Derivative Financial Instruments - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Derivative [Line Items]
Notional amount	$ 381,286,000		$ 381,286,000		$ 496,025,000
Realized losses	4,398,000	$ 7,243,000	9,365,000	$ 14,780,000
Interest rate swaps
Derivative [Line Items]
Notional amount	$ 381,286,000		$ 381,286,000		$ 496,025,000
RAIT I and RAIT II | Interest rate swaps
Derivative [Line Items]
Weighted average strike rate	5.10%		5.10%
Notional amount	$ 83,641,000		$ 83,641,000
Derivative, inception date			Jul. 01, 2015
Derivative, maturity date			Dec. 31, 2015