 143  
Senior, mezzanine, and other loans $ 245 $ 242
Weighted average interest rate at March 31, 2015 6.00%  
Range of stated interest rates at March 31, 2015, minimum 0.00%  
Range of stated interest rates at March 31, 2015. maximum 9.00%