Carrying Amount and Fair Value of Financial Instruments (Detail) - USD ($) $ in Thousands	Mar. 31, 2016		Dec. 31, 2015		Mar. 31, 2015	Dec. 31, 2014
Assets
Commercial mortgages, mezzanine loans, and preferred equity interests	$ 1,612,632		$ 1,623,583
Cash and cash equivalents	94,569		125,886		$ 92,657	$ 121,726
Restricted cash	200,166		213,012
Derivative assets	6		206
Liabilities
Indebtedness	3,267,230		3,328,082
Derivative liabilities	4,181		4,727
Junior subordinated notes	9,785		10,504
Warrants and investor SARs	29,100		26,200
Recourse Indebtedness
Liabilities
Indebtedness	509,466		484,764
Non-recourse indebtedness
Liabilities
Indebtedness	2,733,169		2,843,318
CMBS securitizations
Liabilities
Indebtedness	855,555		885,055
CMBS securitizations | Non-recourse indebtedness
Liabilities
Indebtedness	660,139	[1]	708,510	[2]
Carrying Amount
Assets
Commercial mortgages, mezzanine loans, and preferred equity interests	1,594,467		1,606,486
Cash and cash equivalents	94,569		125,886
Restricted cash	200,166		213,012
Derivative assets	6		206
Liabilities
Indebtedness			63,045
Carrying Amount | 7.0% convertible senior notes
Liabilities
Indebtedness	29,004		28,868
Carrying Amount | 4.0% convertible senior notes
Liabilities
Indebtedness	133,763		133,039
Carrying Amount | 7.625% senior notes due 2024
Liabilities
Indebtedness	58,014		57,952
Carrying Amount | 7.125% Senior Notes due 2019
Liabilities
Indebtedness	69,896		69,749
Carrying Amount | Senior Secured Notes
Liabilities
Indebtedness	61,847		63,045
Carrying Amount | Junior subordinated notes, at amortized cost
Liabilities
Indebtedness	24,887		24,884
Carrying Amount | CDO notes payable, at amortized cost
Liabilities
Indebtedness	905,230		937,569
Carrying Amount | Loans payable on real estate
Liabilities
Indebtedness	757,668		811,666
Carrying Amount | Derivative Liabilities
Liabilities
Derivative liabilities	4,181		4,727
Carrying Amount | Warrants and investor SARs
Liabilities
Warrants and investor SARs	29,100		26,200
Carrying Amount | Recourse Indebtedness | 7.0% convertible senior notes
Liabilities
Indebtedness	29,004		28,868
Carrying Amount | Recourse Indebtedness | 4.0% convertible senior notes
Liabilities
Indebtedness	133,763		133,039
Carrying Amount | Recourse Indebtedness | 7.625% senior notes due 2024
Liabilities
Indebtedness	58,014		57,952
Carrying Amount | Recourse Indebtedness | 7.125% Senior Notes due 2019
Liabilities
Indebtedness	69,896		69,749
Carrying Amount | Recourse Indebtedness | Senior Secured Notes
Liabilities
Indebtedness	61,847
Carrying Amount | Recourse Indebtedness | Junior subordinated notes, at amortized cost
Liabilities
Indebtedness	24,887		24,884
Carrying Amount | Recourse Indebtedness | CMBS Facilities
Liabilities
Indebtedness	122,270		96,723
Carrying Amount | Non-recourse indebtedness | Term Loans
Liabilities
Indebtedness	89,277		118,418
Carrying Amount | Non-recourse indebtedness | CDO notes payable, at amortized cost
Liabilities
Indebtedness	905,230		937,569
Carrying Amount | Non-recourse indebtedness | Loans payable on real estate
Liabilities
Indebtedness	757,668		811,666
Carrying Amount | Other indebtedness
Liabilities
Indebtedness	24,595
Carrying Amount | CMBS securitizations
Liabilities
Indebtedness	660,139		708,510
Carrying Amount | CMBS securitizations | Non-recourse indebtedness
Liabilities
Indebtedness	660,139		708,510
Estimated Fair Value
Assets
Commercial mortgages, mezzanine loans, other loans and	1,538,346		1,537,086
Cash and cash equivalents	94,569		125,886
Restricted cash	200,166		213,012
Derivative assets	6		206
Estimated Fair Value | 7.0% convertible senior notes
Liabilities
Convertible senior notes, Estimated Fair Value	25,541		27,795
Estimated Fair Value | 4.0% convertible senior notes
Liabilities
Convertible senior notes, Estimated Fair Value	113,754		104,184
Estimated Fair Value | 7.625% senior notes due 2024
Liabilities
Senior notes, Estimated Fair Value	47,712		46,560
Estimated Fair Value | 7.125% Senior Notes due 2019
Liabilities
Senior notes, Estimated Fair Value	65,807		62,471
Estimated Fair Value | Senior Secured Notes
Liabilities
Senior notes, Estimated Fair Value	66,521		66,725
