Summary of Total Recourse and Non-Recourse Indebtedness (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Stated interest rate	4.00%
Principal amount of senior secured notes issued	$ 80,000	$ 86,000
Carrying Amount	2,613,317	2,086,401
Principal amount of investment in securities and security-related receivables and loans	959,310	989,781
Fair value of investments securitized	731,911	746,939
Unpaid Principal Balance	3,043,419	2,592,414
Weighted- Average Interest Rate	1.90%	1.40%
7.0% convertible senior notes
Debt Instrument [Line Items]
Stated interest rate	7.00%	7.00%
4.0% convertible senior notes
Debt Instrument [Line Items]
Stated interest rate	4.00%	4.00%
CMBS Facilities
Debt Instrument [Line Items]
Carrying Amount	1,573,559	1,662,537
Independence Realty Trust Inc
Debt Instrument [Line Items]
Carrying Amount	248,833	100,803
Unpaid Principal Balance	246,997	100,803
Weighted- Average Interest Rate	3.70%	3.80%
Minimum | Independence Realty Trust Inc
Debt Instrument [Line Items]
Contractual Maturity, month and year	2016-04	2019-01
Maximum | Independence Realty Trust Inc
Debt Instrument [Line Items]
Contractual Maturity, month and year	2024-08	2022-11
CMBS securitizations
Debt Instrument [Line Items]
Carrying Amount	$ 289,470	$ 131,843