Fair Value Hierarchy for Financial Instruments Not Fair Valued but For Which Fair Value Is Required To Be Disclosed (Detail) - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2017		Dec. 31, 2016
Fair Value Measurement Inputs Disclosure [Line Items]
Total investment in mortgages and loans, net	$ 1,244,191		$ 1,280,285
Indebtedness	1,588,067		1,751,082
Junior subordinated notes	$ 12,524		$ 11,822
Significant Unobservable Inputs (Level 3)
Fair Value Measurement Inputs Disclosure [Line Items]
Valuation Technique	Discounted cash flows		Discounted cash flows
Junior subordinated notes	$ 12,524	[1]	$ 11,822	[2]
CMBS securitizations | Significant Unobservable Inputs (Level 3)
Fair Value Measurement Inputs Disclosure [Line Items]
Valuation Technique	Discounted cash flows		Discounted cash flows
7.0% convertible senior notes | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Measurement Inputs Disclosure [Line Items]
Valuation Technique	Trading price		Trading price
4.0% convertible senior notes | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Measurement Inputs Disclosure [Line Items]
Valuation Technique	Trading price		Trading price
7.625% senior notes due 2024 | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Measurement Inputs Disclosure [Line Items]
Valuation Technique	Trading price		Trading price
7.125% Senior Notes due 2019 | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Measurement Inputs Disclosure [Line Items]
Valuation Technique	Trading price		Trading price
Senior Secured Notes | Significant Unobservable Inputs (Level 3)
Fair Value Measurement Inputs Disclosure [Line Items]
Valuation Technique	Discounted cash flows		Discounted cash flows
Junior subordinated notes, at amortized cost | Significant Unobservable Inputs (Level 3)
Fair Value Measurement Inputs Disclosure [Line Items]
Valuation Technique	Discounted cash flows		Discounted cash flows
CDO notes payable, at amortized cost | Significant Unobservable Inputs (Level 3)
Fair Value Measurement Inputs Disclosure [Line Items]
Valuation Technique	Discounted cash flows		Discounted cash flows
Loans payable on real estate | Significant Unobservable Inputs (Level 3)
Fair Value Measurement Inputs Disclosure [Line Items]
Valuation Technique	Discounted cash flows		Discounted cash flows
Other indebtedness
Fair Value Measurement Inputs Disclosure [Line Items]
Indebtedness	$ 40,880	[3]	$ 23,915	[4]
Other indebtedness | Significant Unobservable Inputs (Level 3)
Fair Value Measurement Inputs Disclosure [Line Items]
Valuation Technique	Discounted cash flows		Discounted cash flows
Carrying Amount
Fair Value Measurement Inputs Disclosure [Line Items]
Total investment in mortgages and loans, net	$ 1,244,191		$ 1,280,285
Total investment in mortgages and loans, net fair value	1,244,191		1,280,285
Carrying Amount | CMBS securitizations
Fair Value Measurement Inputs Disclosure [Line Items]
Indebtedness	713,263		641,077
Carrying Amount | 7.0% convertible senior notes
Fair Value Measurement Inputs Disclosure [Line Items]
Indebtedness	832		831
Carrying Amount | 4.0% convertible senior notes
Fair Value Measurement Inputs Disclosure [Line Items]
Indebtedness	121,065		120,271
Carrying Amount | 7.625% senior notes due 2024
Fair Value Measurement Inputs Disclosure [Line Items]
Indebtedness	55,687		55,568
Carrying Amount | 7.125% Senior Notes due 2019
Fair Value Measurement Inputs Disclosure [Line Items]
Indebtedness	69,477		69,188
Carrying Amount | Senior Secured Notes
Fair Value Measurement Inputs Disclosure [Line Items]
Indebtedness	14,355		58,233
Carrying Amount | Junior subordinated notes, at amortized cost
Fair Value Measurement Inputs Disclosure [Line Items]
Indebtedness	25,100		25,100
Carrying Amount | CDO notes payable, at amortized cost
Fair Value Measurement Inputs Disclosure [Line Items]
Indebtedness	370,379		534,501
Carrying Amount | Loans payable on real estate
Fair Value Measurement Inputs Disclosure [Line Items]
Indebtedness	134,687		185,668
Carrying Amount | Other indebtedness
Fair Value Measurement Inputs Disclosure [Line Items]
Indebtedness	40,880		23,915
Estimated Fair Value
Fair Value Measurement Inputs Disclosure [Line Items]
Total investment in mortgages and loans, net fair value	1,192,723		1,256,342
Estimated Fair Value | Significant Unobservable Inputs (Level 3)
Fair Value Measurement Inputs Disclosure [Line Items]
Total investment in mortgages and loans, net fair value	1,192,723		1,256,342
Estimated Fair Value | CMBS securitizations | Significant Unobservable Inputs (Level 3)
Fair Value Measurement Inputs Disclosure [Line Items]
Notes payable	721,456		646,642
Estimated Fair Value | 7.0% convertible senior notes | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Measurement Inputs Disclosure [Line Items]
Convertible senior notes	590		890
Estimated Fair Value | 4.0% convertible senior notes | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Measurement Inputs Disclosure [Line Items]
Convertible senior notes	119,680		116,861
Estimated Fair Value | 7.625% senior notes due 2024 | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Measurement Inputs Disclosure [Line Items]
Indebtedness, Estimated Fair Value	55,018		53,231
Estimated Fair Value | 7.125% Senior Notes due 2019 | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Measurement Inputs Disclosure [Line Items]
Indebtedness, Estimated Fair Value	70,420		69,118
Estimated Fair Value | Senior Secured Notes | Significant Unobservable Inputs (Level 3)
Fair Value Measurement Inputs Disclosure [Line Items]
Indebtedness, Estimated Fair Value	15,783		62,620
Estimated Fair Value | Junior subordinated notes, at amortized cost | Significant Unobservable Inputs (Level 3)
Fair Value Measurement Inputs Disclosure [Line Items]
Junior subordinated notes	13,995		13,099
Estimated Fair Value | CDO notes payable, at amortized cost | Significant Unobservable Inputs (Level 3)
Fair Value Measurement Inputs Disclosure [Line Items]
Notes payable	329,004		477,032
Estimated Fair Value | Loans payable on real estate | Significant Unobservable Inputs (Level 3)
Fair Value Measurement Inputs Disclosure [Line Items]
Loans payable on real estate	137,583		188,525
Estimated Fair Value | Other indebtedness | Significant Unobservable Inputs (Level 3)
Fair Value Measurement Inputs Disclosure [Line Items]
Indebtedness, Estimated Fair Value	$ 40,830		$ 24,321

