Loans Receivable, At Fair Value - Types of Loans in Loan Portfolio, as the Property Type and Geographic Distribution of the Properties Securing these Loans (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair Value	$ 66,063
CT Legacy Partners [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair Value	66,063
Percentage	100.00%
CT Legacy Partners [Member] | Senior Mortgages Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair Value	25,597
Percentage	39.00%
CT Legacy Partners [Member] | Mezzanine loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair Value	40,466
Percentage	61.00%
CT Legacy Partners [Member] | Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair Value	66,063
Percentage	100.00%
CT Legacy Partners [Member] | Office [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair Value	39,560
Percentage	60.00%
CT Legacy Partners [Member] | Hotel [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair Value	26,503
Percentage	40.00%
CT Legacy Partners [Member] | Northeast [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair Value	39,560
Percentage	60.00%
CT Legacy Partners [Member] | West [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair Value	14,604
Percentage	22.00%
CT Legacy Partners [Member] | Southeast [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair Value	$ 11,899
Percentage	18.00%