Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	9 Months Ended			9 Months Ended
	Sep. 30, 2014	Sep. 30, 2014 Consolidation Variable Interest Entities [Member]	Dec. 31, 2013 Consolidation Variable Interest Entities [Member]	Sep. 30, 2014 Cash and Cash Equivalents [Member]	Sep. 30, 2014 Risk Level, Low [Member] Commercial Real Estate Portfolio Segment [Member]	Sep. 30, 2014 Risk Level, Medium [Member] Commercial Real Estate Portfolio Segment [Member]	Sep. 30, 2014 Risk Level, High [Member] Commercial Real Estate Portfolio Segment [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Other assets		$ 28,900,000	$ 49,800,000
Other liabilities		20,000,000	40,200,000
Income accrual, description	Income accrual is generally suspended for loans at the earlier of the date at which payments become 90 days past due or when, in the opinion of our Manager, recovery of income and principal becomes doubtful.
Cash and cash equivalents, Description	Cash and cash equivalents represent cash held in banks, cash on hand, and liquid investments with original maturities of three months or less.
Expected loss				$ 0
Probability of default or principal loss					15.00%	33.00%	67.00%