Loans Receivable, At Fair Value - Overall Statistics for Loans Receivable Portfolio Held at Fair Value (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2013 Investment	Dec. 31, 2012 Investment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net book value	$ 1,362,891	$ 141,500
Weighted-average cash coupon	L+1.60 %
Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans	22	7
Net book value	1,362,891	141,500
Weighted-average cash coupon	L+4.28 %	L+2.51 %
Weighted-average all-in yield	L+4.91 %	L+4.53 %
CT Legacy Partners [Member] | Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans	9
Net book value	66,063
Weighted-average maximum maturity (years)	1 year 1 month 6 days
Weighted-average cash coupon	5.13%
Weighted-average all-in yield	5.13%
CT Legacy Partners [Member] | Floating Rate [Member] | Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans	6
Net book value	42,452
Weighted-average cash coupon	L+3.78 %
Weighted-average all-in yield	L+3.78 %
Weighted-average maximum maturity (years)	1 year 1 month 6 days
CT Legacy Partners [Member] | Fixed Rate [Member] | Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans	3
Net book value	$ 23,611
Weighted-average maximum maturity (years)	1 year 1 month 6 days
Weighted-average cash coupon	8.14%
Weighted-average all-in yield	8.14%