Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2012	Dec. 31, 2013
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Loss on deconsolidation	$ (8,615,000)	$ 200,283,000
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.
Consolidation Variable Interest Entities [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Other assets			49,800,000
Other liabilities			40,200,000
Loss on deconsolidation	8,600,000
Impairment of residual interests	100.00%
Cash and Cash Equivalents [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Expected loss	$ 0