[1] During the six months ended June 30, 2017, there were no transfers between Level 1 and Level 2, and there were no transfers into and/or out of Level 3.

[2] During the year ended December 31, 2016, there were no transfers between Level 1 and Level 2, and there were no transfers into and/or out of Level 3.

[3] Represents two 40% interests issued to an unaffiliated third party in two ventures to which we contributed the junior notes and equity of two floating rate securitizations. Together these ventures are referred to as the RAIT Venture VIEs. The first of these ventures, the 2016 RAIT Venture VIE, was formed in 2016. The second, the 2017 RAIT Venture VIE, was formed in 2017. We retained a 60% interest in these ventures, and, as a result of our controlling financial interest, we consolidated the ventures. We received approximately $41,689 of proceeds as a result of issuing these 40% interests, which have an unpaid principal balance of $40,830. These 40% interests have no stated maturity date and do not provide for mandatory redemption or any required return or interest payment. These interests of the ventures allocate the distributions on such junior notes and equity when made between the parties to the ventures.

[4] Represents a 40% interest issued to an unaffiliated third party in a venture to which we contributed the junior notes and equity of a floating rate securitization. This venture is referred to as the 2016 RAIT Venture VIE. We retained a 60% interest in this venture, and, as a result of our controlling financial interest, we consolidated the venture. We received approximately $24,796 of proceeds as a result of issuing this 40% interest, which has an unpaid principal balance of $24,321. This 40% interest has no stated maturity date and does not provide for its mandatory redemption or any required return or interest payment. The venture interests allocate the distributions on such junior notes and equity when made between the parties to the venture.