Estimated Fair Value | Junior subordinated notes, at amortized cost
Liabilities
Junior subordinated notes	10,236		11,221
Estimated Fair Value | CDO notes payable, at amortized cost
Liabilities
Notes payable, Estimated Fair Value	741,480		801,289
Estimated Fair Value | Loans payable on real estate
Liabilities
Loans payable on real estate, Estimated Fair Value	787,681		834,816
Estimated Fair Value | Derivative Liabilities
Liabilities
Derivative liabilities	4,181		4,727
Estimated Fair Value | Warrants and investor SARs
Liabilities
Warrants and investor SARs	29,100		26,200
Estimated Fair Value | Recourse Indebtedness | 7.0% convertible senior notes
Liabilities
Convertible senior notes, Estimated Fair Value	25,541		27,795
Estimated Fair Value | Recourse Indebtedness | 4.0% convertible senior notes
Liabilities
Convertible senior notes, Estimated Fair Value	113,754		104,184
Estimated Fair Value | Recourse Indebtedness | 7.625% senior notes due 2024
Liabilities
Senior notes, Estimated Fair Value	47,712		46,560
Estimated Fair Value | Recourse Indebtedness | 7.125% Senior Notes due 2019
Liabilities
Senior notes, Estimated Fair Value	65,807		62,471
Estimated Fair Value | Recourse Indebtedness | Senior Secured Notes
Liabilities
Senior notes, Estimated Fair Value	66,521		66,725
Estimated Fair Value | Recourse Indebtedness | Junior subordinated notes, at amortized cost
Liabilities
Junior subordinated notes	10,236		11,221
Estimated Fair Value | Recourse Indebtedness | CMBS Facilities
Liabilities
Indebtedness	122,801		97,067
Estimated Fair Value | Non-recourse indebtedness | Term Loans
Liabilities
Indebtedness	90,216		120,000
Estimated Fair Value | Non-recourse indebtedness | CDO notes payable, at amortized cost
Liabilities
Notes payable, Estimated Fair Value	741,480		801,289
Estimated Fair Value | Non-recourse indebtedness | Loans payable on real estate
Liabilities
Loans payable on real estate, Estimated Fair Value	787,681		834,816
Estimated Fair Value | Other indebtedness
Liabilities
Indebtedness	24,321
Estimated Fair Value | CMBS securitizations
Liabilities
Notes payable, Estimated Fair Value	657,753		709,001
Estimated Fair Value | CMBS securitizations | Non-recourse indebtedness
Liabilities
Notes payable, Estimated Fair Value	657,753		709,001
Junior subordinated notes, at fair value | Carrying Amount | Recourse Indebtedness
Liabilities
Indebtedness	9,785		10,504
Junior subordinated notes, at fair value | Estimated Fair Value | Recourse Indebtedness
Liabilities
Junior subordinated notes	9,785		10,504
Secured credit facilities | Non-recourse indebtedness
Liabilities
Indebtedness	320,855	[3]	267,155	[4]
Secured credit facilities | Carrying Amount | Non-recourse indebtedness
Liabilities
Indebtedness	320,855		267,155
Secured credit facilities | Estimated Fair Value | Non-recourse indebtedness
Liabilities
Indebtedness			$ 271,500
Secured credit facilities, Estimated Fair Value	$ 324,977

[1] Excludes the RAIT FL2 junior notes, RAIT FL3 junior notes, RAIT FL4 junior notes and RAIT FL5 junior notes purchased by us which are eliminated in consolidation. Collateralized by $855,555 principal amount of commercial mortgages loans and participation interests. These obligations were issued by separate legal entities and consequently the assets of the special purpose entities that collateralize these obligations are not available to our creditors.

[2] Excludes the RAIT FL2 junior notes, RAIT FL3 junior notes, RAIT FL4 junior notes and RAIT FL5 junior notes purchased by us which are eliminated in consolidation. Collateralized by $885,055 principal amount of commercial mortgage loans and participation interests. These obligations were issued by separate legal entities and consequently the assets of the special purpose entities that collateralize these obligations are not available to our creditors.

[3] Floating rate at 245 basis points over 1-month LIBOR. As of March 31, 2016, 1-month LIBOR was 0.43725%. Interest only payments are due monthly.

[4] Floating rate at 245 basis points over 1-month LIBOR. As of December 31, 2015, 1-month LIBOR was 0.4295%. Interest only payments are due monthly.