Internal CRE Debt and Preferred Equity Ratings (Detail) - Commercial Mortgage - USD ($) $ in Thousands		Jun. 30, 2016	Dec. 31, 2015
Transaction to Real Estate Investments [Line Items]
Performing		$ 426,704	$ 520,263
Performing Closely Monitored		414,974	600,561
Performing Special Mention		302,153	234,598
Internal Rating Substandard		0	0
Doubtful		0	0
Loss		0	0
Total	[1]	1,143,831	1,355,422
Senior Mortgages
Transaction to Real Estate Investments [Line Items]
Performing		91,620	71,000
Performing Closely Monitored		243,605	283,148
Performing Special Mention		145,440	33,166
Internal Rating Substandard		0	0
Doubtful		0	0
Loss		0	0
Total		480,665	387,314
Senior Securitized Mortgages
Transaction to Real Estate Investments [Line Items]
Performing	[2]	58,426	106,770
Performing Closely Monitored	[2]	17,500	15,500
Performing Special Mention	[2]	111,396	140,802
Internal Rating Substandard	[2]	0	0
Doubtful	[2]	0	0
Loss	[2]	0	0
Total	[2],[3]	187,322	263,072
Preferred Equity Interests
Transaction to Real Estate Investments [Line Items]
Performing Closely Monitored			81,944
Performing Special Mention		9,000	40,500
Internal Rating Substandard		0	0
Doubtful		0	0
Loss		0	0
Total		9,000	122,444
Mezzanine Loans
Transaction to Real Estate Investments [Line Items]
Performing		276,658	342,493
Performing Closely Monitored		153,869	219,969
Performing Special Mention		36,317	20,130
Internal Rating Substandard		0	0
Doubtful		0	0
Loss		0	0
Total		$ 466,844	$ 582,592

[1] Excludes Loans held for sale, net.

[2] Assets of consolidated VIE.

[3] Assets of consolidated VIEs.