Internal CRE Debt and Preferred Equity Ratings (Detail) (Commercial Mortgage, USD $) In Thousands, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Transaction to Real Estate Investments [Line Items]
Performing Loans	$ 1,530,642		$ 1,555,750
Internal Ratings Watch List
Defaulted-Recovery	28,456		31,473
Workout
Senior Mortgages
Transaction to Real Estate Investments [Line Items]
Performing Loans	359,237		644,039
Internal Ratings Watch List
Defaulted-Recovery	12,973	[1]	25,473	[1]
Workout
Senior Securitized Mortgages
Transaction to Real Estate Investments [Line Items]
Performing Loans	399,541	[2]
Internal Ratings Watch List		[2]
Workout		[2]
Subordinated Notes
Transaction to Real Estate Investments [Line Items]
Performing Loans			41,059
Internal Ratings Watch List
Workout
Mezzanine Loans
Transaction to Real Estate Investments [Line Items]
Performing Loans	522,095		620,883
Internal Ratings Watch List
Defaulted-Recovery	15,483		6,000
Workout
Preferred Equity Interests
Transaction to Real Estate Investments [Line Items]
Performing Loans	249,769		249,769
Internal Ratings Watch List
Workout

[1] Relates to one loan on nonaccrual status.

[2] Assets of consolidated VIE.